A standardized method to measure the membranous urethral length (MUL) on MRI of the prostate with high inter- and intra-observer agreement.

OBJECTIVES: The membranous urethral length (MUL), defined as the length between the apex and penile base as measured on preoperative prostate magnetic resonance imaging (MRI), is an important predictor for urinary incontinence after radical prostatectomy. Literature on inter- and intra - observer agreement of MUL measurement is limited. We studied the inter- and intra-observer agreement between radiologists using a well-defined method to measure the MUL on the prostate MRI. METHODS: Prostate cancer patients underwent a preoperative MRI and robot-assisted radical prostatectomy (RARP) at one high-volume RARP center. MUL measurement was based on well-defined landmarks on sagittal T2-weighted (anatomical) images. Three radiologists independently performed MUL measurements retrospectively in 106 patients blinded to themselves, to each other, and to clinical outcomes. The inter- and intra-observer agreement of MUL measurement between the radiologists were calculated, expressed as intra-class correlation coefficient (ICC). RESULTS: The initial inter-observer agreement was ICC 0.63; 95% confidence interval (CI) 0.28-0.81. Radiologist 3 measured the MUL mean 3.9 mm (SD 3.3) longer than the other readers, interpreting the caudal point of the MUL (penile base) differently. After discussion on the correct anatomical definition, radiologist 3 re-assessed all scans, which resulted in a high inter-observer agreement (ICC 0.84; 95% CI 0.66-0.91). After a subsequent reading by radiologists 1 and 2, the intra-observer agreements were ICC 0.93; 95% CI 0.89-0.96, and ICC 0.98; 95% CI 0.97-0.98, respectively. Limitation is the monocenter design. CONCLUSIONS: The MUL can be measured reliably with high agreement among radiologists. KEY POINTS: • After discussion on the correct anatomical definition, the inter- and intra - observer agreements of membranous urethral length (MUL) measurement on magnetic resonance imaging (MRI) were high. • A reproducible method to measure the MUL can improve the clinical usefulness of prediction models for urinary continence after RARP which may benefit patient counselling.

3D-Reconstructed Contact Surface Area and Tumour Volume on Magnetic Resonance Imaging Improve the Prediction of Extraprostatic Extension of Prostate Cancer.

This study is to determine whether the volume and contact surface area (CSA) of a tumour with an adjacent prostate capsule on MRI in a three-dimensional (3D) model that can predict side-specific extraprostatic extension (EPE) at radical prostatectomy (RP). Patients with localised prostate cancer (PCa) who underwent robot-assisted RP between July 2015 and March 2021 were included in this retrospective study. MRI-based 3D prostate models incorporating the PCa volume and location were reconstructed. The tumour volume and surface variables were extracted. For the prostate-to-tumour and tumour-to-prostate CSAs, the areas in which the distances were ≤ 1, ≤ 2, ≤ 3, ≤ 4, and ≤ 5 mm were defined, and their surface (cm2) were determined. Differences in prostate sides with and without pathological EPE were analysed. Multivariable logistic regression analysis to find independent predictors of EPE. Overall, 75/302 (25%) prostate sides showed pathological EPE. Prostate sides with EPE had higher cT-stage, higher PSA density, higher percentage of positive biopsy cores, higher biopsy Gleason scores, higher radiological tumour stage, larger tumour volumes, larger prostate CSA, and larger tumour CSA (all p < 0.001). Multivariable logistic regression analysis showed that the radiological tumour stage (p = 0.001), tumour volume (p < 0.001), prostate CSA (p < 0.001), and tumour CSA (p ≤ 0.001) were independent predictors of pathological EPE. A 3D reconstruction of tumour locations in the prostate improves prediction of extraprostatic extension. Tumours with a higher 3D-reconstructed volume, a higher surface area of tumour in contact with the prostate capsule, and higher surface area of prostate capsule in contact with the tumour are at increased risk of side-specific extraprostatic extension.

Detection of clinically significant prostate cancer in biopsy-naïve men: direct comparison of systematic biopsy, multiparametric MRI- and contrast-ultrasound-dispersion imaging-targeted biopsy.

