Brain MRI

Question 1

what is the difference between T1 and T2 MRIs?

Answer 1

they are complete opposites
so for T1:
-dark: water, fluids, CSF, gray matter
-bright: fat, white matter

and for T2:

• dark: fat, white matter
• bright: water, fluid, CSF, gray matter

Question 2

how is T1 commonly used?

Answer 2

used before and after contrast, with good gray/white matter contrast

Question 3

what is T2 sensitive to, and how does edema appear? what happens if it’s converted to FLAIR?

Answer 3

T2 is sensitive to water content, so edema appears bright

-FLAIR suppresses CSF signal, so ventricles appear darker (even darker than T1)

Question 4

what is Gadolinium contrast?

Answer 4

Gad-enhanced tissues and fluids appear bright on T1

• helps detect vascular tissues (tumors)
• helps assess brain perfusion (stroke)

Question 5

what is MR angiography used for?

Answer 5

evaluate stenosis or aneurysms

-can be reconstructed into 3D