sup 18^F-Fluorocholine PET/CT as a complementary tool in the follow-up of low-grade glioma: diagnostic accuracy and clinical utility

The follow-up of treated low-grade glioma (LGG) requires the evaluation of subtle clinical changes and MRI results. When the result is inconclusive, additional procedures are required to assist decision-making, such as the use of advanced MRI (aMRI) sequences and nuclear medicine scans (SPECT and PET). The aim of this study was to determine whether incorporating ^sup 18^F-fluorocholine PET/CT in the follow-up protocol for treated LGG improves diagnostic accuracy and clinical utility. This was a prospective case-series study in patients with treated LGG during standard follow-up with indeterminate clinical and/or radiological findings of tumour activity. All patients underwent clinical evaluation, aMRI, ^sup 201^Tl-SPECT and ^sup 18^F-fluorocholine PET/CT. Images were interpreted by visual evaluation complemented with semiquantitative analysis. Between January 2012 and December 2013, 18 patients were included in this study. The final diagnosis was established by histology (five surgical specimens, one biopsy specimen) or by consensus of the Neuro-Oncology Group (11 patients) after a follow-up of >6 months (mean 14.9±2.72 months). The global diagnostic accuracies were 90.9 % for aMRI (38.8 % inconclusive), 69.2 % for ^sup 201^Tl-SPECT (11.1 % inconclusive), and 100 % for ^sup 18^F-fluorocholine PET/CT. ^sup 201^Tl-SPECT led correctly to a change in the initial approach in 38.9 % of patients but might have led to error in 27.8 %. The use of ^sup 18^F-fluorocholine PET/CT alone rather than ^sup 201^Tl-SPECT led correctly to a change in the approach suggested by routine follow-up in 72.2 % of patients and endorsed the approach in the remaining 27.8 %. Our results support the need to complement structural MRI with aMRI and nuclear medicine procedures in selected patients. ^sup 18^F-Fluorocholine PET/CT can be useful in the individualized management of patients with treated LGG with uncertain clinical and/or radiological evidence of tumour activity.