Significance of acute multiple brain infarction on diffusion-weighted imaging.

BACKGROUND AND
PURPOSE: Diffusion-weighted imaging (DWI) is superior to conventional MRI in identification of small new ischemic lesions and discrimination of recent infarcts from old ones. Thus, this technique is useful in the detection of acute multiple brain infarcts (AMBI). We sought to determine the frequency and the topographical and etiologic patterns of AMBI detected on DWI.
METHODS: We studied 329 consecutive ischemic stroke patients who underwent DWI and MRI/MR angiography within 4 days of stroke onset. AMBI was defined as noncontiguous high signal intensities on DWI in >1 vascular territory. Stroke mechanism was determined according to the criteria of the Trial of Org 10172 in Acute Stroke Treatment (TOAST).
RESULTS: We detected AMBI in 95 patients (28.9%). AMBI in anterior circulation was found in 62 cases: in 1 hemisphere in 42 (group A) and in bilateral hemispheres in 20 (group B). Twenty-two patients had AMBI in the posterior circulation (group C) and 11 in both anterior and posterior circulations (group D). The most frequent cause of stroke was large-artery atherosclerosis in groups A (33/42), B (9/20), and C (15/22) (P=0.02) and cardioembolism in group D (6/11) (P=0.02). Elevated fibrinogen or hematocrit was significantly associated with group B (P=0.01). In 9 patients in groups B and D, anatomic variations of anterior or posterior cerebral arteries or patent posterior communicating artery contributed to AMBI.
CONCLUSIONS: Different topographical patterns of AMBI are associated with different vascular pathologies and stroke mechanisms. Hemorheologic abnormality or vascular anatomic variations may be contributing factors in the pathogenesis of AMBI in bilateral cerebral hemispheres or in both anterior and posterior circulations.