Neuroimaging Essentials Flashcards
What is the contrast agent used with MRIs?
Gadolinium
What contrast dyes are used in CT scans?
Iodine based contrast
What generates the MRI signal?
Protons spinning on their axis- they align with the axis of the magnet of the MRI.
Rotation of the magnetic vector generates an electrical signal that is detected by a receiving coil
What time does a T1 scan record?
time of recovery of the of the excited spins
What times does a T2 MRI scan record?
How quickly the MR signal fades after excitation
WHat does it mean to be T1 or T2 weighted?
MRI scans are T1 weighted or T2 weighted based on the time interval between excitation pulses
Which MRI protocol is better for looking at normal anatomy?
T1
WHat color is CSF in a T1 weighted MRI?
CSF is dark in T1 weighted MRI
What color is CSF in a T2 weighted MRI?
CSF is bright (high signal)
Which MRI protocol is better for looking at pathology?
T2
What is FLAIR?
FLAIR is a T2 weighted MRI scan in which the CSF fluid hyperdense signal is removed from the images
How do lesions appear on a T2 FLAIR MRI scan?
Most lesions appear bright
Which imaging technique provides the earliest infarct detection?
DWI MRI - since water diffusion is impaired in infarcted tissue
How do infarcts appear on T2W or FLAIR MRI?
THey appear hyperdense/brightness within a vascular territory
How to ischemic infarcts appear on CT?
hypodensity or lucency with within a vascular territory
