Quick yet systematic approach to MR imaging of brain lesions
In general, there are 4 MR sequences that will tell you 99% of what you need to know:
- T2 FLAIR
- T1 post-contrast
- DWI
- GRE/SWI/SWAN/T2*
T2 FLAIR
“What is grossly abnormal?” anything abnormal = bright on T2 FLAIR
T1+gadolinium
“Where is the BBB disrupted?” Also:“What is the vascular composition?” Always compare T1+gad sequences to pure T1 without contrast (if also bright on pure T1, then BBB not necessarily disrupted)
DWI
Bright = abnormal = “diffusion-restricting” = could be hypercellularity, ischemia, demyelination, abscess, &c The above applies only if the corresponding area is dark on ADC sequence (if also bright on ADC, then just T2 shine-through)
Discussion