Nimg-63. Spatial Characterization of 11c-methionine Pet and High B-value Dw-mri Tumor Subregions in Patients Undergoing Biologically-based Dose-intensified Chemoradiation on a Phase Ii Clinical Trial
Year: 2017
Type: conference-abstract
Abstract: Advanced imaging modalities including 11C-methionine PET (MET-PET) and high b-value diffusion MRI (DW-MRI) identify hypermetabolic and hypercellular tumor subregions and are prognostic for progression in patients undergoing chemoradiation for newly diagnosed glioblastoma (GBM)(1,2). We sought to characterize the relationship between these imaging modalities and conventional MRI. The initial 11 patients enrolled on a prospective phase II study (NCT02805179) of dose-intensified chemoradiation based on advanced imaging in patients with newly diagnosed GBM who underwent post-operative, pre-radiotherapy MET-PET and multiparametric MRI including high b-value DW-MRI (b=3000 s/mm2) were included in this study. Standard treatment volumes including Gd-enhanced tumor and surgical cavity (TVGd) and T2/FLAIR tumor volume (TVFLAIR) were outlined and compared with tumor subregions with abnormal uptake on MET PET (TVMET) and high b-value DW-MRI (TVHCV) using DICE correlation coefficient, defined using previously published methods. Median age was 65 years (56-77), 5/11 (45%) patients underwent subtotal resection, 2/11 (18%) biopsy alone, and 3/10 (30%) patients were MGMT methylated. Mean TVMET was 9.8 cc (0-25.9 cc), and mean TVHCV was 7.6 cc (1.7-20.4 cc), with the union on average 2.5x smaller than TVGd and 8.5x smaller than TVFLAIR. The mean volume of overlap between TVMET and TVHCV was only 1.6 cc (0-8 cc) and percentage overlap was 12% (0-34%), with no spatial overlap in 3 patients. No cases of TVMET and TVHCV extended beyond TVFLAIR, whereas 4 cc (1.1-12.5 cc) of combined TVMET and TVHCV extended beyond TVGd. TVMET and TVHCV subregions identified with known prognostic advanced imaging modalities demonstrate minimal spatial overlap and significant extension beyond the standardly boosted volume. Analyses correlating these subregions with recurrence and their relationship with other advanced imaging parameters before and during treatment are ongoing. Int J Radiat Oncol Biol Phys. 92(4):811-819, 2015. Int J Radiat Oncol Biol Phys. 73(2):479-85, 2009.
Source: Neuro-Oncology
Institution: University of Michigan
Language: English
Subfield: Genetics
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2767691797