^(13)N-NH_3与^(18)F FDG在脑膜瘤显像中的对比研究

Comparative Study of ^(13)N-NH_3 and ^(18)F FDG Positron Emission Imaging for Meningiomas

背景与目的:正电子发射断层显像(PET)是脑膜瘤术前良恶性评估及术后随访的新型工具。201TlCl显像在脑膜瘤显像以及良恶性鉴别方面的应用已被广泛报道,与201Tl类似,13N-NH4+也是K+的类似物,在一些情况下可以替代K+。本研究拟评价13N-NH3 PET显像在脑膜瘤检测中的应用价值,并与18F-FDG的显像结果进行对比。方法:对11例确诊的脑膜瘤患者进行13N-NH3 PET显像,其中10例患者同时行18F-FDG显像。10例患者最终经组织病理学确诊(6例I级,4例II级),另1例患者经影像学资料(CT和MRI)和临床随访确诊为良性。半定量分析计算肿瘤与脑白质摄取比(T/W)用于进一步评估两种显像剂在脑膜瘤显像中的应用。结果:11例脑膜瘤患者对13N-NH3摄取均明显增高,且与周围正常脑组织形成了良好的对比;7例Ⅰ级脑膜瘤患者的18F-FDG的摄取低于对侧正常脑组织,4例Ⅱ级脑膜瘤患者摄取稍高于对侧正常脑组织。半定量分析显示13N-NH3组T/W值明显高于18F-FDG组(7.03±1.62 vs.1.44±0.57,P<0.005)。13N-NH3显像的T/W值对鉴别Ⅰ、Ⅱ级脑膜瘤价值不大(P=0.88),18F-FDG显像的T/W值对鉴别Ⅰ、Ⅱ级脑膜瘤明显优于13N-NH3(P=0.037)。结论:脑膜瘤对13N-NH3的摄取明显高于18F-FDG,但临床上应用3N-NH3 PET检查进行脑膜瘤分级及随访还需进一步研究评价。

BACKGROUND & OBJECTIVE: Positron emission tomography(PET) is novel tool to evaluate the grade of meningiomas pre-operatively and to follow up post-operatively.Relatively high Tl-201 uptakes have been reported in all types of meningiomas,and it have been proposed that 201TlCl SPECT could predict histological types of meningiomas and differentiate the benign and aggressive meningiomas.Similar to Tl-201,13N-NH4+ is an analog of K+and could substitute K+in some cases.The aim of this study was to evaluate the capacity of PET with 13N-NH3 to discriminate meningioma from healthy tissue,and compare with F-18 FDG.METHODS: Eleven patients with the neuroradiological diagnosis of meningiomas were studied with 13N-NH3,and 10 of them were performed with F-18 FDG PET within 3 days.Ten of them were histologically confirmed(6 grade I,4 grade II),and another one was proved by radiologic(computed tomography and magnetic resonance imaging) and clinical investigation.The PET images were evaluated by semiquantitative analysis using tumor-to-white matter ratio(T/W).RESULTS: 13N-NH3 uptake was obviously increased in all 11 meningiomas with a good contrast to the surrounding normal brain tissues.Conversely,F-18 FDG uptake was decreased in comparison with the contralateral side in all 7 patients with grade I meningiomas and moderately increased in the remaining patient with grade II meningioma.The T/W ratio of 13N-NH3 was higher than that of F-18 FDG(7.03 ± 1.62 vs.1.44 ± 0.57,P< 0.005).T/W of 13N-NH3 uptake was not useful for differentiating benign(Grade I) from atypical(Grade II) meningiomas(P = 0.88),whereas the T/W ratio of F-18 FDG uptake was better than that of 13N-NH3 for differentiating benign from malignant meningiomas(P = 0.037).CONCLUSION: These preliminary results suggest that 13N-NH3 has relatively greater uptake in meningiomas in comparison with F-18 FDG.Clinical applications of 13N-NH3 PET for grading and follow-up of meningiomas need to be assessed in further studies.