Mammography Quality Control: Page-by-Page Notes
KVP Range: (depends on composition/thickness)- Controls wavelength of x-ray beams and thus the penetrating power of the x-ray photons. Lower kVp is generally used for thinner, less dense breasts, while higher kVp is used for thicker, denser breasts.
Affects penetrating power, image contrast, and exposure latitude. Proper kVp selection is crucial for optimizing image quality and patient dose, ensuring the spectrum matches the breast tissue type and density.
mAs:- Fixed: ; mA is the tube current, which controls the number of x-ray photons produced, and s is the exposure time. Together, mAs dictates the total quantity of x-rays.
Range: . In automatic exposure control (AEC), the mAs is adjusted automatically based on breast density and thickness to achieve optimal image density.
Back-Up Timer:- With Grid: . This limit prevents excessive patient dose and protects the x-ray tube from overheating in case of AEC malfunction.
Without Grid: . Grids absorb a significant portion of the primary beam, requiring higher mAs, which is why the backup timer limit is higher when a grid is in use.
Mammography Tube:- Cathode: Negative, where electrons are generated and focused towards the anode.
Anode (target): Positive, where x-rays are produced as electrons strike the target material.
Target/Anode Materials:- Molybdenum (Mo), Rhodium (Rh), Tungsten (W).
System selects best material based on system type, breast thickness, and desired x-ray spectrum. Mo and Rh primarily produce characteristic x-rays at lower energies suitable for film-screen mammography and less dense breasts, while W produces a broader Bremsstrahlung spectrum suitable for digital mammography and denser breasts.
If system has 1 target, it is typically Tungsten (W) due to its versatility and high efficiency in digital mammography units.
Filters: - Purpose: Enhance image contrast by removing low-energy (soft) photons that contribute to patient dose without improving image quality, and removing high-energy (hard) photons that reduce contrast.
Materials often used: Molybdenum (Mo), Rhodium (Rh), Aluminum (Al), Silver (Ag) depending on vendor. These materials are chosen for their K-edge properties, which selectively filter out energies above their characteristic K-edge, shaping the x-ray spectrum to optimize contrast for breast tissue.
Filtration Types:
Inherent Filtration: Components of the x-ray tube itself act as filtration. These include the specialized Beryllium (Be) window (which allows medium x-ray photons to pass efficiently, unlike thicker glass windows), the oil in the tube, the mirror assembly, and the compression plate.
Added Filtration: Thin sheets of specific materials (Mo, Rh, Al, Ag) inserted into the beam path to further tailor the x-ray spectrum.
Roles of Filters:
Remove soft photons (dose reduction): Prevents unnecessary radiation exposure to the patient's skin and superficial tissues.
Remove higher-energy photons that reduce contrast: High-energy photons tend to penetrate breast tissue without differential attenuation, leading to poor contrast.
Notes:- Filtration and target/filter choices significantly influence image quality and patient dose by shaping the x-ray spectrum to match the tissue being imaged.
Page 2
Focal Spot Concepts
Actual Focal Spot: The area on the target anode physically bombarded by the electron beam from the cathode. Its size does not change once manufactured.
Effective Focal Spot: The apparent size of the focal spot as projected onto the image receptor. Its size depends on the anode angle (Line Focus Principle).
Steeper anode angle => smaller effective focal spot => better spatial resolution and detail in the image due to reduced geometric unsharpness.
Focal Spot Sizes:- Large: ~ (used for standard imaging and screen-film practice to handle higher mAs settings for thicker breasts, reducing exposure time and motion blur).
Small: ~ (primarily used in mammography for magnification views to enhance detail and for obtaining high-resolution images, where minimizing geometric unsharpness is critical, despite requiring lower mAs settings).
Anode Heel Effect:- A phenomenon resulting in non-uniform x-ray beam intensity across the image receptor, with higher intensity towards the cathode end and lower intensity towards the anode end. This is due to self-filtration by the anode target material.
Cathode end has higher intensity (and dose); anode end has lower intensity (dose). In mammography, the cathode end is typically positioned towards the chest wall, which is the thickest part of the breast, to ensure more uniform penetration and density across the image.
Half-Field Geometry:- This technique utilizes a lead mask to block a portion of the x-ray beam, preventing radiation from exiting the tube and extending beyond the image receptor.
The chest wall is the thickest portion of the breast to image, located closer to the x-ray tube. Lead blocking helps define the imaging field and reduces scatter, optimizing dose and image quality within the relevant area.
Tube Tilt:- A slight angulation of the x-ray tube relative to the image receptor, typically used to create half-field geometry and reduce the exposure of the lung field.
Typical tilt: ; range yielding effective angles around . This angulation helps ensure the x-ray beam primarily covers the breast tissue while minimizing exposure to the patient's chest and lungs.
Question (study prompt):
We use half-field geometry and a tube tilt of in mammography to help eliminate part of the x-ray beam so that the central ray hits the chest wall, ensuring adequate penetration of the densest part of the breast while minimizing unnecessary radiation.
Page 3
Grid usage and dose considerations
Grid:- Purpose: To absorb scattered radiation before it reaches the image receptor, thereby significantly improving image contrast and reducing fog. Mammography grids typically have a high ratio (e.g., 5:1 or higher) and use carbon fiber interspaces to allow primary x-rays to pass through.
Typically transmits 75%-85% of dose to the patient (depends on setup), meaning a substantial portion of the incident radiation is absorbed by the grid itself.
Grid increases patient dose: Because grids remove scatter (and some primary radiation), a higher mAs is required to maintain adequate image density, leading to an increase in patient radiation dose compared to non-grid imaging.
Grid Ratio:- Ratio of the height of the lead strips to the width of the interspace material. For example, a 5:1 grid means the lead strips are 5 times taller than the width of the interspace.
Higher grid ratio => better image contrast (more scatter is removed) but higher patient dose (requires even greater increase in mAs).
Grid Types:- Linear/Focused: Lead strips are aligned in one direction, absorbing scatter primarily in that direction. Often use Carbon as the interspace material. While effective, they may be prone to grid cut-off if not perfectly aligned.
Honeycomb/HTC (High Transmission Cellular): Uses a unique cross-hatch pattern with two directions of lead strips (e.g., perpendicular) to absorb scatter more effectively from multiple directions. Often utilize Air as the interspace material, which minimizes absorption of the primary beam. These grids offer excellent scatter clean-up with potentially less radiation penalty compared to some linear grids.
Compression:- The application of uniform pressure to flatten and immobilize the breast during mammography, typically ranging from (approximately ).
Benefits:
More uniform breast thickness => better visualization of chest wall and glandular tissue, as variations in tissue density are minimized.
Better exposure, reduced motion blur: Flatter breast allows for lower exposure factors and less chance of patient movement during exposure, improving image sharpness.
Reduced scatter radiation dose; improved contrast: By reducing breast thickness, less tissue is available to produce scatter, and the path length of the x-ray beam is shorter, leading to lower patient dose and enhanced contrast.
FDA MQSA Guidelines (compression):- Compression paddle shall not extend beyond chest wall edge of image receptor by more than 1% when average breast compressed. This ensures that the paddle does not obscure any vital breast tissue, especially near the chest wall.
Light field should extend to chest wall without exceeding edges by more than 2%. This provides precise demarcation of the imaging field, ensuring proper positioning and minimizing unnecessary radiation.
Avg illumination: not less than (15 ft-cd) at 100 cm or max SID; annual physicist check. This guideline applies to the viewer area to ensure adequate lighting for technicians and radiologists.
Radiation Barriers:- Shielding: Attenuation capability of at least (lead equivalent) at to limit occupational exposure to below . This provides protection for staff in the control booth.
Effective at : effectively stops the diagnostic range of x-rays typically used in mammography, ensuring safety.
Page 4
System Geometry
Source-To-Image Distance (SID):- Definition: The distance between the x-ray source (focal spot) and the image receptor.
Recommended: ; average ~. A shorter SID increases geometric unsharpness but can be compensated by a small focal spot; a longer SID reduces geometric unsharpness but requires higher mAs.
Object-To-Image Distance (OID):- The distance from the anatomical object (e.g., breast tissue plane) to the image receptor. This distance is deliberately increased during magnification views (mag views).
Effects:
Increase OID => increase magnification (mags). Magnification factor (M) is calculated as , where SOD = SID - OID.
Magnification increases unsharpness due to the inherent blur from the finite focal spot size (geometric blur), especially if a small focal spot is not used. However, it effectively spreads out the small details making them more visible.
Dose increases with larger SOD/OID for equivalent image receptor exposure because the x-ray beam spreads out over a larger area, reducing intensity at the detector, thus requiring more initial radiation from the tube for sufficient signal.
Magnification (Mag) considerations:- Grids: Often not used with magnification views because the increased OID creates an "air gap" between the breast and the detector, which naturally acts as a scatter clean-up mechanism, reducing the need for a physical grid. Grids reduce scatter but are not needed in typical magnification air-gap setups.
Common magnification factors: . These factors are chosen to provide optimal visualization of small details (e.g., microcalcifications, fine mass margins) without excessive dose or unsharpness.
Summary: magnification increases clinical detail by effectively enlarging subtle structures, but this comes at the cost of increased patient dose due to the inverse square law and increased geometric unsharpness if a proper small focal spot and other factors are not optimized.
Page 5
Mammography Spectrum
Characteristic Radiation:
Produced when high-energy electrons from the cathode interact with inner-shell electrons of the target anode material, causing an electron to be ejected. An outer-shell electron then fills the vacancy, emitting a photon with a specific, characteristic energy. This results in two distinct energy spikes (K-alpha and K-beta lines) corresponding to the anode material (e.g., Molybdenum's K-edge at ~).
Bremsstrahlung Radiation:
Also known as "braking radiation." Produced when incident electrons from the cathode are decelerated as they pass near the nucleus of target anode atoms. This deceleration causes the electron to lose energy, which is emitted as an x-ray photon. This interaction produces a continuous spectrum of x-ray energies (keV range) up to the peak kVp applied, depending on the degree of electron slowing.
Digital Acquisition, Display and Informatics (overview of digital mammo workflow)
Acquisition Types:
A. Full Field Digital Mammography / Direct Radiography (FFDM-DR-2D)
Digital detector directly converts x-rays to electrical signal without an intermediate light step (direct conversion) or via a scintillator producing light which is then converted (indirect conversion). This creates immediate digital images.
FDA approval: ~2000, revolutionizing mammography by moving away from film and enabling digital post-processing.
Benefits: Reduced radiation dose (due to higher detector efficiency), extensive post-processing capabilities (e.g., contrast, brightness, magnification, window/level adjustments), immediate image review, and easier archiving and sharing.
Limitations: Summation artifact (superimposed tissue can obscure lesions from different depths into a single 2D projection); superimposed tissue can hide malignancies, making detection challenging in dense breasts.
B. Digital Breast Tomosynthesis (DBT-3D)
FDA approval: 2011, providing a quasi-3D imaging solution to address the limitations of 2D mammography.
About 20%-30% of cancers not detected with 2D alone; DBT detects additional cancers (~41% of invasive cancers in some studies) by reducing the summation artifact.
How it works: The x-ray tube moves in an arc (e.g., , , or more), taking multiple low-dose images (projections) at different angles across a specific arc range. These projections are then reconstructed by a computer into a series of thin, high-resolution slices (typically 1 mm thick) perpendicular to the chest wall. Axial slices depend on breast thickness and arc angle.
