False-Negative Diffusion-Weighted Imaging in Acute Stroke and its Frequency in Anterior and Posterior Circulation Ischemia

Objective: We aimed to investigate the location and size of ischemic stroke lesions that were frequently overlooked by diffusion-weighted imaging (DWI). Materials and Methods: We retrospectively reviewed the medical records of 162 patients who had symptoms suggesting ischemic stroke. National Institutes of Health Stroke Scale and Modified Rankin Scale scores, lesion size, magnetic resonance imaging (MRI) findings, delay between onset of symptoms and initial MRI (MRI latency), and vascular distribution of the stroke lesions were analyzed in patients with false-negative DWI findings. Results: Of the 116 patients with a final diagnosis of acute ischemic stroke, 11 patients (9.48%) had false-negative DWI findings in the initial period. The mean (SD) MRI latency was 4.3 (1.2) hours. There was no statistically significant difference in point of lesion size, the National Institutes of Health Stroke Scale, and the Modified Rankin Scales scores. Conclusions: False-negative DWI findings in acute stroke can be observed both in association with the posterior circulation/small lesions and the anterior circulation/large lesions.