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Purpose: To demonstrate the technical feasibility and the value of ultrahigh-performance gradient in imaging the prostate in a 3T MRI system., Methods: In this local institutional review board-approved study, prostate MRI was performed on 4 healthy men. Each subject was scanned in a prototype 3T MRI system with a 42-cm inner-diameter gradient coil that achieves a maximum gradient amplitude of 200 mT/m and slew rate of 500 T/m/s. PI-RADS V2.1-compliant axial T 2 -weighted anatomical imaging and single-shot echo planar DWI at standard gradient of 70 mT/m and 150 T/m/s were obtained, followed by DWI at maximum performance (i.e., 200 mT/m and 500 T/m/s). In comparison to state-of-the-art clinical whole-body MRI systems, the high slew rate improved echo spacing from 1020 to 596 μs and, together with a high gradient amplitude for diffusion encoding, TE was reduced from 55 to 36 ms., Results: In all 4 subjects (waist circumference = 81-91 cm, age = 45-65 years), no peripheral nerve stimulation sensation was reported during DWI. Reduced image distortion in the posterior peripheral zone prostate gland and higher signal intensity, such as in the surrounding muscle of high-gradient DWI, were noted., Conclusion: Human prostate MRI at simultaneously high gradient amplitude of 200 mT/m and slew rate of 500 T/m/s is feasible, demonstrating that improved gradient performance can address image distortion and T 2 decay-induced SNR issues for in vivo prostate imaging., (© 2023 International Society for Magnetic Resonance in Medicine.)

Background: Diffusion-weighted imaging (DWI) is commonly used to detect prostate cancer, and a major clinical challenge is differentiating aggressive from indolent disease., Purpose: To compare 14 site-specific parametric fitting implementations applied to the same dataset of whole-mount pathologically validated DWI to test the hypothesis that cancer differentiation varies with different fitting algorithms., Study Type: Prospective., Population: Thirty-three patients prospectively imaged prior to prostatectomy., Field Strength/sequence: 3 T, field-of-view optimized and constrained undistorted single-shot DWI sequence., Assessment: Datasets, including a noise-free digital reference object (DRO), were distributed to the 14 teams, where locally implemented DWI parameter maps were calculated, including mono-exponential apparent diffusion coefficient (MEADC), kurtosis (K), diffusion kurtosis (DK), bi-exponential diffusion (BID), pseudo-diffusion (BID*), and perfusion fraction (F). The resulting parametric maps were centrally analyzed, where differentiation of benign from cancerous tissue was compared between DWI parameters and the fitting algorithms with a receiver operating characteristic area under the curve (ROC AUC)., Statistical Test: Levene's test, P < 0.05 corrected for multiple comparisons was considered statistically significant., Results: The DRO results indicated minimal discordance between sites. Comparison across sites indicated that K, DK, and MEADC had significantly higher prostate cancer detection capability (AUC range = 0.72-0.76, 0.76-0.81, and 0.76-0.80 respectively) as compared to bi-exponential parameters (BID, BID*, F) which had lower AUC and greater between site variation (AUC range = 0.53-0.80, 0.51-0.81, and 0.52-0.80 respectively). Post-processing parameters also affected the resulting AUC, moving from, for example, 0.75 to 0.87 for MEADC varying cluster size., Data Conclusion: We found that conventional diffusion models had consistent performance at differentiating prostate cancer from benign tissue. Our results also indicated that post-processing decisions on DWI data can affect sensitivity and specificity when applied to radiological-pathological studies in prostate cancer., Level of Evidence: 1 TECHNICAL EFFICACY: Stage 3., (© 2021 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Objective: The objective of this study was to develop a scoring system for background signal intensity changes or prostate homogeneity on prostate MRI and to assess these changes' influence on cancer detection., Materials and Methods: This institutional review board-approved, HIPAA-compliant, retrospective study included 418 prostate MRI examinations in 385 men who subsequently underwent MRI-guided biopsy. The Likert score for suspicion of cancer assigned by the primary radiologist was extracted from the original report, and histopathologic work-up of the biopsy cores served as the reference standard. Two readers assessed the amount of changes on T2-weighted sequences and assigned a predefined prostate signal-intensity homogeneity score of 1-5 (1 = poor, extensive changes; 5 = excellent, no changes). The sensitivity and specificity of Likert scores for detection of prostate cancer and clinically significant cancer (Gleason score ≥ 3+4) were estimated in and compared between subgroups of patients with different signal-intensity homogeneity scores (≤ 2, 3, and ≥ 4)., Results: Interreader agreement on signal-intensity homogeneity scores was substantial (κ = 0.783). Sensitivity for prostate cancer detection increased when scores were better (i.e., higher) (reader 1, from 0.41 to 0.71; reader 2, from 0.53 to 0.73; p ≤ 0.007, both readers). In the detection of significant cancer (Gleason score ≥ 3+4), sensitivity also increased with higher signal-intensity scores (reader 1, from 0.50 to 0.82; reader 2, from 0.63 to 0.86; p ≤ 0.028), though specificity decreased significantly for one reader (from 0.67 to 0.38; p = 0.009)., Conclusion: Background signal-intensity changes on T2-weighted images significantly limit prostate cancer detection. The proposed scoring system could improve the standardization of prostate MRI reporting and provide guidance for applying prostate MRI results appropriately in clinical decision-making.

