fig 7.

Primary brain tumor in a 72-year-old woman scanned 30 hours after developing aphasia and slurred speech.

A, Diffusion-weighted image with b = 1000 s/mm² is negative for acute infarcts, but an isointense irregularity of the cortical sulci is noted along the left sylvian fissure.

B, Diffusion-weighted image at b = 2500 s/mm² demonstrates a large low-signal lesion along the left sylvan fissure and in white matter posterior to the posterior horns of the lateral ventricles, representing increased diffusion that was not appreciated at b = 1000.

C, Diffusion-weighted image at b = 3000 s/mm² also demonstrates these low-signal lesions not seen at b = 1000.

D, Fast spin-echo T2-weighted image reveals a high signal along the left sylvian fissure and posterior to the posterior lateral ventricles, corresponding to the low-signal lesions seen on the diffusion-weighted images at b = 2500 and b = 3000. Stereotactic biopsy confirmed the large lesion to be an oligostrocytoma.