[Cerebral edema extending to the posterior limb of the internal capsule on MR imaging]

The features of edema extending to the posterior limb of the internal capsule (PLIC) were investigated in a review of MR imaging (MRI), with the following results. Edema was seen along the lateral and medial margins of the PLIC, although the PLIC itself was resistant to edema. The edema along the lateral and medial margins tended to extend into the lentiform nucleus and thalamus, respectively, and was considered to be edema of the extrapyramidal and thalamocortical tracts. When edema was abundant, the PLIC was traversed by many edematous tracts which seemed to connect the lentiform nucleus with the thalamus. The PLIC looked like a comb, and this finding was a good anatomical landmark on MR T 2-weighted images. We have used the term "comb appearance" to describe this finding.