Department of Radiology, Abdominal Imaging Section, University of California San Francisco, San Francisco, California 94143-0628, USA.
Int Braz J Urol. 2009 Mar-Apr;35(2):171-80; discussion 181-2. doi: 10.1590/s1677-55382009000200007.
To retrospectively determine the accuracy of T2-weighted endorectal MR imaging in the detection of prostate cancer after external beam radiation therapy and to investigate the relationship between imaging accuracy and time since therapy.
Institutional review board approval was obtained and the study was HIPPA compliant. We identified 59 patients who underwent 1.5 Tesla endorectal MR imaging of the prostate between 1999 and 2006 after definitive external beam radiation therapy for biopsy-proven prostate cancer. Two readers recorded the presence or absence of tumor on T2-weighted images. Logistic regression and Fisher's exact tests for 2x2 tables were used to determine the accuracy of imaging and investigate if accuracy differed between those imaged within 3 years of therapy (n = 25) and those imaged more than 3 years after therapy (n = 34). Transrectal biopsy was used as the standard of reference for the presence or absence of recurrent cancer.
Thirty-four of 59 patients (58%) had recurrent prostate cancer detected on biopsy. The overall accuracy of T2-weighted MR imaging in the detection cancer after external beam radiation therapy was 63% (37/59) for reader 1 and 71% for reader 2 (42/59). For both readers, logistic regression showed no difference in accuracy between those imaged within 3 years of therapy and those imaged more than 3 years after therapy (p = 0.86 for reader 1 and 0.44 for reader 2).
T2-weighted endorectal MR imaging has low accuracy in the detection of prostate cancer after external beam radiation therapy, irrespective of the time since therapy.
回顾性分析外照射放疗后 T2 加权直肠内磁共振成像（MR）检测前列腺癌的准确性，并探讨其与治疗后时间的关系。
本研究获得了机构审查委员会的批准，并符合 HIPAA 规定。我们共纳入 59 例经活检证实的前列腺癌患者，这些患者在 1999 年至 2006 年间接受了外照射放疗后行 1.5T 直肠内 MR 成像检查。两位阅片者分别记录 T2 加权图像上肿瘤的存在或缺失情况。采用二项式 2x2 表的逻辑回归和 Fisher 精确检验来确定成像的准确性，并探讨治疗后 3 年内（n=25）和 3 年以上（n=34）成像的准确性是否存在差异。以经直肠活检是否存在复发性癌症作为参考标准。
59 例患者中有 34 例（58%）经活检发现复发性前列腺癌。在两位阅片者中，外照射放疗后 T2 加权 MR 成像检测癌症的总体准确性分别为 63%（37/59）和 71%（42/59）。对于两位阅片者，逻辑回归均显示治疗后 3 年内和 3 年以上成像的准确性无差异（阅片者 1：p=0.86；阅片者 2：p=0.44）。
T2 加权直肠内 MR 成像检测外照射放疗后前列腺癌的准确性较低，与治疗后时间无关。
