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Objective: The aim of the study was to compare the distribution of Prostate Imaging and Reporting Data System (PI-RADS) scores, interreader agreement, and diagnostic performance of PI-RADS v2.0 and v2.1 for transition zone (TZ) lesions., Methods: The study included 202 lesions in 202 patients who underwent 3T prostate magnetic resonance imaging showing a TZ lesion that was later biopsied with magnetic resonance imaging/ultrasound fusion. Five abdominal imaging faculty reviewed T2-weighted imaging and high b value/apparent diffusion coefficient images in 2 sessions. Cases were randomized using a crossover design whereby half in the first session were reviewed using v2.0 and the other half using v2.1, and vice versa for the 2nd session. Readers provided T2-weighted imaging and DWI scores, from which PI-RADS scores were derived., Results: Interreader agreement for all PI-RADS scores had κ of 0.37 (v2.0) and 0.26 (v2.1). For 4 readers, the percentage of lesions retrospectively scored PI-RADS 1 increased greater than 5% and PI-RADS 2 score decreased greater than 5% from v2.0 to v2.1. For 2 readers, the percentage scored PI-RADS 3 decreased greater than 5% and, for 2 readers, increased greater than 5%. The percentage of PI-RADS 4 and 5 lesions changed less than 5% for all readers. For the 4 readers with increased frequency of PI-RADS 1 using v2.1, 4% to 16% were Gleason score ≥3 + 4 tumor. Frequency of Gleason score ≥3 + 4 in PI-RADS 3 lesions increased for 2 readers and decreased for 1 reader. Sensitivity of PI-RADS of 3 or greater for Gleason score ≥3 + 4 ranged 76% to 90% (v2.0) and 69% to 96% (v2.1). Specificity ranged 32% to 64% (v2.0) and 25% to 72% (v2.1). Positive predictive value ranged 43% to 55% (v2.0) and 41% to 58% (v2.1). Negative predictive value ranged 82% to 87% (v2.0) and 81% to 91% (v2.1)., Conclusions: Poor interreader agreement and lack of improvement in diagnostic performance indicate an ongoing need to refine evaluation of TZ lesions., Competing Interests: A.B.R. received royalties from Thieme Medical Publishers and salary support for AJR editorship. The other authors declare no conflict of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background Active surveillance (AS) is the recommended treatment option for low-risk prostate cancer (PC). Surveillance varies in MRI, frequency of follow-up, and the Prostate Imaging Reporting and Data System (PI-RADS) score that would repeat biopsy. Purpose To compare the effectiveness and cost-effectiveness of AS strategies for low-risk PC with versus without MRI. Materials and Methods This study developed a mathematical model to evaluate the cost-effectiveness of surveillance strategies in a simulation of men with a diagnosis of low-risk PC. The following strategies were compared: watchful waiting, prostate-specific antigen (PSA) and annual biopsy without MRI, and PSA testing and MRI with varied PI-RADS thresholds for biopsy. MRI strategies differed regarding scheduling and use of PI-RADS score of at least 3, or a PI-RADS score of at least 4 to indicate the need for biopsy. Life-years, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios were calculated by using microsimulation. Sensitivity analysis was used to assess the impact of varying parameter values on results. Results For the base case of 60-year-old men, all strategies incorporating prostate MRI extended QALYs and life-years compared with watchful waiting and non-MRI strategies. Annual MRI strategies yielded 16.19 QALYs, annual biopsy with no MRI yielded 16.14 QALYs, and watchful waiting yielded 15.94 QALYs. Annual MRI with PI-RADS score of at least 3 or of at least 4 as the biopsy threshold and annual MRI with biopsy even after MRI with negative findings offered similar QALYs and the same unadjusted life expectancy: 23.05 life-years. However, a PI-RADS score of at least 4 yielded 42% fewer lifetime biopsies. With a cost-effectiveness threshold of $100 000 per QALY, annual MRI with biopsy for lesions with PI-RADS scores of 4 or greater was most cost-effective (incremental cost-effectiveness ratio, $67 221 per QALY). Age, treatment type, risk of initial grade misclassification, and quality-of-life impact of procedural complications affected results. Conclusion The use of active surveillance (AS) with biopsy decisions guided by findings from annual MRI reduces the number of biopsies while preserving life expectancy and quality of life. Biopsy in lesions with PI-RADS scores of 4 or greater is likely the most cost-effective AS strategy for men with low-risk prostate cancer who are younger than 70 years. © RSNA, 2021 Online supplemental material is available for this article. An earlier incorrect version appeared online. This article was corrected on July 13, 2021.