Projections -> slices: Radiologist reads these individual slices, which helps differentiate overlapping tissues and visualize lesions more clearly in 3D. The total dose per view in DBT is typically comparable to or slightly higher than a single FFDM view, but the diagnostic benefit often outweighs the dose consideration.
MQSA references: per view dose values (e.g., per view for 2D, per view for DBT in some contexts) are typically average glandular dose (AGD) limits.
Tungsten (W) is a common material choice for digital mammography tubes due to its ability to produce a broad Bremsstrahlung spectrum with a higher average energy, which is well-suited for penetrating various breast densities in digital imaging, balancing imaging performance and dose considerations.
Target/Filter combinations significantly influence dose and image quality; Tungsten targets with appropriate filters (e.g., Rhodium or Aluminum) can improve contrast in dense breasts by optimizing the x-ray spectrum for better tissue differentiation.
DMIST (Digital Mammographic Imaging Screening Trial): A large, landmark trial published in 2005 involving ~150,000 women that conclusively compared digital vs film mammography. It found that digital mammography was significantly better for women with dense breasts, pre- and perimenopausal women, and women under 50.
Page 6
Image acquisition and processing details
DBT slices: Typically thick (varies by protocol, vendor, and breast thickness). This thin slice thickness allows for precise visualization of tissue without significant overlap, facilitating lesion detection and characterization.
Synthesized 2D image created from tomosynthesis slices: A 2D image is computationally generated from the 3D DBT datasets. This synthesized 2D image (s2D) aims to replicate a standard 2D mammogram, providing a familiar overview for radiologists and often reducing the need for an additional full-dose 2D acquisition.
Radiologists often read both the individual DBT slices and the synthesized 2D image for comprehensive evaluation.
Doses:- MQSA per view: The average glandular dose (AGD) for a standard 2D mammography view is typically limited to per view (historical/mode-specific context). This is a critical regulatory threshold to ensure patient safety.
DBT per view: The AGD for a single DBT view is around per view (context-dependent), indicating that while it involves multiple projections, the dose per single projection is lower, resulting in a total breast dose that is often comparable to or slightly higher than a single 2D view, depending on the system.
FDA: 2D images must be Read with 3D images; in many modern protocols, the 2D image is synthesized from 3D data, meaning a separate 2D exposure is not always required when DBT is performed.
Materials and dose considerations:- Tungsten target is common in digital mammography tubes because its broad x-ray spectrum is efficient for generating a wide range of energies, adaptable to various breast densities.
Target/filter combinations significantly influence image quality and dose; the judicious choice of target (e.g., Tungsten) and filter (e.g., Rhodium, Aluminum) improves visualization, especially in dense breast tissue, by optimizing the x-ray beam's energy profile.
DMIST findings supported the shift toward digital mammography due to its dose efficiency and image quality advantages, particularly for specific patient populations with dense breasts.
Page 7
Image Receptors (IR): how x-rays are captured
Indirect Conversion (First Gen):- X-ray photons pass through the breast and strike a scintillator layer (typically composed of Cesium Iodide, CsI, or Gadolinium Oxysulfide). The scintillator absorbs the x-ray energy and converts it into visible light photons.
This visible light is then detected by a photodiode array (often Amorphous Silicon, a-Si) coupled with thin-film transistors (TFTs). The photodiodes convert the light into an electrical signal (charge), which is then read out by the TFTs and digitized to form the image. This two-step process can introduce some light spread, affecting spatial resolution.
Direct Conversion (Second Gen):- X-ray photons are directly converted into an electrical signal without an intermediate light production step.
Materials: Amorphous Selenium (a-Se) is the most common material used. When x-rays strike the a-Se layer, they directly generate electron-hole pairs (charge). These charges are then collected by electrodes, amplified, and converted into a digital signal. This direct conversion process can offer higher spatial resolution and detective quantum efficiency (DQE) as there is no light spread.
Monitors: Acquisition Workstation (AWS) and Radiologist Interpretation Workstation (RWS)
AWS: Used by the technologist during the mammography examination. It displays patient identification data, allows for exam setup (e.g., view sequencing, technique factor selection), displays exposure status, and performs initial image quality checks. It interfaces with the Hospital Information System (HIS) and Radiology Information System (RIS) via Health Level Seven (HL7) standards for patient data exchange.
RWS: The primary workstation used by radiologists for soft-copy image review and interpretation. These workstations typically feature high-end, high-resolution monitors (3-megapixel (3MP) to 5MP+ monochrome monitors with specific luminance requirements) designed for diagnostic imaging. They offer advanced post-processing tools (e.g., multi-planar reconstructions, computer-aided detection (CAD), advanced magnification), are located in dark review rooms to optimize viewing conditions, and integrate priors (previous exams) for comparison, often using sophisticated viewing rules (hanging protocols).
Page 8
AWS vs RWS QC and workflows
AWS QC: Performs initial Accept/Reject decisions based on technical image quality (e.g., positioning, exposure, artifacts) prior to sending images to the RWS for final diagnosis. Technologies might include automated image critique tools that flag potential issues.
Adjustments available on AWS/RWS:- Window Width (contrast) and Window Level (brightness): Allows manipulation of the grayscale display to enhance specific tissue densities or lesion visibility.
Magnification and zoom: Digital tools to enlarge regions of interest for closer inspection.
View labeling and other metadata adjustments: Ensures accurate documentation of laterality, view type, and other patient/exam-specific information.
RWS QC: Requires stringent quality control, including high-resolution (2.5K–5MP; 3MP minimum per MQSA for primary interpretive monitors) monochrome monitors. Often includes additional monitors for displaying priors or supplementary modalities (e.g., ultrasound, MRI).
Digital reading room characteristics:- Darkened environment (about or less): This low ambient light level is critical for maximizing the perception of contrast and subtle details on the diagnostic monitors, reducing eye strain and improving diagnostic accuracy, adhering to professional guidelines like AAPM TG18.
Priors integrated for comparison: Immediate access to previous mammograms and other relevant studies is crucial for assessing changes over time and confirming the stability of findings.
Priors retrieval methods:- Manual transfer: Images are physically brought or manually transferred from external media or separate systems (less common now).
Pre-fetch via broker: Images are automatically retrieved from archives (PACS) to the RWS based on scheduled appointments, often hours before the patient's arrival, to ensure they are immediately available for the radiologist.
Auto-fetch when a prior image arrives into PACS: The system is configured to automatically pull relevant prior studies as soon as a new image from the same patient is acquired and stored in the Picture Archiving and Communication System (PACS).
Page 9
Medical Records and Health Informatics
HIS (Hospital Information System):- A comprehensive system that manages all aspects of patient care within a hospital, including patient demographics, laboratory results, physician orders, and administrative, financial, and clinical data. It uses HL7 (Health Level Seven) standards for data interchange, enabling seamless communication between different hospital departments and systems.
Stores patient data, lab results, prescriptions, and billing information, acting as the central repository for patient administrative and clinical information.
RIS (Radiology Information System):- A specialized information system designed specifically for managing the workflow of a radiology department. It uses HL7 for data communication (e.g., patient demographics, orders) and DICOM (Digital Imaging and Communications in Medicine) for image-related data. RIS tracks patient registration, scheduling of appointments, film room management, generation of accession numbers (unique identifiers for each exam), billing, and reporting services.
Plays a critical role in optimizing radiology workflow, from ordering an exam to reporting the findings.
EMR/Electronic Medical Records:- A digital version of a patient's chart, providing a comprehensive and integrated medical history across different healthcare providers and encounters. It includes diagnoses, medications, treatment plans, immunization dates, allergies, radiology images, and lab results, making patient information readily accessible and sharable among authorized users.
Page 10
PACS (Picture Archiving and Communication System)
Imaging storage and access across modalities; utilizes the DICOM standard for seamless interchange of images and related information between various imaging devices and viewing stations.
4 major components: Imaging modalities (e.g., mammography, MRI, CT, ultrasound), a secured network (for fast and reliable image transmission), workstations (for interpreting images by radiologists and reviewing by clinicians), and robust archiving solutions (for long-term storage and retrieval).
Workflow: The typical information flow for an imaging study often follows this path: HIS (patient registration, order entry) -> RIS (scheduling, exam accession) -> AWS (image acquisition, initial QC) -> PACS (image storage, distribution) -> RWS (image interpretation) -> reports (generated in RIS/HIS).
Data management: Includes strategies for deep archiving (long-term, cost-effective storage), disaster recovery (to ensure data integrity and availability in case of system failure), and increasingly, cloud storage (offering scalability and remote access with various security levels).
Data compression: Refers to reducing file size for efficient storage and transmission.
Lossless vs Lossy: Lossless compression allows the original data to be perfectly reconstructed without any loss of detail (1:1 mapping), which is critical for diagnostic images like FFDM (Full Field Digital Mammography); lossy compression permanently discards some data to achieve higher compression ratios but is not suitable for diagnostic images due to potential loss of subtle details.
Page 11
CAD (Computer-Aided Detection)
Role: CAD systems are sophisticated software tools designed to assist radiologists in detecting and classifying potential abnormalities, such as microcalcifications and masses, on mammographic images. They function as a "second reader" to highlight suspicious areas.
Goals: To improve mammography sensitivity by increasing the detection rate of subtle lesions, reducing false negatives, and potentially improving diagnostic accuracy.
FDA 2018 approvals and AI advances (ICADX) in CAD and AI-based workflows: The FDA has continued to approve new CAD systems and advanced AI-based workflows, such as those by ICADX, which incorporate machine learning to improve detection algorithms, reduce false positives, and streamline interpretation.
QA and evaluation framework:- Accreditation bodies (ACR - American College of Radiology) and FDA oversight: These organizations mandate stringent quality control and quality assurance programs for mammography facilities, including regular performance evaluation of CAD systems.
MQSA mandates QC and QA: The Mammography Quality Standards Act requires facilities to establish and maintain comprehensive quality control and quality assurance programs, which include ongoing training and certification for personnel, as well as regular equipment checks to ensure optimal performance and patient safety.
Page 12
MQSA inspections and QA documentation
Record-keeping and audits: Facilities must maintain meticulous QC books (documenting daily, weekly, monthly, quarterly, and annual tests), medical audit results (tracking patient outcomes), and equipment test records. These records are vital for demonstrating compliance with MQSA and ACR standards.
EQUIP program (Enhancing Quality Using the Inspection Program):- A program by the FDA designed to improve facility quality by linking deficiencies discovered during inspections to specific corrective actions.
Two levels of violations: Level 1 (highest risk to patient safety or image quality, requiring immediate or rapid corrective action and careful follow-up) and Level 2 (less severe, but still requiring attention to maintain quality standards).
Corrective actions and timelines (e.g., 15–30 days depending on the severity of the violation) are mandated to ensure deficiencies are addressed promptly.
Personnel requirements and records: MQSA mandates specific training, experience, and continuing education (CE) credits for all mammography personnel (radiologists, technologists, medical physicists). This includes specialized 3D training for DBT interpretation and acquisition. Comprehensive records of these qualifications must be maintained.
What inspectors look at: During inspections, FDA and state inspectors review lay letters (patient result letters), medical records (for completeness and follow-up), annual medical audits, QC/QA documentation, phantom image performance (to assess image quality), and observe clinical operations to ensure compliance with all MQSA regulations.
