Evaluation of parenchymal changes at the operation site with early postoperative brain diffusion-weighted magnetic resonance imaging.

PURPOSE To evaluate diffusion changes in the brain parenchyma at the operation site during the first 24 hours following surgery. MATERIALS AND METHODS The study group consisted of 52 patients, 39 who had tumor resection surgery and 13 who had epilepsy surgery. Early postoperative magnetic resonance imaging (MRI) included diffusion-weighted imaging (DWI) and routine contrast-enhanced cranial MRI, together with T2* weighted images on a 3T system. DWI findings and the presence of hemorrhage in the brain parenchyma were evaluated. Correlation between the findings, the primary lesion leading to surgery, and operation site were evaluated. RESULTS Diffusion restriction in the parenchyma surrounding the resection cavity was seen in 17 tumor patients (32.7%, n=52) and in 8 epilepsy patients (15.4%, n=52). DWI showed increased diffusion in 7 patients and no abnormality in 4 patients. Twenty patients showed restricted diffusion pattern related to hemorrhage (38.5%, n=52). CONCLUSION Restricted diffusion was the most common abnormality observed in the early postoperative DWI of brain parenchyma at the operation site after surgery, which suggested tissue injury caused by surgery. Yet, hemorrhaging in the operation bed can constitute another cause of a reduced apparent diffusion coefficient (ADC) value. Increased diffusion and normal diffusion can also be observed, though rarely.