高分辨率扩散加权成像表观扩散系数与前列腺癌Gleason评分的相关性

Prostate cancer： the correlation between apparent diffusion coefficient values obtained from high resolution diffusion-weighted imaging and Gleason scores

目的 探讨前列腺癌病灶分段读出平面回波成像（RS-EPI）序列和单次激发平面回波成像（SS-EPI）序列ADC值的差异以及与前列腺癌Gleason评分的相关性.方法 回顾性分析经穿刺病理证实为前列腺癌,且在穿刺活检前行MRI检查（包括RS-EPI与SS-EPI序列）的23例患者.患者均行前列腺常规MRI、RS-EPI与SS-EPI序列检查.根据病理阳性穿刺部位,参照T2WI低信号区、DWI高信号区域,在RS-EPI序列和SS-EPI序列ADC图上共同绘制ROI并记录RS-EPI序列ADC值和SS-EPI序列ADC值.将癌灶按照Gleason评分分为高分化组（Gleason评分≤6）和低中分化组（Gleason评分≥7）.不同分化组RS-EPI序列ADC值和SS-EPI序列ADC值的比较采用配对样本t检验和独立样本t检验.不同序列ADC值与Gleason评分的相关性采用Smarman相关分析.采用ROC曲线,获得区分低中分化癌灶和高分化癌灶的RS-EPI序列最佳ADC界值及诊断的敏感度和特异度.结果 前列腺癌高分化组病灶29个,低中分化组病灶126个.高分化组RS-EPI序列ADC值为（1.136±0.136）× 103mm2/s,SS-EPI序列ADC值为（1.125±0.198）×10-3mm2/s;低中分化组RS-EPI序列ADC值为（0.891 ±0.161）×10-3mm2/s,SS-EPI序列ADC值为（0.875±0.184）×103mm2/s.RS-EPI序列ADC值和SS-EPI序列ADC值比较,高分化组和低中分化组的差异均无统计学意义（t值分别为0.359和1.727,P值分别为0.722和0.087）;高分化组和低中分化组的ADC值进行比较,RS-EPI序列和SS-EPI序列ADC值的差异均有统计学意义（t值分别为7.572和6.499,P均＜0.01）.RS-EPI序列ADC值和SS-EPI序列ADC值均与Gleason评分呈负相关（r值分别为-0.638和-0.565,P均＜0.01）.RS-EPI序列ADC值鉴别前列腺癌高分化和低中分化的ROC曲线下面积为0.882,最佳界值为1.041× 10-3mm2/s,诊断的敏感度和特异度分别为85.7％（108/126）和86.2％（25/29）.结论 RS-EPI序列ADC值和SS-EPI序列ADC值差异不明显,均与Gleason评分呈负相关.RS-EPI ADC值可以用于癌灶的分化程度的初步评估.

Objective To compare ADC values obtained from readout-segmented echo-planar imaging （RS-EPI） and single-shot echo-planar imaging （SS-EPI） techniques of prostate cancer and to investigate the correlation between RS-EPI ADC values and Gleason scores.Methods A retrospective analysis of RS-EPI and SS-EPI DWI were performed in 23 patients with pathologically confirmed prostate cancer.Routine MRI,RS-EPI DWI and SS-EPI DWI were obtained prior to ultrasound guided systemic biopsy in all cases.According to the location of lesion from biopsy report,a ROI was drawn on ADC map obtained from RS-EPI DWI and SS-EPI DWI,respectively,at cancerous foci with low T2WI and high DWI signal intensity.Foci were classified into well differentiated group （Gleason score≤6） and poorly and moderately differentiated group （Gleason score≥7）.ADC values between RS-EPI and SS-EPI were compared by using t test.The relationship between ADC values and Gleason scores was assessed using Spearman test.The sensitivity and specific ity of RS-EPI ADC value for differential diagnosis of two groups and the best cutoff were evaluated from ROC.Results Twenty nine well differentiated foci and 126 poorly and moderately differentiated foci were identified.The mean RS-EPI ADC value and the mean SS-EPI ADC value of well differentiated group and poorly and moderately differentiated group were （1.136± 0.136）×10-3mm2/s,（1.125±0.198） × 10-3mm2/s; （0.891 ± 0.161） × 10-3mm2/s,（0.875 ±0.184） × 10-3mm2/s,respectively.Neither well differentiated group nor poorly and moderately differentiated group had a significant difference between the mean ADC value of two techniques （t values were 0.359 and 1.727,P values were 0.722 and 0.087,respectively）.Either mean RS-EPI ADC value or mean SS-EPI ADC value between two groups had a significant difference （t values were 7.572 and 6.499,P＜0.01,respectively）.There was an inverse relationship between ADC values obtained from RS-EPI and SS-EPI and Gleason scores （r values were-0.638 and-0.565,P＜0.01,respectively）.When the cutoff value was 1.041× 1 0-3mm2/s,the sensitivity and specificity of RS-EPI ADC value to differentiate two groups were 85.7％ （108/126）,86.2％ （25/29）,respectively,and the area under ROC curve was 0.882.Conclusions There were no significant difference between ADC values obtained from RS-EPI and SS-EPI.ADC values of both techniques had positive correlation with Gleason scores.RS-EPI ADC values may have potential to allow noninvasive assessment of prostate cancer aggressiveness,which could help in the stratification of patients for appropriate therapy.