Fundamentals of Diagnostic Imaging

vindicate

what is the mnemonic that is used for universal differential diagnosis?

yes

can PTs order x-rays?

PCP

PTs must communicate the x-ray order to the patients _____ or health care provider about significant findings

plain film radiographs

-accuracy to less than a mm

- cheapest with exception of diagnostic US

- point source distortion

- 3D info --> 2D media

- BEST FOR BONE

less; more

things that are black on a radiograph are:

______ radiodense and ______ radiolucent (air)

more; more

things that are white on a radiograph are:

_____ radiodense and _____ radiopaque (bone)

true

T/F: cortical bone is more dense than trabecular bone

less

on a radiograph structures that are closest to the beam source are enlarged and have _____ resolution on film

higher

on a radiograph structures that are farther away are less enlarged and show _____ resolution

contrast

_____ can improve visualization of areas with minimal amounts

myelography

a radiographic study of the spinal cord after the injection of a contrast medium through a lumbar puncture

- abnormal results include: ruptured disc, spinal stenosis, nerve root injury, intervertebral tumor

arthrography

taking x-ray images after injection of contrast material into a joint

arthrogram

contrast media study of a joint and its soft tissue structures

- shows abnormalities of synovium, articular cartilage, capsule, and soft tissue

- limitations: not multiplanar and invasive

fluoroscopy

Real-time imaging technique using open-shutter X-rays

many uses include:

- angiography

- catheter placement

- arthrography

- myelography

- facet joint injection

alignment, bones, cartilage, and soft tissue

what are the ABCS of reading radiographs?

subluxation

an incomplete dislocation when some contact between the joint surfaces remains

dislocation

the total displacement of a bone from its joint

diastasis

separation of normally joined parts

- SI joint and cranial sutures

lucency

decreased opacity

sclerosis

increased opacity

osteoblasts

osteoclasts have the capability of reabsorbing bone about 20x faster than _____ can lay it down

- leads to net bone loss and decreased opacity (increased lucency)

lucent line

fracture

focal lucency

common causes: bone tumor, osteomyelitis

appears less dense on an X-ray or CT scan compared to the surrounding tissues, resulting in a darker appearance

diffuse lucency

drugs

endocrine/metabolic (osteoporosis)

tumor

- usually a global process

- metabolic disorder is most common

- a wide area of decreased density or less dense tissue, resulting in a darker appearance on the image

increased opacity (sclerosis)

bone impaction or rotation --> fracture

bone production (reactive sclerosis)

- fracture --> callus

- tumor --> tumor bone formation or periosteal rxn

- infection --> periosteal rxn

- osteoarthritis --> subchondral sclerosis

fracture callus

some fractures are so subtle that they might be missed at first

can only be seen once they have started to heal with ____ ____ formation

solid; aggressive

periosteal reactions:

- benign processes = _____ pattern

- malignant processes = _____ pattern

decreased joint space

infers arthritis (OA most common and then RA)

increased joint space

acromegaly or joint effusion

chondrocalcinosis

Radiographic finding of fine, linear calcifications in cartilage diagnostic of pseudogout

- most commonly due to CPPD in the joints

swelling

usually not very diagnostically helpful

gas

penetrating injuries, following surgery, soft tissue infections due to gas-forming organisms

calcification

usually non-specific

mass

hematoma, abscess, tumor

MRI is more helpful imaging choice for most masses

scotty dog fracture

Fracture of Pars Interarticularis, = spondylolysis. Could lead to spondylolisthesis. Head = TP, Body = Lamina & SP, Ear = SAP, Forefoot = IAP

ultrasound

doesn't use ionizing radiation

- imaging using sound waves

- diagnostic and therapeutic uses

- generally considered cheapest and safest imaging modality

- real time

evaluates

ultrasound ______

- lesions to muscles, tendons, ligaments

- detection of cysts

- measurement of blood flow

dynamic

ultrasound images can be _____

- resisted contractions, passive stretching, etc.

limitations

ultrasound _____

- operator dependent

- does not penetrate bone

- does not cross air interfaces

- obese patients not imaged well

nuclear imaging

tracer is absorbed by specific tissue in varying amounts, based on metabolic activity within that tissue

- pathologies identified by variations in the uptake of tracer

- gamma rays emitted from body are detected by gamma cameras

- types: nuclear scintigraphs (bone scan), PET, SPECT and SPECT CT

SPECT

lower cost

uses gamma emitting radioisotope

provides metabolic and functional information

PET

very expensive

uses positron emitting radioisotope

better contrast and spatial resolution

bone scan

used for stress fractures

- early indicator of increased bone activity

- abnormal conditions show increased uptake of the tracer

- tracer Technetium 99m

CT

X-rays on steroids

- merges X-ray and computer technology

- provides detailed cross sectional images

- same imaging principles as radiology

- radiodense structures are bright white

MRI

magnetic resonance imaging

magnetic field and radiofrequency signals

- hydrogen nuclei emit signals

- different tissues = different signals

- converted to image

best

MRI is _____ for:

- bone marrow changes

- soft tissue

- disc herniations

- nerve root impingements

- neoplasms

- bone METs (more sensitive than bone scan)

T1

best for soft tissues

T2

best for fluid (H2O)