written practical Flashcards
failure to refer for imaging =
non-feasance
who reviews “studies” and gives written explanation of findings? (clinical diagnosis)
radiologist
X-ray Technician
18 month degree with clinicals
speciality certifications available
general rules / considerations for imaging
- no radiographs for pregnant women
- some risk for development of cancer with repetitive exposure
- use of clinical prediction rules & physical exam used to limit exposures
EXAMPLES of clinical prediction rules and physical exam used to limit exposures
ottowa ankle rules
non-displaced growth plate fractures
clear, focus initiative to ______ pediatric patients exposure to radiographs
limit
what is a radiography?
(x-ray)
electromagnetic radiation passed thru a structure
what tissue shows up dark in a x-ray?
lass dense tissue (soft tissue)
what tissue shows up bright white in a x-ray?
bony tissue
what does an x-ray rule out (R/O) ?
fracture
foreign objects
degenerative disk disease
mal-alignments
facet joint dysfunction
lungs appear ________ in x-ray
dark
fat appears ________ in x-ray
grey
bone appears ________ in x-ray
bright white
what can be used during x-ray?
contrast agent (dye)
but often reserved for MRI and CT
when do we need an x-ray?
primary uses (indications)
considerations for x-ray usage:
inexpensive
accessible
quick
generally comfortable
ABCs
A - assess general skeletal structure
A - assess general contour
B - general bone density
C- cartilage space
Assess general skeletal structure
- gross size and appearance
- presence of accessory bones
- congenital anomalies
- absence of bones
- deformity
Assess general contour
- irregular in cortical outlines
- presence of osteophytes
- break in continuity of cortex
- angles in cortex
- muscles, tendon, ligament attachment
- previous surgical sites
general bone density
- adequate contrast between bone and surrounding
- adequate contrast within bone including distinct cortex
- bone density influenced by age, activity level, disorders
texture abnormalities:
altered trabecular appearance is hallmark of disease process
cartilage space:
- well preserved joint space indicates that cartilage is normal thickness
- joint space identified as “potential space” or “radiographic joint space”
- specific to the joint and best measured in WB
epiphyseal plate in growing child are . . .
cartilaginous
why are epiphyseal plates evaluated?
for size comparing skeletal maturity to age
epiphyseal plate borders bound by . . .
smooth margin with band of sclerosis
may need _______________ for comparison
contralateral films
radionuclide bone scan
- nuclear imaging
- short-lived radionuclide to assess abnormalities in bone tissue
bone scan
- tracer is injected (emits gamma radiation)
- circulates through body (30 m - 2 hrs)
- special camera reveals “hot spots” on bone
- indications
what are “hot spots” ?
areas of increased metabolic activity
what do bone scans rule out?
fracture, infections, tumors, arthritis
fluoroscopy
- ionizing radiation
- allows for “real-time image”
(used during clinical procedures) - indications/uses are similar to x-rays
- clarity depends on power and type of machine
what does PET stand for?
positron emission tomography
what is a PET used for?
to examine the cell metabolism and biochemistry of tissue and organs
- used extensively to identify cancers, thyroid conditions, infections, bleeding
what kind of injection for a PET scan?
radionuclide injection
what does MRI stand for?
magnetic resonance imaging
what is an MRI?
- applies a magnetic field to the body (body atoms align along magnetic field, releasing radio wave)
MRI indications:
to image organs, soft tissue, bone, tumors, bleeding, inflammation, infection
what kind of imaging is used extensively in orthopedics, ortho-spine & neurology?
MRI
MRI considerations:
- excessive movement can cause blurry images
- claustrophobia
- no radiation
- cannot have any metal present
- high cost!!
what are the two types of MRIs?
T1 & T2
T1 weighed image:
fluid: low signal intensity (black)
muscle: intermediate signal intensity (grey)
fat: high signal intensity (white)
CNS/brain:
- grey matter: intermediate signal intensity (grey)
- white matter: hyperintense compared to grey matter (white-ish)
T2 weighed image:
fluid: high signal intensity (white)
muscle: intermediate signal intensity (grey)
fat: high signal intensity (white)
CNS/brain:
- grey matter: intermediate signal intensity (grey)
- white matter: hypointense compared to grey matter (dark-ish)
MR arthrogram
adds dye into the structure
MR arthrogram good for ID of:
- cartilage lesions
- neuro-trauma
ultrasound:
uses non-thermal sound wave to image soft tissue structures
clarity depends on machine & level of skill of the technician
ultrasound indications:
- image musculoskeletal structures
- used to guide clinical procedures
Doppler US:
ID blood flow / obstruction of blood flow (thromboembolism)
what does CT stand for?
computed tomography
CT scan
- ionizing radiation (larger dose than x-ray)
CT of the skull & brain (spinal cord) indications:
non-contrast (most common)
- numerous: stroke, trauma, headaches. tumors seizures, change in mental status
combination of non-contrast & post-contrast study
combination of non-contrast & post-contrast is . . .
less common
combination of non-contrast & post-contrast is performed when?
brain tumors or abscesses are suspected & patient cannot get MRI
- IV contrast is also given to assess vasculature
CT scan of skull/ brain/ spinal cord findings are discussed in terms of __________.
densities
white
hyperdense
- bone, calcium deposits, fresh blood, melanin, contrast
grey
isodense
- brain parenchyma, glial tumors, subacute blood
dark grey
hypodense
- CSF, brain edema, fat, chronic blood
black
hypodense
- air
MRI of the brain indications:
- confirmation of stroke
- assessment of intracranial tumor
- chronic headache
- seizure disorder
- demyelinating disorder
GAD =
gadolinium (multiple sclerosis)
MRI of the brain benefits:
- multiplanar assessment
- different sequences allow for assessment of different pathology
- no ionizing radiation (good for children)
MRI of the brain limitations:
- much longer study (20-40 minutes)
- less available
- issues with claustrophobic patients
- contraindicated in patients with metallic fragments or implants
MRI of the brain findings are discussed in terms of ____________
intensities
MRI of brain : T1
fluid is dark
grey matter is darker than white matter
MRI of brain : T2
fluid is bright
white matter is darker than grey matter
what does FLAIR stand for?
fluid attenuation inversion recovery
FLAIR is similar to _____, but . . .
T2
fluid is “suppressed” and is therefore dark
what is FLAIR useful for?
assessing edema / inflammation
FLAIR involves
DWI (diffusion-weighted imaging)
ADC (apparent diffusion coefficient)
what imaging can be used for spinal column?
x-rays
MRI
CT
cervical MRI indications:
- neurologic signs & symptoms referable to the cervical spine
- soft tissue injury evaluation
neurologic signs & symptoms referable to the cervical spine : assessing for . . .
disc herniation
cervical stenosis
soft tissue injury evaluation : assessing for . . .
ligamentous injury
tumors or infections
cervical MRI : T1
fluid is dark
cervical MRI : T2
fluid is bright
what does STIR stand for?
short tau inversion recovery
what is STIR?
fat suppression technique that is used to assess for soft tissue injuries
thoracic / lumbar x-ray confirm / monitor what?
scoliosis
how many lobes does the right lung have? and what are they?
3:
superior
middle
lower
how many fissure does the right lung have? and what are they?
2
horizontal
oblique
how many fissure does the left lung have? and what are they?
1
oblique
how many lobes does the left lung have? and what are they?
2
superior
inferior
