盆腔磁共振T2加权像前列腺外周带影像特征对PSA〈20μg／L前列腺癌诊断的意义

The significance of peripheral zone imaging features on pelvic T2 weighted imaging for the diagnosis of prostate cancer with PSA 〈20μg/L

目的探讨磁共振检查在前列腺癌早期诊断中的意义，分析T2加权成像（T2weightedimaging，T2WI）中有助于早期前列腺癌诊断的影像学特征。方法收集2006年2月至2011年1月收治的359例PSA〈20μg／L、行前列腺穿刺患者的临床资料。年龄（70．1±7．6）岁。血清PSA（8．1±4．5）μg／L，其中PSA〉4μg／L者343例。回顾性分析盆腔磁共振检查T2WI影像特征，评估外周带及精囊信号、前列腺包膜与周围组织的关系，以前列腺穿刺活检病理结果作为对照，分析阅片结果。结果本组359例中穿刺活检病理诊断为前列腺癌137例，T2WI外周带有低信号者332例。单因素Logistic回归分析发现，年龄、PSA与前列腺癌的发生密切相关（P〈0．05）；T2WI上外周带出现低信号有助于在影像上诊断前列腺癌；病灶数目、形态、边界、前列腺包膜的轮廓、外周带与增生腺体界限均与前列腺癌的诊断显著相关（P均〈0．05）；多因素Logistic回归分析发现影响前列腺癌诊断的危险因素为年龄、PSA、前列腺体积、病灶形态及前列腺包膜的轮廓，受试者工作特征曲线下面积为0．833（P〈0．05）。结论盆腔磁共振检查T2WI中，病灶形态及前列腺包膜的轮廓是影响前列腺癌诊断的危险因素，年龄、PSA、前列腺体积等也与前列腺癌的发生有显著相关性。

Objective To explore the significance of 1.5-Tesla MRI in the early diagnosis of pros- tate cancer, and analyze the imaging features in T2WI which are helpful for the diagnosis on early prostate cancer. Methods The clinical data of patients with PSA 〈 20 μg/L who received prostate biopsy between Feb. 2006 and Jan. 2011 were reviewed including pelvic MRI and biopsy results. We retrospectively ana- lyzed T2WI image features and evaluated the signal of peripheral zone, seminal vesicles, prostate capsule and the relationship with their surrounding tissues. The results of the reading were analyzed with reference to histopathologic evaluation of prostate biopies. Results Among 359 patients, 137 patients were diagnosed prostate cancer and 332 cases were found with low signal lesions on peripheral zone of T2WI. Univariate lo- gistic regression analysis showed that age and PSA are closely related to the diagnosis of prostate cancer （P 〈 0.05）. Low signal lesions on peripheral zone of T2WI are more helpful for the diagnosis of prostate cancer on the image. Number, shape, margin of lesions, the contour of the prostatic capsule, the boundary of peripheral zone and transitional zone are significantly associated with the diagnosis of prostate cancer. Through multivariate logistic regression analysis, it was found that age （ P 〈 0.05 ） , PSA （ P 〈 0.05 ） , pros- tate volume （ P 〈 0.05 ） , lesion shape （ flaky vs nodular, P 〈 0.05 ; diffuse vs nodular, P 〈 0.05 ） and thecontour of the prostatic capsule （ disappearing vs completely clear, P 〈 0.05） are risk factors of prostate cancer. The areas under receiver operating characteristic curve are 0. 833 （P 〈 0.05）. Conclusions In T2WI, lesion shape and the contour of the prostatic capsule are risk factors of prostate cancer. Age, PSA, prostate volume are also significantly associated with the diagnosis of prostate cancer.