Purpose: The purpose of our study was to retrospectively evaluate and categorize temporal changes in MRI appearances of the prostate in patients who underwent focal therapy with MRI follow-up., Methods: The Institutional Review Board approved this retrospective study and waived the requirement for informed consent. Thirty-seven patients (median age 61; 48-70 years) with low-to-intermediate-risk, clinically organ-confined prostate cancer underwent focal ablation therapy from 2009 to 2014. Two radiologists reviewed post-treatment MRIs (n = 76) and categorized imaging features blinded to the time interval between the focal therapy and the follow-up MRI. Inter-reader agreement was assessed (kappa) and generalized linear regression was used to examine associations between an imaging feature being present/absent and days between ablation and MRI., Results: Inter-reader agreement on MRI features ranged from fair to substantial. Edema was found present at earlier times after ablation (median 16-25 days compared to MRIs without edema, median 252-514 days), as was rim enhancement of the ablation zone (18-22.5 days vs. 409-593 days), a hypointense rim around the ablation zone on T2-weighted images (53-57.5 days vs. 279-409 days) and the presence of an appreciable ablation cavity (48.5-60 days vs. 613-798 days, all p < 0.05). Enhancement of the ablation zone/scar (553-731 days vs. 61.5-162 days) and the formation of a T2-hypointense scar were found to be present on later MRI scans (514-553 days vs. 29-32 days, one reader)., Conclusions: The MRI appearance of the prostate after focal ablation changes substantially over time. Identification of temporal patterns in the appearance of imaging features should help reduce image interpretation variability and errors when assessing post-therapeutic scans.

Purpose: To retrospectively measure metabolic ratios and apparent diffusion coefficient (ADC) values from 3-Tesla MR spectroscopic imaging (MRSI) and diffusion-weighted imaging (DWI) in benign and malignant peripheral zone (PZ) prostate tissue, assess the parameters' associations with malignancy, and develop and test rules for classifying benign and malignant PZ tissue using whole-mount step-section pathology as the reference standard., Methods: This HIPAA-compliant, IRB-approved study included 67 men (median age, 61 years; range, 41-74 years) with biopsy-proven prostate cancer who underwent preoperative 3 T endorectal multiparametric MRI and had ≥1 PZ lesion >0.1 cm 3 at whole-mount histopathology. In benign and malignant PZ regions identified from pathology, voxel-based choline/citrate, polyamines/choline, polyamines/creatine, and (choline + polyamines + creatine)/citrate ratios were averaged, as were ADC values. Patients were randomly split into training and test sets; rules for separating benign from malignant regions were generated with classification and regression tree (CART) analysis and assessed on the test set for sensitivity and specificity. Odds ratios (OR) were evaluated using generalized estimating equations., Results: CART analysis of all parameters identified only ADC and (choline + polyamines + creatine)/citrate as significant predictors of cancer. Sensitivity and specificity, respectively, were 0.81 and 0.82 with MRSI-derived, 0.98 and 0.51 with DWI-derived, and 0.79 and 0.90 with MRSI + DWI-derived classification rules. Areas under the curves (AUC) in the test set were 0.93 (0.87-0.97) with ADC, 0.82 (0.72-0.91) with MRSI, and 0.96 (0.92-0.99) with MRSI + ADC., Conclusion: We developed statistically-based rules for identifying PZ cancer using 3-Tesla MRSI, DWI, and MRSI + DWI and demonstrated the potential value of MRSI + DWI., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: To determine whether water diffusion and the perfusion fraction coefficients in prostate peripheral zone (PZ) and prostate cancer (PCa) are affected by intravenous contrast injection and explore the potential mechanism behind previously reported differences between pre- and post-contrast ADC values., Methods: Our institutional review board waived informed consent for this HIPAA-compliant, retrospective study, which included 32 patients (median age, 63 years; range, 47-77 years) with biopsy-proven, untreated PCa who underwent 3-Tesla MRI, including DW-MRI at b-values 0, 400, 700, 1000 s/mm 2 before and after gadolinium injection. For regions of interest (ROIs) in presumed benign PZ and PZ PCa, apparent diffusion coefficient (ADC), perfusion fraction f, and diffusion coefficient D were estimated voxel-wise, and signal-to-noise ratio (SNR) and contrast-to-noise (CNR) were estimated. Pre- and post-contrast measurements were compared by Wilcoxon signed-rank test; P < 0.05 was considered significant., Results: In PZ, f (P = 0.002) was significantly higher on post-contrast imaging than on pre-contrast imaging, but ADC and D values did not change significantly (P = 0.562 and 0.295 respectively). In PCa, all parameters differed significantly between post-contrast and pre-contrast imaging (P < 0.0001 for ADC, P = 0.0084 for D, and P = 0.029 for f). On post-contrast imaging, SNR was not significantly different in PZ (P = 0.260) but was significantly lower in PCa (P < 0.0001); CNR did not change significantly (P = 0.059)., Conclusion: After contrast injection, ADC and D declined significantly in PCa only, while f increased significantly in both PCa and PZ. Pre- and post-contrast diffusion parameters cannot be used interchangeably for diagnostic purposes that require quantitative diffusion estimates., (Copyright © 2018. Published by Elsevier Inc.)