Page 13
Compliance timelines and required content of patient communications
Density reporting and density categories (A–D): Facilities are required to inform patients about their breast density. The BI-RADS (Breast Imaging-Reporting and Data System) categories for breast density are:
A: Almost entirely fatty
B: Scattered areas of fibroglandular density
C: Heterogeneously dense (may obscure small masses)
D: Extremely dense (reduces sensitivity of mammography)
Medical reporting timelines: Facilities must send a written report of the mammography findings to the referring physician within 30 days. For positive findings (BI-RADS 0, 4, 5), patient notification is often required sooner (e.g., within a few days).
Reports must include the facility name, interpreting physician's name, patient identifiers, date of examination, final BI-RADS assessment, and clear recommendations for follow-up (e.g., recall for additional imaging, biopsy, routine screening).
Breast density reporting and regulatory considerations: State and federal laws often mandate specific language in patient lay letters regarding breast density and its implications for cancer detection, advising high-density patients to discuss supplemental screening with their doctors.
Policies to review for EQUIP: Facilities must have well-documented policies for infection control and consumer complaint handling. Additionally, comprehensive medical audits and clear procedures for follow-up on positive mammography assessments (BI-RADS 4 and 5) are crucial for EQUIP compliance.
Page 14
Detailed EQUIP violations and management
Level 1 vs Level 2 violations and corrective actions (CA): Level 1 violations pose significant direct risk to patient health and require immediate corrective action and robust documentation of resolution. Level 2 violations are less severe but indicate a departure from quality standards and must also be addressed within specified timelines (e.g., 15-30 days).
Documentation requirements and CA processes: All corrective actions for EQUIP violations must be thoroughly documented, including the nature of the violation, the specific steps taken to correct it, the timeline for completion, and verification of effectiveness. This includes documenting any retraining or equipment adjustments.
Guidance on evaluating CA effectiveness and ongoing monitoring: Facilities must not only implement CAs but also have a system in place to ensure these actions have permanently resolved the issue and to monitor for recurrence. This involves ongoing QA activities and periodic review of processes.
Breast density reporting and related regulatory considerations: Continued emphasis on accurate patient notification of breast density and adherence to state-specific legislative requirements regarding supplemental screening recommendations for dense breasts.
Page 15
Common EQUIP questions and scenarios:- CA procedure for poor-quality clinical images with IP feedback loops: How a facility identifies the root cause of poor image quality (e.g., technologist error, equipment malfunction), implements specific corrective actions (e.g., retraining, repair), and establishes feedback mechanisms with interpreting physicians (IP) and technologists to prevent recurrence.
Image quality standards and compliance mechanisms: Understanding and adhering to MQSA and ACR image quality standards (e.g., phantom image criteria, artifact limits) and the systems in place to monitor and ensure compliance.
How frequently EQUIP evaluations should be performed and oversight responsibilities: EQUIP evaluations are recommended to be performed at least once between annual inspections, but more frequent internal assessments are encouraged. Radiologists and lead technologists share oversight responsibilities for QC/QA programs.
Breast density reporting and related regulatory categories: Ongoing emphasis on understanding and correctly applying BI-RADS density categories (A, B, C, D) in reporting and patient communications, complying with both federal and state laws.
Page 16
Phantom Image QC (QA phantom):- Purpose: To quantitatively assure the consistent image quality and performance of the x-ray imaging system over time, detecting any degradation before it impacts clinical images.
Frequency: Weekly. This regular check allows for prompt identification and correction of issues, preventing significant clinical impact.
Phantom specifics: Based on the ACR (American College of Radiology) Accreditation phantom configuration. This typically includes a 4.0 mm thick Lucite block containing various test objects: fibers (to assess spatial resolution), specks (to assess microcalcification detection), and masses (to assess low-contrast detection). These are embedded to mimic different breast tissue densities and pathologies.
Performance criteria: Imaging the phantom must demonstrate acceptable visibility of a minimum number of fibers, specks, and masses. For exposure, the Average Glandular Dose (AGD) should be within established limits (e.g., \pm 15\% of the baseline, depending on the system and specific test).
Compression Thickness QC:- Purpose: To ensure that the indicated breast thickness displayed on the mammography unit accurately matches the actual measured thickness of an object placed in the compression paddle, within specified tolerance.
Frequency: Monthly. Consistent accuracy is vital for accurate dose calculation and consistent image quality across different patient breasts.
The tolerance for thickness accuracy is typically \pm or \pm
Equipment: details on phantoms and thickness tolerances
Page 17
Visual Checklist (Monthly):- Purpose: To ensure that all visible indicators, locks, detents, and mechanical safety components of the mammography unit are functioning correctly and safely. This is a critical component of equipment maintenance.
Critical items to verify before clinical use: Emergency stop buttons, compression release mechanisms, and interlocks must be checked daily. Less critical items related to general functionality and cleanliness are checked monthly.
Critical vs non-critical checks and standard housekeeping: Critical checks include ensuring proper operation of compression paddles, breast supports (e.g., no damage, clean), and radiation shields. Non-critical checks involve verifying indicator lights, smooth movement of the gantry, and general cleanliness. Locks and detents (mechanisms that hold the gantry in position) must ensure the unit remains stable during imaging.
DBT assembly motion and calibration checks: For Digital Breast Tomosynthesis (DBT) units, specific checks are required to verify the smooth and accurate motion of the x-ray tube assembly along its arc, as well as the calibration of the projection angles. Any inaccuracies here can lead to artifacts or poor image reconstruction.
Page 18
Acquisition and Radiologist Workstation QC
Monitoring and cleaning procedures for AWS and RWS monitors: Regular cleaning of monitor screens is essential to remove dust and smudges that can obscure subtle image details. Monitors also require periodic calibration and quality control tests to ensure consistent luminance, contrast, and color reproduction over time.
SMPTE patterns (test patterns) and AAPM TG18 test patterns for display quality: Standardized test patterns (e.g., SMPTE pattern, American Association of Physicists in Medicine Task Group 18 (AAPM TG18) patterns) are used to evaluate monitor performance. These patterns test various aspects, including luminance, contrast response, spatial resolution, and the presence of artifacts or dead pixels.
Performance criteria for blemishes and artefacts on monitors: MQSA and ACR guidelines specify acceptable limits for the number and size of visible blemishes or artifacts (e.g., non-functioning pixels, dust) on diagnostic monitors. Excessive blemishes can interfere with image interpretation.
Daily to monthly maintenance routines and QC checks: Daily checks often include a simple visual inspection and a basic test pattern review. Monthly checks involve more detailed evaluations using specialized software and photometers to measure luminance and contrast, ensuring the monitor maintains its diagnostic quality.
RWS-specific QC similar to AWS QC, but often with higher resolution and more stringent requirements for luminance and calibration stability due to the critical nature of diagnostic image interpretation.
Page 19
Repeated Analysis (RA) to quantify image repeats
Purpose: To systematically determine the number and identify the underlying causes of repeated digital mammograms. The ultimate goal is to reduce unnecessary patient dose by minimizing these repeats while maintaining diagnostic image quality.
Frequency: As needed, typically when repeat rates exceed established thresholds (e.g., quarterly or semi-annually). A typical target for repeat rate is ~ to \ (or ~250 exams per 1000 exams) for screening mammography; rates for diagnostic mammography might be slightly higher due to more challenging cases.
Scope: Excludes specific types of additional images that are part of a complete examination, such as wire localization images, additional views specifically requested by the radiologist for diagnostic purposes, and QA-only images (e.g., phantom images). The focus is on unnecessary repeats of standard views.
Common causes include patient-related factors (e.g., motion, improper positioning resulting in body part exclusion or skin folds, artifacts from clothing or jewelry), technologist/equipment issues (e.g., poor technique selection, equipment malfunction, artifacts specific to the detector), and other miscellaneous factors.
Page 20
RA details and QA thresholds
Test parameters and documentation requirements for RA: Detailed documentation of each repeated image, including the original image parameters, the reason for the repeat, the technologist involved, and the corrective action taken. This data is then aggregated to identify trends and common root causes.
The goal is to minimize unnecessary repeats and patient dose while maintaining diagnostic quality: By systematically analyzing repeats, facilities can implement targeted training for technologists, perform equipment maintenance, or update protocols to prevent future occurrences, thereby improving efficiency and patient safety.
Regular QA workflow integrates RA findings into ongoing QC: The findings from repeat analysis should inform and be incorporated into the broader quality control and quality assurance program, leading to continuous improvement cycles.
Page 21
System performance tests (Mammographic QA Suite)
Test categories include: resolution tests (e.g., Modulation Transfer Function (MTF) to measure spatial resolution), Contrast-to-Noise Ratio (CNR) and Signal-to-Noise Ratio (SNR) evaluations (to assess low-contrast detectability), Automatic Exposure Control (AEC) performance (consistency across breast thicknesses), artifact evaluation (to detect unwanted image blemishes), KVP accuracy (ensuring proper beam energy), Half-Value Layer (HVL) measurements (beam quality and dose), average glandular dose assessment, ambient room illuminance (for reading rooms), and overall QA workflow assessments.
Sample test items and acceptable criteria (high-level): For example, AEC reproducibility should be within a given percentage, kVp accuracy within \pm \, and a minimum number of phantom objects must be visible. These criteria ensure that the system consistently delivers high-quality images with acceptable patient dose.
Page 22
Low-contrast performance: SNR and CNR measures
Signal-to-Noise Ratio (SNR): A measure of the strength of the signal (relevant image information) relative to the background noise. A higher SNR indicates a clearer image with less random fluctuation, reflecting the detector's ability to capture signal efficiently and minimizes noise.
Contrast-to-Noise Ratio (CNR): A measure of the ability to distinguish a lesion from its surrounding background tissue, considering the noise present in the image. A higher CNR means better visibility of subtle lesions, as the difference in signal between the lesion and its background is greater relative to the noise level.
AEC system performances: Tests ensure that the AEC system consistently produces optimal image receptor exposure regardless of varying breast thicknesses and densities. This is critical for maintaining consistent image quality and dose across all patients.
Artifacts evaluation: Involves thorough checks for artifacts (e.g., detector defects, dust, ghosting, grid lines) that may appear on images and potentially degrade image quality or mimic pathology. Clinically insignificant artifacts must not interfere with diagnostic interpretation.
KVP accuracy and reproducibility: Ensures that the actual kVp output of the x-ray tube is within \pm \ of the indicated setting and that the output is highly reproducible (e.g., Coefficient of Variation (VCV) \le ).
HVL (Half-Value Layer): The thickness of a specific material (typically aluminum) required to reduce the x-ray beam intensity by half. HVL is a measure of beam quality (penetrating power) and is critical for ensuring dose minimization while preserving sufficient image contrast. It confirms the appropriate filtration is in use.
Average glandular dose: A critical measurement of the mean radiation dose absorbed by the glandular tissue of the breast per examination. MQSA sets strict limits for AGD (e.g., for 2D, for DBT) to protect patients.
Room illuminance: Ambient light considerations for interpretation are vital. Diagnostic reading rooms must maintain low ambient light levels (e.g., <) to optimize the radiologist's perception of contrast and detail on the high-luminance monitors, reducing eye strain and improving diagnostic accuracy.
Page 23
Continued QA parameters
Summary of QA metrics for QA program evaluation: A comprehensive QA program integrates all these individual test results (SNR, CNR, kVp accuracy, HVL, dose, phantom scores, artifact rates) into an overall evaluation to ensure continuous compliance and high clinical standards.
