[Value of 18F-FDG and 11C-MET PET-CT in differentiation of brain ringlike-enhanced neoplastic and non-neoplastic lesions on MRI imaging].

OBJECTIVE: To evaluate the value of (18)F-FDG and (11)C-MET PET-CT scan in differentiation of brain ringlike-enhanced lesions on MRI imaging. METHODS: Forty-one brain ringlike-enhanced lesions on MRI imaging including 30 brain tumors and 11 non-neoplastic lesions confirmed pathologically or clinically underwent (18)F-FDG and (11)C-MET PET-CT brain scan. Among them, 15 patients who were suspected to have brain metastasis received body scan by (18)F-FDG PET-CT. Both images were analyzed visually and semi-quantitatively. RESULTS: Visual analysis: for brain tumors the diagnostic sensitivity, specificity and accuracy of (18)F-FDG PET-CT was 53.3%, 72.7%, 58.5%, versus 96.7%, 90.9%, 95.1% of (11)C-MET PET-CT, respectively. All the primary foci in 9 patients with brain metastases were detected by body (18)F-FDG PET-CT scan. Semiquantitative analysis: There was a significant difference in the uptake between highly differentiated malignant and poorly differentiated tumors as well as non-neoplastic lesions for both tracers (P < 0.01), while between low-grade malignant tumors and non-neoplasm lesions, there was a difference in uptake only by (11)C-MET (P < 0.01). No significant difference between the uptakes in brain metastasis and glioblastomas was found by both tracers (P > 0.05). CONCLUSION: Both (18)F-FDG and (11)C-MET PET-CT are useful in differentiation of brain ringlike-enhanced lesions on MRI imaging. (11)C-MET PET-CT is more helpful than (18)F-FDG PET-CT in differential diagnosis of low-grade neoplastic from non-neoplastic lesions. Combination of (18)F-FDG and (11)C-MET PET-CT scans can improve the accuracy of differential diagnosis for brain ringlike-enhanced lesions on MRI imaging.