Brain metastases are increasingly common tumours but little is known about their biological mechanisms of local brain invasion in vivo. Samples across the leading edge are not easy to obtain using conventional neurosurgical methods as these tumours frequently show cysts, haemorrhage and necrosis. Apparent diffusion coefficient (ADC) maps were generated following diffusion-weighted imaging at 3T using b-values of 0 and 1000 second/mm(2) and fused with a 1 mm slice fast spoiled gradient echo sequence. This fused image was used to guide intraoperative biopsies. The technique was performed in ten cases with excellent sampling of the brain-to-metastasis interface, gross total resection and no additional morbidity. Fusing ADC maps with structural scans for intraoperative neuronavigation is a useful method for sampling the leading edge of brain metastases.
Keywords: ADC; DWI; brain metastasis; diffusion MRI; neurosurgery.