Purpose: 18 F-Fluciclovine is indicated for evaluation of suspected prostate cancer (PCa) biochemical recurrence. There are few studies investigating fluciclovine with PET/MR and none evaluated osseous metastases. Our aim was to assess the performance of 18 F-fluciclovine PET/MR (fluciclovine-PET/MR) for detecting osseous metastases in patients with castration-resistant prostate cancer (CRPC). We also investigated possible correlations between SUVmax and ADCmean., Methods: We evaluated 8 patients with CRPC metastatic to bones, some before and some after radium therapy, who underwent 13 fluciclovine-PET/MR studies. We analyzed the performance of radionuclide bone scan (RBS), MR alone, fluciclovine-PET alone, and fluciclovine-PET/MR in detecting osseous metastases. Lesion size, characteristics (early sclerotic, late sclerotic, mixed, lytic), SUVmax, and ADCmean were assessed. The reference standard was a combination of clinical information and correlation with both prior and follow-up imaging., Results: Of 347 metastatic bony lesions in 13 studies, 238/347 (68%) were detected by fluciclovine-PET alone, 286/347 (82%) by RBS, 344/347 (99%) by MR alone, and 347/347 (100%) by fluciclovine-PET/MR. Fluciclovine-PET/MR and MR had the best performance (p < 0.001). There was no statistically significant difference between fluciclovine-PET/MR and MR alone (p = 0.25). Fluciclovine-PET had a lower detection rate especially with late sclerotic lesions (p < 0.001). There was a moderate inverse correlation between lesion SUVmax and ADCmean (r = - 0.49; p < 0.001)., Conclusions: This study suggests that fluciclovine-PET/MR and MR have high sensitivity for detecting osseous metastases in CRPC. Fluciclovine-PET alone underperformed in detecting late sclerotic lesions. The inverse correlation between SUVmax and ADCmean suggests a possible relationship between tumor metabolism and cellularity.

Background: The value of dynamic contrast-enhanced (DCE) sequences in prostate MRI compared with noncontrast MRI is controversial., Purpose: To evaluate the population net benefit of risk stratification using DCE-MRI for detection of high-grade prostate cancer (HGPCA), with or without high spatiotemporal resolution DCE imaging., Study Type: Decision curve analysis., Population: Previously published patient studies on MRI for HGPCA detection, one using DCE with golden-angle radial sparse parallel (GRASP) images and the other using standard DCE-MRI., Field Strength/sequence: GRASP or standard DCE-MRI at 3 T., Assessment: Each study reported the proportion of lesions with HGPCA in each Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) category (1-5), before and after reclassification of peripheral zone lesions from PI-RADS 3-4 based on contrast-enhanced images. This additional risk stratifying information was translated to population net benefit, when biopsy was hypothetically performed for: all lesions, no lesions, PI-RADS ≥3 (using NC-MRI), and PI-RADS ≥4 on DCE., Statistical Tests: Decision curve analysis was performed for both GRASP and standard DCE-MRI data, translating the avoidance of unnecessary biopsies and detection of HGPCA to population net benefit. We standardized net benefit values for HGPCA prevalence and graphically summarized the comparative net benefit of biopsy strategies., Results: For a clinically relevant range of risk thresholds for HGPCA (>11%), GRASP DCE-MRI with biopsy of PI-RADS ≥4 lesions provided the highest net benefit, while biopsy of PI-RADS ≥3 lesions provided highest net benefit at low personal risk thresholds (2-11%). In the same range of risk thresholds using standard DCE-MRI, the optimal strategy was biopsy for all lesions (0-15% risk threshold) or PI-RADS ≥3 on NC-MRI (16-33% risk threshold)., Data Conclusion: GRASP DCE-MRI may potentially enable biopsy of PI-RADS ≥4 lesions, providing relatively preserved detection of HGPCA and avoidance of unnecessary biopsies compared with biopsy of all PI-RADS ≥3 lesions. J. Magn. Reson. Imaging 2019;49:1400-1408., (© 2019 International Society for Magnetic Resonance in Medicine.)

