Department of MRI, Clínica Girona, Lorenzana 36, Girona 17002, Spain.
AJR Am J Roentgenol. 2011 Jun;196(6):W715-22. doi: 10.2214/AJR.10.5700.
The purpose of the study was to assess the predictive value for prostate cancer of MRI using morphologic (T2-weighted imaging [T2WI]) and functional (MR spectroscopy [MRS], diffusion-weighted imaging [DWI], and dynamic contrast-enhanced [DCE] MRI) sequences and the free-to-total prostate-specific antigen (PSA) ratio, alone and combined.
This retrospective study included 70 patients (PSA level, > 4 ng/mL; free-to-total PSA ratio, < 20%) who underwent endorectal 1.5-T MRI before biopsy. We graded the likelihood of cancer on a 5-point scale. Imaging data were compared with histologic results on biopsy or prostatectomy. Accuracies were estimated from the area under receiver operating characteristic using the hemiprostate as the unit of analysis. A p value less than 0.05 denoted statistical significance.
The model combining all variables was more accurate than each variable alone (95.2% vs 73.5% for T2WI, 76.0% for MRS, 81.8% for DWI, 75.6% for DCE-MRI, and 78.8% for free-to-total PSA ratio). The complete model had accuracy similar to that of combining two imaging variables with free-to-total PSA ratio, especially free-to-total PSA ratio, T2WI, and DWI (94.0%); and free-to-total PSA ratio, DWI, and MRS (93.8%); with negative predictive values of 91.0% and 89.5%, respectively. The best models combining two imaging variables (MRS and DWI, 85.8%; T2WI and DWI, 84.8%) had accuracy that was similar to that of the combination of all imaging variables (87.3%) and higher than that of the best individual imaging variable (DWI, 81.8%), but lower than that of the complete model.
The combination of at least one functional technique with free-to-total PSA ratio is more accurate than combining only imaging variables in cancer detection. The use of more than two imaging variables does not increase the detection rate. Functional MRI has the potential to help avoid a large number of negative biopsies.
本研究旨在评估 MRI 形态学（T2 加权成像 [T2WI]）和功能学（磁共振波谱 [MRS]、弥散加权成像 [DWI]和动态对比增强 [DCE] MRI）序列以及游离前列腺特异性抗原（PSA）与总 PSA 比值（f/t PSA）单独及联合预测前列腺癌的价值。
本回顾性研究纳入 70 例（PSA 水平＞4ng/ml；f/t PSA 比值＜20%）患者，所有患者均在前列腺穿刺活检前行直肠内 1.5T MRI 检查。我们对癌症的可能性进行了 5 分制评分。对影像学数据和活检或前列腺切除术的组织学结果进行比较。采用半前列腺作为分析单位，通过接受者操作特征曲线下面积来评估准确性。p 值＜0.05 表示有统计学意义。
与单独变量相比，联合所有变量的模型更准确（T2WI 为 95.2%比 73.5%，MRS 为 76.0%，DWI 为 81.8%，DCE-MRI 为 75.6%，f/t PSA 比值为 78.8%）。完整模型的准确性与联合两种影像学变量加 f/t PSA 比值相似，尤其是联合 f/t PSA 比值、T2WI 和 DWI（94.0%）以及 f/t PSA 比值、DWI 和 MRS（93.8%），阴性预测值分别为 91.0%和 89.5%。联合两种影像学变量（MRS 和 DWI，85.8%；T2WI 和 DWI，84.8%）的最佳模型准确性与联合所有影像学变量（87.3%）相似，且高于最佳单一影像学变量（DWI，81.8%），但低于完整模型。
至少联合一种功能技术和 f/t PSA 比值比单纯联合影像学变量在癌症检测中更准确。使用两种以上影像学变量不会增加检出率。功能 MRI 具有帮助避免大量阴性活检的潜力。
