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:

1. T2 FLAIR
2. T1 post-contrast
3. DWI
4. GRE/SWI/SWAN/T2*

“What is grossly abnormal?” anything abnormal = bright on T2 FLAIR

“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)

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)

This helps to distinguish nuances among entities on your differential. In general, abnormal = dark (blood, vascularity, &c; abscesses tend to have dark rims on SWI)