Purpose: To assess the abilities of the standard mono-exponential (ME), bi-exponential (BE), diffusion kurtosis (DK) and stretched exponential (SE) models to characterize diffusion signal in malignant and prostatic tissues and determine which of the four models best characterizes these tissues on a per-voxel basis., Materials and Methods: This institutional-review-board-approved, HIPAA-compliant, retrospective study included 55 patients (median age, 61years; range, 42-77years) with untreated, biopsy-proven PCa who underwent endorectal coil MRI at 3-Tesla, diffusion-weighted MRI acquired at eight b-values from 0 to 2000s/mm 2 . Estimated parameters were apparent diffusion coefficent (ME model); diffusion coefficients for the fast (D fast ) and slow (D slow ) components and fraction of fast component, f fast (BE model); diffusion coefficient D, and kurtosis K (DK model); distributed diffusion coefficient DDC and α for (SE model). For one region-of-interest (ROI) in PZ and another in PCa in each patient, the corrected Akaike information criterion (AICc) and the Akaike weight (w) were calculated for each voxel., Results: Based on AICc and w, all non-monoexponential models outperformed the ME model in PZ and PCa. The DK model in PZ and SE model in PCa ROIs best fit the greatest average percentages of voxels (39% and 43%, respectively) and had the highest mean w (35±16×10 -2 and 41±22×10 -2 , respectively)., Conclusion: DK and SE models best fit DWI data in PZ and PCa, and non-ME models consistently outperformed the ME model. Voxel-wise mapping of the preferential model demonstrated that the vast majority of voxels in either tissue type were best fit with one of the non-monoexponential models. At the given SNR levels, the maximum b-value of 2000s/mm 2 is not sufficiently high to identify the preferred non-monoexponential model., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: The objective of this study was to investigate whether the apparent diffusion coefficient (ADC) value from DWI and the forward volume transfer constant (K(trans)) value from dynamic contrast-enhanced MRI independently predict prostate cancer aggressiveness, and to determine whether the combination of both parameters performs better than either parameter alone in assessing tumor aggressiveness before treatment., Materials and Methods: This retrospective study included 158 men with histopathologically confirmed prostate cancer who underwent 3-T MRI before undergoing prostatectomy in 2011. Whole-mount step-section pathologic maps identified 195 prostate cancer foci that were 0.5 mL or larger; these foci were then volumetrically assessed to calculate the per-tumor ADC and K(trans) values. Associations between MRI and histopathologic parameters were assessed using Spearman correlation coefficients, univariate and multivariable logistic regression, and AUCs., Results: The median ADC and K(trans) values showed moderate correlation only for tumors for which the Gleason score (GS) was 4 + 4 or higher (ρ = 0.547; p = 0.042). The tumor ADC value was statistically significantly associated with all dichotomized GSs (p < 0.005), including a GS of 3 + 3 versus a GS of 3 + 4 or higher (AUC, 0.693; p = 0.001). The tumor K(trans) value differed statistically significantly only between tumors with a GS of 3 + 3 and those with a primary Gleason grade of 4 (p ≤ 0.015), and it made a statistically significant contribution only in differentiating tumors with a GS of 4 + 3 or higher (AUC, 0.711; p < 0.001) and those with a GS of 4 + 4 or higher (AUC, 0.788; p < 0.001) from lower-grade tumors. Combining ADC and K(trans) values improved diagnostic performance in characterizing tumors with a GS of 4 + 3 or higher and those with a GS of 4 + 4 or higher (AUC, 0.739 and 0.856, respectively; p < 0.01)., Conclusion: Although the ADC value helped to differentiate between all GSs, the K(trans) value was only a benefit in characterizing more aggressive tumors. Combining these parameters improves their performance in identifying patients with aggressive tumors who may require radical treatment.

Purpose: To investigate the effects of androgen-deprivation therapy (ADT) on MRI parameters and evaluate their associations with treatment response measures., Materials and Methods: The study included 30 men with histopathologically confirmed prostate cancer who underwent MRI before and after initiation of ADT. Thirty-four tumours were volumetrically assessed on DW-MRI (n = 32) and DCE-MRI (n = 18), along with regions of interest in benign prostatic tissue, to calculate apparent diffusion coefficient (ADC) and transfer constant (K(trans)) values. Changes in MRI parameters and correlations with clinical parameters (change in prostate-specific antigen [PSA], treatment duration, PSA nadir) were assessed., Results: Prostate volume and PSA values decreased significantly with therapy (p < 0.001). ADC values increased significantly in tumours and decreased in benign prostatic tissue (p < 0.05). Relative changes in ADC and absolute post-therapeutic ADC values differed significantly between tumour and benign tissue (p < 0.001). K(trans) decreased significantly only in tumours (p < 0.001); relative K(trans) changes and post-therapeutic values were not significantly different between tumour and benign tissue. The relative change in tumour ADC correlated significantly with PSA decrease. No changes were associated with treatment duration or PSA nadir., Conclusions: Multi-parametric MRI shows significant measurable changes in tumour and benign prostate caused by ADT and may help in monitoring treatment response., Key Points: • Androgen-deprivation therapy caused changes of ADC, K (trans) in tumour and benign prostate. • Prostate volume and PSA values decreased significantly with therapy. • ADC values may be helpful for monitoring treatment response.

Rationale and Objectives: To compare prostate volume measurements from 3-Tesla endorectal coil magnetic resonance imaging (ERC MRI) obtained with the prolate ellipsoid volume formula (EVF) and volumetry to pathology-based volume measurements., Methods: The institutional review board waived informed consent for this retrospective, health insurance portability and accountability act (HIPAA) compliant study, which included 195 patients who underwent 3-T ERC MRI between January 2008 and October 2011 and had pathologic prostate measurements available. Two readers in consensus measured the prostate length, height, and width on each MRI. They estimated prostate volumes using the prolate EVF (length × height × width × [π/6]) and also by performing three-dimensional volumetry. Pathologic specimen mass and dimensions were used to calculate prostate volume. Agreement was measured with Lin's concordance correlation coefficient (CCC). Volume differences were assessed using the Wilcoxon signed-rank test. Correct prostate-specific antigen (PSA) density classification rates were compared between EVF-based and volumetry-based PSA density levels using the exact McNemar test, with pathology-based PSA density as the reference standard., Results: Concordance was high between EVF and volumetry measurements (CCC, 0.950 [95% confidence interval, 0.935-0.962]) and between both kinds of MRI measurements and pathology (both CCC > 0.80). Based on a cut-off of ≤0.15 ng/mL/cm(3), use of EVF-based volume produced correct classification of 46 of 48 PSA density levels >15 ng/mL/cm(3) and 113 of 147 PSA density levels ≤15 ng/mL/cm(3); use of volumetry-based volume produced correct classification of 47 of 48 PSA density levels >15 ng/mL/cm(3) and 121 of 147 PSA density levels ≤15 ng/mL/cm(3). Rates of underclassification (P > .95) and overclassification (P = .10) did not differ significantly between EVF and volumetry., Conclusions: EVF appears to be suitable for measuring prostate volume from ERC-MRI., (Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.)