Purpose To compare standard diffusion-weighted (DW) imaging and diffusion kurtosis (DK) imaging for prostate cancer (PC) detection and characterization in a large patient cohort, with attention to the potential added value of DK imaging. Materials and Methods This retrospective institutional review board-approved study received a waiver of informed consent. Two hundred eighty-five patients with PC underwent 3.0-T phased-array coil prostate magnetic resonance (MR) imaging, including a DK imaging sequence (b values 0, 500, 1000, 1500, and 2000 sec/mm 2 ) before prostatectomy. Maps of apparent diffusion coefficient (ADC) and diffusional kurtosis (K) were derived by using maximal b values of 1000 and 2000 sec/mm 2 , respectively. Mean ADC and K were obtained from volumes of interest (VOIs) placed on each patient's dominant tumor and benign prostate tissue. Metrics were compared between benign and malignant tissue, between Gleason score (GS) ≤ 3 + 3 and GS ≥ 3 + 4 tumors, and between GS ≤ 3 + 4 and GS ≥ 4 + 3 tumors by using paired t tests, analysis of variance, receiver operating characteristic (ROC) analysis, and exact tests. Results ADC and K showed significant differences for benign versus tumor tissues, GS ≤ 3 + 3 versus GS ≥ 3 + 4 tumors, and GS ≤ 3 + 4 versus GS ≥ 4 + 3 tumors (P < .001 for all). ADC and K were highly correlated (r = -0.82; P < .001). Area under the ROC curve was significantly higher (P = .002) for ADC (0.921) than for K (0.902) for benign versus malignant tissue but was similar for GS ≤ 3 + 3 versus GS ≥ 3 + 4 tumors (0.715-0.744) and GS ≤ 3 + 4 versus GS ≥ 4 + 3 tumors (0.694-0.720) (P > .15). ADC and K were concordant for these various outcomes in 80.0%-88.6% of patients; among patients with discordant results, ADC showed better performance than K for GS ≤ 3 + 4 versus GS ≥ 4 + 3 tumors (P = .016) and was similar to K for other outcomes (P > .136). Conclusion ADC and K were highly correlated, had similar diagnostic performance, and were concordant for the various outcomes in the large majority of cases. These observations did not show a clear added value of DK imaging compared with standard DW imaging for clinical PC evaluation. © RSNA, 2017 Online supplemental material is available for this article.

Purpose: To assess the impact of patient race and age on the performance of apparent diffusion coefficient (ADC) values for assessment of prostate cancer aggressiveness., Materials and Methods: 457 prostate cancer patients who underwent 3T phased-array coil prostate MRI including diffusion-weighted imaging (DWI; maximal b-value 1000 s/mm 2 ) before prostatectomy were included. Mean ADC of a single dominant lesion was measured in each patient, using histopathologic findings from the prostatectomy specimen as reference. In subsets defined by race and age, ADC values were compared between Gleason score (GS) ≤ 3 + 4 and GS ≥ 4 + 3 tumors., Results: 81% of patients were Caucasian, 12% African-American, 7% Asian-American. 13% were <55 years, 42% 55-64 years, 41% 65-74 years, and 4% ≥75 years. 63% were GS ≤ 3 + 4, 37% GS ≥ 4 + 3. ADC was significantly lower in GS ≥ 4 + 3 tumors than in GS ≤ 3 + 4 tumors in the entire cohort, as well as in Caucasian, African-American, and all four age groups (P ≤ 0.015). AUC for differentiation of GS ≤ 3 + 4 and GS ≥ 4 + 3 as well as optimal ADC threshold was Caucasian: 0.73/≤848; African-American: 0.76/≤780; Asian-American: 0.66/≤839: <55 years, 0.73/≤830; 55-64 years, 0.71/≤800; 65-74 years, 0.74/≤872; ≥75 years, 0.79/≤880. A race-optimized ADC threshold resulted in higher specificity in African-American than Caucasian men (84.9% vs. 67.1%, P = 0.045); age-optimized ADC threshold resulted in higher sensitivity in patients aged ≥75 years than <55 years or 55-64 years (100.0% vs. 53.6%-73.3%; P < 0.001)., Conclusion: Patients' race and age may impact the diagnostic performance and optimal threshold when applying ADC values for evaluation of prostate cancer aggressiveness.

