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

Abstract

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.

The combination of 13N-ammonia and 11C-methionine in differentiation of residual/recurrent pituitary adenoma from the pituitary gland remnant after trans-sphenoidal Adenomectomy

“…13 N-ammonia is not only a good indicator of the blood flow of the pituitary gland, but also a potential tracer to indicate glutamine synthesis metabolism, as reported in our previous studies [20][21][22]. Pituitary tissue exhibited significantly high uptake of 13 N-ammonia due to the absence of the blood-brain barrier (BBB), high regional cerebral blood flow (CBF), and high capillary permeability surface area product [22]. Glutamine synthetase (GS) is a catalyst in the glutamine synthesis reaction and its activity was confirmed in the anterior lobe of the pituitarium [23] As for displaying the position of pituitary tissue, the ability of 13 N-ammonia is comparable to MRI [14].…”

“…13 N-ammonia is not only a good indicator of the blood flow of the pituitary gland, but also a potential tracer to indicate glutamine synthesis metabolism, as reported in our previous studies [20][21][22]. Pituitary tissue exhibited significantly high uptake of 13 N-ammonia due to the absence of the blood-brain barrier (BBB), high regional cerebral blood flow (CBF), and high capillary permeability surface area product [22].…”

“…To avoid this phenomenon, another imaging comparison has been suggested to identify residual pituitary tissue [25]. We selected 13 N-ammonia to locate the pituitary gland based on our previous studies [13,[20][21][22]. When 13 N-ammonia was combined with 11 C-MET, the differential accuracy of these 2 clinical entities was 96.43%.…”

Advances in PET imaging for meningioma patients

“…Further observations of incidentally increased PET tracer uptake in patients with meningioma have been reported for 68 Ga-NOTA-PRGD2, an integrin-targeting radiotracer, 102 18 F-AV1451, a tracer that binds to the paired helical tau filament in patients with Alzheimer’s disease, 103 13 N-ammonia, targeting glutamine synthetase expression, 104–106 18 F-FMAU, a synthetic pyrimidine analog, 107 and, 18 F-FP-CIT targeting dopamine transporters in patients with Parkinson’s disease. 108 Overall, the clinical relevance of these tracers for meningioma imaging remains to be elucidated.…”