Aim: To compare prostate volumes and distances between anatomical landmarks on MRI images obtained with a phased-array coil (PAC) only and with a PAC and an endorectal coil (ERC)., Materials and Methods: Informed consent was waived for this Health Insurance Portability and Accountability Act-compliant study. Fifty-nine men underwent PAC-MRI and ERC-MRI at 1.5 (n = 3) or 3 T (n = 56). On MRI images, two radiologists independently measured prostate volume and distances between the anterior rectal wall (ARW) and symphysis pubis at the level of the verumontanum; ARW and symphysis pubis at the level of the mid-symphysis pubis; and bladder neck and mid-symphysis pubis. Differences between measurements from PAC-MRI and ERC-MRI were assessed with the Wilcoxon RANK SUM test. Inter-reader agreement was assessed using the concordance correlation coefficient (CCC)., Results: Differences in prostate volume between PAC-MRI and ERC-MRI [median: -0.75 mm(3) (p = 0.10) and median: -0.84 mm(3) (p = 0.06) for readers 1 and 2, respectively] were not significant. For readers 1 and 2, median differences between distances were as follows: -10.20 and -12.75 mm, respectively, ARW to symphysis pubis at the level of the verumontanum; -6.60 and -6.08 mm, respectively, ARW to symphysis pubis at the level of the mid-symphysis pubis; -3 and -3 mm respectively, bladder neck to mid-symphysis pubis. All differences in distance were significant for both readers (p ≤ 0.0005). Distances were larger on PAC-MRI (p ≤ 0.0005). Inter-reader agreement regarding prostate volume was almost perfect on PAC-MRI (CCC: 0.99; 95% CI: 0.98-1.00) and ERC-MRI (CCC: 0.99; 95% CI: 0.99-1.00); inter-reader agreement for distance measurements varied (CCCs: 0.54-0.86)., Conclusion: Measurements of distances between anatomical landmarks differed significantly between ERC-MRI and PAC-MRI, although prostate volume measurements did not., (Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Purpose: To investigate whether tumor volume derived from apparent diffusion coefficient (ADC) maps (VolumeADC) and tumor mean ADC value (ADCmean) are independent predictors of prostate tumor Gleason score (GS)., Experimental Design: Tumor volume and GS were recorded from whole-mount histopathology for 131 men (median age, 60 years) who underwent endorectal diffusion-weighted MRI for local staging of prostate cancer before prostatectomy. VolumeADC and ADCmean were derived from ADC maps and correlated with histopathologic tumor volume and GS. Univariate and multivariate analyses were performed to evaluate prediction of tumor aggressiveness. Areas under receiver-operating characteristics curves (AUC) were calculated to evaluate the performance of VolumeADC and ADCmean in discriminating tumors of GS 6 and GS ≥7., Results: Histopathology identified 116 tumor foci >0.5 mL. VolumeADC correlated significantly with histopathologic tumor volume (ρ = 0.683). The correlation increased with increasing GS (ρ = 0.453 for GS 6 tumors; ρ = 0.643 for GS 7 tumors; ρ = 0.980 for GS ≥8 tumors). Both VolumeADC (ρ = 0.286) and ADCmean (ρ = -0.309) correlated with GS. At univariate analysis, both VolumeADC (P = 0.0325) and ADCmean (P = 0.0033) could differentiate GS = 6 from GS ≥7 tumor foci. However, at multivariate analysis, only ADCmean (P = 0.0156) was a significant predictor of tumor aggressiveness (i.e., GS 6 vs. GS ≥7). For differentiating GS 6 from GS ≥7 tumors, AUCs were 0.644 and 0.704 for VolumeADC and ADCmean, respectively, and 0.749 for both parameters combined., Conclusion: In patients with prostate cancer, ADCmean is an independent predictor of tumor aggressiveness, but VolumeADC is not. The latter parameter adds little to the ADCmean in predicting tumor GS., (©2014 American Association for Cancer Research.)

Purpose: To evaluate the relationship between prostate cancer aggressiveness and histogram-derived apparent diffusion coefficient (ADC) parameters obtained from whole-lesion assessment of diffusion-weighted magnetic resonance (MR) imaging of the prostate and to determine which ADC metric may help best differentiate low-grade from intermediate- or high-grade prostate cancer lesions., Materials and Methods: The institutional review board approved this retrospective HIPAA-compliant study of 131 men (median age, 60 years) who underwent diffusion-weighted MR imaging before prostatectomy for prostate cancer. Clinically significant tumors (tumor volume > 0.5 mL) were identified at whole-mount step-section histopathologic examination, and Gleason scores of the tumors were recorded. A volume of interest was drawn around each significant tumor on ADC maps. The mean, median, and 10th and 25th percentile ADCs were determined from the whole-lesion histogram and correlated with the Gleason score by using the Spearman correlation coefficient (ρ). The ability of each parameter to help differentiate tumors with a Gleason score of 6 from those with a Gleason score of at least 7 was assessed by using the area under the receiver operating characteristic curve (Az)., Results: In total, 116 clinically significant lesions (89 in the peripheral zone, 27 in the transition zone) were identified in 85 of the 131 patients (65%). Forty-six patients did not have a clinically significant lesion. For mean ADC, median ADC, 10th percentile ADC, and 25th percentile ADC, the Spearman ρ values for correlation with Gleason score were -0.31, -0.30, -0.36, and -0.35, respectively, whereas the Az values for differentiating lesions with a Gleason score of 6 from those with a Gleason score of at least 7 were 0.704, 0.692, 0.758, and 0.723, respectively. The Az of 10th percentile ADC was significantly higher than that of the mean ADC for all lesions and peripheral zone lesions (P = .0001)., Conclusion: When whole-lesion histograms were used to derive ADC parameters, 10th percentile ADC correlated with Gleason score better than did other ADC parameters, suggesting that 10th percentile ADC may prove to be optimal for differentiating low-grade from intermediate- or high-grade prostate cancer with diffusion-weighted MR imaging., (RSNA, 2013)

