G e nit ou r i n a r y I m ag i ng • O r ig i n a l Re s e a rc h AJR 2015; 205:70-76 0361-803X/15/2051-70 OBJECTIVE. The purpose of this prospective study was to assess the clinical utility of generalized autocalibrating partial parallel acquisition (GRAPPA)-accelerated readoutsegmented echo-planar imaging (rs-EPI) DWI and compare it with standard single-shot EPI ( ss-EPI) DWI in visualization of the prostate during 3-T MRI.SUBJECTS AND METHODS. One hundred sixteen consecutively registered patients (mean age, 63.5 years; range 24-93 years) underwent 3-T MRI that included rs-EPI DWI and standard ss-EPI DWI with identical FOVs, slices, acceleration factors, b values, and image postprocessing procedure. The datasets were independently evaluated by two blinded radiologists. Images were evaluated for sharpness, anatomic distortion, imaging contrast, lesion conspicuity, detailed anatomic visualization, and overall image quality on a 5-point Likert scale (1, nondiagnostic; 5, excellent).RESULTS. The kappa values were 0.73 for image sharpness, 0.71 for anatomic distortion, 0.54 for imaging contrast, 0.56 for lesion conspicuity, 0.61 for detailed anatomic visualization, and 0.63 for overall image quality (all p < 0.05), indicating moderate to substantial agreement between the two observers. The mean Likert scores for standard ss-EPI and rs-EPI were as follows: image sharpness, 2.9 and 4.6; distortion level, 2.8 and 4.4; contrast, 3.1 and 3.8; lesion conspicuity, 3.0 and 4.0; structure, 3.1 and 4.2; and overall image quality, 3.1 and 4.2. The rs-EPI DWI sequence was associated with significantly better image quality and fewer susceptibility artifacts than was ss-EPI (all p < 0.05). The rs-EPI sequence was considered better overall in 90% of cases.CONCLUSION. The technique of rs-EPI DWI combined with GRAPPA enables robust prostate imaging with high image quality and may provide great benefit in routine clinical practice. Li et al. DWI of Prostate Genitourinary Imaging Original Research Downloaded from www.ajronline.org by NYU Langone Med Ctr-Sch of Med on 07/02/15 from IP address 128.122.253.228. Copyright ARRS. For personal use only; all rights reserved AJR:205, July 2015

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ObjectivesTo evaluate the diagnostic performance of different mathematical models and different b-value ranges of diffusion-weighted imaging (DWI) in peripheral zone prostate cancer (PZ PCa) detection.MethodsFifty-six patients with histologically proven PZ PCa who underwent DWI-magnetic resonance imaging (MRI) using 21 b-values (0–4500 s/mm2) were included. The mean signal intensities of the regions of interest (ROIs) placed in benign PZs and cancerous tissues on DWI images were fitted using mono-exponential, bi-exponential, stretched-exponential, and kurtosis models. The b-values were divided into four ranges: 0–1000, 0–2000, 0–3200, and 0–4500 s/mm2, grouped as A, B, C, and D, respectively. ADC, , D*, f, DDC, α, Dapp, and Kapp were estimated for each group. The adjusted coefficient of determination (R2) was calculated to measure goodness-of-fit. Receiver operating characteristic curve analysis was performed to evaluate the diagnostic performance of the parameters.ResultsAll parameters except D* showed significant differences between cancerous tissues and benign PZs in each group. The area under the curve values (AUCs) of ADC were comparable in groups C and D (p = 0.980) and were significantly higher than those in groups A and B (p< 0.05 for all). The AUCs of ADC and Kapp in groups B and C were similar (p = 0.07 and p = 0.954), and were significantly higher than the other parameters (p< 0.001 for all). The AUCs of ADC in group D was slightly higher than Kapp (p = 0.002), and both were significantly higher than the other parameters (p< 0.001 for all).ConclusionsADC derived from conventional mono-exponential high b-value (3200 s/mm2) models is an optimal parameter for PZ PCa detection.