Positron emission tomography (PET) using L-[methyl-(11)C]-methionine (MET) is the most popular amino acid imaging modality in oncology, although its use is restricted to PET centers with an in-house cyclotron facility. This review focuses on the role of MET-PET in imaging of cerebral gliomas. The biological background of tumor imaging with methionine is discussed with particular emphasis on cellular amino acid transport, amino acid utilization in brain, normal metabolism of methionine, and its alterations in cancer. The role of MET-PET in clinical management of cerebral gliomas in initial diagnosis, differentiation of tumor recurrence from radiation injury, grading, prognostication, tumor-extent delineation, biopsy planning, surgical resection and radiotherapy planning, and assessment of response to therapy is also reviewed in detail.

Objectives The role of the norepinephrine transporter (NET) in cocaine dependence has never been demonstrated via in vivo imaging due to the lack of suitable NET radioligands. Here we report our preliminary studies evaluting the NET in individuals with cocaine dependence (COC) in comparison to healthy controls (HC) using (S,S)-[11C]methylreboxetine ([11C]MRB), the most promising C-11 labeled positron-emission tomography (PET) radioligand for NET developed to date. Methods Twenty two human volunteers (10 COC and 12 HC) underwent dynamic 11C-MRB-PET acquisition using a High Resolution Research Tomograph (HRRT). Binding potential (BPND) parametric images were computed using the simplified reference tissue model (SRTM2) with occipital cortex as reference region. BPND values were compared between the two groups. Results Locus coeruleus (LC), hypothalamus, and pulvinar showed a significant inverse correlation with age among HC (age range = 25–54 years; p = 0.04, 0.009, 0.03 respectively). The BPND was significantly increased in thalamus (27%; p < 0.02) and dorsomedial thalamic nuclei (30%; p < 0.03) in COC as compared to HC. Upon age normalization, the upregulation of NET in COC also reached significance in LC (63%, p < 0.01) and pulvinar (55%, p < 0.02) regions. Conclusion Our results suggest that (a) brain NET concentration declines with age in HC, and (b) there is a significant upregulation of NET in thalamus and dorsomedial thalamic nucleus in COC as compared to HC. Our results also suggest that the use of [11C]MRB and HRRT provides an effective strategy for studying alterations of the NET system in humans.

[ 11 C]P943 is a new radioligand recently developed to image and quantify serotonin 5-Hydroxytryptamine (5-HT 1B ) receptors with positron emission tomography (PET). The purpose of this study was to evaluate [ 11 C]P943 for this application in humans, and to determine the most suitable quantification method. Positron emission tomography data and arterial input function measurements were acquired in a cohort of 32 human subjects. Using arterial input functions, compartmental modeling, the Logan graphical analysis, and the multilinear method MA1 were tested. Both the two tissue-compartment model and MA1 provided good fits of the PET data and reliable distribution volume estimates. Using the cerebellum as a reference region, BP ND binding potential estimates were computed.

The aim of this study was to compare the grading and prognostic value of L-[methyl-11 C]-methionine ( 11 C-MET) PET in glioma patients with 18 F-FDG PET and contrast-enhanced MRI. Methods: Patients (n 5 102) with histopathologically confirmed gliomas were followed up for an average of 34.6 6 3.8 mo after PET. The median survival was 18 6 4.7 mo in the high-grade glioma group and 58 6 27 mo in the low-grade glioma group. Patients underwent 18 F-FDG PET, 11 C-MET PET, and MRI in the diagnostic and preoperative stage. The ratio of the mean standardized uptake value in the tumor to mean standardized uptake value in contralateral normal cortex (T/N ratio) was calculated. Kaplan-Meier survival analysis and ANOVA were performed. Results: T/N ratios for 11 C-MET PET and 18 F-FDG PET were significantly higher in high-grade gliomas than in low-grade gliomas (2.15 6 0.77 vs. 1.56 6 0.74, P , 0.001, and 0.85 6 0.61 vs. 0.63 6 0.37, P , 0.01, respectively). Median survival was 19 6 5.4 mo in patients with a T/N ratio greater than 1.51 for 11 C-MET PET and 58 6 26.7 mo in those with a T/N ratio less than 1.51 (P 5 0.03). Among the LGGs, median survival was lower in patients with a mean T/N ratio greater than 1.51 for 11 C-MET PET (16 6 10 mo; 95% confidence interval, 1-36 mo) than in those with a T/N ratio less than 1.51 (P 5 0.04). No significant difference in survival in LGGs was based on 18 F-FDG uptake and MRI contrast enhancement. Conclusion: 11 C-MET PET can predict prognosis in gliomas and is better than 18 F-FDG PET and MRI in predicting survival in LGGs.