Purpose: To evaluate the role of conventional endorectal prostate MRI in patients with initial suspicion of prostate cancer., Materials and Methods: Ethics board approval was received for this retrospective study of 87 men who underwent 1.5-Tesla conventional prostate MRI with a combination of endorectal and body phased-array coils for suspected prostate cancer before their first systematic 12-core TRUS-guided biopsy. Three radiologists independently analyzed the images, dividing the prostate into 12 regions corresponding to the biopsy scheme and scoring each region for the presence of prostate cancer on a 5-point scale. Results were analyzed by prostate region. ROC analysis was done and descriptive statistics were calculated. The negative predictive value, specificity, sensitivity and positive predictive value were calculated using dichotomized scores (benign tissue = scores of 1 and 2; malignant tissues = scores of 3, 4, and 5)., Results: Biopsy revealed cancer in 47/87 patients (26 low-grade [Gleason score 6]; 21 high-grade [Gleason score ≥ 3 + 4]), and 184/1044 cores (77 low-grade and 107 high-grade) with a median of 3 positive cores per cancer patient (range 1 – 12). The areas under ROC curves were 0.65 – 0.67 for cancer detection by region overall and 0.75 – 0.76 for the detection of high-grade cancer by region. Statistic figures for the detection of all cancers/high-grade cancers by region were as follows: negative predictive value, 87.4 – 88.2 %/92.6 – 93.1 %; specificity, 72.3 – 79.4 %/71.5 – 79.8 %; sensitivity, 49.5 – 54.8 %/62.6 – 69.2 %; and positive predictive value, 29.3 – 34.0 %/29.4 – 34.7 %., Conclusion: In patients with suspected prostate cancer, negative MRI findings indicate the absence of high-grade prostate cancer on subsequent TRUS-guided 12-core biopsy with high probability. However, agreement between conventional 1.5-T endorectal prostate MRI and systematic 12-core TRUS-guided biopsy for the detection of prostate cancer appears to be moderate.

Purpose: To compare ADC values measured from diffusion-weighted MR (DW-MR) images of the prostate obtained with both endorectal and phased-array coils (ERC+PAC) to those from DW-MRI images obtained with an eight-channel torso phased-array coil (PAC) at 3.0 T., Methods: The institutional review board issued a waiver of informed consent for this HIPAA-compliant study. Twenty-five patients with biopsy-proven prostate cancer underwent standard 3-T MRI using 2 different coil arrangements (ERC+PAC and PAC only) in the same session. DW-MRI at five b-values (0, 600, 1000, 1200, and 1500 s/mm(2)) were acquired using both coil arrangements. On b=0 images, signal-to-noise ratios (SNRs) were measured as the ratio of the mean signal from PZ and TZ ROIs to the standard deviation from the mean signal in an artifact-free ROI in the rectum. Matching regions-of-interest (ROIs) were identified in the peripheral zone and transition zone on ERC-MRI and PAC-MRI. For each ROI, mean ADC values for all zero and non-zero b-value combinations were computed., Results: Mean SNR with ERC-MRI at PZ (66.33 ± 27.07) and TZ (32.69 ± 12.52) was 9.27 and 5.52 times higher than with PAC-MRI ((7.32 ± 2.30) and (6.13 ± 1.56), respectively) (P<0.0001 for both). ADCs from DW-MR images obtained with all b-values in the PZ and TZ were significantly lower with PAC-MRI than with ERC-MRI (P<0.001 for all)., Conclusion: Lower SNR of DW-MR images of the prostate obtained with a PAC can significantly decrease ADC values at higher b-values compared to similar measurements obtained using the ERC. To address these requirements, clinical MR systems should have image processing capabilities which incorporate the noise distribution., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To evaluate the role of conventional endorectal prostate MRI in patients with initial suspicion of prostate cancer., Materials and Methods: Ethics board approval was received for this retrospective study of 87 men who underwent 1.5-Tesla conventional prostate MRI with a combination of endorectal and body phased-array coils for suspected prostate cancer before their first systematic 12-core TRUS-guided biopsy. Three radiologists independently analyzed the images, dividing the prostate into 12 regions corresponding to the biopsy scheme and scoring each region for the presence of prostate cancer on a 5-point scale. Results were analyzed by prostate region. ROC analysis was done and descriptive statistics were calculated. The negative predictive value, specificity, sensitivity and positive predictive value were calculated using dichotomized scores (benign tissue = scores of 1 and 2; malignant tissues = scores of 3, 4, and 5)., Results: Biopsy revealed cancer in 47/87 patients (26 low-grade [Gleason score 6]; 21 high-grade [Gleason score ≥ 3 + 4]), and 184/1044 cores (77 low-grade and 107 high-grade) with a median of 3 positive cores per cancer patient (range 1 - 12). The areas under ROC curves were 0.65 - 0.67 for cancer detection by region overall and 0.75 - 0.76 for the detection of high-grade cancer by region. Statistic figures for the detection of all cancers/high-grade cancers by region were as follows: negative predictive value, 87.4 - 88.2 %/92.6 - 93.1 %; specificity, 72.3 - 79.4 %/71.5 - 79.8 %; sensitivity, 49.5 - 54.8 %/62.6 - 69.2 %; and positive predictive value, 29.3 - 34.0 %/29.4 - 34.7 %., Conclusion: In patients with suspected prostate cancer, negative MRI findings indicate the absence of high-grade prostate cancer on subsequent TRUS-guided 12-core biopsy with high probability. However, agreement between conventional 1.5-T endorectal prostate MRI and systematic 12-core TRUS-guided biopsy for the detection of prostate cancer appears to be moderate., (© Georg Thieme Verlag KG Stuttgart · New York.)

