FIG 2. 37-year-old woman with an aneurysm of the left posterior communicating artery who presented with subarachnoid hemorrhage (WFNS, grade II).

A, Before embolization, diffusion-weighted images (2825/92.6/1) show foci of slight hyperintense signal due to the presence of subarachnoid hemorrhage.

B and C, Two hours after embolization, four silent small lesions were observed on diffusion-weighted images (2825/92.6/1) (only two of the four lesions are shown [arrows, B]). An area of hypointense signal is seen on ADC maps (arrow, C), with decreased ADC values.

D and E, Twenty-four hours after embolization, lesions are more visible on diffusion-weighted images (D), with a fifth lesion (arrow) apparent in the posterior fossa. On ADC maps (E), decreased ADC values are seen as dark areas for all lesions (arrows), except for the small left frontal lesion. These silent lesions are not all related to the aneurysm's parent artery, and their origin remains uncertain.