Vessel Imaging
Cerebral vessels: CTA head is better than MRA head. (You can see aneurysms better.)
Order of best to worst image quality of cerebral vessels: Angio > CTA +c > MRA +c > MRA/V time of flight (-c)
Neck vessels: MRA neck +c dissection protocol w/ black blood
For neck dissections, it’s unclear whether CTA or MRA is better
CTA and MRA can overestimate degree of stenosis compared with CDs and DSA
CT Perfusion
CBV – decreased cerebral blood volume tells you the area of infarct
CBF – decreased cerebral blood flow tells you the area of ischemia
MTT – mean transit time, tells you area of ischemia
TTP – time to peak, tells you area of ischemia
MRI Sequences
DWI: T2 weighted trace = Isotropic image
ADC: w/acute stroke, will stay dark for 7-10 days
SWI/GRE: old/new blood products ‘bloom’, 100% sensitive for SAH at 4d.
Blood Aging on MRI:
