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PURPOSE The objective of this study was to determine the diagnostic performance of quantitative diffusion-weighted magnetic resonance imaging in detection of prostate cancer. METHODS A comprehensive search was performed for English articles published before May 2012 that fulfilled the following criteria: patients had histopathologically proved prostate cancer; diffusion-weighted imaging (DWI) was performed for the detection of prostate cancer, and data for calculating sensitivity and specificity were included. Methodological quality was assessed by using the quality assessment of diagnostic studies instrument. Publication bias analysis, homogeneity, inconsistency index, and threshold effect were performed by STATA version 12. RESULTS Of 119 eligible studies, 12 with 1637 malignant and 4803 benign lesions were included. There was notable heterogeneity beyond threshold effect and publication bias. The sensitivity and specificity with 95% confidence interval (CI) estimates of DWI on a per-lesion basis were 77% (CI, 0.76-0.84) and 84% (CI, 0.78-0.89), respectively, and the area under the curve of summary receiver operating characteristic curve was 0.88 (CI, 0.85-0.90). The overall positive and negative likelihood ratios with 95% CI were 4.93 (3.39-7.17) and 0.278 (0.19-0.39), respectively. CONCLUSIONS Quantitative DWI has a relative sensitivity and specificity to distinguish malignant from benign in prostate lesions. However, large-scale randomized control trials are necessary to assess its clinical value because of nonuniformed diffusion gradient b factor, diagnosis threshold, and small number of studies.

OBJECTIVES To assess the diagnostic accuracy of computed tomographic (CT) perfusion technique in discriminating recurrent nasopharyngeal carcinoma (NPC) after radiation therapy. METHODS Forty-eight patients with a pathologic finding as reference standards were divided into 2 groups, recurrent and nonrecurrent NPCs. Perfusion parameters blood flow (BF), blood volume (BV), permeability surface (PS), and mean transit time were statistically analyzed. A receiver operating characteristic curve was used to study whether CT perfusion parameters could aid in detecting recurrent NPC. RESULTS Blood flow, BV, and PS values between recurrent NPC (n = 27) and nonrecurrent NPC (n = 21) were 526.8 (168.1) versus 312.1 (214.4) mL/100 g per minute, 35.1 (23.6) versus 9.2 (8.0) (ml/100 g), and 53.4 (34.3) versus 17.6 (14.7) mL/100 g per minute, respectively. There was a significant difference between these 2 groups (P < 0.01). Mean transit time values in these 2 groups were 3.5 (2.0) versus 4.3 (2.7) seconds; there was no statistical difference. To optimize sensitivity and specificity, BF, BV, and PS threshold values for differentiating between recurrent and nonrecurrent NPCs were 537.20 mL/100 g per minute, 37.18 (ml/100 g), and 57.34 mL/100 g per minute, respectively. According to threshold values of BF, BV, and PS, sensitivity and specificity for distinguishing recurrent and nonrecurrent NPCs were 92.6% and 76.2%, 96.3% and 81%, and 81.5% and 61.9%, respectively. CONCLUSIONS The CT perfusion technique may be helpful to find patients with recurrent NPC after radiation therapy.