Perfusion-weighted imaging of peritumoral edema can aid in the differential diagnosis of glioblastoma mulltiforme versus brain metastasis

Background: MRI differentiation between metastases and high grade gliomas is a challenging task. Contrast enhancement and size of edema do not provide clear-cut differentiators. The differences in the properties of the peritumoral edema between these tumor types may be exploited to distinguish between them, using MRI perfusion sequences, which are capable of imaging edema in the clinical setting and may be a reliable method to make this differentiation. Objectives: To assess the ability of perfusion-weighted imaging to differentiate between high grade gliomas and brain metastases. Methods: During 5 months, 21 patients (age 40-85, median age 61, 16 males and 5 females) with either glioblastoma multiforme (GBM) or metastasis (pathology proven), underwent MRI for assessment of the tumor prior to surgery. Most of the scans were done at 3 Tesla. The scans included perfusionweighted imaging sequences. Perfusion in the tumor, in the peritumoral edema and in normal tissue were assessed using Functool® software. The ratios of tumor perfusion and peritumoral edema perfusion to normal tissue perfusion were calculated and compared. Results: Bleeding artifact precluded perfusion assessment in four patients. There was no statistically significant difference between the tumor perfusion ratios of high grade gliomas and those of metastases. The edema perfusion ratios were higher in GBM than in metastases (P = 0.007). Conclusions: Perfusion-weighted imaging of peritumoral edema can help to differentiate between GBM and metastases.