Perfusion MRI in the Evaluation of Cerebral Blood Volume and Mean Transit Time in Untreated and Recurrent Glioblastomas

Perfusion MRI by means of dynamic contrast-enhanced T2-weighted MR imaging allows quantitative analysis of cerebral blood volume (CBV) and mean transit time (MTT) in intraaxial brain tumors. Our aim was to compare recurrent glioblastomas to untreated glioblastomas, determining if there are differences in perfusion parameters between the two groups. Serial MR examinations were performed in 26 patients with glioblastoma histologically demonstrated before surgical resection and in 19 patients with recurrent glioblastoma after surgery and radiotherapy. Tumor recurrence was established using both histological and clinical criteria. Normalized CBV and MTT ratios were considered and compared between the two groups. A statistically significant difference, both in average and maximum normalized CBV ratios between the two groups was found. In particular, average and maximum normalized CBV ratios were greater in untreated than in recurrent glioblastomas. On the contrary, average and maximum normalized MTT ratios were greater in the recurrent glioblastomas, than in untreated tumors. Perfusion MRI by means of dynamic contrast-enhanced T2-weighted MR imaging is a valuable adjunct to conventional MR imaging in assessing different hemodynamic features between untreated and recurrent glioblastomas. In particular, tumor recurrence must be suspected even if the average and maximum normalized CBV ratios are far below those of untreated glioblastomas. In addition, increased average and maximum MTT ratios could be considered typical markers of neoplastic recurrence in irradiated cerebral tissue.