OBJECTIVES: To compare and evaluate a multiparametric magnetic resonance imaging (mpMRI)-targeted biopsy (TBx) strategy, contrast-ultrasound-dispersion imaging (CUDI)-TBx strategy and systematic biopsy (SBx) strategy for the detection of clinically significant prostate cancer (csPCa) in biopsy-naïve men. PATIENTS AND METHODS: A prospective, single-centre paired diagnostic study included 150 biopsy-naïve men, from November 2015 to November 2018. All men underwent pre-biopsy mpMRI and CUDI followed by a 12-core SBx taken by an operator blinded from the imaging results. Men with suspicious lesions on mpMRI and/or CUDI also underwent MRI-TRUS fusion-TBx and/or cognitive CUDI-TBx after SBx by a second operator. A non-inferiority analysis of the mpMRI- and CUDI-TBx strategies in comparison with SBx for International Society of Urological Pathology Grade Group [GG] ≥2 PCa in any core with a non-inferiority margin of 1 percentage point was performed. Additional analyses for GG ≥2 PCa with cribriform growth pattern and/or intraductal carcinoma (CR/IDC), and GG ≥3 PCa were performed. Differences in detection rates were tested using McNemar's test with adjusted Wald confidence intervals. RESULTS: After enrolment of 150 men, an interim analysis was performed. Both the mpMRI- and CUDI-TBx strategies were inferior to SBx for GG ≥2 PCa detection and the study was stopped. SBx found significantly more GG ≥2 PCa: 39% (56/142), as compared with 29% (41/142) and 28% (40/142) for mpMRI-TBx and CUDI-TBx, respectively (P < 0.05). SBx found significantly more GG = 1 PCa: 14% (20/142) compared to 1% (two of 142) and 3% (four of 142) with mpMRI-TBx and CUDI-TBx, respectively (P < 0.05). Detection of GG ≥2 PCa with CR/IDC and GG ≥3 PCa did not differ significantly between the strategies. The mpMRI- and CUDI-TBx strategies were comparable in detection but the mpMRI-TBx strategy had less false-positive findings (18% vs 53%). CONCLUSIONS: In our study in biopsy-naïve men, the mpMRI- and CUDI-TBx strategies had comparable PCa detection rates, but the mpMRI-TBX strategy had the least false-positive findings. Both strategies were inferior to SBx for the detection of GG ≥2 PCa, despite reduced detection of insignificant GG = 1 PCa. Both strategies did not significantly differ from SBx for the detection of GG ≥2 PCa with CR/IDC and GG ≥3 PCa.

Location of Prostate Cancers Determined by Multiparametric and MRI-Guided Biopsy in Patients With Elevated Prostate-Specific Antigen Level and at Least One Negative Transrectal Ultrasound-Guided Biopsy.

OBJECTIVE: The purpose of this article is to identify histopathologically proven prostate cancer locations using MRI followed by MRI-guided biopsy in patients with elevated prostate-specific antigen (PSA) levels and at least one negative transrectal ultrasound (TRUS)-guided biopsy session. Our hypothesis is that in this patient group most cancers are located in the anterior portion of the prostate. This may have implications for the biopsy strategy regarding the location of sampling. MATERIALS AND METHODS: This retrospective study consisted of 872 consecutive men who had undergone MRI-guided prostate biopsy. Inclusion criteria were PSA level greater than or equal to 4 ng/mL, one or more negative TRUS-guided biopsy session, the presence of suspicious lesions on previous multiparametric MRI, and prostate cancer histopathologically proven by MRI-guided biopsy. Thereafter, the location of intermediate- or high-risk cancers and cancers with a maximum cancer core length of 6 mm or longer were determined. The proportion of cancer locations was compared using a chi-square test. One-way ANOVA analyses were performed to compare patient characteristics. RESULTS: Results were presented on both a patient and lesion basis because a single patient can have multiple lesions. In total, 176 of 872 patients met the inclusion criteria. Prostate cancer was detected in 202 of 277 (73%) suspicious lesions. In total, 76% of patients had cancer of the transition zone and anterior fibromuscular stroma. Peripheral zone cancers were found in 30% of the patients, and 6% had cancers in both zones. In 70% of cases (141/202; 95%, CI, 63-76%), lesions were located anteriorly; this included 75% (132/176; 95%, CI, 69-81%) of patients. Intermediate- or high-risk prostate cancer was found in 93% (128/138; 95%, CI, 88-96%) of patients. Of these patients, 73% (94/128; 95%, CI, 66-81%) had anterior involvement. Cancers with a maximum cancer core length of 6 mm or more were more likely to be located in the anterior part of the prostate than were cancers with a core length of less than 6 mm (66% vs 6%). Most cancers 58% (102/176; 95% CI, 51-65%) were found in the mid prostate. Anterior involvement of prostate cancer detected by MRI-guided biopsy was statistically significantly (p = 0.04) higher in patients with two or more negative TRUS-guided biopsy sessions (79%) than in those with one negative TRUS-guided biopsy session (55%). CONCLUSION: Anterior involvement was high (76%) in patients with an elevated PSA level and one or more negative TRUS-guided biopsy session, and the majority of these cancers (93%) were intermediate or high risk.

