Imaging intro - exam 3 Flashcards
why study imaging as a PT?
add to examination and evaluation
assist with intervention
–> motion barriers, WB/functional levels, intensity based on the integrity of injury, location
contribute to prognosis
better communication of involved parties
what does radiology utilize and what is it used for?
utilizes radiant energy and radioactive substances
used for prevention, diagnosis, and intervention
what is typically the first imaging performed?
x-ray
what is the major advantage of x-rays?
most efficient for assessing initial bone or joint abnormality
what is the major disadvantage of x-rays?
limited for complex and subtle bony and soft tissue abnormalities
how many images are needed to view all 3 dimensions with an x-ray?
at least 2 images at 90 deg
“one view is no view”
what is considered standard for positions and views of x-rays?
greatest visualization
minimize radiation exposure
projection of x-ray beams
– AP > PA, lateral, oblique
when an x ray enters the body it is absorbed by __________
x-ray beam emerges from patient and onto _______
tissues at differing amounts
interpretation device or image receptor
what type of relationship exists between density and an x-ray?
inverse
less dense = black
more dense = white
list what you would see on a x-ray and the color of it from least dense to most dense
air - black
fat and bone marrow - black/gray
water like muscle and soft tissue - gray
bone - white
contrast dyes - bright white
metal - solid white
how should you place an anterior-posterior and posterior-anterior projection x ray on the viewer? what is the exception to this?
place on viewer as if patient were facing you and in anatomical position
exception: hands and feet viewed with toes or fingers pointing up
how should you place a lateral projection x ray on the viewer?
in the path of the beam
what are 2 markers on an x ray to help orient yourself?
PHI
side of body w a R or L (orientation of this letter does not depict correct position)
what are the ABCS to understanding an x ray
alignment
bone density
cartilage space
soft tissues
what are two generalities on a x ray that help with alignment?
general architecture/anatomy - size, number of bones, position
general contour - spurs, breaks, markings
is it necessary to always take hardware out after a fracture/dislocation?
no, only take out if problematic
what is the outer layer of bone predominately in appendicular skeleton? density? color?
cortical (80%)
most dense and white
what is the layer that is interspersed within marrow and predominantly in axial skeleton? density? color?
cancellous (20%)
least dense and gray
what are definitive characteristics you see on an x ray to contrast between bone and other tissue?
bone contrast
texture
local density (sclerotic changes)
what could you see on a x ray of the cartilage spaces?
narrowing
subchondral bone sclerosis and erosion
epiphyseal plates - position, size, smooth margin
what are some characteristics of soft tissue on an x ray/
muscle wasting/edema
fat pad displacement
capsular effusion
periosteum
what is periosteum?
bone covering that shows up as a soft tissue shadow
what are the 4 types of periosteum?
solid - slow growth of healing or infection
laminated or layered - repetitive stress
spiculated or pointed - breakthrough due to tumor
codman’s triangle - raised periosteum with any of the above conditions
What are x-rays best for imaging?
bone
what is a CT scan?
images generated by computerized and targeted x rays are passing through slices of tissues
what are major advantages of CT scan?
less overlap of structures due to slicing
able to locate subtle bone changes
what are major disadvantages of CT scan/
greater radiation exposure
limited with soft tissue abnormalities
where is CT scan the standard modality? particularly for what?
in ER due to shorter scanning times and quick availability
particularly for head and abdominal trauma
what imaging takes less time than MRI and US?
CT
how do you start to understand a CT image?
start with scout image
locate specific slice position and image
how do you read transverse plane slices of CT?
patient is supine so anterior surface is at the top of each image slice
looking upward at the anatomic structures from below so your right is patient’s left
how are sagittal plane slices viewed on CT image?
left to right
what are MRIs best at looking at?
soft tissue
how does an MRI work?
radiofrequency waves introduced in the presence of strong magnetic fields
what are major advantages of MRI?
less overlap like CT due to slicing
excellent at soft tissue abnormalities, cancellous bone, staging metastasis
no radiation like with CT and X ray
high resolution
what are major disadvantages of MRI?
contraindications with magnetic implants except for stable joint implants
precaution with claustrophobia
diagnosis from an MRI image is based on differences between T1 and T2. what does that refer to?
the time between magnetic pulses and when the image is taken
each type is used to assess different structures or conditions
In a T2 image, fluid is ____
bright
in a T1 image, fluid is _____
dark
in a T1 image bright signals are from and dark signals are from:
bright: fat and bone marrow
dark: cortical bone and fluid
what are T1 best for demonstrating?
anatomical definition of structure
in a T2 image bright signals occur from?
fluid and water
what are T2 best for demonstrating?
swelling and neoplasms particularly in cancellous bone
what two structures are often gray in both T1 and T2 images?
nerve
muscle
how does inflammation present on T1 images? T2?
low (dark)
high (white)
MRI has high __________ meaning:
sensitivity
so good at finding + that when it doesn’t you can really rule conditions out
which imaging is the least used?
ultrasound
how do ultrasound waves construct an image?
US waves are absorbed, reflected and diffused differently from varying tissues to construct an image
what are major advantages of US?
offers real time information for superficial soft tissue
higher resolution for superficial tendon, ligament and muscle than MRI
what are major disadvantages of US?
inability to scan deeper joint structures
image quality highly dependent on operator
what does a brighter signal indicate from an ultrasound?
swelling, tendinosis aka hyperechoic appearance
what do irregular borders or lack of structure indicate on an ultrasound?
tears
what does wider structure on an US indicate?
swelling, thickening
what imaging is excelllent for seeing muscle and tendons?
US and MRI
what imaging is good/excellent at seeing ligaments?
US (good)
MRI (excellent)
what imaging is excellent at seeing bone? Good?
CT (excellent)
US, MRI (good)
what imaging is excellent at seeing cartilage?
MRI
if there is no trauma, what questions should you consider when deciding whether to recommend imaging or not?
will the results of any imaging influence intervention or psychosocial factors?
what is the clinical decision rule for determining whether a patient should get imaging or not?
follow trauma based on supportive clinical findings
diagnostic and prognostic decisions
evidenced based with research
what are factors used for decision making under the appropriateness criteria for imaging recommendation?
age
trauma presense/absence
MOI
prior surgery/injury/imaging results
clinical findings, particularly P! provocation and function
what are the 4 possible outcomes of what you find on imaging vs your clinical findings?
- imaging (-) without clinical findings = normal/asymptomatic
- imaging (+) with matching clinical findings
- imaging (-) with clinical findings
— suspicious condition, no structural changes w/ symptoms - imaging (+) without matching clinical findings
— asymptomatic age related changes, unrelated findings contributing to symptoms, potential neg. effects on psychosocial status
