Introduction to MRI Flashcards
what happens in T1 relaxation?
realignment with the magnetic field
what are T1 weighted images like with repetition time and time to echo?
repetition time is short
time to echo is short
what does CSF look like in T1 weighted images?
CSF is dark
what does CSF look like in T2 weighted images?
CSF is bright
what does a flair MRI look like?
T2 weighted but CSF appears dark
what is flair useful for?
differentiates CSF from pathology
what is T2* (star sequence) useful for?
to detect hemorrhage
cannot distinguish from mineralization
what is stir like?
fat appears dark
what is stir good for?
bone and orbit pathology
what is DWI/ADC (diffusion weight images) map good for?
ischemia
when is vasogenic edema bright?
T2w
FLAIR
what is a mass effect on an MRI?
midline shift
ventricular compression
displacement of adjacent structures
herniation
hydrocephalus
syringohydromyelia
what is T1 relaxation?
realignment with magnetic field
what is T2 relaxation?
stop spinning synchronously
what are T2 weighted images like with repetition time and time to echo?
both long
what do T1 weighted images look like?
fat bright
CSF dark
what do T2 weighted images look like?
fat bright
CSF bright
what does hemorrhage look like on a T2* image?
dark
what images are good for ischemia?
diffusion weighted images
ADC map
what are T1 weighted images good for?
anatomy and post contrast
what is leptomeningeal (pial) enhancement?
visualization of meningeal enhancement that follows the gyri into the sulci
how can you tell something is extraaxial?
broad-based
strong enhancement
displace brain tissue
distort white matter
can cause bone reaction
can expand ipsilateral subarachnoid space
dural tail
what are intraaxial lesions like?
surrounded by brain tissue
invade, expand substance of brain
lesions spread across well-defined borders
variable enhancement
no extracerebral changes