Differentiation of prostatitis and prostate cancer by using diffusion-weighted MR imaging and MR-guided biopsy at 3 T.

PURPOSE: To determine if prostatitis and prostate cancer (PCa) can be distinguished by using apparent diffusion coefficients (ADCs) on magnetic resonance (MR) images, with specimens obtained at MR-guided biopsy as the standard of reference. MATERIALS AND METHODS: The need for institutional review board approval and informed consent was waived. MR-guided biopsies were performed in 130 consecutive patients with cancer-suspicious regions (CSRs) on multiparametric MR images obtained at 3 T. In this retrospective study, 88 patients met the inclusion criteria. During the biopsy procedure, an axial diffusion-weighted sequence was performed and ADC maps were generated (repetition time msec/echo time msec, 2000/67; section thickness, 4 mm; in-plane resolution, 1.8 × 1.8 mm; and b values of 0, 100, 500, and 800 sec/mm(2)). Subsequently, a confirmation image with the needle left in situ was acquired and projected on the ADC map. The corresponding ADCs at the biopsy location were compared with the histopathologic outcomes of the biopsy specimens. Linear mixed-model regression analyses were used to test for ADC differences between the histopathologic groups. RESULTS: The study included 116 biopsy specimens. Median ADCs of normal prostate tissue, prostatitis, low-grade PCa (Gleason grade components 2 or 3), and high-grade PCa (Gleason grade components 4 or 5) were 1.22 × 10(-3) mm(2)/sec (standard deviation, ± 0.21), 1.08 × 10(-3) mm(2)/sec (± 0.18), 0.88 × 10(-3) mm(2)/sec (± 0.15), and 0.88 × 10(-3) mm(2)/sec (± 0.13), respectively. Although the median ADCs of biopsy specimens with prostatitis were significantly higher compared with low- and high-grade PCa (P < .001), there is a considerable overlap between the tissue types. CONCLUSION: Diffusion-weighted imaging is a noninvasive technique that shows differences between prostatitis and PCa in both the peripheral zone and central gland, although its usability in clinical practice is limited as a result of significant overlap in ADCs.

Transition zone prostate cancer: detection and localization with 3-T multiparametric MR imaging.

PURPOSE: To retrospectively compare transition zone (TZ) cancer detection and localization accuracy of 3-T T2-weighted magnetic resonance (MR) imaging with that of multiparametric (MP) MR imaging, with radical prostatectomy specimens as the reference standard. MATERIALS AND METHODS: The informed consent requirement was waived by the institutional review board. Inclusion criteria were radical prostatectomy specimen TZ cancer larger than 0.5 cm(3) and 3-T endorectal presurgery MP MR imaging (T2-weighted imaging, diffusion-weighted [DW] imaging apparent diffusion coefficient [ADC] maps [b < 1000 sec/mm(2)], and dynamic contrast material-enhanced [DCE] MR imaging). From 197 patients with radical prostatectomy specimens, 28 patients with TZ cancer were included. Thirty-five patients without TZ cancer were randomly selected as a control group. Four radiologists randomly scored T2-weighted and DW ADC images, T2-weighted and DCE MR images, and T2-weighted, DW ADC, and DCE MR images. TZ cancer suspicion was rated on a five-point scale in six TZ regions of interest (ROIs). A score of 4-5 was considered a positive finding. A score of 4 or higher for any ROI containing TZ cancer was considered a positive detection result at the patient level. Generalized estimating equations were used to analyze detection and localization accuracy by using ROI-receiver operating characteristics (ROC) curve analyses for the latter. Gleason grade (GG) 4-5 and GG 2-3 cancers were analyzed separately. RESULTS: Detection accuracy did not differ between T2-weighted and MP MR imaging for all TZ cancers (68% vs 66%, P = .85), GG 4-5 TZ cancers (79% vs 72%-75%, P = .13), and GG 2-3 TZ cancers (66% vs 62%-65%, P = .47). MP MR imaging (area under the ROC curve, 0.70-0.77) did not improve T2-weighted imaging localization accuracy (AUC = 0.72) (P > .05). CONCLUSION: Use of 3-T MP MR imaging, consisting of T2-weighted imaging, DW imaging ADC maps (b values, 50, 500, and 800 sec/mm(2)), and DCE MR imaging may not improve TZ cancer detection and localization accuracy compared with T2-weighted imaging. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120281/-/DC1.