Lossless vs Lossy compression in PACS storage (FFDM typically lossless, 1:1): For diagnostic images like FFDM, lossless compression is mandated to ensure that every pixel's original data is preserved, preventing any potential loss of subtle diagnostic information. Lossy compression, which discards some data, is unacceptable for primary diagnostic images.
Beam quality and energy considerations as part of QA: Regular checks of beam quality (e.g., HVL) and energy (kVp accuracy) ensure the x-ray spectrum is optimized for mammography, balancing image contrast needs with minimal patient radiation dose.
Page 24
Additional QA items mainly focused on: compression paddle alignment, chest wall edge alignment, and overall system geometry integrity. These factors are crucial for uniform compression, accurate positioning, and artifact-free imaging.
Compression paddle deflection tests; ensuring paddles sit parallel to breast tissue and chest wall: Ensuring the compression paddles are rigid and do not excessively deflect under pressure, which could lead to non-uniform compression of the breast. The paddle must sit parallel to the breast tissue and the chest wall connection line to ensure even pressure and prevent tissue slippage.
Annual or per-new-unit checks: These rigorous checks are typically performed annually by a qualified medical physicist or whenever a new mammography unit is installed, to verify its initial performance and ongoing integrity against manufacturer specifications and regulatory standards.
Page 25
AWS QC and RWS QC details continued
Emphasis on monitor calibration, viewing conditions, and ensuring QC pathways are robust: Consistent monitor calibration (including grayscale, color, and luminance), maintaining optimal darkroom viewing conditions, and establishing clear, documented QC pathways are essential. These pathways ensure that any deviations in monitor performance are detected and corrected promptly.
Mammographic Technique/Image Evaluation: technical factors
KVP controls wavelength and penetration; mAs controls exposure; back-up timers; AEC optimization: Lower kVp (typically ) produces longer wavelength, less penetrating x-rays, which are ideal for maximizing contrast in breast tissue due to the photoelectric effect. mAs determines the quantity of x-ray photons produced, directly impacting the overall image density. Back-up timers are safety mechanisms to terminate exposure if AEC fails. AEC automatically adjusts mAs for consistent image receptor exposure.
Page 26
Mammographic X-ray Spectrum details
KVP and filtration interplay; target materials influence spectrum: The selected kVp determines the maximum energy of the x-ray photons produced. Filters (e.g., Mo, Rh, Al) selectively absorb photons, especially those above their K-edge energy, to 'harden' or 'soften' the beam, thereby shaping the final x-ray spectrum to optimally image breast tissue. The target material (Mo, Rh, W) primarily dictates the characteristic x-ray energies.
Filtration types and K-edge concepts (K-edge as a threshold energy for filtering): K-edge filtration utilizes the abrupt change in attenuation properties of a material at its K-edge energy. For example, a Molybdenum filter will strongly absorb photons with energies just above Molybdenum's K-edge (around ), which are undesirable in mammography, allowing characteristic Molybdenum x-rays to pass, thereby producing a more monochromatic and optimal beam for breast imaging.
Target/Filter combinations (example combos):
Mo/Mo, Mo/Rh, Rh/Rh, etc.: These combinations are carefully chosen to optimize contrast and dose for different breast compositions and thicknesses. Mo/Mo is ideal for fatty to moderately dense breasts; Mo/Rh for denser breasts; Rh/Rh for very dense or thick breasts. Tungsten targets (e.g., W/Rh, W/Ag, W/Al) are common in digital mammography for their broad spectrum and versatility.
Mammographic X-ray Spectrum synonyms and measurement: The x-ray spectrum is often described by its peak energy (kVp) and its average energy (related to HVL, Half-Value Layer). controls the quality (heat and energy distribution) of the beam; filter materials precisely shape the spectrum by selectively removing unwanted energies.
EQUIP: Positioning specifics
CC (Cranio-Caudal): The x-ray beam enters superiorly (from the head side) and exits inferiorly (towards the feet). This view is optimally designed for visualizing medial breast tissue (near the sternum). It can often include ~30-40% of the pectoral muscle, indicating good posterior inclusion. A known limitation is that it often misses the extreme lateral tissue, particularly the axillary tail of Spence.
MLO positioning references and common errors: The Mediolateral Oblique (MLO) view is the most common and comprehensive view. Common errors include missing superior/posterior tissue (high-axilla cut-off), drooping breast (inframammary fold not open), and inadequate pectoral muscle visualization.
Page 27
Positioning evaluation criteria (examples):- PNL (Posterior Nipple Line) distance checks: The PNL, measured on a CC view, should be within ~ of the PNL on the MLO view to ensure consistent inclusion of posterior breast tissue in both projections. A discrepancy indicates inadequate inclusion in one of the views.
MLO coverage from axilla to IMF; retromamm space visibility; muscle evident near central breast: The MLO view must visualize all posterior breast tissue from the axilla (armpit) superiorly down to the Inframammary Fold (IMF) inferiorly. Clear visualization of the fat planes behind the glandular tissue (retromammary space), often extending to the chest wall, is crucial. The pectoral muscle should be clearly visible, extending down to or below the posterior nipple line (PNL) on the MLO view, indicating proper positioning and inclusion of deep tissue.
Common TOP FAILURES: These are frequent reasons for technologist repeats or suboptimal studies, often related to inadequate tissue inclusion or distorted anatomy:
Tissue poorly visualized (top-of-image issues): Often due to high axilla cut-off on MLO or insufficient superior tissue inclusion on CC, resulting in missed pathology.
Muscle visibility: Poor or absent pectoral muscle visualization on MLO, indicating the breast was not pulled forward enough or the angle was incorrect, leading to missed posterior tissue.
Poor chest wall contact: Gap between the breast and the chest wall receptor or compression paddle, leading to missed tissue and potential motion blur.
Specific landmarks and common faults like skin folds (often caused by incomplete tissue pull or improper compression, obscuring underlying tissue), improper compression (too little, causing blur/increased dose; too much, causing pain/thinning), and nipple positioning (nipple not in profile, making it difficult to differentiate from a mass or determine its location accurately).
Page 28
Additional positioning considerations and error mechanisms
Compression, focal spot adjustment, OID management, and beam path considerations to optimize tissue visualization: Adequate compression (taut but tolerable) reduces breast thickness and scatter. Small focal spots are used for magnification to improve detail. OID can lead to magnification blur. The beam path must optimally cover the area of interest.
Noise/Artifact concerns, including ghosting (a faint image of a previous exposure remaining on the detector), grid lines (improper grid alignment or selection), and patient motion blur. These can obscure subtle pathology and lead to diagnostic errors.
Labeling requirements per MQSA: All mammograms must be clearly labeled with specific information for legal and diagnostic purposes: patient name, unique Medical Record Number (MRN), date of examination, view type (e.g., CC, MLO), facility name and location, technologist ID, cassette ID (if applicable), and unit ID (if multiple units are present in the facility).
Page 29
Miscellaneous Quality Control concepts
Characteristic radiation (2 spikes) vs Bremsstrahlung (continuous spectrum): Characteristic radiation produces discrete energy peaks specific to the anode material (e.g., Mo K-alpha and K-beta lines at ~ and ~). Bremsstrahlung radiation produces a continuous range of energies determined by the kVp and electron deceleration.
Filter materials and k-edge concepts: Filter materials (Mo, Rh, Al, Ag) are chosen for their K-edge absorption properties which allow them to selectively remove unwanted low- and high-energy photons, thus shaping the x-ray spectrum to maximize contrast in breast tissue while minimizing dose.
Target materials:
Molybdenum: Ideal for fatty and moderately dense breasts. Characterized by its K-emission spectrum, producing peaks around ~ and ~\ which are well-suited for high contrast.
Rhodium: Offers slightly higher energy characteristic peaks (around ~ and ~) than Molybdenum, providing better penetration for dense breasts while still maintaining good contrast.
Tungsten: Used predominately in modern digital mammography. Produces a broad Bremsstrahlung spectrum with a higher average energy, making it versatile for all breast densities, especially denser ones, when combined with appropriate filters (e.g., Rh, Ag, Al).
Bremsstrahlung dose shaping and energy distribution by filtration; K-edge filtering: Filters modify the Bremsstrahlung spectrum by selectively absorbing photons. K-edge filters optimize the spectrum for mammography by allowing desirable characteristic x-rays to pass while removing lower and higher energies efficiently, thereby optimizing dose and contrast.
Digital mammography metrics: Detective Quantum Efficiency (DQE) and Modulation Transfer Function (MTF) are key performance indicators for digital detectors.
DQE: Measures the detector's efficiency in converting x-ray input into useful image signal, reflecting its dose efficiency and overall imaging performance. Higher DQE means better image quality at lower doses.
MTF: Measures the spatial resolution performance of the system (its ability to display fine details or distinguish between closely spaced objects).
Matrix considerations: Digital images are composed of pixels, and each pixel's grayscale value is stored in a specific bit depth. 10-bit (1024 gray levels) vs 8-bit depth (256 gray levels): 10-bit depth offers a much wider range of distinguishable shades of gray, crucial for subtle contrast differences in breast imaging, minimizing contouring or banding artifacts often seen with lower bit depths.
Page 30
DQE and MTF concepts in detector performance
Window centering = window leveling (brightness control): The window level (or center) determines the overall brightness of the image by setting the center of the grayscale range. This adjustment helps highlight structures within a specific range of pixel values.
DQE: Detective Quantum Efficiency refers to how efficiently an imaging system converts incident x-ray energy into a diagnostically useful signal, relative to an ideal detector. A higher DQE indicates better image quality at lower patient doses.
MTF: Modulation Transfer Function is a quantitative measure of how well an imaging system transfers (or reproduces) object detail (spatial frequency) from the actual object to the image. A higher MTF value at higher spatial frequencies indicates better spatial resolution and ability to visualize fine details.
Matrix bit-depth considerations for image storage and display: A greater bit depth (e.g., 12-bit or 14-bit often refers to acquisition, while 10-bit refers to display) allows for a larger number of grayscale values per pixel, providing more subtle distinctions in tissue density and contrast, which is crucial for distinguishing between healthy and pathological breast tissue.
Flat-field uniformity: This QC test ensures that the detector's response is uniform across its entire active area when exposed to a uniform x-ray beam. Any non-uniformity (e.g., from detector elements that are less sensitive or non-functional) would appear as an artifact and could obscure pathology if not properly corrected or compensated for.
Page 31
Anatomy and Physiology: Localization Terminology
Clock positions, quadrants, and triangulation for lesion localization in 2D mammography (CC, MLO, ML): Lesions are localized using a combination of clock positions (e.g., 12 o'clock, 3 o'clock), breast quadrants (upper outer, upper inner, lower outer, lower inner), and triangulation (using two orthogonal views, typically CC and MLO, or ML) to determine their exact location (depth and mediolateral/superoinferior position).
External Anatomy overview: Includes the breast skin, margins, nipple, and areola.
Skin layers: Epidermis (outermost protective layer), dermis (connective tissue with blood vessels, nerves, glands), hypodermis (subcutaneous fat layer, where superficial breast tissue resides).
Breast margin attachments: Cooper’s ligaments (fibrous connective tissue bands that extend from the deep fascia to the skin, providing support and shape to the breast); superficial and deep fasciae (layers of connective tissue that encase the breast and its underlying structures); chest wall attachment (pectoralis major muscle).
Nipple/Areola anatomy and Montgomery glands: The nipple is the central projection from which lactiferous ducts exit. The areola is the pigmented skin surrounding the nipple. Montgomery glands are sebaceous glands within the areola.
