Metabolic assessment of intracranial tuberculomas using 11C-methionine and 18F-FDG PET/CT

Background F-18-fluorodeoxyglucose (F-18-FDG) has limited specificity in the evaluation of intracranial lesions as it is taken up by inflammatory and granulomatous lesions as well. C-11-methionine is known to have a higher specificity in tumor detection, delineation, and differentiation of benign from malignant lesions. However, its uptake in granulomatous lesions remains unclarified. Objective The aim of this study was to explore the value of C-11-methionine PET/CT and F-18-FDG in the evaluation of intracranial tuberculomas. Methods C-11-methionine PET/CT followed by F-18-FDG PET/CT study was performed on 12 patients with intracranial tuberculomas. The diagnosis was confirmed for all cases on histopathological evaluation and/or follow-up. Quantitative analysis was performed for all cases by measuring the lesion-to-normal gray matter uptake ratio. Results A high lesion-to-normal gray matter uptake ratio was observed on both C-11-methionine (1.8 +/- 0.38) and F-18-FDG scans (1.64 +/- 0.26) in all newly diagnosed cases. Lesion detection and delineation was superior on C-11-methionine PET/CT. In addition, C-11-methionine appeared to be a more sensitive indicator for assessing early therapeutic response and incomplete therapeutic response in intracranial tuberculomas. There was complete concordance in the number and sites of lesions detected on C-11-methionine PET/CT and radiological imaging modalities (namely, CT and MRI). Conclusion This preliminary study suggests that in newly diagnosed, untreated intracranial tuberculomas, C-11-methionine, like F-18-FDG, may have limited specificity in distinguishing it from a neoplastic lesion. However, it may play an important role in assessing the response to antitubercular treatment. Further studies are warranted to explore the potential of C-11-methionine in this regard. Nucl Med Commun 33:408-414 (C) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.