Objective: The purpose of this study is to evaluate the roles of self-directed learning and continual feedback in the learning curve for tumor detection by novice readers of prostate MRI., Materials and Methods: A total of 124 prostate MRI examinations classified as positive (n = 52; single Prostate Imaging Reporting and Data System [PI-RADS] category 3 or higher lesion showing Gleason score ≥ 7 tumor at MRI-targeted biopsy) or negative (n = 72; PI-RADS category 2 or lower and negative biopsy) for detectable tumor were included. These were divided into four equal-sized batches, each with matching numbers of positive and negative examinations. Six second-year radiology residents reviewed examinations to localize tumors. Three of the six readers received feedback after each examination showing the preceding case's solution. The learning curve, plotting accuracy over time, was assessed by the Akaike information criterion (AIC). Logistic regression and mixed-model ANOVA were performed., Results: For readers with and without feedback, the learning curve exhibited an initial rapid improvement that slowed after 40 examinations (change in AIC > 0.2%). Accuracy improved from 58.1% (batch 1) to 71.0-75.3% (batches 2-4) without feedback and from 58.1% to 72.0-77.4% with feedback (p = 0.027-0.046), without a difference in the extent of improvement (p = 0.800). Specificity improved from 53.7% to 68.5-81.5% without feedback and from 55.6% to 74.1-81.5% with feedback (p = 0.006-0.010), without a difference in the extent of improvement (p = 0.891). Sensitivity improved from 59.0-61.5% (batches 1-2) to 71.8-76.9% (batches 3-4) with feedback (p = 0.052), though did not improve without feedback (p = 0.602). Sensitivity for transition zone tumors exhibited larger changes (p = 0.024) with feedback than without feedback. Sensitivity for peripheral zone tumors did not improve in either group (p > 0.3). Reader confidence increased only with feedback (p < 0.001)., Conclusion: The learning curve in prostate tumor detection largely reflected self-directed learning. Continual feedback had a lesser effect. Clinical prostate MRI interpretation by novice radiologists warrants caution.

Objective: To provide insight into the impact of radical prostatectomy (RP) on prostate cancer-specific mortality (PCSM) in a primarily prostate-specific antigen screen-detected cohort of men with localized prostate cancer (PCa)., Methods: Between 2000 and 2013, 1864 men consented to participate in a prospective longitudinal outcomes study after RP for localized PCa by a single surgeon. Men lost to follow-up were queried to the National Death Index to acquire mortality data., Results: From our cohort of 1864 men (median age 59 years, median preoperative prostate-specific antigen 5.0, median follow-up 9.1 years), Kaplan-Meier analysis demonstrated 10-year all-cause mortality and PCSM of 4.6% and 1.4%, respectively. Ten-year PCSM for low, intermediate, and high D'Amico risk were 0.9%, 1.0%, and 7.4%, respectively (P <.001). For men with postoperative Gleason score 4-6, 7, and 8-10, 10-year PCSM was 0.8%, 1.0%, and 11.5%, respectively (P <.001). Men with pT2, pT3a, and pT3b disease had 10-year PCSM of 0.7%, 2.6%, and 9.5%, respectively (P <.001). Pathologic stage and grade were the only significant independent predictor of PCSM at 10 years (P = .002 and P = .025, respectively)., Conclusion: In our series with up to 13 years of follow-up from the National Death Index, 10-year PCSM after RP for clinically localized PCa was very low and strongly predicted by pathologic stage and grade. Death unrelated to PCa was a rare event, suggesting that we are identifying candidates for RP who are likely to live long enough to benefit from surgical intervention., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: To examine public and media response to the draft (October 2011) and finalised (May 2012) recommendations of the United States Preventive Services Task Force (USPSTF) against prostate-specific antigen (PSA) testing via Twitter, a popular social network with over 200 million active users., Materials and Methods: We used a mixed-methods design to analyse posts on Twitter, known as 'tweets'. Using the search term 'prostate cancer', we archived tweets in the 24-h periods following the release of both the draft and the finalised USPSTF recommendations. We recorded tweet rate per h and developed a coding system to assess the type of user and sentiment expressed in tweets and linked articles., Results: After the draft and finalised USPSTF recommendations were released, 2042 and 5357 tweets focused on the USPSTF report, respectively. The tweet rate nearly doubled within 2 h of both announcements. Fewer than 10% of tweets expressed an opinion about screening, and the majority of these were pro-screening during both periods. By contrast, anti-screening articles were tweeted more frequently in both the draft and finalised study periods. Between the draft and the finalised recommendations, the proportion of anti-screening tweets and anti-screening article links increased (P = 0.03 and P < 0.01, respectively)., Conclusions: There was increased Twitter activity surrounding the USPSTF draft and finalised recommendations. The percentage of anti-screening tweets and articles appeared to increase, perhaps due to the interval public comment period. Despite this, most tweets did not express an opinion, suggesting a missed opportunity in this important arena for advocacy., (© 2014 The Authors BJU International © 2014 BJU International Published by John Wiley & Sons Ltd.)

