imaging midterm Flashcards
sensitivity
SnNout
negative, out
good for ruling out if test is negative
specificity
SpPin
positive, in
good for ruling in if test is positive
potential errors in imaging
pt mistaken for another
wrong extremity
less obvious injuries missed
areas of referred pain imaged not area of symptoms
misinterpreted by radiologist
poor quality images
ordering images
understand most current standards
evidence base screening
mech of injury and location
brief anatomically correct descriptions
can request priority for routine, serious, life threatening
relevance of pathology
comprehensive history and physical examination
radiologist suggests clinical correlation
interpretation
interpreting rests primarily with radiologist
skilled review
reflective imaging
ultrasound and MRI
energy inserted into system, captured, and converted into and image when returned
ultrasound
form mechanical compression of molecules
MRI
combination of electromagnetic and radio energy to produce signals from body that can be collected and analyzed to produce an image
ionizing radiation
x-rays, CT
require ionizing radiation exposure with attendant risks
CT
IR penetrates matter and creates image through computer
hounsfield units- over 2000 levels between black and white
water point in hounsfields
negative 1000
air point in hounsfields
postive 1000
what is CT good for?
bony pathologies
what is MRI good for?
soft tissue pathologies
emission imaging
bone scan
add radiopharmaceutical agent in blood
shows areas with increased metabolic activity
are bony scans binary
yes, give either yes or no answer.
they demonstrate only increased metabolic activity, not the cause
are bone scans diagnostic?
no, they are also non-specific
what are bone scans used for
injuries to skeleton
degenerative changes
extent of certain metastatic lesions
are bone scans good for fractures?
bone scans are time sensitive and positive in case of fractures, such as overuse or stress syndromes
are bone scans expensive?
bone scans are more expensive than standard films, but significantly less expensive than CT or MRI
standard x-ray films
follows series of analytical steps
requires knowledge of anatomy and spatial relationships
creates bony displacement or reactions such as lesions in surrounding skeletal structures
cost-effective and highly specific for skeletal pathology
ionizing radiation
air density
most radiolucent and absorbs least number of particles
darkest portion
fat density
considered radiolucent
not as dark as air, but darker than others