Prostate cancer: multiparametric MR imaging for detection, localization, and staging.

This review presents the current state of the art regarding multiparametric magnetic resonance (MR) imaging of prostate cancer. Technical requirements and clinical indications for the use of multiparametric MR imaging in detection, localization, characterization, staging, biopsy guidance, and active surveillance of prostate cancer are discussed. Although reported accuracies of the separate and combined multiparametric MR imaging techniques vary for diverse clinical prostate cancer indications, multiparametric MR imaging of the prostate has shown promising results and may be of additional value in prostate cancer localization and local staging. Consensus on which technical approaches (field strengths, sequences, use of an endorectal coil) and combination of multiparametric MR imaging techniques should be used for specific clinical indications remains a challenge. Because guidelines are currently lacking, suggestions for a general minimal protocol for multiparametric MR imaging of the prostate based on the literature and the authors' experience are presented. Computer programs that allow evaluation of the various components of a multiparametric MR imaging examination in one view should be developed. In this way, an integrated interpretation of anatomic and functional MR imaging techniques in a multiparametric MR imaging examination is possible. Education and experience of specialist radiologists are essential for correct interpretation of multiparametric prostate MR imaging findings. Supportive techniques, such as computer-aided diagnosis are needed to obtain a fast, cost-effective, easy, and more reproducible prostate cancer diagnosis out of more and more complex multiparametric MR imaging data.

Value of Serial Multiparametric Magnetic Resonance Imaging and Magnetic Resonance Imaging-guided Biopsies in Men with Low-risk Prostate Cancer on Active Surveillance After 1 Yr Follow-up.

BACKGROUND: Active surveillance (AS) aims to reduce overtreatment of low-risk prostate cancer (PC). Incorporating multiparametric magnetic resonance imaging (mp-MRI) and MR-guided biopsy (MRGB) in an AS protocol might contribute to more accurate identification of AS candidates. OBJECTIVE: To evaluate the value of 3T mp-MRI and MRGB in PC patients on AS at inclusion and after 12-mo follow-up. DESIGN, SETTING, AND PARTICIPANTS: Patients with cT1c-cT2 PC, prostate-specific antigen (PSA) ≤10ng/ml, PSA density <0.2ng/ml/ml, and Gleason scores (GSs) of ≤6 and ≤2 positive biopsy cores were included and followed in an AS protocol including mp-MRI and MRGB. The mp-MRI and MRGB were performed at <3 and 12 mo after diagnosis. Reclassification was defined as GS >6, >2 positive cores at repeat transrectal ultrasound-guided biopsy (TRUSGB), presence of PC in >3 separate cancer foci upon both MRGB and TRUSGB, or cT3 tumor on mp-MRI. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Reclassification rates, treatment after discontinuation, and outcome on radical prostatectomy after discontinuing AS were reported. Uni- and multivariate analyses were performed to identify predictors of reclassification after 1 yr. RESULTS AND LIMITATIONS: From 2009 to 2013, a total of 111 of 158 patients were consecutively and prospectively included. Around initial diagnosis, 36 patients were excluded from the study protocol; mp-MRI+MRGB reclassified 25/111 (23%) patients, and 11 patients were excluded at own request. Reasons for reclassification were as follows: GS upgrade (15/25, 60%); cT3 disease (3/25, 12%); suspicion of bone metastases (1/25, 4%); and multifocal disease upon MRGB (6/25, 24%). Repeat examinations after 1 yr showed reclassification in 33/75 patients (44%). Reasons were the following: GS upgrade upon TRUSGB (9/33, 27%); volume progression upon TRUSGB (9/33, 27%); cT3 disease upon mp-MRI (1/33, 3%); GS upgrade upon MRGB (1/33, 3%); volume progression upon MRGB (1/33, 3%); multifocal disease upon MRGB (2/33, 6%); and upgrade or upstage upon both TRUSGB and MRGB (10/33, 30%). On logistic regression analysis, the presence of cancer at initial mp-MRI and MRGB examinations was the only predictor of reclassification after 1 yr (odds ratio 5.9, 95% confidence interval 2.0-17.6). CONCLUSIONS: Although mp-MRI and MRGB are of additional value in the evaluation of PC patients on AS, the value of mp-MRI after 1 yr was limited. As a considerable percentage of GS ≥7 PC after 1 yr was detected only by TRUSGB, TRUSGB cannot be omitted yet. PATIENT SUMMARY: More aggressive tumors are detected if low-risk prostate cancer patients are additionally monitored by magnetic resonance imaging. However, some high-grade tumors are detected only by transrectal ultrasound-guided biopsy.