Rationale and Objectives: To identify the presence and extent of artifacts in prostate diffusion-weighted magnetic resonance imaging (DW-MRI) and discuss tradeoffs between imaging at 1.5 T (1.5 T) and 3.0 T (3.0 T). In addition, we aim to provide quantitative estimates of signal-to-noise ratios (SNRs) at both field strengths., Materials and Methods: The institutional review board waived informed consent for this Health Insurance Portability and Accountability Act-compliant, retrospective study of 53 consecutive men who underwent 3.0 T endorectal DW-MRI and 53 consecutive men who underwent 1.5 T endorectal DW-MRI between October and December 2010. One radiologist and one physicist, blinded to patient characteristics, image acquisition parameters, and field strength, scored DW-MRI artifacts. On b = 0 images, SNR was measured as the ratio of the mean signal from a region of interest (ROI) at the level of the verumontanum (the "reference region") to the standard deviation from the mean signal in an artifact-free ROI in the rectum., Results: Both readers found geometric distortion and signal graininess significantly more often at 3.0 T than at 1.5 T (P < .0001, all comparisons). Reader 2 (but not reader 1) found ghosting artifacts more often at 3.0 T (P = .001) and blurring more often at 1.5 T (P = .006). Mean SNR at the urethra (87.92 ± 27.76) at 3.0 T was 1.43 times higher than at 1.5 T (64.51 ± 14.96) (P < .0001)., Conclusions: At 3.0 T (as compared to 1.5 T), increased SNR on prostate DW-MRI comes at the expense of geometric distortion and can also lead to more pronounced ghosting artifacts. Therefore, to take full advantage of the benefits of 3.0 T, further improvements in acquisition techniques are needed to address DW-MRI artifacts corresponding to higher field strengths., (Copyright © 2013. Published by Elsevier Inc.)

Purpose: This study aimed to compare the intraclass correlation coefficients of parameters estimated with stretched exponential and biexponential diffusion models of in vivo diffusion-weighted magnetic resonance imaging (MRI) of the prostate., Methods: After the institutional review board issued a waiver of informed consent for this Health Insurance Portability and Accountability Act-compliant study, 25 patients with biopsy-proven prostate cancer underwent 3T endorectal MRI and diffusion-weighted MRI of the prostate at 10 b values (0, 45, 75, 105, 150, 225, 300, 600, 900, and 1200 s/mm). The full set of b values was collected twice within a single acquisition. Intraclass correlation coefficients were calculated for intra-acquisition variability. From the biexponential model, the quantitative parameters diffusion coefficient (D), perfusion coefficient (D*), and perfusion fraction (f) were estimated. From the stretched exponential model, the quantitative parameters Kohlrausch decay constant (DK) and alpha (α) were estimated., Results: For the 25 patient data sets, the average intraclass correlation coefficients for DK and α were 95.8%, and 64.1%, respectively, whereas those for D, D*, and f were 84.4%, 25.3%, and 41.3%, respectively., Conclusions: The stretched exponential diffusion model captures the nonlinear effects of intravoxel incoherent motion in the prostate. The parameters derived from this model are more reliable and reproducible than the parameters derived from the standard, widely used biexponential diffusion/perfusion model.

Purpose: To compare the accuracy of standard and revised monoexponential models of diffusion-weighted magnetic resonance imaging (DW-MRI) data for differentiating malignant from benign prostate tissue, using surgical pathology as the reference standard., Materials and Methods: The Institutional Review Board waived informed consent for this Health Insurance Portability and Accountability Act (HIPAA)-compliant, retrospective study of 46 patients (median age = 61 years; range: 42-85 years) who underwent DW-MRI between May and December 2008 before radical prostatectomy for biopsy-proven prostate cancer, had no prior treatment, and had whole-mount step-section pathology maps available showing at least one peripheral zone (PZ) lesion >0.1 cm(3) . DW-MRI data were obtained for b-values of 0, 400, and 700 s/mm(2) . Apparent diffusion coefficients (ADCs) were estimated from PZ regions of interest (ROIs) on b = 0, 700 and b = 0, 400 s/mm(2) images, using a standard monoexponential model. The true diffusion coefficient (D) and perfusion fraction (f) were measured using a revised monoexponential model incorporating all three b-values. Areas under receiver operating characteristic curves (AUCs) were calculated to assess the accuracy of individual parameters and a logistic regression model combining D and f (D+f) in distinguishing malignant ROIs; P < 0.05 denoted significance., Results: ADC(400) (AUC = 0.81, P < 0.0001), ADC(700) (AUC = 0.79, P < 0.0001), D (AUC = 0.71, P = 0.0001) and D + f distinguished malignant from benign ROIs (AUC = 0.82, P < 0.0001), but f did not (AUC = 0.56, P = 0.28); D + f was significantly more accurate than D (P = 0.016) but not more accurate than ADC(400) (P = 0.26) or ADC(700) (P = 0.12)., Conclusion: The true diffusion coefficient provides an additional DW-MRI parameter for distinguishing prostate cancer that is less influenced than the ADC by b-value selection., (Copyright © 2011 Wiley-Liss, Inc.)

