Differentiation of suprasellar meningiomas from non-functioning pituitary macroadenomas by (18)F-FDG and (13)N-Ammonia PET/CT

BACKGROUND: Differentiation of suprasellar meningiomas (SSMs) from non-functioning pituitary macroadenomas (NFPMAs) is useful for clinical management. We investigated the utility of (13)N-ammonia combined with (18)F-FDG positron emission tomography (PET)/computed tomography (CT) in distinguishing SSMs from NFPMAs retrospectively. METHODS: Fourteen NFPMA patients and eleven SSM patients with histopathologic diagnosis were included in this study. Every patient underwent both (18)F-FDG and (13)N-ammonia PET/CT scans. The tumor to gray matter (T/G) ratios were calculated for the evaluation of tumor uptake. RESULTS: The uptake of (18)F-FDG was higher in NFPMAs than SSMs, whereas the uptake of (13)N-ammonia was obviously lower in NFPMAs than SSMs. The differences of (18)F-FDG and (13)N-ammonia uptake between the two groups were significant respectively (0.92[0.46] vs 0.59[0.29], P < 0.05, (18)F-FDG; 1.58 ± 0.56 vs 2.80 ± 1.45, P < 0.05, (13)N-ammonia). Tumor classification demonstrated a high overall accuracy of 96.0% for differential diagnosis. When the two traces were combined, only 1 SSM was misclassified into the NFPMA group. CONCLUSION: SSMs and NFPMAs have different metabolic characteristics on (18)F-FDG and (13)N-ammonia PET images. The combination of these two tracers can effectively distinguish SSMs from NFPMAs.