Montgomery Glands/Morgagni tubercles: Specialized sebaceous glands in the areola that produce a lubricating and protective substance during lactation. Their openings appear as small bumps on the areola (Morgagni tubercles).
Axillary Tail location and density distribution (UOQ central upper outer quadrant): The Axillary Tail (or Tail of Spence) is an extension of breast tissue that projects into the axilla. This region, commonly in the upper outer quadrant (UOQ), is a frequent site for breast cancer development due to its high concentration of glandular tissue.
Page 32
Internal Anatomy: Fasciae, glands, and tissue planes
Fascial layers: The breast is enclosed between the superficial fascia (dividing subcutaneous fat into pre-mammary and retro-mammary spaces) and the deep fascia (pectoral fascia) that covers the pectoralis major muscle. These layers help compartmentalize the breast and its movements.
Retroglandular space and retropectoral fat space: The retroglandular space, located between the glandular tissue of the breast and the deep pectoral fascia, typically contains fat. The retropectoral space is behind the pectoral muscle, also usually containing fat. These fat-filled spaces allow for breast mobility and provide clear planes for imaging.
Cooper’s ligaments and the connective tissue framework that maintains breast shape: These strong, fibrous suspensory ligaments extend from the deep fascia through the glandular tissue to the skin, acting as the primary support structure for the breast. Their integrity is crucial for maintaining breast contour and preventing ptosis (sagging).
Page 33
Lobes, Lobules, and ducts
Glandular tissue and stroma; lobar structure and milk production: The breast is composed of 15-20 lobes, each containing numerous lobules. These lobules contain acini (milk-producing glands). The glandular tissue is supported by stroma, which includes fibrous connective tissue and fat. Milk production occurs in the acini within the lobules.
Lactiferous ducts and sinuses; TD LU (Terminal Ductal Lobular Unit): Milk from the acini travels through tiny ductules that merge into larger lactiferous ducts, which then widen into lactiferous sinuses (reservoirs) before opening at the nipple. The TDLU, consisting of a terminal duct and its associated lobule, is considered the functional unit of the breast and is where most breast cancers originate.
Acini/Alveoli and cytology layers surrounding TDLU:- Luminal Epithelium: The innermost layer of cells lining the ducts and acini, responsible for milk secretion.
Myoepithelium: A contractile layer of cells surrounding the luminal epithelium, which helps propel milk through the ducts.
Basement membrane: An extracellular matrix layer that supports both the luminal and myoepithelial cells, forming a barrier to prevent abnormal cell growth from invading surrounding tissue.
Pathology origins: The vast majority of breast cancers (over 90%) commonly originate from the epithelial cells lining the lactiferous ducts and lobules, particularly within the TDLU.
Common cancers: Ductal Carcinoma In Situ (DCIS), an early, non-invasive form of cancer confined to the ducts; Invasive Ductal Carcinoma (IDC), the most common type of invasive breast cancer; and Invasive Lobular Carcinoma (ILC), which originates in the lobules and often grows in a more diffuse pattern.
Page 34
Milk production anatomy recap: Alveoli (acini) are the primary sites of milk production within the lobules. Milk travels through tiny ductules, collecting into lactiferous ducts, which then expand into lactiferous sinuses located behind the nipple, before exiting through the nipple pores.
Cytology layers in ducts: The ducts are lined by two main cell layers: the luminal epithelium (secretory cells) and the myoepithelium (contractile cells), both supported by an intact basement membrane. The integrity of these layers is crucial in distinguishing in-situ from invasive disease.
Cancer development in ducts/lobules; discussion of common benign vs malignant pathways: Breast cancer typically begins with abnormal cell growth within the ductal or lobular epithelium. Benign changes involve proliferation but maintain normal architectural features, while malignant pathways involve uncontrolled growth and often, eventually, invasion through the basement membrane.
Summary of breast cancer subtypes and progression: DCIS (Ductal Carcinoma In Situ) represents early, non-invasive malignant cells confined to ducts. IDC (Invasive Ductal Carcinoma) means cancerous cells have breached the basement membrane and invaded surrounding tissue. ILC (Invasive Lobular Carcinoma) originates in the lobules and is characterized by a diffuse growth pattern. These classifications determine treatment strategies and prognosis, distinguishing between in-situ (non-invasive) and invasive forms.
Page 35
Breast cancer staging and grading overview
Stages: Breast cancer staging describes the extent of the cancer based on tumor size (T), involvement of nearby lymph nodes (N), and presence of distant metastasis (M). Stages range from 0 (non-invasive, e.g., DCIS) to IV (metastatic disease).
Grades: Reflect how abnormal the cancer cells look under a microscope and how quickly they are growing and dividing compared to normal healthy cells. Grades range from 1 (low grade, cells look more like normal cells, slow-growing) to 3 (high grade, cells look very abnormal, fast-growing).
Vascular and lymphatic considerations in staging and spread: The rich vascular and lymphatic networks of the breast are primary pathways for cancer cells to spread (metastasize) to regional lymph nodes (e.g., axillary) and distant organs. Assessment of lymph node involvement is a key factor in staging and prognosis.
Milk line concept and embryology of accessory breast tissue: The "milk line" (or mammary ridge) is an embryological structure extending from the axilla to the groin. Accessory breast tissue (polymastia) or nipples (polythelia) can develop anywhere along this line, though they are most common in the axilla.
Cooper’s ligament role in breast shape and ptosis prevention: These strong, fibrous suspensory ligaments extend from the deep fascia through the glandular tissue to the skin, acting as the primary support structure for the breast. Their integrity is crucial for maintaining breast contour and preventing sagging (ptosis).
Vascular and lymphatic anatomy overview including axillary, internal mammary, and parasternal nodes: The primary venous drainage is via the axillary vein. Lymphatic drainage is predominantly to the axillary lymph nodes (75-90%), with secondary pathways to internal mammary nodes (along the sternum) and sometimes parasternal nodes, all crucial for understanding cancer spread.
Page 36
Lymphatic drainage and nodes
Axillary drainage is predominant (75-90% of lymph from the breast drains to the axillary nodes); parasternal ~20% (drains to internal mammary nodes); intercostal/posterior intercostal ~5% (drains to posterior mediastinal nodes). Understanding these pathways is critical for surgical planning and assessing metastasis.
Key node groups: Axillary nodes (main drainage route, critical for staging), Parasternal nodes (internal mammary nodes along the sternum, involved in medial breast cancer spread), Interpectoral (Rotter’s nodes, located between the pectoralis major and minor muscles).
Levels of axillary nodes: These are surgically defined relative to the pectoralis minor muscle, guiding surgical dissection and staging:
Level 1: Lateral to the pectoralis minor muscle.
Level 2: Deep to the pectoralis minor muscle.
Level 3: Medial to the pectoralis minor muscle and extending up to the subclavian vein.
Page 37
Sentinel Lymph Node Procedures
Rationale: To identify the first draining lymph node(s) from a breast tumor. These are the nodes where cancer cells are most likely to spread first. Assessing these "sentinel" nodes helps determine if the cancer has spread beyond the breast without requiring a full axillary lymph node dissection (ALND), which has more complications.
Technique: A radioactive isotope (e.g., Technetium- labeled sulfur colloid) and/or a blue dye (e.g., isosulfan blue) is injected into the breast near the lesion site 2-6 hours prior to surgery. The surgeon then uses a gamma detector (to locate the radioactive tracer) and visually inspects for blue-stained nodes during surgery to identify and remove the sentinel node(s).
Typical management: Usually 1-5 sentinel nodes are removed. If these sentinel nodes are negative for cancer, no further axillary lymph node surgery is typically performed. If they are positive, further axillary treatment (e.g., ALND or radiation) may be considered, depending on the number of positive nodes and other patient factors.
Implication: This procedure significantly reduces the need for extensive axillary dissection, thereby decreasing the risk of complications such as lymphedema, pain, and numbness in the arm.
Page 38
Pathology: BI-RADS terminology and imaging-pathology correlation
BI-RADS categories and standardized reporting: The Breast Imaging-Reporting and Data System (BI-RADS) is a standardized system for reporting mammography, ultrasound, and MRI findings. Categories range from 0 (Incomplete) to 6 (Known Biopsy-Proven Malignancy), providing a common language for radiologists and clinicians.
Additional lesions: Beyond masses, other findings include:
Asymmetry: An area of fibroglandular tissue that is visible on one view or is different in size/shape compared to the corresponding area in the opposite breast. Global asymmetry is a broader assessment, while focal asymmetry is more localized and may be suspicious.
Architectural distortion: Disruption of the normal breast architecture without a definite mass. This can be a very subtle but important sign of malignancy, often appearing as spicules radiating from a central point or an area of straightened or retracted Cooper's ligaments.
Calcifications: Small calcium deposits often found in the breast; their morphology, distribution, and changes over time are critical for determining their benign or suspicious nature.
Masses: Three-dimensional lesions with different characteristics (benign vs malignant features).
Benign vs malignant mass characteristics: Malignant masses often have irregular shapes (e.g., spiculated, angular, obscured), ill-defined or microlobulated margins, and appear high density. Benign masses typically have round, oval, or macrolobulated shapes, well-circumscribed margins, and often have a lower or similar density to surrounding tissue.
Calcifications: Very common, present in up to 85% of mammograms. Their morphology (shape), distribution (pattern), and etiology (cause) are key to assessment. They can be benign, indeterminate, or suspicious for malignancy.
Benign calcifications patterns: Typically round, punctate (<1 mm), skin calcifications (often lucent centers), vascular calcifications (tram-track appearance); suspicious patterns include amorphous/indistinct (too small or hazy to give a specific shape), coarse heterogeneous (irregular, varying size, larger than typical benign calcifications), fine pleomorphic (small, irregular, varying in size and shape), and fine linear/linear branching (thin, irregular lines, sometimes branching, suggestive of ductal involvement).
Page 39
Calcifications: densities, distribution, morphology; changes over time
Benign vs malignant calcifications: Differentiated by their specific features. Suspicious calcifications tend to be new, clustered, linear, pleomorphic, or associated with a mass. Benign calcifications are often scattered, larger, round, or have characteristic lucent centers.
Calcification descriptors: Density (e.g., milky, dense), distribution (e.g., scattered, grouped, linear), shape (e.g., round, linear, amorphous), and age-related changes (e.g., stable benign calcifications over time vs. new/changing suspicious ones) are all factors considered in BI-RADS assessment.
Page 40
Calcification morphology and distribution continued
Distribution patterns: Crucial for determining significance.
Single: An isolated calcification, less concerning unless rapidly changing.
Clustered: Usually refers to 5 or more calcifications within a small volume (e.g., ). This pattern significantly raises suspicion for malignancy, especially if the morphology is also suspicious.
Diffuse: Widely scattered throughout the breast, typically benign.
Regional: Spread over a larger segment of breast tissue, not conforming to ductal distribution; can be benign or suspicious depending on morphology.
Grouped: Similar to clustered but often covering a larger area, still raising suspicion.
Linear: Arranged in a line, often following a duct, which can be suspicious.
Segmental: Distributed in a ductal arrangement, suggesting involvement of a duct and its branches; highly suspicious for malignancy (especially DCIS).
Suspicious calcifications: Often poorly defined, grouped (clustered), variable density and shape, microcalcifications (typically <), and may be restricted to one breast or segment. These features warrant further investigation (e.g., biopsy).
