Background and purpose: New diffusion-weighted imaging (DWI) lesions are common in patients with acute ischemic stroke. They are associated with an initial nonsingle lesion pattern. Previous studies have not analyzed this association in detail. We differentiated nonsingle lesions in 1 vascular supply territory only (scattered lesion pattern) from nonsingle lesions in ≥2 vascular supply territory (multiple territory lesion -pattern).
Methods: Patients with an acute ischemic stroke underwent 3 MRI (3T) examinations: on admission, on the following day, and 4 to 7 days after symptom onset. First, DWI lesions were delineated manually by raters blinded to clinical details. Second, DWI images were coregistered and analyzed visually for new hyperintensities. The initial lesion pattern was categorized as single, scattered, or multiple territory.
Results: Of 340 patients enrolled, 43% had a single lesion pattern, 40% had a scattered lesion pattern, and 17% had a multiple territory lesion pattern. In multivariable analysis, the categorical variable lesion pattern was independently associated with new DWI lesions (odds ratio multiple territory lesion pattern, 3.64 [95% confidence interval, 1.75-7.58]; odds ratio scattered lesion pattern, 1.96 [95% confidence interval, 1.09-3.56]). Patients with multiple territory lesion pattern had significantly more often diabetes mellitus, and their new lesions were more often located remotely from the initial area of hypoperfusion compared with patients with scattered lesion pattern.
Conclusion: Lesion pattern on initial image is an independent risk factor for new DWI lesions. The risk for new DWI lesions is highest in patients with multiple territory lesion pattern.
Keywords: diffusion-weighted imaging; magnetic resonance imaging; new DWI lesions; silent brain infarction; stroke.