A surgical strategy using a fusion image constructed from 11C-methionine PET, 18F-FDG-PET and MRI for glioma with no or minimum contrast enhancement

Abstract

The objective of this study was to investigate the distribution of 11C-methionine (MET) and F-18 fluorodeoxyglucose (FDG) uptake in positron emission tomography (PET) imaging and the hyperintense area in T2 weighted imaging (T2WI) in glioma with no or poor gadolinium enhancement in magnetic resonance imaging (GdMRI). Cases were also analyzed pathologically. We prospectively investigated 16 patients with non- or minimally enhancing (< 10% volume) glioma. All patients underwent MET-PET and FDG-PET scans preoperatively. After delineating the tumor based on MET uptake, integrated 3D images from FDG-PET and MRI (GdMRI, T2WI or FLAIR) were generated and the final resection plane was planned. This resection plane was determined intraoperatively using the navigation-guided fencepost method. The delineation obtained by MET-PET imaging was larger than that with GdMRI in all cases with an enhanced effect. In contrast, the T2WI-abnormal signal area (T2WI+) tended to be larger than the MET uptake area (MET+). Tumor resection was > 95% in the non-eloquent area in 4/5 cases (80%), whereas 10 of 11 cases (90.9%) had partial resection in the eloquent area. In a case including the language area, 92% resection was achieved based on the MET-uptake area, in contrast to T2WI-based partial resection (65%), because the T2WI+/MET- area defined the language area. Pathological findings showed that the T2WI+/MET+ area is glioma, whereas 6 of 9 T2WI+/MET- lesions included normal tissues. Tissue from T2W1+/MET+/FDG+/GdMRI+ lesions gave an accurate diagnosis of grade in six cases. Non- or minimally enhancing gliomas were classified as having a MET uptake area that totally or partially overlapped with the T2WI hyperintense area. Resection planning with or without a metabolically active area in non- or minimally enhancing gliomas may be useful for accurate diagnosis, malignancy grading, and particularly for eloquent area although further study is needed to analyze the T2WI+/MET- area.

18F-FDOPA PET and MRI characteristics correlate with degree of malignancy and predict survival in treatment-naïve gliomas: a cross-sectional study

“…In a prospective study of 16 glioma patients with <10% MRI CE tumor volume who also underwent preoperative 11C-methionine PET and 18F-FDG PET, the tissue from lesions positive for CE, T2 hyperintensity, 11C-methionine signal, and 18F-FDG signal gave an accurate diagnosis of grade in only 40% of cases [36]. Taken together with previous investigations[6, 7], these studies highlight the diagnostic dilemma of determining high-grade glioma based on MRI alone, or in combination with 11C-methionine PET and 18F-FDG PET, in the newly-diagnosed setting.…”

The Additional Value of 18F-FDG PET and MRI in Patients with Glioma: A Review of the Literature from 2015 to 2020

“…Furthermore, the extent of delineation by 11 C-MET PET was larger than 18 F-FDG-PET and Gd MRI, but smaller than a T2-w abnormal signal area. In five out of six patients, tumoral tissue extracted from the 18 F-FDG and Gd MRI positive areas presented anaplastic features, whereas tissue extracted from 18 F-FDG and Gd MRI negative areas resulted in grade II glioma at pathological examination [34]. Based on these findings, 11 C-MET PET appears superior to 18 F-FDG for tumor delineation.…”

Current and Future Imaging Methods for Evaluating Response to Immunotherapy in Neuro-Oncology

“…The most common PET amino acid analogs target system L amino acid transporters and include L-[ 11 C]methionine ([ 11 C]MET, Figure 1E,F), O -(2-[ 18 F]fluoro-ethyl)-L-tyrosine ([ 18 F]FET), and 3,4,-dihydroxy-6-[ 18 F]fluoro-l-phenylalanine ([ 18 F]FDOPA). System L amino acid transporters are overexpressed in malignant glioma and CNS metastases relative to normal cells 45, 88-93. Low background uptake of amino acid analogs in normal brain provides increased contrast in brain tumors with these imaging agents.…”