Prognostic value of 11C-methionine PET/CT and MRI in diffuse intrinsic brain stem glioma patients

Objective To explore the prognostic value of 11C-methionine positron emission tomography/CT (MET-PET/CT) combined with MRI in patients with diffuse intrinsic pontine glioma (DIPG). Methods A total of 41 patients clinically suspicious of DIPG admitted to Department of Neurosurgery of Beijing Tiantan Hospital, Capital Medical University from March 2016 to June 2017 were prospectively included and underwent MET-PET/CT scan and brain MRI. The measurements on MET-PET/CT included tumor metabolic volume (MTV), maximum standardized uptake value (SUVmax) and mean standardized uptake value (SUVmean), while those on MRI enhancement volume (EV) and FLAIR displayed volume (FV). The EV/MTV values were also calculated for analysis. Within 2 weeks after imaging, 33 patients underwent tumor resection, and the remaining 8 underwent stereotactic biopsy. Postoperative radiotherapy and/or chemotherapy were performed in 27 patients. Cox regression analysis was used to analyze the effects of MET-PET/CT and MRI measurements on the overall survival (OS) of DIPG patients. Results Of the 41 patients, 24 (58.5%) FLAIR hyperintensity and 39 (95.1%) MRI enhancement presented and all (100.0%) MET-PET/CT uptake increased. The median follow-up time of 41 patients was 9 months (1-27months). The median survival time was 14.4 months (12.0-16.7 months). At the end of follow-up, 20 patients survived and 21 died. Univariate prognostic analysis discovered that age 18 or older and adjuvant therapy were prognostic protective factors, while EV, SUVmax, SUVmean and tumor grade were prognostic risk factors (all P<0.05). Multivariate analysis showed that EV (HR=2.983, 95%CI: 1.074-8.284, P=0.036), tumor grade (HR=7.568, 95% CI: 2.029-28.229, P=0.003) and adjuvant therapy (HR=0.212, 95%CI: 0.078-0.582, P=0.003) were independent prognostic factors. Conclusion MET-PET/CT combined with MR could predict the prognosis of DIPG patients in this prospective cohort study. Key words: Brain stem tumor; Glioma; Positron emission tomography; 11C- methionine