Fig 2. Patient 8. A, Initial unenhanced CT shows parenchymal hypoattenuation and loss of gray-white matter distinction in the left frontal lobe of ACA and MCA territory (arrows). Echo-planar spin-echo T2-weighted image (EPI T2, DWI of b value of 0, TR, 6500 ms; TE, 96.8 ms) shows no hyperintensity in the left frontal lobe. DWI (6500/96.8) and ADC map show hyperintensity and reduced ADC only in the medial frontal cortex and precentral gyrus that are only a part of hypoattenuated ischemic lesion depicted on CT. Perfusion maps show a TTP delay in the DWI lesion but no significant perfusion abnormality in the left frontal lobe lesion with reversed discrepancy on CT and DWI (arrowheads). MRA shows decreased signal intensity of the left distal MCA branches (arrow) and there was occlusion of the left A2 on MRA (not shown).

B, Follow-up MR images at day 1 show delayed DWI hyperintensity and ADC decrease in the left frontal lobe lesion with reversed discrepancy (arrows) and more severe cytotoxic edema in the medial frontal cortex and precentral gyrus of the left frontal lobe. Follow-up MRA shows recanalization of distal MCA branches but persistent perfusion abnormality in the ischemic lesion found on the initial DWI.

C, Follow-up CT image obtained 7 days after the initial CT demonstrates ischemic edema with heterogeneous hypoattenuation in the left frontal lobe. CT image obtained 11 months after the initial CT shows overt infarction with necrosis in the lesion with reversed discrepancy.