Purpose: To assess the incremental value of diffusion-weighted (DW) magnetic resonance (MR) imaging over T2-weighted MR imaging at 3 T for prostate cancer detection and to investigate the use of the apparent diffusion coefficient (ADC) to characterize tumor aggressiveness, with whole-mount step-section pathologic analysis as the reference standard., Materials and Methods: The Internal Review Board approved this HIPAA-compliant retrospective study and waived informed consent. Fifty-one patients with prostate cancer (median age, 58 years; range, 46-74 years) underwent T2-weighted MR imaging and DW MR imaging (b values: 0 and 700 sec/mm(2) [n = 20] or 0 and 1000 sec/mm(2) [n = 31]) followed by prostatectomy. The prostate was divided into 12 regions; two readers provided a score for each region according to their level of suspicion for the presence of cancer on a five-point scale, first using T2-weighted MR imaging alone and then using T2-weighted MR imaging and the ADC map in conjunction. Areas under the receiver operating characteristic curve (AUCs) were estimated to evaluate performance. Generalized estimating equations were used to test the ADC difference between benign and malignant prostate regions and the association between ADCs and tumor Gleason scores., Results: For tumor detection, the AUCs for readers 1 and 2 were 0.79 and 0.76, respectively, for T2-weighted MR imaging and 0.79 and 0.78, respectively, for T2-weighted MR imaging plus the ADC map. Mean ADCs for both cancerous and healthy prostatic regions were lower when DW MR imaging was performed with a b value of 1000 sec/mm(2) rather than 700 sec/mm(2). Regardless of the b value used, there was a significant difference in the mean ADC between malignant and benign prostate regions. A lower mean ADC was significantly associated with a higher tumor Gleason score (mean ADCs of [1.21, 1.10, 0.87, and 0.69] × 10(-3) mm(2)/sec were associated with Gleason score of 3 + 3, 3 + 4, 4 + 3, and 8 or higher, respectively; P = .017)., Conclusion: Combined DW and T2-weighted MR imaging had similar performance to T2-weighted MR imaging alone for tumor detection; however, DW MR imaging provided additional quantitative information that significantly correlated with prostate cancer aggressiveness., (RSNA, 2011)

MRI of the prostate can aid in many aspects of prostate cancer management, from initial detection to treatment planning and follow-up. This review describes the current strengths and limitations of conventional anatomic and molecular MR imaging techniques (including MR spectroscopic imaging and dynamic contrast-enhanced imaging) for aiding prostate cancer management. It also describes promising emerging approaches for acquiring, analyzing, and applying MR imaging data, and the major research and educational efforts that will be required to realize the potential of prostate MR imaging in routine clinical practice., (Copyright © 2011 Wiley-Liss, Inc.)

Objective: To assess the effect of histopathological lesion characteristics on the sensitivity of magnetic resonance imaging (MRI) for per-lesion identification of extracapsular extension (ECE) of prostate cancer., Patients and Methods: The study included 176 patients (median age 58.9 years, range 38-77) who underwent endorectal MRI before radical prostatectomy between January 2001 and July 2004, had no previous treatment and had whole-mount step-section pathological specimens showing at least one capsule-abutting lesion. The likelihood of ECE of capsule-abutting lesions was retrospectively scored from 1 to 5 based on radiologists' prospective MRI interpretations. Generalized estimating equation regression models were used to determine the effect of the following histological variables on the sensitivity of MRI for identifying ECE of capsule-abutting lesions: maximum diameter, largest perpendicular diameter (LPD), bi-dimensional diameter product, Gleason grade, and zonal extent., Results: On histopathology, 339 capsule-abutting lesions were found, including 54 with ECE. MRI correctly identified ECE in 36/54 capsule-abutting lesions, including nine of 18 with focal ECE and 27/36 with established ECE, giving sensitivities (95% confidence interval) of 67 (53-78)%, 50 (27-73)% and 75 (58-87)%, respectively. MRI incorrectly identified ECE in 27/285 (9%) capsule-abutting lesions without ECE. MRI sensitivity for per-lesion ECE identification was significantly associated only with histopathological LPD (P = 0.009). Fifty-one patients (29%) had ECE. MRI had a sensitivity (95% confidence interval) of 69 (54-81)% and specificity of 90 (83-94)% for per-patient ECE identification., Conclusions: The sensitivity of MRI in per-lesion identification of prostate cancer ECE is significantly associated with the lesion LPD at histopathology., (© 2010 THE AUTHORS. JOURNAL COMPILATION © 2010 BJU INTERNATIONAL.)

Purpose: To retrospectively determine the accuracy of diffusion-weighted (DW) magnetic resonance (MR) imaging for identifying cancer in the prostate peripheral zone (PZ) and to assess the accuracy of tumor volume measurements made with T2-weighted imaging and combined T2-weighted and DW MR imaging by using surgical pathologic examination as the reference standard., Materials and Methods: The institutional review board issued a waiver of informed consent for this HIPAA-compliant study. Forty-two patients underwent endorectal MR at 1.5 T before undergoing radical prostatectomy for prostate cancer and had at least one PZ tumor larger than 0.1 cm(3) at surgical pathologic examination. On T2-weighted images, an experienced radiologist outlined suspected PZ tumors. Two apparent diffusion coefficient (ADC) cutoff values were identified by using the Youden index and published literature. Image cluster analysis was performed on voxels within the suspected tumor regions. Associations between volume measurements from imaging and from pathologic examination were assessed by using concordance correlation coefficients (CCCs). The sensitivity and specificity of ADCs for identifying malignant PZ voxels were calculated., Results: In identifying malignant voxels, respective ADC cutoff values of 0.0014 and 0.0016 mm(2)/sec yielded sensitivity of 82% and 95% and specificity of 85% and 65%, respectively. Sixty PZ cancer lesions larger than 0.1 cm(3) were found at pathologic examination; 43 were detected by the radiologist. CCCs between imaging and pathologic tumor volume measurements were 0.36 for T2-weighted imaging, and 0.46 and 0.60 for combined T2-weighted and DW MR imaging with ADC cutoffs of 0.0014 and 0.0016 mm(2)/sec, respectively; the CCC of combined T2-weighted and DW MR imaging (ADC cutoff, 0.0016 mm(2)/sec) was significantly higher (P = .006) than that of T2-weighted imaging alone., Conclusion: Adding DW MR to T2-weighted imaging can significantly improve the accuracy of prostate PZ tumor volume measurement., Supplemental Material: http://radiology.rsnajnls.org/cgi/content/full/252/2/449/DC1.

