MR弥散加权成像在前列腺癌诊断中的应用价值

摘要

Objective To investigate the value of magnetic resonance (MR) diffusion weighted imaging(DWI) in the diagnosis of prostate cancer(PCa). Methods Fifty-seven patients with suspected prostate cancer underwent DWI and T_2-weighted imaging (T_2W). These images and apparent diffusion coefficient (ADC) maps results were compared with histopathologic findings. Receiver operating characteristic(ROC) analysis was used to compare the cancer detection performance of them. The results were rated on a scale of scores Ⅰ (benign) to Ⅴ (malignant) on the basis of ADC maps. Abnormal voxels were overlaid on the corresponding transverse TRUS images and used to perform voxel-guided biopsy. Results DWI had a sensitivity of 85%, specificity of 82%, positive predictive value of 80%, negative predictive value of 86% , and accuracy of 83%. T2WI had a sensitivity of 77%, specificity of 71%, positive predictive value of 69%, negative predictive value of 79%, and accuracy of 74%. The areas under the ROC curves for DWI and T_2WI were 0. 830 and 0. 742, respectively. The performance of DWI in PCa detection was significantly better than of T_2WI (P<0. 05). 6 of 30 patients with negative DWI results also had negative biopsy findings. PCa was detected in 17(85%) of 24 men findings with voxel score Ⅳ , with a sensitivity of 100%, specificity of 46%, positive predictive value of 71 %, negative predictive value of 100% , and accuracy of 77%. Conclusions The performance of DWI in PCa detection was better than of T_2 WI. ADC maps can be transferred to TRUS images and used to sample regions of cancer in men with rising PSA levels and negative findings at prior biopsy with good accuracy. DWI appears to be a robust and reliable method to examine the whole prostate within an acceptable scan time in clinical settings.%目的 探讨MR弥散加权成像(MRDWI)在前列腺癌(PCa)诊断中的应用价值. 方法 临床怀疑PCa患者57例行MRDWI与T_2 WI检查,通过表观弥散系数(ADC)图对可疑病灶进行良恶性评判.并与穿刺或手术病理结果 进行比较,利用曲线下面积(ROC)分析比较MRDWI与T_2 WI在PCa病灶检出中的价值.同时对30例直肠指检无结节,前列腺穿刺活检阴性患者行MRDWI检查,通过ADC值将可疑病灶按照Ⅰ(良性)～Ⅴ(恶性)级标准划分,在经直肠超声横断面上对异常区域进行定位穿刺.评价以MRDWI定位再次穿刺的价值. 结果 57例患者MRDWI与T_2WI的ROC分别为0.830和0.742,MRDWI诊断敏感性为85%、特异性为82%、阳性预测值80%、阴性预测值86%、准确率为83%;T_2 WI的敏感性为77%、特异性为71%、阳性预测值69%、阴性预测值79%、准确率为74%.MRDWI诊断准确性优于TzWl(P<0.05).30例穿刺定位患者中ADC图诊断为PCa 24例(≥Ⅳ级),BPH 6例(Ⅰ～Ⅲ级).穿刺病理证实为PCa 17例(85%),以Ⅳ级为界划分良恶性,诊断敏感性100%、特异性46%、阳性预测值71%、阴性预测值100%、准确率77%.如果以至少有1个区域为V级划为恶性,则17例PCa患者中DWI诊断恶性13例,敏感性77%、特异性85%、阳性预测值87%、阴性预测值73%、准确率80%. 结论 MR弥散加权成像诊断PCa准确性优于T2加权成像,能有效提高PSA持续升高患者前列腺再次穿刺活检的检出率.