Clinical comparison between a currently available single-loop and an investigational dual-channel endorectal receive coil for prostate magnetic resonance imaging: a feasibility study at 1.5 and 3 T.

OBJECTIVES: The objectives of this study were to test the feasibility of an investigational dual-channel next-generation endorectal coil (NG-ERC) in vivo, to quantitatively assess signal-to-noise ratio (SNR), and to get an impression of image quality compared with the current clinically available single-loop endorectal coil (ERC) for prostate magnetic resonance imaging at both 1.5 and 3 T. MATERIALS AND METHODS: The study was approved by the institutional review board, and written informed consent was obtained from all patients. In total, 8 consecutive patients with prostate cancer underwent a local staging magnetic resonance examination with the successive use of both coils in 1 session (4 patients at 1.5 T and 4 other patients at 3 T). Quantitative comparison of both coils was performed for the apex, mid-gland and base levels at both field strengths by calculating SNR profiles in the axial plane on an imaginary line in the anteroposterior direction perpendicular to the coil surface. Two radiologists independently assessed the image quality of the T2-weighted and apparent diffusion coefficient maps calculated from diffusion-weighted imaging using a 5-point scale. Improvement of geometric distortion on diffusion-weighted imaging with the use of parallel imaging was explored. Statistical analysis included a paired Wilcoxon signed rank test for SNR and image quality evaluation as well as κ statistics for interobserver agreement. RESULTS: No adverse events were reported. The SNR was higher for the NG-ERC compared with the ERC up to a distance of approximately 40 mm from the surface of the coil at 1.5 T (P < 0.0001 for the apex, the mid-gland, and the base) and approximately 17 mm (P = 0.015 at the apex level) and 30 mm at 3 T (P < 0.0001 for the mid-gland and base). Beyond this distance, the SNR profiles of both coils were comparable. Overall, T2-weighted image quality was considered better for NG-ERC at both field strengths. Quality of apparent diffusion coefficient maps with the use of parallel imaging was rated superior with the NG-ERC at 3 T. CONCLUSIONS: The investigational NG-ERC for prostate imaging outperforms the current clinically available ERC in terms of SNR and is feasible for continued development for future use as the next generation endorectal coil for prostate imaging in clinical practice.

Value of 3-T multiparametric magnetic resonance imaging and magnetic resonance-guided biopsy for early risk restratification in active surveillance of low-risk prostate cancer: a prospective multicenter cohort study.

OBJECTIVES: The objective of this study was to evaluate the role of 3-T multiparametric magnetic resonance imaging (MP-MRI) and magnetic resonance-guided biopsy (MRGB) in early risk restratification of patients on active surveillance at 3 and 12 months of follow-up. MATERIALS AND METHODS: Within 4 hospitals participating in a large active surveillance trial, a side study was initiated. Pelvic magnetic resonance imaging, prostate MP-MRI, and MRGB were performed at 3 and 12 months (latter prostate MP-MRI and MRGB only) after prostate cancer diagnosis in 1 of the 4 participating hospitals. Cancer-suspicious regions (CSRs) were defined on prostate MP-MRI using Prostate Imaging Reporting And Data System (PI-RADS) scores.Risk restratification criteria for active surveillance discontinuance were (1) histopathologically proven magnetic resonance imaging suspicion of node/bone metastases and/or (2) a Gleason growth pattern (GGP) 4 and/or 5 and/or cancer multifocality (≥3 foci) in MRGB specimens of a CSR on MP-MRI. RESULTS: From 2009 to 2012, a total of 64 of 82 patients were consecutively and prospectively included and underwent MP-MRI and a subsequent MRGB. At 3 and 12 months of follow-up, 14% (9/64) and 10% (3/30) of the patients were risk-restratified on the basis of MP-MRI and MRGB. An overall CSR PI-RADS score of 1 or 2 had a negative predictive value of 84% (38/45) for detection of any prostate cancer and 100% (45/45) for detection of a GGP 4 or 5 containing cancer upon MRGB, respectively. A CSR PI-RADS score of 4 or higher had a sensitivity of 92% (11/12) for detection of a GGP 4 or 5 containing cancer upon MRGB. CONCLUSIONS: Application of MP-MRI and MRGB in active surveillance may contribute in early identification of patients with GGP 4 or 5 containing cancers at 3 months of follow-up. If, during further follow-up, a PI-RADS score of 1 or 2 continues to have a negative predictive value for GGP 4 or 5 containing cancers, a PI-RADS standardized reported MP-MRI may be a promising tool for the selection of prostate cancer patients suitable for active surveillance.