Benign calcifications: Typically well-defined, scattered throughout both breasts, similar density, usually larger, and specific shapes like ring-like (fat necrosis) or round (TDLUs).
Benign calcifications that are common:
Round/punctate: Small (<), often seen in the acini of the Terminal Ductal Lobular Units (TDLUs).
Dystrophic: Larger, irregular, often with a lucent center, associated with scar tissue or fat necrosis.
Skin calcifications: Located superficially in the dermis, often with a lucent center, best confirmed with a tangential view.
Vascular calcifications: Parallel linear calcifications outlining blood vessels (tram-track appearance), indicating atherosclerosis, typically benign.
Page 41
Suspicious Morphology for calcifications
Amorphous/Indistinct; Coarse Heterogeneous; Fine Pleomorphic; Fine Linear/Linear Branching:
Amorphous/Indistinct: Calcifications that are too small or hazy in outline to be given a more specific shape. They are often intermediate concern; if clustered, they are often biopsied.
Coarse Heterogeneous: Irregular calcifications, generally larger than but less than , that are associated with a high probability of malignancy, especially if clustered or segmental.
Fine Pleomorphic: Small, irregular, and variable in shape and size (often <). These are highly suspicious for malignancy, particularly DCIS, especially when clustered or linear/segmental.
Fine Linear/Linear Branching: Thin, linear calcifications that are irregular and discontinuous, sometimes branching. This morphology is highly suspicious and often indicates malignancy (DCIS) filling the ductal lumen.
Benign pathologies with mammographic features:- Cyst (simple, complex): Simple cysts are typically round/oval, with smooth margins and often demonstrate posterior acoustic enhancement on ultrasound. Complex cysts may have internal septations or debris and require further evaluation.
Galactocele (milk-filled cyst): A benign cyst that develops from an obstructed milk duct, typically presenting after lactation ceases.
Fibroadenoma: A common benign solid tumor, typically round or oval with smooth or macrolobulated margins, often mobile and firm to palpation. May contain characteristic "popcorn" calcifications.
Lipoma: A benign fatty tumor, appearing as a radiolucent (fat-dense) mass with a thin capsule.
Hamartoma (fibro-adeno-lipoma): A benign overgrowth of normal breast tissues (fibrous, glandular, and fatty components), often presenting as a well-circumscribed mass with a characteristic mixed-density appearance.
Ductal ectasia: Dilation of the major lactiferous ducts, typically benign, often associated with periductal inflammation or discharge.
Hematoma: A collection of blood resulting from trauma or biopsy, which can appear as a mass, architectural distortion, or skin thickening.
Abscess/inflammation: A localized collection of pus or generalized inflammatory changes, often with skin thickening and increased density. May be indistinguishable from inflammatory carcinoma on imaging alone.
Fat necrosis: Damage to fat cells, often caused by trauma or surgery, resulting in a variety of benign appearances including oil cysts (lucent with thin capsule), calcifications (dystrophic, ring-like), or architectural distortion.
Lymph nodes: Intramammary lymph nodes are typically reniform (kidney-shaped) with a fatty hilum, usually benign. Axillary lymph nodes are larger but have similar features.
Gynecomastia: Benign enlargement of male breast tissue, often centrally located beneath the nipple, presenting as a flame-shaped or triangular density.
Radical scar (complex sclerosing lesion): A benign lesion that mimics cancer due to its spiculated appearance. It is a central fibrous core with radiating ducts and lobules and often requires biopsy.
Papilloma: A benign tumor that grows within a milk duct, often associated with nipple discharge.
Edema: Swelling of the breast tissue, leading to increased density and skin thickening, often secondary to inflammation, heart failure, or lymphatic obstruction.
Seroma: A collection of serous fluid, often developing post-surgically in the surgical cavity.
High-risk conditions: proliferative lesions with atypia, such as Atypical Ductal Hyperplasia (ADH) and Atypical Lobular Hyperplasia (ALH), are not cancer but indicate an increased risk of developing breast cancer and often require surgical excision.
Page 42
Benign lesions continued: cysts, galactocele, fibroadenoma, lipoma, hamartoma, ductal ectasia, hematoma, abscess, fat necrosis, lymph nodes, gynecomastia. This page reiterates some additional benign breast conditions with their general characteristics and imaging features: cysts (simple, complex), galactocele (milk-filled cyst), fibroadenoma (common, benign solid tumor), lipoma (benign fatty tumor), hamartoma (benign tumor-like malformation of normal breast tissue elements), ductal ectasia (dilation of major breast ducts), hematoma (collection of blood), abscess (localized pus), fat necrosis (changes in fat tissue), lymph nodes (normal lymph nodes), gynecomastia (benign enlargement of male breast tissue).
Malignant lesions and distinguishing features discussed in prior pages: Malignant lesions are typically characterized by irregular shapes, spiculated or ill-defined margins, high density, and often associated with suspicious calcifications or architectural distortion.
Page 43
High-risk and less common pathologies described:
Papilloma: A benign, wart-like growth within a milk duct, often causing nipple discharge. Atypical papillomas or multiple papillomas can be associated with increased cancer risk.
Radical scar (complex sclerosing lesion): A benign lesion that clinically and mammographically mimics cancer due to its spiculated appearance. It has a central fibrous core with radiating ducts and lobules. Excision is often recommended to exclude malignancy.
Lobular Carcinoma in Situ (LCIS): A non-invasive proliferation of abnormal cells within the lobules. It is considered a marker of increased risk for invasive cancer in either breast, rather than a true cancer itself, but can be managed with surveillance or risk reduction strategies.
Atypical Ductal Hyperplasia (ADH): A proliferative lesion where abnormal cells partly fill a duct, but the changes are not extensive enough to be classified as DCIS. ADH is associated with an increased risk of developing invasive breast cancer.
Atypical Lobular Hyperplasia (ALH): A proliferation of abnormal cells within the lobules that partially fill the acini. Similar to LCIS, it's a marker of increased risk for future cancer.
Flat Epithelial Atypia (FEA): A minor proliferative lesion characterized by a uniform layer of slightly atypical cells lining the ducts. It is considered a low-grade precursor lesion with a modest increase in cancer risk.
Phyllodes tumor: A rare fibroepithelial tumor characterized by a leaf-like growth pattern. These can be benign, borderline, or malignant. They tend to grow rapidly and can recur after removal, even if benign, and aggressive surgical removal with clear margins is often required.
Page 44
Malignant Pathology and Mammographic Appearance (summary):
DCIS: Ductal Carcinoma In Situ; represents non-invasive cancer where malignant cells are confined within the breast ducts without invading the basement membrane. It is an early form of breast cancer. Calcifications (fine pleomorphic, fine linear/branching) are seen in ~22-23% of cases on mammograms, often being the only sign.
IDC: Invasive Ductal Carcinoma; the most common type of invasive breast cancer, accounting for ~80% of all breast cancers. Mammographically, it often presents as an irregular mass with spiculated margins, architectural distortion, or a high-density lesion.
ILC: Invasive Lobular Carcinoma; the second most common type of invasive breast cancer (5-15%). It often does not form a palpable lump or a distinct mass on mammograms, instead growing in a diffuse, infiltrative pattern. It can manifest as architectural distortion, an ill-defined asymmetry, or a subtle area of increased density, making it challenging to detect.
InflammatoryCarcinoma: A rare and aggressive form of breast cancer (1-5% of cases) characterized by rapid onset of redness, swelling, warmth, and dimpling of the breast skin (peau d’orange, resembling an orange peel due to lymphatic obstruction). It is often an underlying invasive ductal carcinoma that has spread rapidly through the dermal lymphatics. It may not form a distinct mass on mammography.
Paget’s disease: A rare form of breast cancer (1-4%) where malignant cells (Paget cells) extend from an underlying ductal carcinoma (often DCIS or invasive) to the nipple and areola. Clinically, it presents with eczematous changes of the nipple (redness, scaling, crusting, itching), which can sometimes be confused with benign dermatological conditions.
Page 45
Additional malignant pathologies and special conditions
SITU/Invasive (rare): In the context of Paget's disease, symptoms like itchiness on the nipple or eczematous changes of the nipple/areola are caused by the presence of malignant cells in this region. Nipple involvement is a key diagnostic feature.
Sarcoma: A rare type of cancer (less than 1% of breast cancers) that arises from connective tissue within the breast (e.g., fat, nerves, muscle, cartilage, vessels, bone), rather than from the glandular or ductal tissue. Breast sarcomas can spread to distant organs like the lungs, bones, and liver, typically via the bloodstream.
Lymphomas: Neoplasms (cancers) that originate from lymph tissue. Primary breast lymphoma (PBL) is very rare (0.04-0.5% of breast malignancies) but can mimic breast cancer in its early stages, presenting as a palpable mass or areas of increased density on imaging.
Metastatic lesions: Represents cancer spread to the breast from a primary site elsewhere in the body (e.g., melanoma, lung, ovarian, prostate cancer). These often appear as well-circumscribed or multifocal masses, differing from primary breast cancers.
Summary of mammographic positioning and procedures (lead into next pages): This section establishes the foundation for understanding the various standard and specialized mammographic views, their rationale, and the techniques used to acquire high-quality images. Proper positioning is paramount for accurate diagnosis and to avoid missing pathology.
Page 46
Breast cancer vascular and systemic considerations
SITU/Invasive details continued: This section would likely elaborate on distinguishing features of in-situ vs. invasive disease beyond mere cellular confinement. For example, invasive disease has the potential for distant spread via vascular and lymphatic systems.
Tissue-related pathologies and differential diagnosis: Deeper discussion on how different tissue compositions (e.g., dense vs. fatty breast) influence the appearance of both benign and malignant pathologies, necessitating a careful differential diagnosis based on imaging features and clinical context.
Page 47
Mammographic positioning views – CC (Craniocaudal)
CC: The x-ray beam enters superiorly (from the head side) and exits inferiorly (towards the feet). This view is optimally designed for visualizing medial breast tissue (near the sternum). Limitations include often missing the extreme lateral breast tissue, particularly the Tail of Spence (the axillary prolongation of breast tissue into the armpit).
Steps:
Physician/technologist positioning: The patient stands facing the mammography unit. The technologist holds the breast at the inframammary fold (IMF).
Raise IR to IMF level: The image receptor (IR) is raised to the level of the patient's inframammary fold, ensuring inclusion of the maximum possible inferior breast tissue.
Ensure breast is well supported: The breast is pulled forward and onto the image receptor, ensuring the nipple is centered and the breast is flat against the detector.
Watch for nipple-in-profile (NP) and retromammary space: The nipple should ideally be in profile. Visualizing the retromammary fat space behind the glandular tissue indicates good posterior inclusion.
Optimal CC: To ensure a comprehensive CC view:
All posterior tissue visualized: The image should include as much posterior breast tissue as possible, ideally up to the pectoral muscle.
Retromammary space visible: Clear visualization of the fat planes posterior to the glandular tissue, allowing differentiation from chest wall.
Pectoral muscle central/medial: The presence of pectoral muscle, especially centrally or medially, indicates good posterior tissue inclusion.
PNL (Posterior Nipple Line) within ~ of MLO: The PNL, a line drawn from the nipple perpendicular to the chest wall, should be within 1 cm of the PNL measured on the MLO view, indicating consistent tissue inclusion.
NP in profile: The nipple should be seen in true profile to avoid obscuring any subareolar pathology or mistaking it for a mass.
