Chapter 2 Specialized Imaging Techniques

PET/CT

Type of nuclear medicine imaging that combines positron emission tomography (PET) and computed tomography (CT)

What can PET scan detection do?

Functional changes in metabolism (cell activity)

What is CT scan visualization?

Detailed structural images of bones, organs, and tissues

What is the Advantage of PET/CT?

Provides exact location of high cell activity and more accurate diagnosis

What are Radiotracers?

Small amounts of radioactive materials used to diagnose and evaluate disease

What is Location (imaging)?

The site where anatomical changes are evident

What is Size (imaging)?

The measurement of changes on the image

Density and structure (imaging)

Abnormal appearance compared to normal tissue

Shape and border (imaging)

Anatomical structure changes and involvement

Perfusion

The degree of blood flow (vascularity)

Integrated (imaging)

Space-occupying tissue

What is Mammography?

A low-dose X-ray used to examine the breast

Screening mammogram

Two standard breast images used for routine screening

Diagnostic mammogram

Additional imaging performed when abnormalities are suspected

What is Ultrasound?

A noninvasive imaging method using high-frequency sound waves

What are the advantages of Ultrasound?

It is non-ionizing and low cost

Echogenicity

ability of tissues to reflect sound waves

Anechoic

echo free; tissue appears dark (black)

Hypoechoic

echoes appear darker than adjacent structures

Hyperechoic

echoes appear brighter than adjacent structures

Isoechoic

describes two structures that have the same echogenicity

Contrast Agents in Ultrasound

Low-solubility gas bubbles used to enhance visibility of tumors, stenosis in blood vessels, heart studies and uterine studies

Elastography

Assesses the level of fibrosis (stiffness and elasticity) of tissue/organ

Common uses of ultrasound

Pregnancy, abdominal, vascular, cardiac, and soft tissue exams

What is Ultrasound safety?

No known harmful effects at diagnostic levels

What is CT (Computed Tomography)?

An imaging method using X-rays to create cross-sectional images(3D/2D)

What is a Hounsfield Unit (HU)?

A scale used to measure tissue density in CT

HU value of water

0

HU value of bone

+1000

HU value of air

-1000

HU value of fat

Less than 0

What is IV contrast in CT?

To differentiate blood vessels, tumors, and infections

What is Oral contrast in CT?

To visualize the GI tract and abdominal organs

What is Spiral (helical) CT?

Continuous scanning for faster imaging and 3D reconstruction

What is MSMD CT?

A CT scanner with multiple detectors for faster, more detailed images

MSMD stands for?

Multi-section Multidetector

Multi-section Multidetector (MSMD) Scanners are also known as

Multiple Array Scanners

What is High-resolution CT?

Detailed imaging of structures like the lungs

MIP in CT imaging

Highlights the brightest pixels

What is MinIP in CT imaging?

Enhances darker structures

MIPs

Maximum Intensity Projections

MinIPs

Minimum Intensity Projections

Shaded Surface Rendering

reconstruct a 2D image into a 3D image

Shaded Surface Rendering

reconstruct a 2D image into a 3D image

Volume Rendered Imaging

allows a 360-degree visualization of the vascular system

VR Reconstruction

used for virtual colonoscopies to visualize the area inside the bowel

What is the ALARA principle?

Radiation exposure should be kept as low as reasonably achievable

Three ALARA methods

Time, distance, shielding

What is MRI?

An imaging technique using magnetic fields and radio waves (Magnetic Resonance Imaging)

Advantage of MRI

Excellent soft tissue contrast with no radiation

Disadvantages of MRI

Expensive, longer scan time, claustrophobia risk

How an MRI works?

Hydrogen ions align in a magnetic field and release signals after RF pulses

T1-weighted imaging bright signal

Fat

T2-weighted imaging bright signal

Fat and water

What is Gadolinium contrast?

Enhances blood vessels and abnormal tissues

What is Fat suppression?

A technique to remove fat signal for better pathology visualization

What is STIR imaging?

A sequence that nullifies fat signal

STIR

Short Tau Inversion Recovery

FLAIR

Fluid Attenuated Inversion Recovery

What is FLAIR imaging?

A sequence that nullifies cerebrospinal fluid

What is DWI ?

Detecting early stroke and water diffusion changes
Diffusion-Weighted imaging

DWI stands for

Diffusion Weighted Imaging

ADC stands for

Apparent Diffusion Coefficient

MRA stands for

MR Angiography

MRS stands for

MR Spectroscopy

What is ADC with DWI (diffusion-weighted imaging)?