Diffusion-weighted magnetic resonance imaging in the prostate transition zone: histopathological validation using magnetic resonance-guided biopsy specimens.

OBJECTIVES: The objective of this study was to evaluate the apparent diffusion coefficient (ADC) of diffusion-weighted magnetic resonance (MR) imaging for the differentiation of transition zone cancer from non-cancerous transition zone with and without prostatitis and for the differentiation of transition zone cancer Gleason grade (GG) using MR-guided biopsy specimens as a reference standard. MATERIALS AND METHODS: From consecutive MR-guided prostate biopsies (2008-2012) in our referral center, we retrospectively included patients from whom diffusion-weighted MR imaging ADC values were acquired during MR-guided biopsy and whose biopsy cores had a (cancer) core length 10 mm or greater and originated from the transition zone. Two radiologists, who were blinded to the ADC data, annotated regions of interest on biopsy sampling locations of MR-guided biopsy confirmation scans in consensus. Median ADC (mADC) of the regions of interest was related to histopathology outcome in MR-guided biopsy core specimens. Mixed model analysis was used to evaluate mADC differences between 7 histopathology categories predefined as MR-guided biopsy core specimens with primary and secondary GG 4-5 (I), primary GG 4-5 secondary GG 2-3 (II), primary GG 2-3 secondary GG 4-5 (III) and primary and secondary GG 2-3 cancer (IV), and noncancerous tissue without (V) or with degree 1 (VI) or degree 2 prostatitis (VII). Diagnostic accuracy was evaluated using areas under the receiver operating characteristic (AUC) curve. RESULTS: Fifty-two patients with 87 cancer-containing biopsy cores and 53 patients with 101 non-cancerous biopsy cores were included. Significant mean mADC differences were present between cancers (mean mADC, 0.77-0.86 × 10 mm/s) and noncancerous transition zone without (1.12 × 10 mm/s) and with degree 1 to 2 prostatitis (1.05-1.12 × 10 mm/s; P < 0.0001-0.05). Exceptions were mixed primary and secondary GG cancers versus a degree 2 of prostatitis (P = 0.06-0.09). No significant differences were found between subcategories of primary and secondary GG cancers (P = 0.17-0.91) and between a degree 1 and 2 prostatitis and non-cancerous transition zone without prostatitis (P = 0.48-0.94).The mADC had an AUC of 0.84 to differentiate cancer versus non-cancerous transition zone. AUCs of 0.84 and 0.56 were found for mADC to differentiate prostatitis from cancer and from non-cancerous transition zone. The mADC had an AUC of 0.62 to differentiate a primary GG 4 versus GG 3 cancer. CONCLUSIONS: The mADC values can differentiate transition zone cancer from non-cancerous transition zone and from a degree 1, and from most cases of a degree 2 prostatitis. However, because of substantial overlap, mADC has a moderate accuracy to differentiate between different primary and secondary GG subcategories and cannot be used to differentiate non-cancerous transition zone from degrees 1 to 2 of prostatitis. Diffusion-weighted imaging ADC may therefore contribute in the detection of transition zone cancers; however, as a single functional MR imaging technique, diffusion-weighted imaging has a moderate diagnostic accuracy in separating higher from lower GG transition zone cancers and in differentiating prostatitis from non-cancerous transition zone.

Evaluation of diffusion-weighted MR imaging at inclusion in an active surveillance protocol for low-risk prostate cancer.

