11碳-蛋氨酸与18氟－脱氧葡萄糖在脑良性病变及低级别胶质瘤诊断中的比较

A comparative study of carbon-11 methionine PET and Fluorine-18 fluorodeoxyglucose PET for the differentiation of benign lesion and low grade glioma

目的:鉴于11碳-蛋氨酸(11C-Methionine,MET)在良性病变和在低级别胶质瘤鉴别诊断价值的研究尚少,本研究目的是筛选出术前用11C-MET和18氟-脱氧葡萄糖(18F-FDG)两种显像剂进行脑正电子断层显像(PET/CT)成像对良性和低级别胶质瘤(共22例)进行回顾性研究,评价两种显像剂分别对上述两种病变的显示能力,病变边界勾画情况以及鉴别诊断价值,为11C-蛋氨酸在脑内良恶性病变的诊断提供依据.方法:本研究包括脑内占位病变22例(其中良性病变5例,新发低级别胶质瘤WHO I级和II级共17例).每例外科手术或活检前均行18F-FDG和11C-MET PET扫描(两次扫描间隔时间在1周以内),根据病灶及正常对照区(大脑对侧相应正常区域)勾画出的感兴趣区(region of interest,ROI)进行标准摄取值(Standard uptake value,SUV)平均值测量,计算良性及低级别胶质瘤的肿瘤/非瘤比(tumor/normal brain uptake ratio,T/NT比值)的平均值及标准差.对比两种显像剂在上述两组病变中T/N比值的差别并进行统计学分析.结果:(1)11C-MET在良性病变和低级别胶质瘤中的T/NT比值分别是1.59±0.28和1.52±0.48,组间差别无统计学意义(P>0.05);18F-FDG在良性病变和低级别胶质瘤中的T/NT比值分别是0.91±0.48和0.77±0.65,组间差别无统计学意义(P>0.05).(2)在本组所有22例病变中,11C-MET显示病变呈高代谢者19例,18F-FDG显示病变呈低代谢者17例.(3)11C-MET所示病灶边界清晰者17例,18F-FDG对病灶边界显示清晰者仅2例.(4)17例病灶显示清晰的患者11C-MET显示病变范围均大于18F-FDG.结论:虽然11CMET和18F-FDG两种显像剂均无法将良性病变与低级别胶质瘤区分开,但11C-MET对病灶侵犯范围及边界的显示均明显优于18F-FDG FDG,11C-MET还可检测和随访低级别胶质瘤(即惰性肿瘤)的生长情况,可为临床提供更多诊断、预后及治疗信息,因此,11C-MET可常规应用于脑内占位病变的显示,且其效果优于18F-FDG.

Aim：As the study of Carbon-11 methionine （MET）and fluorine-18 fluorodeoxyglucose 〈br〉 （FDG）in differentiating brain benign and low grade glioma was seldom.The aim of this study was to de-termine the effect of these two tracers for distinguishing two groups of patients and evaluating the extent of lesions.Methods：Both carbon-11 MET and fluorine-18 FDG have been used to evaluate brain benign and low grade glioma （LGG）.MET positron emission tomography （PET）and FDG PET were all per-formed in 22 patients （5 brain benign lesions,17 low grade glioma WHO grade I and II）within one week for a single patient,Both MET and FDG uptake of the lesions were evaluated by a semiquantitative analy-sis using the standardized uptake value.The Tumor/normal brain uptake ratio （T/N ratio）were calculat-ed in two groups of patients.Results：MET uptake was not significantly different among these two groups （benign：1.59 ±0.28 and LGG：1.52 ±0.48）.Similarily,FDG uptake was not significantly different among the two groups （benign：0.91 ±0.48 and 0.77 ±0.65）also.No significantly correlation was ob-served between MET uptake and FDG uptake.19 /22 hypermetabolization of patients were found in MET PET and 17 /22 hypometabolization of patients were found in FDG PET.The extents of increased MET uptake in 17 cases were larger than that of the increased FDG uptake.Conclusion：It is found that both MET and FDG are not useful for distinguishing with benign and LGG.MET was found to be highly useful for detecting benign and LGG,and for evaluating the extent of these lesions which were blurred in FDG PET.MET was also useful for monitoring the growth of LGG.In a word,MET was considered as routine examination for brain lesions.