Background and purpose: Infarct patterns on brain imaging contribute to the etiologic classification of ischemic stroke. However, the association of specific subtypes of infarcts and etiologic mechanisms is often weak, and acute lesions are frequently missed on initial computed tomography (CT). Diffusion-weighted imaging (DWI) is superior in visualizing acute ischemic lesions as compared to CT and conventional magnetic resonance imaging (MRI). In our prospective study, we addressed the question whether a distinct pattern of infarction on DWI is associated with infarct etiology and clinical outcome.
Methods: Sixty-two patients with clinical signs of acute ischemic stroke and negative acute CT upon admission underwent DWI within 10 days after the ictus. Neurological status was documented using the NIH stroke scale. A scattered lesion pattern was defined by at least 2 separate hyperintense DWI lesions within the territory of one of the major cerebral arteries. Ischemic lesions were defined as acute if the region was demarcated strongly hyperintense in all DW images, and if the apparent diffusion coefficient was below normal.
Results: In 32 patients, DWI revealed a scattered lesion pattern, while in 30 patients a single acute lesion was detected. In patients with scattered lesions, potential arterial or cardiac embolic sources were detected in 26 patients (81.3%), as compared to 5 patients (16.6%) in the group with single lesions (chi(2) test, p < 0.0001). The neurological status of patients with scattered lesions improved significantly more than among patients with single lesions (Mann-Whitney test, p < 0.0003).
Conclusion: A scattered lesion pattern on DWI in patients with acute brain infarction and negative initial CT scan is associated with an embolic etiology and may indicate a favorable clinical outcome.
Copyright 2001 S. Karger AG, Basel