Imaging Study of Glioblastomas Treated With Avastin

Overview

This study aims to assess the effect of Avastin on brain vascularity and blood-brain permeability using dynamic contrast ct scans (DECT) and MRI imaging. Previous publications have documented the method by which DECT can determine alterations in vascular volume and tissue permeability within tumors and normal brain tissue. Functional maps of cerebral blood flow cerebral blood volume and permeability-surface area can be generated from the DECT studies to assess tumor perfusion. MRI spectroscopy analyzes brain chemistry to detect tumour versus edema versus normal brain. Thirty patients will receive MRI spectroscopy and DECT imaging at the time of presumed recurrence and 3 months later. 15 patients who do not receive Avastin and 15 patients who do receive Avastin as standard treatment for recurrence will be studied with DECT and MRI spectroscopy at baseline and then again in 3 months.

The clinical determination of the point of tumour progression or response is difficult to determine using standard diagnostic imaging ie CT/MRI especially following previous treatment with surgery, radiation and chemotherapy. Hemorrhage, edema, inflammation and vascular necrosis. Both MR spectroscopy and DECT have been reported as being able to define areas of recurrent tumour as opposed to treatment-related effects. We wish to investigate the correlation between MR spectroscopy and DECT in assessing tumour progression or response to Avastin in comparison with patients not receiving Avastin. Health Canada has approved Avastin for clinical use in patients with recurrent glioblastoma who have previously received temozolomide and radiotherapy. We propose to perform a DECT scan at baseline at presumed tumour progression and again 3 months to determine the effects of tumour progression/response on blood brain barrier permeability and vascular volume. The group of 15 patients will be compared to a group of 15 patients who do not receive Avastin at recurrence involving DECT scanning and MR spectroscopy at the time of the radiological progression and 3 months later.