Imaging Tutorial: Differential Diagnosis of Bright Lesions on Diffusion

Tadeusz W. Stadnik, MD, PhD; Philippe Demaerel, MD, PhD; Robert R Luypaert, PhD; Christo Chaskis, MD; Katrijn L. Van Rompaey, MD; Alex Michotte, MD; Michel J. Osteaux, MD, PhD

High sensitivity (94%) and specificity (100%) have been reported in the diagnosis of acute cerebral infarction with diffusion-weighted magnetic resonance (MR) imaging. However, high signal intensity on diffusion-weighted MR images and low apparent diffusion coefficient values (similar to the findings in acute cerebral infarction) were reported in such diverse conditions as hemorrhage, abscess, lymphoma, and even Creutzfeldt-Jakob disease. The differential diagnosis of these conditions (e.g., acute ischemic infarction and acute cerebral hemorrhage) is critical for the determination of appropriate treatment. The authors present a systematic review of bright lesions on diffusion-weighted MR images and their differential diagnosis, with emphasis on the practical and clinical approaches of differential diagnosis.