NI-28 * ANALYSIS OF BEVACIZUMAB RESPONSE TO DISTINGUISH BETWEEN TUMOR RECURRENCE AND CEREBRAL RADIATION NECROSIS

Abstract

OBJECTIVE: Recurrent malignant gliomas are the disease stage difficult to control progressive tumor (PT). Most of them has a treatment history of radiotherapy and there are more than a few lesion with a component of cerebral radiation necrosis (RN) (Fujimoto, 2013). Bevacizumab (BEV) is a possible therapeutic option for RN as well as recurrent malignant glioma. In this study, we investigate the components of PT and RN in patients with recurrent malignant glioma by image analysis before and after administration of BEV. PATIENTS AND METHODS: Six patients with malignant glioma had been treated with radiation therapy. Their disease progression were identified, which contained a component of RN detected by MRI and 11C-methionine-PET (met-PET). All patients received BEV 5mg/kg every 2 week. We analyzed the lesion with MRI and met-PET. RESULTS: The enhanced lesions with high uptake (SUV > 1.8) in met-PET got decreased enhancement and stable apparent diffusion coefficient (ADC) value after BEV treatment, in which tumor recurrence appeared to occur. The enhanced lesions with low uptake (SUV < 1.8) in met-PET decreased both their enhancement and ADC value, in which no tumor recurrence was identified. CONCLUSION: It is difficult to distinguish between PT and RN because of both lesions have similar findings on MRI. Our findings suggests that the enhanced lesion decreasing ADC value followed by BEV mainly consists of RN. The changes of ADC value by BEV may be concerned with the declining neovascularity and interstitial edema.