2 Diagnostic Imaging

what are the types of diagnostic imaging

conventional radiology

contrast-enhanced imaging

computerized tomography

magnetic resonance imaging

nuclear imaging

diagnostic ultrasound

fluoroscopy

what is an x-ray

invisible light beam (EM radiation, high energy/short wave length) that can penetrate deeply

radiograph

image is produced by the x-ray penetrating through the body. various structures absorb energy differently

what is radiodensity

thickness, anatomic weight of the structure

how does a more radiodense structure appear on film? less radiodense?

more radiodense will be white (contrast medium like barium or metal implant will appear white)

less radiodense will be darker

most radiographs have at least ___ projections at __º of separation

2, 90

position of the patient in relation to the x-ray beam

sagittal, frontal/coronal, axial/transverse

projection of x-ray across the sagittal plane

A-P/P-A

projection of x-ray across the frontal plane

lateral (left or right, named depending on side closest tot he film casette)

oblique x-ray projections

approximately 45º from the sagittal plane, named for the side closest to the film cassette

anterior or posterior and right or left

what types of radiological images exist? what is most commonly used now?

plain films - standard film image on hard copy

digital radiology - stores the diagnostic image in a computer and computer reproduces the image

most commonly used now is digital

analyzing radiographs

viewing - computer

A-P or P-A - views pt in anatomical position

lateral/oblique films - view in the same direction as x-ray

markers - name/side of the body

what is the systemized approach when viewing radiographs?

ABC’s - alignment, bone density, cartilage spaces

alignment in radiograph

general skeletal architecture, contour of bone, alignment of bone relative to adjacent bones

bone density in radiographs

general bone density, local bone density, texture abnormalities

cartilage spaces in radiographs

joint space width

subchondral bone

epiphyseal plates

soft tissues in radiographs

muscles, fat pads and fat lines, joint capsules

indications of conventional radiology

most frequently used and most commonly performed imaging

other imaging techniques are used to confirm or deny a diagnosis made with conventional radiology

primary indication is bone injury

what is a CT scan (computerized tomography)

radiographs taken in 360º

patient is placed on a table moving through a circular ring

radiographs are taken axially every 0.3-1.5 cm

originally only axial views were available but other planes are now available

pros of CT scan

complex fractures/tumors (wrist, face, pelvis, spine)

eliminates superimposition of one anatomical part on another

can look at blood flow

cons of CT scan

insufficient for visualization of articular cartilage, tendon rupture/tendonitis

what is fluoroscopy

similar to plain-films but can be static or dynamic

x-ray beam passes through the patient and interacts with an image intensifier tube

image is transferred to a screen

used during casting/splinting/surgery

fluoroscopy indications

open reduction for fracture reduction/fixation

observe abnormal movement of a jointf

fluoroscopy negative factors

increased radiation

poor quality image

what has the most radiation exposure?

CT scan

x-ray absorptiometry indications

bone density may be evaluated radiologically but plain-films are not very sensitive to changes in bone density. changes in bone density is called osteopenia

bone densitometry

name for all radiological studies of osteopenia. bone densitometry uses standard anatomical parts as a reference and compares them to a normative model

does a bone scan have high sensitivity or specificity?

high sensitivity

low specificity

dual x-ray absorptiometry (DEXA)

measures the changes of an x-ray beam from 2 levels of energy as it passes through the body

what is quantitative CT

takes a CT of 3 lumbar vertebrae

assesses bone density against a normative model

what is nuclear imaging aka bone scan?

nuclear medicine study that is very sensitive to changes in bony metabolism

bone scan procedure

radiopharmaceutical agent injected

pt placed under scintillation camera

entire body scanned simultaneously

side to side comparison possible

normal bone is lighter than pathologic bone

indications of bone scan

tumors, metastatic disease, infections, stress reactions, fractures, avascular necrosis

what is MRI

produced by the interaction of tissues with radio frequency within a magnetic field

each tissue type has a typical energy pattern that the computer reconstructs into an image

indications for MRI

ideal for bone, soft tissue lesions, surgical planning

stress fx

AVN/tumors

ligament injury

bone marrow edema

articular cartilage/meniscus cartilage

head trauma/spinal cord injured

T1 vs T2

T1 - bone, fat, subacute hemorrhage is bright

T2 - fluid and soft tissue are bright

when is T1 used vs T2

T1 for anatomy in detail

T2 for acute trauma

what is contrast enhanced imaging

contrast medium is injected into an anatomical part followed by a radiograph

helps with improved visualization of pathology

can be used with most diagnostic imaging modalities

types of contrast-enhanced radiology

arthrography - joint

myelography - spine

what is diagnostic ultrasound

most commonly used to image soft tissue lesions in tendon and muscle

does not use ionizing radiation

image quality is not as good as CT or MRI

becoming more popular

indications for ultrasound

prevalent in research and some PT practices

pre and post movement re-education - abdominal muscles, pelvic floor (urinary incontinence), lumbopelvic

who orders imaging?

MD’s, nurses, PT’s (in the military), outside the military PT’s cannot order but can recommend

ottawa ankle rules

ottawa knee rules

an x-ray is indicated if the patient has any of the following features

age > 55

inability to bear weight both immediately and in the emergency department (4 step) **

isolated tenderness of the patella *

tenderness at head of fibula

inability to flex to 90º

*no bone tenderness of knee other than patella

**unable to bear weight wice onto each limb regardless of limping

canadian c-spine rules