Board-style question prompts on hand positioning and opposite hand duties: These often focus on proper ergonomic and technical practices for technologists, for example, the hand supporting the breast should not be in the beam path.
Page 48
MLO (Mediolateral Oblique):
CR (Central Ray): Enters Medially (near the sternum) and exits Laterally (towards the axilla). This is an oblique view, typically at an angle of . It is the most comprehensive view, best for visualizing both lateral and superior-posterior tissues, and usually captures the most breast tissue in a single projection, including the axilla.
Optimal MLO: For a diagnostically optimal MLO view:
Posterior tissue visualized from axilla to IMF: The image must extend from the deepest portion of the axilla superiorly, across the entire breast, and inferiorly to include the open inframammary fold.
Open chest wall edge: The superior aspect of the pectoral muscle should be visible and extending down past the posterior nipple line, forming an open angle with the chest wall. There should be no superior (axillary) cut-off.
Convex shape: The pectoral muscle should appear convex, running diagonally under the breast tissue, indicating that the breast has been properly pulled forward and not allowed to droop.
Muscle should be seen under the breast: The pectoral muscle should be visible and extend sufficiently into the image to indicate inclusion of deep posterior tissue.
NP: absence of skin fold; taut compression: The absence of skin fold indicates taut compression with proper tissue pull, which is essential for clear imaging without obscuring artifacts.
Steps:
Angle IR parallel to pectoralis major: The image receptor is angled to be parallel to the patient's pectoral muscle, typically between and . The angle is chosen based on patient height and body habitus:
\ degrees for short, stocky patients.
\ degrees for average height patients.
\ degrees for tall, thin patients.
Tilt degree options: Adjusting the angle ensures optimal inclusion of the pectoral muscle and posterior breast tissue.
NP considerations for positioning: Ensuring the nipple is in profile is ideal to differentiate it from a potential subareolar lesion. If not in profile, additional maneuvers or specialized views might be needed.
Page 49
Further positioning specifics and anatomy references
Pectoralis major as key muscle in MLO positioning: The orientation of the pectoralis major muscle serves as a guide for selecting the correct MLO angle. Proper inclusion and visualization of this muscle indicate that deep posterior breast tissue, which can harbor occult cancers, has been captured.
PNL (Posterior Nipple Line) height and IR height considerations; avoid high IRs that cause vertical muscle appearance: The PNL should be measured on both CC and MLO views. If the IR is positioned too high during MLO, it can lead to a high axilla cut-off (missing superior tissue) and cause the pectoral muscle to appear vertical rather than convex, indicating improper breast pull-forward.
MLO variations and anatomical landmarks for proper compression and tissue inclusion: Minor adjustments to patient rotation, arm position, and IR height can help optimize MLO views. Landmarks include the axilla, inframammary fold, and the anterior limits of the breast.
ML (Mediolateral) and LM (Lateromedial) views explained; use cases to separate tissue and visualize lateral/medial lesions: These are true lateral views used diagnostically.
ML (Mediolateral): The x-ray beam enters medially and exits laterally. Used to localize lesions that move up on the MLO view (medial lesions).
LM (Lateromedial): The x-ray beam enters laterally and exits medially. Used to localize lesions that move down on the MLO view (lateral lesions), or to improve visualization of medial breast tissue.
Both ML and LM views are useful for separating superimposed tissues that might obscure a lesion on the standard oblique view, and specifically for triangulating lesions to determine their exact medial-lateral position.
Page 50
Exaggerated views and specialized projections
XCCL (Exaggerated Craniocaudal Lateral) and XCCM (Exaggerated Craniocaudal Medial): These are modified CC views with a slight medial or lateral pivot of the C-arm (\ angle) to visualize tissue not fully captured on a standard CC or MLO.
XCCL: Exaggerated Craniocaudal Lateral is used to image far lateral breast tissue, particularly the axillary tail (Tail of Spence), which is often missed on a standard CC view.
XCCM: Exaggerated Craniocaudal Medial is used to visualize more medial breast tissue, especially in the cleavage area.
Cleavage View (CV): Also known as Valley View. Used to visualize posterior, deep, and medial aspects of both breasts simultaneously. The breasts are slightly separated (not overlapping at the sternum) to avoid motion blur or tissue superimposition, but enough medial tissue is included to demonstrate the cleavage area. It's particularly useful for lesions near the sternum or deep in the medial aspect.
Axillary Tail (AT): A dedicated view to demonstrate the entire axillary tail of Spence. It's often used when an abnormality is palpated in this area or when it's not fully included on the MLO. This view (sometimes referred to as superolateral to inferomedial oblique, SIO) ensures clips and palpable lesions are visible. It should not be used as a substitute for a poorly positioned MLO.
Tangential (TAN): A specialized view used for palpable lesions or superficial abnormalities (e.g., skin calcifications) that are not well seen or are obscured by overlapping breast tissue on standard views. The x-ray beam is directed tangential to the skin surface over the area of interest.
Guidelines on when to use tangential views: When a palpable lump or skin lesion requires clear depiction without superimposition, or when differentiating skin calcifications from intramammary ones.
How to interpret BB shadow and ROI positions: A metallic marker (BB, for Ball Bearing) is placed on the palpable lump or skin area. The tangential view is then centered on the BB, and the beam is positioned perpendicular to the nipple line (or the tangent of the skin surface at the lesion) to clearly demonstrate the lesion's relationship to the skin or superficial tissue, allowing assessment of ROI (Region of Interest) positions.
Page 51
More specialized views
CC/ML rolled views (RL, RM, RS, RI) to separate superimposed tissue and localize abnormalities: These views involve rolling the breast in a specific direction before compression on either a CC or ML projection to separate superimposed glandular tissue. This helps determine if an abnormality is located superiorly or inferiorly, or medially or laterally relative to its apparent position on the standard view.
Rolled Lateral (RL): Superior aspect of the breast rolled laterally on a CC view.
Rolled Medial (RM): Superior aspect of the breast rolled medially on a CC view.
Rolled Superior (RS) and Rolled Inferior (RI): Similar concepts applied to ML views.
MLO rolled views to separate oblique tissues: Less common but can also be performed to separate obliquely superimposed tissue on MLO views.
Anterior Compression (AC): Utilized to re-image the anterior portion of the breast when it is not adequately compressed on a standard view. This can improve visualization of subareolar or anterior lesions by reducing thickness and motion.
NP (Nipple in Profile): It is an MQSA requirement that at least one mammographic view per side must show the nipple in true profile to ensure the nipple and subareolar region are clearly visualized and to avoid mistaking the nipple for a mass.
Spot Compression (S, SP, Spot): Involves applying localized, firm compression over a specific region of interest (ROI) using a smaller compression paddle. This technique aims to:
Reduce thickness: Minimizes the amount of tissue the x-ray beam has to penetrate, reducing scatter and dose to the localized area.
Displace tissue over ROI: Spreads out overlying glandular tissue that might be obscuring a lesion, making it more visible.
Improves lesion definition: By reducing tissue thickness and scatter, it enhances the visibility of lesion margins, density, and internal features, aiding in differentiation between benign and malignant findings.
Magnification (M): Magnification views are often combined with spot compression. These views use an increased OID and a small focal spot to optically enlarge small structures. Typical factors: x. Magnification helps resolve fine details like microcalcifications.
Page 52
Lesion localization concepts
How to locate lesion depth relative to PNL; measure distance from PNL to lesion in superior-inferior or medial-lateral directions; distance from lesion to skin: Localization in 2D mammography often involves triangulating the lesion's position using two orthogonal views (e.g., CC and MLO). The distance from the Posterior Nipple Line (PNL) to the lesion in superior-inferior or medial-lateral directions is measured. Similarly, the distance from the lesion to the skin edge helps define its depth.
Magnification and spot compression devices used for precise ROI imaging: Once a suspicious finding is identified on initial screening images, magnification and spot compression views are employed to provide detailed visualization of the Region of Interest (ROI). These techniques help confirm the presence, characterize the features, and precisely localize the lesion for further diagnostic work-up or biopsy.
Page 53
More on magnification and spot compression
Centering of lesion and ROI considerations; smaller paddles facilitate targeted compression: When performing magnification or spot compression, precise centering of the lesion within the small field of view is critical. Smaller compression paddles are used to apply targeted compression directly over the abnormality, which helps spread out surrounding tissue and ensures optimal visualization of the lesion's margins and internal characteristics.
Imaging technique orders (CC, MLO, ML/ML, MLO, CC) for rolled views: For rolled views, specific sequences (e.g., standard CC and MLO, followed by special views like ML/LM, and then rolled views) are employed to achieve the desired tissue separation and localization. The order is crucial to prevent re-positioning errors.
Practical tips for rolled views and lesion localization: These often include ensuring firm but tolerable compression, accurate patient positioning, careful use of markers, and correlation with prior images and clinical findings to guide precise localization for diagnostic interpretation or interventional procedures.
Page 54
Implant displacement (Eklund view) and implant displacement strategies
Implant displacement details for CC and MLO views; how to visualize tissue not obscured by implants: The Eklund view (or implant displacement view) is a specialized technique used for patients with breast implants. The implant is manually displaced posteriorly and medially onto the chest wall, away from the breast tissue, allowing for visualization and compression of the natural breast tissue.
For CC views, the implant is pushed posteriorly. For MLO views, it's pushed posteriorly and medially. This maneuver ensures that the breast glandular tissue is adequately visualized and compressed without the implant obscuring vital areas. Four standard views and four Eklund views (8 views total) are usually taken for screening implanted breasts.
Patient variance in chest wall morphology and tissue distribution; pectus deformities and their effect on imaging: Anatomical variations can significantly affect mammography positioning. Pectus excavatum (concave sternum) and pectus carinatum (protruding sternum) deformities can make it challenging to achieve complete inclusion of medial or deep tissue and may require special positioning adaptations.
Common strategies for pectus excavatum and carinatum in CC/MLO projections: For pectus excavatum, more exaggerated oblique angles or specialized views (e.g., Cleopatra view) may be needed to include medial tissue. For pectus carinatum, careful patient rotation and modified compression are used to minimize discomfort and ensure adequate tissue visualization around the protruding sternum.
Page 55
Specific challenging patient scenarios and their solutions
Irradiated breast (post-surgical): Breasts that have undergone radiation therapy often exhibit tenderness, skin thickening, scar distortion, and fat necrosis. Positioning needs to be adjusted accordingly to minimize discomfort. Supplemental views like CC, XCCL (Exaggerated Craniocaudal Lateral), and LM (Lateromedial) may be used to overcome distortions and visualize affected areas. Compression should be gentle but firm enough for diagnostic quality.
Reduction mammoplasty: Post-surgical anatomy considerations are unique in patients who have undergone breast reduction. The tissue is repositioned, nipple location may be altered, and scar tissue can cause architectural distortion. Challenges include medial tissue exclusion and unusual nipple position. Specific strategies include ensuring inclusion of all remaining glandular tissue, careful palpation to identify any remaining breast tissue extensions, and potentially utilizing supplemental views like XCCM or CV.
Supplemental views and alternative projections (XCCM, CV, NP; LM/ML alternatives): These views are crucial for addressing complex anatomical challenges or specific areas of concern that standard views may miss. They aid in achieving comprehensive tissue inclusion and improving lesion detection reliability.
