体素内不相干运动MRI与DWI对前列腺癌的诊断

Investigation of Prostate Cancer: Intravoxel Incoherent Motion MRI Versus Conventional Diffusion Weighted Imaging

目的研究体素内不相干运动(IVIM)MRI对前列腺癌的诊断价值,并对比其与DWI的诊断效能。方法收集接受前列腺MR平扫及10个b值IVIM扫描(b=0~800s/mm2)的患者共36例,依据经直肠超声引导下穿刺活检的病理结果分为前列腺癌组共20例,良性组共16例。在各例患者前列腺的癌区或非癌区画取感兴趣区,应用单指数模型运算出ADC(表观扩散系数);应用IVIM的双指数模型运算出D(真实扩散系数)、D*(灌注扩散系数)与f(灌注分数)。采用非参数Mann-Whitney检验法对前列腺癌组与良性组的ADC、D、D*、f值进行差异性分析。采用ROC曲线评价ADC与D的诊断效能。结果前列腺癌组的ADC值与D值均低于良性组,差异均有显著的统计学意义(P<0.01);两组间D*值与f值的差异没有统计学意义(P>0.05)。ADC与D的ROC曲线下面积分别为0.859与0.961。ADC值的最佳诊断阈值、敏感度和特异度分别为1.24×10-3mm^2/s、93.8%和65.0%;D值最佳诊断阈值、敏感度和特异度分别为0.95×10-3mm^2/s、93.8%和85%。结论 IVIM MRI的D对前列腺癌的诊断效能要优于传统DWI的ADC,IVIM DWI诊断前列腺癌的具备良好的应用前景。

Objective To evaluate the ability of the intravoxel incoherent motion（IVIM） MRI to differentiate prostate cancer from benign tissue, and to compare its diagnostic performance with conventional diffusion-weighted imaging（DWI）. Methods Conventional MRI and IVIM MRI（b=0~800s/mm2） were performed in 36 patients. Regions of interest were drawn in cancerous tissue of 20 patients and benign tissue of 16 patients proved by transrectal ultrasound guided prostate biopsy and fitted to a monoexponential model [yielding the apparent diffusion coefficient（ADC）] and the IVIM signal equation（yielding the diffusion constant D, the pseudodiffusion coefficient of perfusion D＊and the perfusion fraction f）. Mann-Whitney tests were performed to evaluate statistical differences of ADC, D, D＊ and f between prostate cancer and benign tissue. Receiver operating characteristic（ROC） analysis were utilized for diagnostic performance of ADC and D. RReessuullttss ADC values and D values were significantly lower（P〈0.01） in cancerous tissue. Area under the curve（AUC） of ADC and D was 0.859 and 0.961, respectively. The best diagnostic threshold, sensitivity and specificity for ADC was 1.24×10-3mm^2/s, 93.8% and 65.0%, meanwhile, 0.95×10^（-3）mm^2/s, 93.8% and 85% for D. CCoonncclluussiioonn D of IVIM DWI provides better diagnostic performance than ADC of conventional DWI, IVIM DWI holds potential for investigation of prostate cancer.