Magnetic resonance imaging (MRI) is the imaging tool of choice in the evaluation of prostate cancer. The main applications of MR imaging in the management of prostate cancer are: (1) to guide targeted biopsy when prostate cancer is clinically suspected and previous ultrasound-guided biopsy results are negative; (2) to localize and stage prostate cancer and provide a roadmap for treatment planning; and (3) to detect residual or locally recurrent cancer after treatment. Other MR techniques such as proton MR spectroscopic imaging (MRSI), diffusion-weighted imaging (DWI), and contrast-enhanced MRI (CE-MRI) complement conventional MR imaging by providing metabolic and functional information that can improve the accuracy of prostate cancer detection and characterization. In everyday clinical practice, and to account for patient comfort, MR imaging studies are limited to 1 h. To obtain consistently high-quality images, a well-designed protocol is necessary. Routine MR imaging can be supplemented by other MR techniques such as MRSI, DWI or CE-MRI depending on the expertise available and the clinical questions that need to be answered. This review summarizes the role of MR imaging in the management of prostate cancer and describes practical approaches to implementing anatomic, metabolic and functional MR imaging techniques in the clinic.

Purpose: To retrospectively measure the mean apparent diffusion coefficient (ADC) with diffusion-weighted magnetic resonance (MR) imaging and the mean metabolic ratio (MET) with three-dimensional (3D) hydrogen 1 ((1)H) MR spectroscopic imaging in regions of interest (ROIs) drawn over benign and malignant peripheral zone (PZ) prostatic tissue and to assess ADC, MET, and combined ADC and MET for identifying malignant ROIs, with whole-mount histopathologic examination as the reference standard., Materials and Methods: The institutional review board approved this HIPAA-compliant retrospective study and issued a waiver of informed consent. From among 61 consecutive patients with prostate cancer, 38 men (median age, 61 years; range, 42-72 years) who underwent 1.5-T endorectal MR imaging before radical prostatectomy and who fulfilled all inclusion criteria of no prior hormonal or radiation treatment and at least one PZ lesion (volume, >0.1 cm(3)) at whole-mount pathologic examination were included. ADC maps were generated from diffusion-weighted MR imaging data, and MET maps of (choline plus polyamine plus creatine)/citrate were calculated from 3D (1)H MR spectroscopic imaging data. ROIs in the PZ identified by matching pathologic slides with T2-weighted images were overlaid on MET and ADC maps. Areas under the receiver operating characteristic curves (AUCs) were used to evaluate accuracy., Results: The mean ADC +/- standard deviation, (1.39 +/- 0.23) x 10(-3) mm(2)/sec, and mean MET (0.92 +/- 0.32) for malignant ROIs differed significantly from the mean ADC, (1.69 +/- 0.24) x 10(-3) mm(2)/sec, and mean MET (0.73 +/- 0.18) for benign ROIs (P < .001 for both). In distinguishing malignant ROIs, combined ADC and MET (AUC = 0.85) performed significantly better than MET alone (AUC = 0.74; P = .005) and was also better than ADC alone (AUC = 0.81), although the difference was not statistically significant (P = .09)., Conclusion: The combination of ADC and MET performs significantly better than MET for differentiating between benign and malignant ROIs in the PZ., ((c) RSNA, 2008.)

Purpose: To retrospectively investigate whether the signal intensity (SI) of prostate cancer on T2-weighted magnetic resonance (MR) images correlates with the Gleason grade at whole-mount step-section pathologic evaluation after radical prostatectomy., Materials and Methods: The institutional review board approved and issued a waiver of informed consent for this HIPAA-compliant study of 74 patients (median age, 57.5 years; range, 32-72 years) who underwent endorectal MR imaging before radical prostatectomy, with subsequent whole-mount step-section pathologic evaluation, between January 2001 and July 2004. Inclusion criteria were that they had: no prior treatment; at least one lesion of uniform Gleason grade 3 or 4 or with Gleason grade 5 components, with a bidimensional diameter product of 20 mm2 or greater; no high SI on T1-weighted MR images indicative of postbiopsy changes; and an interval of more than 4 weeks between biopsy and MR imaging. SI of prostate tumors, nontumor prostatic tissue, and internal obturator muscles was measured on uncorrected and corrected T2-weighted MR images. Correlations between Gleason grades and SI ratios were assessed by using generalized estimating equations. SI ratios in peripheral zone (PZ) and transition zone (TZ) lesions of the same Gleason grade were compared with an unpaired t test., Results: Seventy-nine Gleason grade 3, eight Gleason grade 4, and four mixed Gleason grades 4 and 5 lesions identified at pathologic evaluation were analyzed. Gleason grade correlated significantly with tumor-muscle SI ratio for PZ tumors on corrected and uncorrected images (P = .006 and <.001, respectively). Higher Gleason grades were associated with lower tumor-muscle SI ratios. Nontumor-muscle SI ratios did not correlate with patients' Gleason grades. Tumor-muscle SI ratios were lower in TZ than in PZ tumors (P < .001)., Conclusion: Higher Gleason grades were associated with lower tumor-muscle SI ratios on T2-weighted MR images. SI evaluation on T2-weighted MR images may facilitate noninvasive assessment of prostate cancer aggressiveness., (RSNA, 2007)