Metabolic assessment of intracranial tuberculomas using 11C-methionine and 18F-FDG PET/CT.
BACKGROUND
18F-fluorodeoxyglucose (18F-FDG) has limited specificity in the evaluation of intracranial lesions as it is taken up by inflammatory and granulomatous lesions as well. 11C-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 11C-methionine PET/CT and 18F-FDG in the evaluation of intracranial tuberculomas.


METHODS
11C-methionine PET/CT followed by 18F-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 11C-methionine (1.8 ± 0.38) and 18F-FDG scans (1.64 ± 0.26) in all newly diagnosed cases. Lesion detection and delineation was superior on 11C-methionine PET/CT. In addition, 11C-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 11C-methionine PET/CT and radiological imaging modalities (namely, CT and MRI).


CONCLUSIONS
This preliminary study suggests that in newly diagnosed, untreated intracranial tuberculomas, 11C-methionine, like 18F-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 11C-methionine in this regard.
Division of PET Imaging, Institute of Nuclear Medicine and Allied Sciences, Delhi, India. maria.md@rediffmail.com
Maria Mathew
MM
D'Souza
Rajnish
R
Sharma
Abhinav
A
Jaimini
Puja
P
Panwar
Abhishek
A
Bansal
Madhavi
M
Tripathi
Raunak
R
Varshney
Santosh
S
Pandey
Anupam
A
Mondal
D000293:Adolescent; D000328:Adult; D001927:Brain Diseases / Q000000981:diagnostic imaging*; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008715:Methionine / Q000493:pharmacokinetics*; D064847:Multimodal Imaging / Q000379:methods*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D014057:Tomography, X-Ray Computed; D016862:Tuberculoma, Intracranial / Q000000981:diagnostic imaging*; D055815:Young Adult
D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D008715:Methionine