Purpose: The prevalence of lower urinary tract symptoms increases with age and impairs quality of life. Radical prostatectomy has been shown to relieve lower urinary tract symptoms at short-term followup but the long-term effect of radical prostatectomy on lower urinary tract symptoms is unclear., Materials and Methods: We performed a prospective cohort study of 1,788 men undergoing radical prostatectomy. The progression of scores from the self-administered AUASS (American Urological Association symptom score) preoperatively, and at 3, 6, 12, 24, 48, 60, 84, 96 and 120 months was analyzed using models controlling for preoperative AUASS, age, prostate specific antigen, pathological Gleason score and stage, nerve sparing, race and marital status. This model was also applied to patients stratified by baseline clinically significant (AUASS greater than 7) and insignificant (AUASS 7 or less) lower urinary tract symptoms., Results: Men exhibited an immediate worsening of lower urinary tract symptoms that improved between 3 months and 2 years after radical prostatectomy. Overall the difference between mean AUASS at baseline and at 10 years was not statistically or clinically significant. Men with baseline clinically significant lower urinary tract symptoms experienced immediate improvements in lower urinary tract symptoms that lasted until 10 years after radical prostatectomy (13.5 vs 8.81, p <0.001). Men with baseline clinically insignificant lower urinary tract symptoms experienced a statistically significant but clinically insignificant increase in mean AUASS after 10 years (3.09 to 4.94, p <0.001). The percentage of men with clinically significant lower urinary tract symptoms decreased from baseline to 10 years after radical prostatectomy (p = 0.02)., Conclusions: Radical prostatectomy is the only treatment for prostate cancer shown to improve and prevent the development of lower urinary tract symptoms at long-term followup. This previously unrecognized long-term benefit argues in favor of the prostate as the primary contributor to male lower urinary tract symptoms., (Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Background: The long-term impact of radical prostatectomy (RP) on sexual function (SF) and erectile function (EF) has important implications related to the risk-to-benefit ratio of this treatment., Objective: To determine the long-term effect of RP on male SF and EF over 10 yr of follow-up., Design, Setting, and Participants: This was a prospective, longitudinal outcomes study in 1836 men following RP at a university hospital. Men were invited to complete the University of California, Los Angeles, Prostate Cancer Index SF survey at baseline, 3, 6, 12, 24, 96, and 120 mo postoperatively and a survey at 4 and 7 yr postoperatively assessing global changes in their EF over the preceding 2 yr., Intervention: All men underwent open RP., Outcome Measurements and Statistical Analysis: Multiple, generalized linear regression models were used to evaluate the association between time following RP and SF and EF scores controlling for age, prostate-specific antigen, Gleason scores, stage, nerve sparing, race, and marital status., Results and Limitations: After an expected initial decline, time-dependent improvements in SF and EF were observed through 2 yr postoperatively. Overall, SF and EF were both generally stable between 2 and 10 yr following RP. The subgroups of younger men and men with better preoperative function were more likely to maintain their EF and SF through 10 yr following RP. The primary limitation is the potential bias attributable to nonresponders., Conclusions: The recovery of EF can extend well beyond 2 yr. There is a significant association between younger age and better preoperative function and the likelihood of experiencing improvements beyond 2 yr. Assessing the comparative effectiveness of treatment options for localized prostate cancer must examine SF beyond 2 yr to account for delayed treatment effects and the natural history of SF in the aging male population., (Copyright © 2013. Published by Elsevier B.V.)

