CNS imaging Flashcards
what is tissue appearance in CT (dark to light)
air, fat, soft tissue, water, bone, metal
what is mutlidetector CT
allows volume to be scanned at a time
adv of multidetector
fast - can capture physio
allows reconstruciton
adv of CT
- fast
- available eerwhere
- can scan mutli parts
2 ways contrast can be injected
- intravenous
2. intrathecal
2 dis of CT
- radiation
2. contrast can cause renal dysfunction
what are 2 types of CT windowing
- soft tissue
2. bone
what are diffs in hounsfield units between 2 types
bone - large diff.
tissue - only a few
2 good uses of CT
- bone
2. blood
why is CT good for blood
high attenuation, good for acute sits.- can localize
what is epidural hematoma
blood leak into dural space after menigeal artery break - good at first and then deteriorate
characterisitics of epi hematoma
lentile shape, slow onset
what does acute subdural look like on CT
high density region
what does subacute look like
almost isodense
what does chronic look like
hypodense compared to parenchyma
what is cerebral contusion
brain hitting skull
2 types of cerebral contusion
- coup - direct hit
2. contre-coup - bounce back to the other side
test for spine fracture?
CT - fast and large areas
what is MRI measure of (3)
- number of protons in voxel
- T1 of tissue
- T2 of tissue
what is T1 relaxation
spin-lattice - relies on longitudinal relaxation
what shows on T1 (2)
fat - white
fluid - dark
what is T2 relaxation
spin-spin - relies on transverse relaxation
what shows on T2 (2)
fat - intermdiate bright
fluid - bright
what are 3 basic flavors of pulse sequences
- T1 - dark CSF
- PD weighted - CSF and everything is grey
- T2 - CSF is white