Page 56
Additional patient-specific view strategies
Male breast imaging considerations: Male breasts are typically smaller and contain less glandular tissue, often with significant chest hair. Special considerations include managing chest hair (which can create artifacts) and adjusting positioning for the smaller breast footprint. Alternative views such as FB (Flipped Breast lateral), XCCL (Exaggerated Craniocaudal Lateral), and LM/ML (Lateromedial/Mediolateral) may be employed to ensure all relevant tissue is visualized.
Kyphotic/lordotic patients: Patients with kyphosis (excessive outward curvature of the spine) or lordosis (excessive inward curvature) have abnormal head and neck positions that can interfere with standard CC/MLO views, making it difficult to achieve proper tissue inclusion and patient comfort. Alternate views recommended include XCCL, XCCM, CV (Cleavage View), FB (Flipped Breast), and AT (Axillary Tail) to adapt to the patient's posture and ensure comprehensive imaging.
Protruding abdomen: Patients with a large or protruding abdomen can present positioning challenges, particularly with the CC view, as the abdomen can interfere with proper breast placement and full compression. Strategies include having the patient lean back, pulling the breast well forward, and potentially using supplemental views to ensure complete inclusion of inferior tissue.
Supplemental views and implant considerations continued: For challenging cases, especially with implants, a combination of standard displacement views and additional targeted views may be necessary to visualize all native breast tissue adequately.
Page 57
Implanted devices and lactating breast considerations
Implanted devices: Patients with pacemakers, defibrillators, port-a-caths, or other implanted electronic devices require careful positioning to avoid contact or compression of the device, which could cause discomfort, damage, or malfunction. The compression device should avoid skimming or directly compressing near these generators. Alternate views are recommended to image breast tissue without interfering with the device.
Lactating breast: The breasts of lactating (breastfeeding) women are engorged with milk, making them dense, heavy, and often tender. To maximize compression, reduce discomfort, and improve visualization of glandular tissue, patients are advised to pump or breastfeed prior to the imaging examination. This reduces breast volume and density, leading to a better-quality study at a lower dose.
Extremely large breasts: Patients with very large breasts pose challenges in achieving full tissue inclusion and adequate compression on a single image. Strategies may include anterior compression views, tiling (taking multiple images that overlap to cover the entire breast), and specialized positioning techniques. This often increases the number of exposures.
Extremely small breasts: Small breasts can be difficult to compress and keep on the image receptor, as tissue may slip out. Solutions include using smaller compression paddles designed for focal compression or small breasts, and potentially using a spatula or specialized foam support to gently hold the breast in place on the image receptor during compression.
Breast augmentation considerations continue: Further discussions may include the increased difficulty in detecting early cancers in augmented breasts due to tissue displacement and obscuring by the implant.
Page 58
Breast implants: types and risks
Saline vs Silicone implants; radiographic properties and risks (deflation, rippling, capsular contracture): Breast implants are typically filled with either saline (sterile salt water) or silicone gel. Saline implants are radiolucent (appear dark on mammography) and are often inserted empty and then filled. Silicone implants are radiopaque (appear dense/white on mammography), obscuring underlying breast tissue, and are pre-filled gels. Risks include deflation (saline), rippling, capsular contracture (hardening and tightening of the fibrous capsule around the implant, more common with silicone), infection, and rupture.
BIA-ALCL (Breast Implant-Associated Anaplastic Large Cell Lymphoma): A rare type of T-cell lymphoma that can develop in the fluid or capsule surrounding breast implants, particularly textured implants. It is a cancer of the immune system, not breast tissue itself, and requires specific diagnosis and treatment.
Implant lumens and envelopes: Implants consist of an outer shell (envelope) and often contain internal compartments (lumens). They can have single-lumen, double-lumen (e.g., saline in outer, silicone in inner), or triple-lumen configurations, each with different radiographic appearances and implications for rupture detection.
Page 59
Implant placement and incision sites
Placement planes: Implants can be placed in different planes relative to the pectoral muscle:
Subfascial: Directly beneath the deep pectoral fascia, overlying the muscle.
Subglandular (prepectoral): Placed directly behind the breast glandular tissue, but in front of the pectoral muscle.
Subpectoral (retropectoral): Placed partially or completely behind the pectoral muscle. This position is often preferred as it provides more soft tissue coverage, potentially reducing capsular contracture and making mammography of the glandular tissue easier.
Incision sites: The surgical incision to place an implant can be made in several locations:
Transaxillary: Through an incision in the armpit.
Periareolar: Around the edge of the areola.
Inframammary: In the fold under the breast (most common today).
Transumbilical (for specific implant types): Through the belly button, less common and typically for saline implants only.
MQSA requirement: It is an MQSA requirement to record patient implant status prior to imaging (unless medically contraindicated) and to ensure that imaging guidance (e.g., positioning, compression) is compatible with the presence of implants. This ensures patient safety and optimal image acquisition.
Displacement contraindications and implant rupture types (intracapsular vs extracapsular): In some cases, implant displacement (Eklund views) may be contraindicated due to surgical factors, severe capsular contracture, pain, or recent surgery. Rupture refers to a breach in the implant's outer shell:
Intracapsular rupture: The implant shell ruptures, but the silicone gel remains contained within the fibrous capsule that the body forms around the implant. This can be challenging to detect on mammography or ultrasound, often requiring MRI (classic "linguini sign" on MRI).
Extracapsular rupture: The implant shell and the fibrous capsule both rupture, allowing silicone gel to leak into the surrounding breast tissue or beyond. This is often more obvious clinically and on imaging (free silicone droplets).
Imaging examination modalities for implants (mammography, ultrasound, MRI): While mammography is complex with implants, ultrasound can evaluate the integrity of saline implants and search for free silicone. MRI is considered the most sensitive and specific modality for detecting implant ruptures (especially intracapsular) and evaluating surrounding breast parenchyma.
Implant rupture visualization modalities and typical findings: Each modality has characteristic findings (e.g., "stepladder sign" or "linguini sign" for intracapsular rupture on MRI, free silicone droplets).
Page 60
Screening vs Diagnostic mammography; indications for supplemental views
Breast ultrasound indications and operator training: Ultrasound is widely used for problem-solving in breast imaging, particularly for evaluating palpable masses, assessing dense breasts where mammography sensitivity is reduced, characterizing mammographic findings (e.g., distinguishing solid from cystic masses), and guiding biopsies. Its effectiveness is highly operator-dependent, requiring skilled sonographers and radiologists.
Indication for automated whole-breast ultrasound (ABUS) or WBUS in dense breasts: ABUS/WBUS is used as a supplemental screening tool for women with dense breasts who have no symptoms, due to the recognized limitation of mammography in dense tissue.
How ultrasound images are generated: Ultrasound imaging involves emitting high-frequency sound waves from a transducer into the breast. These sound waves travel through tissues, reflecting (echoing) back when they encounter interfaces between different tissue densities (e.g., muscle/fat, fluid/solid). The transducer then receives these echoes, and a computer processes them to create real-time images.
Ultrasound properties and tissue characterization (fatty vs dense glandular tissue; implant considerations): Different tissues have characteristic echogenicity. Fatty tissue typically appears hypoechoic (darker), while dense glandular tissue appears hyperechoic (brighter) and heterogeneous. For implants, ultrasound can assess their integrity and look for periprosthetic fluid or silicone leakage.
Automated breast ultrasound (ABUS/WBUS) indications and FDA approvals: ABUS/WBUS is specifically indicated as an adjunct to mammography for screening asymptomatic women with dense breast tissue. It received FDA approval as a screening tool to provide additional information not visible on a mammogram.
Page 61
Ultrasound image interpretation basics
Echogenicity categories: Describes the brightness of tissues relative to surrounding structures on ultrasound.
Anechoic: Appears black, indicating no internal echoes, characteristic of simple fluid (e.g., simple cyst, urine).
Hypoechoic: Appears darker than surrounding tissues, characteristic of many solid masses (benign and malignant).
Hyperechoic: Appears brighter than surrounding tissues, characteristic of fat lobules, some benign masses (e.g., fibroadenomas with fatty components), or scar tissue.
Isoechoic: Appears with similar brightness to surrounding tissues, often making lesions difficult to detect.
Benign lesion features on ultrasound: Typically well-defined margins; smooth, regular borders; macrolobulation (large, smooth scallops); round/oval shapes; and often demonstrate posterior acoustic enhancement (increased brightness posterior to the lesion due to sound's unimpeded passage through fluid). Examples include simple cysts, fibroadenomas.
Cyst contents on ultrasound: Simple cysts are purely anechoic, round/oval, with smooth walls and strong posterior enhancement. Complex cysts may have internal septations, debris, or a solid component, which increases suspicion and often requires biopsy.
Suspicious ultrasound features: Irregular borders, micro-lobulation (small, irregular scallops), taller-than-wide shape (longer in the anteroposterior dimension than transverse), hypoechoic with angular or spiculated margins, and posterior shadowing (reduced sound transmission posterior to the lesion, typical of fibrous/desmoplastic reactions in malignancies). Vascular flow on Doppler (especially chaotic or pronounced internal flow) can indicate malignancy due to angiogenesis.
Page 62
Ultrasound lesion characterization continued; rolled views and correlation with mammography: Further characterization involves assessing changes in lesion appearance with compression or patient position (e.g., rolled views on ultrasound). Crucially, ultrasound findings must be correlated with mammography findings to arrive at a comprehensive BI-RADS assessment.
Stereotactic biopsy guidance (vacuum-assisted for calcifications): Stereotactic biopsy uses mammographic imaging (2D or 3D) to precisely localize non-palpable lesions, especially calcifications, for biopsy. Vacuum-assisted core biopsy (VAB) is often preferred for calcifications due to its ability to obtain larger tissue samples.
2D vs 3D imaging modalities in guiding biopsy: 2D stereotactic biopsy relies on two different angle views to triangulate the lesion. DBT-guided biopsy uses 3D tomosynthesis data for more precise localization, especially beneficial for subtle lesions or those obscured by dense tissue.
Interventional biopsy overview: This serves as a general introduction to the various image-guided procedures used to obtain tissue samples for histological diagnosis, including core biopsies, excisional biopsies, and fine-needle aspirations.
Page 63
Breast MRI overview and indications
MRI uses: Breast MRI is a highly sensitive advanced imaging modality used for specific indications, including new cancer staging (especially for lobular or multifocal disease), evaluation of breast implants (for rupture), investigation of nipple discharge (when mammogram/ultrasound are negative), assessment of scarring versus recurrence post-surgery, and monitoring response to neoadjuvant chemotherapy.
MRI as a problem-solving tool; use of gadolinium contrast; hypervascular lesions enhancement patterns: MRI uses a strong magnetic field and radio waves. Gadolinium-based contrast agents are typically administered intravenously; malignant lesions often enhance rapidly and washout quickly due to their increased vascularity and abnormal vessel permeability (hypervascular enhancement patterns), which helps differentiate them from benign lesions.
MRI-guided biopsy (MRI Bx) and preoperative planning: MRI can guide biopsies for lesions seen only on MRI. It's also vital for preoperative planning, providing a comprehensive map of known and occult cancer extent before surgery.
Dedicated breast coil usage: To maximize image quality and signal-to-noise ratio, breast MRI requires the patient to lie prone (face down) in a specialized dedicated breast coil that cradles both breasts, allowing for optimal imaging of bilateral breasts.
Page 64
Interventional procedures: patient preparation and safety
Informed consent, time-out procedures, sterile technique for all interventional procedures: Prior to any interventional procedure, thorough informed consent must be obtained, explaining risks and benefits.