Background: Urinary incontinence is a common short-term complication of radical prostatectomy (RP). Little is known about the long-term impact of RP on continence., Objective: To elucidate the long-term progression of continence after RP., Design, Setting, and Participants: From October 2000 through September 2012, 1788 men undergoing open RP for clinically localized prostate cancer by a single surgeon at an urban tertiary care center prospectively signed consent to be followed before RP and at 3, 6, 12, 24, 96, and 120 mo after RP. A consecutive sampling method was used and all men were included in this study., Intervention: Men underwent open RP., Outcome Measurements and Statistical Analysis: Regression models controlled for preoperative University of California, Los Angeles-Prostate Cancer Index urinary function score (UCLA-PCI-UFS), age, prostate-specific antigen level, Gleason score, stage, nerve-sparing status, race, and marital status were used to evaluate the association of time since RP with two dependent variables: UCLA-PCI-UFS and continence status., Results and Limitation: The mean UCLA-PCI-UFS declined between 2 yr and 8 yr (83.8 vs 81.8; p=0.007) and marginally between 8 yr and 10 yr (81.8 vs 79.6; p=0.036) after RP, whereas continence rate did not significantly change during these intervals. Men ≥ 60 yr old experienced a decline in mean UCLA-PCI-UFS between 2 yr and 8 yr (p=0.002) and a marginal decline in continence rate between 2 yr and 10 yr (p=0.047), whereas these variables did not change significantly in men <60 yr old. These outcomes are for an experienced surgeon, so caution should be exercised in generalizing these results., Conclusions: Between 2 yr and 10 yr after RP, there were slight decreases in mean UCLA-PCI-UFS and continence rates in this study. Men aged <60 yr had better long-term outcomes. These results provide realistic long-term continence expectations for men undergoing RP., (Copyright © 2013 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Objective: The purpose of this study was to compare findings at nongaussian diffusional kurtosis imaging and conventional diffusion-weighted MRI as markers of adverse pathologic outcomes among prostate cancer patients who are active surveillance candidates and choose to undergo prostatectomy., Materials and Methods: Fifty-eight active surveillance candidates (prostate-specific antigen concentration, < 10 ng/mL; clinical tumor category less than T2a; Gleason score, 3 + 3; ≤ 25% of biopsy cores positive for tumor; ≤ 50% tumor involvement of any individual core; ≤ 20% tumor involvement across all cores) who underwent prostatectomy and preoperative 3-T MRI including diffusional kurtosis imaging (b values, 0, 500, 1000, 1500, and 2000 s/mm(2)) were included. Adverse pathologic features at prostatectomy were defined using two schemes of varying stringency. One scheme (less stringent) was presence of a Gleason score greater than 6 or extracapsular extension (n = 19). The other scheme (more stringent) was presence of a Gleason score greater than 6, extracapsular extension, or an index tumor 10 mm or larger (n = 35). Parametric maps displaying standard apparent diffusion coefficient (ADC), kurtosis (K) representing nongaussian diffusion behavior, and diffusion (D) representing a diffusion coefficient adjusted for nongaussian (kurtosis) behavior were reviewed, and the most abnormal region was recorded for each metric. Associations between these metrics and the presence of adverse final pathologic findings were assessed with unpaired Student t tests and receiver operating characteristic analyses., Results: For both schemes, only D was significantly lower in patients with adverse final pathologic findings (p = 0.006, p = 0.025). K tended to be greater in patients with adverse final pathologic findings for the more stringent scheme (p = 0.072). ADC was not significantly different in the presence of adverse final pathologic findings for either scheme (p = 0.357, p = 0.383). With either scheme, D had a larger area under the receiver operating characteristics curve (AUC) for predicting adverse final pathologic results (AUC, 0.691 and 0.743) than did ADC (AUC, 0.569 and 0.655) or K (AUC, 0.617 and 0.714), but the difference was not significant (p = 0.183, p = 0.734)., Conclusion: Preliminary results suggest that diffusional kurtosis imaging findings may have more value than findings at conventional diffusion-weighted MRI as a marker of adverse final pathologic outcome among active surveillance candidates.

A cDNA microarray comprising 5184 different cDNAs spotted onto nylon membrane filters was developed for prostate gene expression studies. The clones used for arraying were identified by cluster analysis of > 35 000 prostate cDNA library-derived expressed sequence tags (ESTs) present in the dbEST database maintained by the National Center for Biotechnology Information. Total RNA from two cell lines, prostate line 8.4 and melanoma line UACC903, was used to make radiolabeled probe for filter hybridizations. The absolute intensity of each individual cDNA spot was determined by phosphorimager scanning and evaluated by a bioinformatics package developed specifically for analysis of cDNA microarray experimentation. Results indicated 89% of the genes showed intensity levels above background in prostate cells compared with only 28% in melanoma cells. Replicate probe preparations yielded results with correlation values ranging from r = 0.90 to 0.93 and coefficient of variation ranging from 16 to 28%. Findings indicate that among others, the keratin 5 and vimentin genes were differentially expressed between these two divergent cell lines. Follow-up northern blot analysis verified these two expression changes, thereby demonstrating the reliability of this system. We report the development of a cDNA microarray system that is sensitive and reliable, demonstrates a low degree of variability, and is capable of determining verifiable gene expression differences between two distinct human cell lines. This system will prove useful for differential gene expression analysis in prostate-derived cells and tissue.