====== 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)
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===== 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)



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=====GRE/SWI/SWAN/T2===== 
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)




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