18F-脱氧葡萄糖PET/CT与弥散加权成像在原发性中枢神经系统淋巴瘤中的相关性研究

Relationship between ^(18)F-fluorodeoxyglucose PET/CT and diffusion weighted imaging in primary central nervous system lymphoma

目的:本研究回顾性分析原发性中枢系统淋巴瘤(primary central nervous system lymphoma,PCNSL)病灶^(18)F-脱氧葡萄糖(^(18)F-fluorodeoxyglucose,^(18)F-FDG)半定量摄取与表观扩散系数(apparent diffusion coefficient,ADC)之间的关系。方法:纳入14例在复旦大学附属华山医院同时行FDG PET/CT及弥散加权成像(diffusion weighted imaging,DWI)检查的初诊PCNSL患者。手动在经滤波反投影(filtered back projection,FBP)重建后的脑PET图勾画PCNSL病灶感兴趣区(region of interest,ROI),测算肿瘤FDG摄取半定量参数平均标准摄取值(mean standardized uptake value,SUVmean)及最大标准摄取值(maximum standardzed uptake value,SUVmax)。在ADC图上肿瘤实质、对侧相应正常脑白质区各自勾画ROI并分别测定ADC值,病灶ADC值取最小值(ADCmin),对侧正常脑白质ADC值取平均值(ADCmean),rADC为病灶ADCmin与对侧正常脑白质ADCmean的比值。采用Pearson分析对SUV与ADC半定量参数之间的相关性进行分析。结果:14例PCNSL患者共计纳入18个病灶,SUVmax与r ADC(r=-0.584,P=0.011)、SUVmean与rADC(r=-0.559,P=0.016)均呈负相关。结论:基于病灶分析的治疗前SUV与ADC值存在负相关,PCNSL肿瘤细胞的代谢信息与其致密程度存在相关性,为DWI作为FDG PET诊断PCNSL和进行疗效监测的替代技术提供了一定的理论依据。

Objective: To retrospectively evaluate the relationship between ^(18)F-fluorodeoxyglucose(^(18)F-FDG) uptake using PET/CT and apparent diffusion coefficient(ADC) in patients with primary central nervous system lymphoma(PCNSL). Methods: A total of 14 PCNSL cases with 18 lesions underwent both FDG PET/CT scan and diffusion weighted imaging at onset. The meanstandardized uptake value(SUVmean) and maximum standardized uptake value(SUVmax) were calculated to assess the tumor FDG uptake on brain PET/CT images with filtered back projection(FBP) reconstruction. On ADC map, ADCmin of the lesions and ADCmean of the contralateral normal white matters were calculated. The relative ADC(r ADC) was obtained by the ratio of ADCmin of the tumor to ADCmean of the contralateral normal white matter. Pearson's correlation analysis was used to assess the relationship between FDG uptake and ADC-derived parameters. Results: Negative correlations between SUVmax and r ADC, between SUVmean and r ADC were found for PCNSL cases(r=-0.584, P=0.011; r=-0.559, P=0.016, respectively). Conclusion: There is negative correlation between SUV and r ADC before treatment. Both FDG PET/CT and DWI are useful methods in diagnosing PCNSL by evaluating tumor metabolic activity and cellular density. They are closely correlated. DWI could be an alternative imaging technique for FDG PET/CT in the diagnosis and therapy monitoring of PCNSL.