A comparison study of ¹¹ C-methionine and ¹⁸ F-fluorodeoxyglucose positron emission tomography-computed tomography scans in evaluation of patients with recurrent brain tumors

Abstract

Introduction:11C-methonine ([11C]-MET) positron emission tomography-computed tomography (PET-CT) is a well-established technique for evaluation of tumor for diagnosis and treatment planning in neurooncology. [11C]-MET reflects amino acid transport and has been shown to be more sensitive than magnetic resonance imaging (MRI) in stereotactic biopsy planning. This study compared fluorodeoxyglucose (FDG) PET-CT and MET PET-CT in the detection of various brain tumors.Materials and Methods:Sixty-four subjects of brain tumor treated by surgery, chemotherapy, and/or radiotherapy were subjected to [18F]-FDG, [11C]-MET, and MRI scan. The lesion was analyzed semiquantitatively using tumor to normal contralateral ratio. The diagnosis was confirmed by surgery, stereotactic biopsy, clinical follow-up, MRI, or CT scans.Results:Tumor recurrence was found in 5 out of 22 patients on [F-18] FDG scan while [11C]-MET was able to detect recurrence in 18 out of 22 patients in low-grade gliomas. Two of these patients were false positive for the presence of recurrence of tumor and later found to be harboring necrosis. Among oligodendroglioma, medulloblastoma and high-grade glioma out of 42 patients 39 were found to be concordant MET and FDG scans. On semiquantitative analysis, mean T/NT ratio was found to be 2.96 ± 0.94 for lesions positive for recurrence of tumors and 1.18 ± 0.74 for lesions negative for recurrence of tumor on [11C]-MET scan. While the ratio for FDG scan on semiquantitative analysis was found to be 2.05 ± 1.04 for lesions positive for recurrence of tumors and 0.52 ± 0.15 for lesions negative for recurrence of tumors.Conclusion:The study highlight that [11C]-MET is superior to [18F]-FDG PET scans to detect recurrence in low-grade glioma. A cut-off value of target to nontarget value of 1.47 is a useful parameter to distinguish benign from malignant lesion on an [11C]-MET Scan. Both [18F]-FDG and [11C]-MET scans were found to be useful in high-grade astrocytoma, oligodendroglioma, and medulloblastoma.

Diagnostic Accuracy of PET Tracers for the Differentiation of Tumor Progression from Treatment-Related Changes in High-Grade Glioma: A Systematic Review and Metaanalysis

“…In 26.6% (n 5 221) of lesions, follow-up was not specified on the individual lesion level. Several of the included studies analyzed 2 PET tracers per lesion (21,29,(33)(34)(35)41,46,52,53); in total, 951 PET studies (Supplemental Table 5 shows the tracer distribution) were included.…”

“…Fifth, the comparisons between different PET tracers in this review lack statistical support, as this metaanalysis contains largely noncomparative studies of the different PET tracers. Only 2 studies compared 18 F-FDG and 11 C-MET in the same patient population (21,46). We did not directly compare the PET tracers, because the differences in study design, patient groups, and reference standards can confound the differences in diagnostic accuracy (60).…”

The performance of 11C-Methionine PET in the differential diagnosis of glioma recurrence

“…After screening the records for duplications, only 41 of them were potentially eligible for further full text evaluation. In all, 23 articles with a total sample size of 891 patients representing 899 scans that met all inclusion and exclusion criteria were included for the meta-analysis [ 7 – 9 , 11 – 30 ]. The PRISMA flow diagram of the study selection process is displayed in Figure 1 , and the basic characteristics of all 23 articles are summarized in Table 1 .…”

“…Positron emission tomography (PET) is a promising imaging modality that has been extensively applied in the field of neuro-oncology. The 11C-methionine has been reported to be an excellent tracer for PET imaging, and many prior studies have reported the use of 11C-methionine PET for identifying recurrent tumors [ 7 – 9 ]. In a previously published meta-analysis [ 10 ], the performance of 11C-methionine PET in distinguishing glioma recurrence was evaluated, but it included few studies and lacked a comprehensive subgroup analysis.…”

Emerging Functional Imaging Biomarkers of Tumour Responses to Radiotherapy

“…11 C-methionine has been the most widely used amino acid PET tracer. It can differentiate tumours from normal brain with an accuracy of 94% versus 80% for 18 F-FDG [151] and is also more sensitive for differentiating recurrence from radiation necrosis following radiotherapy [152]. However, the application of 11 C-labelled substrates will always be limited by the short half-life (20 min) requiring onsite production of the tracer.…”