TY - JOUR T1 - Evaluation of <sup>11</sup>C-Methionine PET and Anatomic MRI Associations in Diffuse Intrinsic Pontine Glioma JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 312 LP - 319 DO - 10.2967/jnumed.118.212514 VL - 60 IS - 3 AU - Christopher L. Tinkle AU - Elizabeth C. Duncan AU - Mikhail Doubrovin AU - Yuanyuan Han AU - Yimei Li AU - Hyun Kim AU - Alberto Broniscer AU - Scott E. Snyder AU - Thomas E. Merchant AU - Barry L. Shulkin Y1 - 2019/03/01 UR - http://jnm.snmjournals.org/content/60/3/312.abstract N2 - The role of metabolic imaging in the diagnosis, treatment, and response assessment of diffuse intrinsic pontine glioma (DIPG) is poorly defined. We investigated the uptake of 11C-methionine in pediatric patients with newly diagnosed DIPG and evaluated the associations of 11C-methionine PET metrics with conventional MRI indices and survival outcomes. Methods: Twenty-two patients with newly diagnosed DIPG were prospectively enrolled on an institutional review board–approved investigational study of 11C-methionine PET. All patients underwent baseline 11C-methionine PET/CT, and initial treatment-response scans after chemotherapy or radiation therapy were obtained for 17 patients. Typical and atypical DIPGs were assessed clinically and radiographically and defined by multidisciplinary consensus. Three-dimensional regions of interest, reviewed by consensus between a nuclear medicine physician and a radiation oncologist, were delineated after coregistration of PET and MR images. Associations of 11C-methionine uptake intensity and uniformity with survival, along with associations between 11C-methionine uptake and conventional MRI tumor indices over time, were evaluated. 11C-methionine PET voxel values within regions of interest were assessed as threshold values across proportions of the study population, and 11C-methionine uptake at baseline was assessed relative to MRI-defined tumor progression. Results: 11C-methionine uptake above that of uninvolved brain tissue was observed in 18 of 22 baseline scans (82%) and 15 of 17 initial response scans (88%). 11C-methionine avidity within MRI-defined tumor was limited in extent, with 11 of 18 positive baseline 11C-methionine PET scans (61%) showing less than 25% 11C-methionine–avid tumor. The increase in total tumor volume with 11C-methionine PET was relatively limited (17.2%; interquartile range, 6.53%–38.90%), as was the extent of 11C-methionine uptake beyond the MRI-defined tumor (2.2%; interquartile range, 0.55%–10.88%). Although baseline 11C-methionine PET intensity and uniformity metrics did not correlate with survival outcomes, initial 11C-methionine avidity overlapped with recurrent tumor in 100% of cases. A clinical diagnosis of atypical DIPG was associated with borderline significantly prolonged progression-free survival (P  =  0.07), yet 11C-methionine PET indices at diagnosis did not differ significantly between atypical and typical DIPGs. Conclusion: Most newly diagnosed DIPGs are successfully visualized by 11C-methionine PET. Baseline 11C-methionine uptake delineates regions at increased risk for recurrence, yet intensity and uniformity metrics did not correlate with treatment outcomes in children with DIPG in this study. ER -