Diffusion

Q: What is the second set of images (bright CSF) in the diffusion series?

A: They are the b 0 images (b=0 s/mm2)

Q: What is it good for?

A: They are T2 EPI images which can show susceptibility effects that may not be apparent on the FSE T2 images. We have a GRE sequence that is better at showing susceptibility effects.

We send exponential ADC(apparent diffusion coefficient) and ADC images to PACS. ADC should help us differentiate T2 “shine-through” from restricted diffusion

Q: What entities are bright on the diffusion series?

A: Infarct, abscess, epidermoid, some tumors (e.g. lymphoma, “small blue cell tumors”), some meningiomas, MS placques can be bright, hematomas (oxyhemoglobin and extracellular methemoglobin, other blood products have susceptibility effects masking restricted diffusion on the diffusion trace image (“T2 blackout effect”, (deoxyhemoglobin, intracellular methemoglobin, and hemosiderin) the ADC map can not be trusted in these cases. HSS 2638948 (thanks to Vikash Singh '15)  

for the interested reader see http://radiographics.rsna.org/content/23/1/e7.abstract

Also see Case-in-Point (7/26/2012) regarding Transient Splenial Lesions

http://3s.acr.org/CIP/CaseView.aspx?CaseId=7sZ9al9/blo=