-To confirm true restricted diffusion,
-Apparent Diffusion Coefficient

what does MR Angiography (MRA) do?

Produces high-resolution images of the vascular system

what does MR Spectroscopy (MRS) do?

Analyzes chemical composition of tissues in vivo

What is MRI Perfusion Imaging?

Technique used to assess blood flow to tissues, providing insights into tissue perfusion

What is fMRI (functional MRI)?

Imaging that shows brain activity based on blood flow

What is Nuclear medicine?

Imaging that uses radioactive tracers to evaluate organ function

What is Gamma camera?

A device that detects radiation from tracers to create images

What is SPECT?

A 3D imaging technique using gamma rays

What is PET?

A 3D imaging method using positron-emitting tracers

Main purpose of PET scans

Detect cancer and monitor treatment

SPECT stands for?

Single-Photon Emission Computed Tomography

PET stands for?

Positron Emission Tomography

Fusion imaging

Combines functional and anatomical imaging (e.g., PET/CT)

AI in imaging

Technology that improves accuracy, efficiency, and workflow

What is Computer-aided diagnosis (CAD)?

A tool that helps detect abnormalities in imaging

What is personalized medicine?

Treatment tailored to individual patient characteristics

Main difference between SPECT and PET scans is

the type of radiotracers used

The _________________ describes where the pathophysiologic changes are visualized in relative position to the other organs or vessels in the body.

Location

A pathophysiologic change that appears as a similar tissue structure is termed _________________.

a. heterogeneous

b. isodense

c. sharply marginated

d. hyperdense

isodense

Pathophysiologic changes described as tubular, nodular, and diffuse are descriptors of _________________.

Shape

Screening mammography recommends that ________________ and ________________ projections be performed.

a. craniocaudal, mediolateral oblique

b. mediolateral oblique, 90-degree mediolateral

c. craniocaudal, 90-degree mediolateral

d. craniocaudal, mediolateral oblique, and 90-degree mediolateral

craniocaudal, mediolateral oblique

Ultrasound depends on the echo of high-frequency sound waves produced by the transducer. Tissue that produces a strong reflection is known as _________________.

a. hypoechoic

b. anechoic

c. isoechoic

d. hyperechoic or echogenic

hyperechoic or echogenic

Ultrasound is limited by acoustic barriers, such as _________________.

a. liver and splenic tissue

b. air and bone

c. urine in the bladder

d. gallstones or kidney stones

air and bone

The modality that views tissue from multiple angles using a narrow x-ray beam is _________________.

a. CT

b. SPECT

c. PET

d. MRI

CT

The CT technique using continuous scanning while the table moves the patient through the gantry is _________________.

a. helical scanning

b. conventional single-slice scanning

c. high-resolution scanning

d. CTA

helical scanning

Currently, the term multidetector CT indicates _______________________.

a. multitransducer crystals

b. a two-detector array

c. 16- to 320-multidetector array

d. 128- to 256-channel array

16- to 320-multidetector array

Which of the following is not a postprocessing imaging technique for CT?

a. volume rendering

b. VR

c. maximum intensity projection

d. fat suppression

fat suppression

To create an image in MRI, the technology depends on _________________.

a. hydrogen atoms and their response to radiofrequency pulses

b. x-radiation attenuation

c. radiopharmaceuticals

d. electrical stimulation of transducer crystals

Hydrogen atoms and their response to radiofrequency pulses

Multiple-pulse sequences may be required to illustrate pathophysiologic changes. Examples of MRI pulse sequences are _________________.

a. T1- and T2-weighted images

b. positron emission (gamma)

c. single-photon emission

d. 2-MHz to 15-MHz images

T1- and T2-weighted images

Nuclear medicine and SPECT imaging rely on scintillation cameras to detect _________________.

a. multiple-photon emission

b. electron annihilation

c. gamma rays

d. photoelectric interaction

gamma rays

PET imaging is especially useful to evaluate __________________________.

a. chest for pneumothorax

b. reproductive organs for cysts

c. preradiation and postradiation or chemotherapy

d. cerebral ventricle displacement

preradiation and postradiation or chemotherapy

Hybrid imaging equipment combines two ___________________________.

a. image modalities using software to fuse images

b. images comparatively viewed side by side

c. modalities simultaneously to produce one set of images

d. technologists and a radiologist viewing images

modalities simultaneously to produce one set of images

The earliest use of AI techniques in radiology was ________________________.

CAD

What is the goal of personalized medicine?

Improve the effectiveness of treatments