AJR:199, July 2012 103 In particular, diffusion-weighted imaging (DWI) is an unenhanced technique that can be easily acquired and processed and that in- creases the accuracy for tumor localization compared with the use of T2WI alone [4]. Recent studies have reported that DWI combined with T2WI has improved diagnos- tic performance over T2WI alone. However, the diagnostic performances that were evalu- ated in these prior studies varied depending on many factors, such as the field strength of the MRI scanner, the b value used, and the ref- erence standard that was used in each study. Signal-to-noise ratio will also affect detecta- bility, particularly with a low signal-to-noise ratio technique such as DWI. Moreover, dis- ease stage, lesion size, and presence of hemor- rhage from previous biopsy may influence the diagnostic performance as well. Because a large number of studies explor- ing the role of T2WI combined with DWI in detecting prostate carcinoma have been pub- The Clinical Value of Diffusion- Weighted Imaging in Combination With T2-Weighted Imaging in Diagnosing Prostate Carcinoma: A Systematic Review and Meta-Analysis Lian-Ming Wu 1 Jian-Rong Xu 1 Yong-Quan Ye 2 Qing Lu 1 Jia-Ni Hu 2 Wu LM, Xu JR, Ye YQ, Lu Q, Hu JN 1 Department of Radiology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, No. 1630, Dongfang Rd, Pudong, Shanghai 200127, China. Address correspondence to J. R. Xu (China.xujianr@yeah.net). 2 Department of Radiology, Wayne State University, Detroit, MI. Genitourinary฀Imaging฀•฀Original฀Research AJR 2012; 199:103–110 0361–803X/12/1991–103 © American Roentgen Ray Society P rostate cancer is a leading cause of morbidity and mortality among men in the United States [1]. At present, serum prostate-specific antigen (PSA) levels and digital rectal exami- nation are the mainstays of clinical detection of prostate cancer. Abnormal findings are fol- lowed up by transrectal ultrasound–guided biopsy. MRI provides incremental value to biopsy and digital rectal examination for prostate cancer localization [2]. It can aid in many aspects of prostate cancer manage- ment, from initial detection to treatment plan- ning and follow-up. The sensitivity and speci- ficity of T2-weighted imaging (T2WI) for prostate cancer vary widely, because of differ- ences in imaging techniques, reference stan- dards, criteria for defining disease involve- ment on MRI, and interobserver variability [3]. Functional imaging techniques are being developed to complement conventional MRI in the detection and staging of prostate cancer. Keywords: diffusion-weighted imaging, meta-analysis, prostate carcinoma, systematic review, T2-weighted imaging DOI:10.2214/AJR.11.7634 Received August 2, 2011; accepted after revision September 24, 2011. This work was supported by Shanghai Leading Academic Discipline Project No. S30203 and Shanghai Jiaotong University School of Medicine Leading Academic Discipline Project. OBJECTIVE. We aimed to explore the role of diffusion-weighted imaging (DWI) in com- bination with T2-weighted imaging (T2WI) in detecting prostate carcinoma through a syste- matic review and meta-analysis. MATERIALS฀AND฀METHODS. The MEDLINE, EMBASE, Cancerlit, and Cochrane Library databases were searched for studies published from January 2001 to July 2011 evalu- ating the diagnostic performance of T2WI combined with DWI in detecting prostate carcino- ma. We determined sensitivities and specificities across studies, calculated positive and nega- tive likelihood ratios, and constructed summary receiver operating characteristic curves. We also compared the performance of T2WI combined with DWI with T2WI alone by analyzing studies that had also used these diagnostic methods on the same patients. RESULTS. Across 10 studies (627 patients), the pooled sensitivity of T2WI combined with DWI was 0.76 (95% CI, 0.65–0.84), and the pooled specificity was 0.82 (95% CI, 0.77–0.87). Overall, the positive likelihood ratio was 4.31 (95% CI, 3.12–5.92), and the negative likelihood ra- tio was 0.29 (95% CI, 0.20–0.43). In seven studies in which T2WI combined with DWI and T2WI alone were performed, the sensitivity and specificity of T2WI combined with DWI were 0.72 (95% CI, 0.67–0.82) and 0.81 (95% CI, 0.76–0.86), respectively, and the sensitivity and specificity of T2WI alone were 0.62 (95% CI, 0.55–0.68) and 0.77 (95% CI, 0.71–0.82), respectively. CONCLUSION. T2WI combined with DWI may be a valuable tool for detecting pros- tate cancer in the overall evaluation of prostate cancer, compared with T2WI alone. High- quality prospective studies of T2WI combined with DWI to detect prostate carcinoma still need to be conducted. Wu et al. Role of Imaging in Diagnosing Prostate Cancer Genitourinary Imaging Original Research Downloaded from www.ajronline.org by Queen's Univ on 03/06/14 from IP address 130.15.241.167. Copyright ARRS. For personal use only; all rights reserved