F18-choline PET/CT and atypical meningioma: a feasibility study.

Objectives Agtypical meningioma is a very rare brain tumor with poor outcome mainly due to the high rate of loco regional recurrence. We compared F18-choline PET/CT with brain MRI, the current gold standard, to assess the local extent of the postoperative residue or the recurrence before radiation treatment. We also assessed if additional imaging abnormalities (IA) found only on the PET imaging were included in the radiation treatment plan.

Methods Patients (pts) with pathological proven atypical meningioma were included from December 2014 to April 2015. They had a DCE-T1 brain MRI and were scheduled to undergo radiation therapy either in an adjuvant setting or for loco regional recurrence. F18-choline PET/CT protocol was performed on a GE Discovery LS scanner as follows: 3.5MBq/kg I.V injection on table with a dynamic brain acquisition (DBA) performed 5 to 20 min post-injection, followed by a whole body acquisition (from mid-thighs to skull) and a 5 min static brain acquisition at a late time point of 60 min post-injection. Images were reconstructed using using a list-mode iterative algorithm BLOB-OS-TF (2 iterations, 33 subsets). The location and the number of IA were compared between brain MRI and PET/CT. Average SUV and conventional indexes were measured after a threshold method(40% SUVmax) of each IA.

Results Seven pts were included in this study, among those 5 had a recent brain MRI. DBA did not show relevant data probably due to an early acquisition time. The late time point showed the best Tumor to Normal Brain Tissue ratio on PET/CT (25.3 and 10.5 for SUVmean and SUVmax, respectively). All the IA on MRI were also found in PET. A total of 19 IA in 7 patients was found on PET, among those two patients had discordant IA found only in PET. Additional IA found on PET were included in the radiation treatment plan for at least one patient with recurrent multifocal meningioma. Average SUV and conventional indexes are presented on table 1.

Conclusions This feasibility study showed matching results between F18-Choline PET/CT and MRI for assessment of postoperative residue or recurrence in atypical meningioma. Furthermore, for one patient, additional Imaging abnormalities were found in F18-Choline PET/CT and included in the radiation treatment plan. Thus, F18-Choline PET/CT might be a valuable tool to improve radiation treatment plan for loco regional recurrence and at initial diagnosis to decrease recurrence rate.