N-13-NH3: a selective contrast-enhancing tracer for brain tumor

作者：Zhang Xiangsong^*; Wu Xinjian; Zhang Yong; Chen Weian

来源：Nuclear Medicine Communications, 2008, 29(12): 1052-1058.

DOI：10.1097/MNM.0b013e328310af34

• ammonia
• blood-brain barrier
• brain tumor
• nitrogen radioisotopes
• PET

Purpose The purpose of this study is to determine whether there is a qualitative and quantitative relationship between the breakdown of the blood-brain barrier, defined radiologically by the contrast enhancement of MRI, and the uptake of N-13-NH3 in brain tumors.
Methods The results of N-13-NH3 PET in 42 patients suspected of having brain tumors were compared with the findings of contrast-enhanced MRI. A histopathological diagnosis was carried out in 33 patients, and a clinical diagnosis was performed in the remaining patients. PET and MRI images were visually inspected, and the contrast index (CI) of MRI and the uptake index (UI) of N-13-NH3 were measured.
Results Contrast enhancement of MRIs was seen in 20 of 29 brain tumors (69%). Increased uptake of N-13-NH3 was seen in 24 of 29 brain tumors (83%). Nineteen of 20 contrast-enhancing brain tumors exhibited the increased uptake of N-13-NH3 (95%). Areas of the increased N-13-NH3 uptake corresponded to areas enhanced on MR images in the majority of cases. Five out of nine nonenhancing tumors exhibited increased uptake of N-13-NH3 (56%). The contrast enhancement of MRIs was seen in nine of 13 nonneoplastic lesions (69%). None of the nonneoplastic lesions showed increased uptake of N-13-NH3, yielding a specificity of 100% for brain tumors (0 of 13). CI for tumor tissue was 1.46 +/- 0.64. UI of N-13-NH3 for tumor tissue was 1.64 +/- 0.71. CI and UI for tumor tissue were significantly correlated (r=0.86, P < 0.01). A statistically significant difference in uptake levels of N-13-NH3 between contrast-enhancing tumors and nonenhancing tumors (1.88 +/- 0.66, n = 20 vs. 1.11 +/- 0.52, n = 9, P < 0.01) was observed. UI was higher in brain tumors compared with the nonneoplastic lesions (1.64 0.71 vs. 0.71 +/- 0.19, P < 0.01).
Conclusion N-13-NH3 is a potential selective contrast-enhanced tracer for brain tumor, and may prove especially useful for evaluating the contrast-enhancing lesions on MRI to distinguish brain tumors from nonneoplastic lesions.

• 出版日期2008-12
• 单位中山大学