^(13)N-NH_3 PET在星形细胞瘤病理分级中的应用价值

The application value of ^(13)N-ammonia PET imaging in pathological grading of astrocytomas

目的探讨13氮-氨(13N-NH3)正电子发射断层显像(PET)在脑星形细胞瘤病理分级中的应用价值。方法47例拟诊胶质瘤患者进行13N-NH3PET动态显像,所有患者均有MRI或CT检查结果,并且通过手术进行病理分级。分别进行定性和半定量分析,至少在三个断面同一位置连续两帧以上出现无摄取或相对低的摄取且病灶与健侧对应位置放射性计数比值小于1.2定为阴性,高度或中度摄取且病灶与健侧对应位置放射性计数比值大于1.2定为阳性;同时测定肿瘤组织(T)与脑白质(WM)的比值以及灌注指数(PI)。结果29例星形细胞瘤中,经病理分级证实Ⅰ级4例,Ⅱ级8例,Ⅲ级9例,Ⅳ级8例。Ⅲ~Ⅳ级显像均见摄取(+);Ⅰ~Ⅱ级有1例未见摄取(-)。Ⅰ~Ⅱ级星形细胞瘤T/WM比值为0.97~2.07(1.62±0.67),Ⅲ~Ⅳ级T/WM比值为1.75~2.53(2.18±0.48)。Ⅰ~Ⅱ级PI值为0.74~2.01(1.52±0.83),Ⅲ~Ⅳ级PI值为1.92~2.69(2.33±0.54)。统计分析两组半定量指标(T/WM和PI)有显著性差异。结论13N-NH3PET可以对脑星形细胞瘤进行初步病理分级。

Objective To evaluate the application value of ^13N-ammonia positron emission tomography （PET） in pathological grading of astrocytomas. Method Dynamic ^13N-ammonia PET was performed in 47 patients with suspected cerebral gliomas. All patients were detected by MRI or CT. The pathological grading of astrocytomas had been acquired by post-operation histopathological diagnosis. The results were analyzed qualitatively and quantitatively. At least more than two images at the same place of three dimensional slices, moderate uptake or intense uptake as well as a high ratios （〉1.2） between the lesion and the counterparts were defined as positive of visual interpretation （ ＋ ）, and faint uptake or no uptake as well as the low ratios （ 〈 1.2） between the lesion and the counterparts were defined as negative results （-）. Tumor （T）-to-white matter （WM） count ratios and perfusion index （PI） were calculated by region-of-interests （ROI） methods. Results Among 29 astrocytomas there were 4 cases of astreeytoma in grade Ⅰ, 8 in grade Ⅱ, 9 in grade Ⅲ, and 8 in grade Ⅳ. Eleven cases of grade Ⅰ and Ⅱ astreeytomas were positive, but one of them was negative. Seventeen cases of grade Ⅲ and Ⅳ astrocytomas were positive . The average T/WM ratios in grade Ⅰ and Ⅱ astrocytomas were 1.62 =t=0. 67. qhe average T/WM ratios in grade Ⅲ and Ⅳ were 2.18 ±0. 48. qhe average PI of the lesion of grade Ⅰ and Ⅱ astrocytomas were 1.52 ±0. 83. qhe average PI of the lesion of grade Ⅲ and Ⅳ were 2. 33 ±0. 54. The ratios of two groups were significant different. Conclusion The pathological grading of astreeytomas can be diagnosed preliminarily with ^13N-ammonia PET.