PURPOSE: We aimed to determine whether diffusion-weighted magnetic resonance imaging, by means of the apparent diffusion coefficient (ADC), is able to guide magnetic resonance-guided biopsy in patients fit for active surveillance (AS) and identify patients harboring high-grade Gleason components not suitable for AS. MATERIALS AND METHODS: Our study was approved by the institutional review board of all participating hospitals, and all patients signed informed consent at inclusion. Fifty-four consecutive patients with low-risk prostate cancer (PCa) underwent multiparametric magnetic resonance imaging (MP-MRI) at inclusion for AS. Cancer-suspicious regions (CSRs) upon 3-T MP-MRI were identified in all patients, and magnetic resonance-guided biopsy was performed in all CSRs to obtain histopathological verification. For all CSRs, a median ADC (mADC) was calculated. Wilcoxon signed ranks and Mann-Whitney tests was performed to detect differences between the groups. We used the area under the receiver operating characteristic curve to evaluate the accuracy of mADC to predict the presence of PCa in a CSR. Level of statistical significance was set at P < 0.05. RESULTS: Mean mADC in the CSRs with PCa was 1.04 × 10⁻³ mm²/s (SD, 0.29), whereas the CSRs with no PCa displayed a mean mADC of 1.26 × 10⁻³ mm²/s (SD, 0.25; P < 0.001). Cancer-suspicious regions with a high-grade Gleason component displayed a mean mADC of 0.84 × 10⁻³ mm²/s (SD, 0.35) vs a mean mADC for the low-grade CSRs of 1.09 × 10⁻³ mm²/s (SD, 0.25; P < 0.05). A diagnostic accuracy of mADC for predicting the presence of PCa in a CSR with an area under the receiver operating characteristic curve of 0.73 was established (95% confidence interval, 0.61-0.84). CONCLUSIONS: Median ADC is able to predict the presence and grade of PCa in CSRs identified by MP-MRI.

Active surveillance for low-risk prostate cancer.

Active surveillance (AS) is an important management strategy for men diagnosed with low-risk prostate cancer (PCa). The need for AS is increasing due to the awareness that many PCa are identified that show a low growth potential and therefore are likely to remain clinically asymptomatic during the lifetime of an individual. Currently there is no good method to prevent the overdiagnosis of indolent cancers upfront. During the last decade, several studies on AS around the world have made observations that feed the discussion on how to select and monitor these patients, how to proceed with the research to develop a better and more precise clinical definition of indolent cancers and how to manage men under AS clinically. Furthermore, patients' perspectives have become clearer, and quality of life studies give direction to the practical approach and care for patients and partners. This paper reflects the consensus on the state of the art and the future direction of AS, based on the Inside Track Conference "Active Surveillance for low risk prostate cancer" (Chairmen: C.H. Bangma, NL, and L. Klotz, CA; Co-Chairmen: L.J. Denis, BE, and C. Parker, UK; Scientific Coordinators: M. J. Roobol, NL, and E.W. Steyerberg, NL), organized by the European School of Oncology in collaboration with Europa Uomo in Rotterdam, the Netherlands in January 2012. Topics for discussion were the optimisation of patient selection based on indolent disease definition, the incorporation of therapeutic agents into AS programs, the optimisation of patient care, and the application of emerging technologies and biomarkers.

Three-Tesla magnetic resonance-guided prostate biopsy in men with increased prostate-specific antigen and repeated, negative, random, systematic, transrectal ultrasound biopsies: detection of clinically significant prostate cancers.

BACKGROUND: Patients with elevated prostate-specific antigen (PSA) and one or more previous negative transrectal ultrasound (TRUS) biopsy sessions are subject to diagnostic uncertainty due to TRUS-biopsy undersampling. Magnetic resonance (MR)-guided biopsy (MRGB) has shown high prostate cancer (PCa)-detection rates in studies with limited patient numbers. OBJECTIVE: Determine the detection rate of (clinically significant) PCa for MRGB of cancer-suspicious regions (CSRs) on 3-T multiparametric MR imaging (MP-MRI) in patients with elevated PSA and one or more negative TRUS-biopsy sessions. DESIGN, SETTING, AND PARTICIPANTS: Of 844 patients who underwent 3-T MP-MRI in our referral centre between March 2008 and February 2011, 438 consecutive patients with a PSA >4.0 ng/ml and one negative TRUS-biopsy session or more were included. MRGB was performed in 265 patients. Exclusion criteria were existent PCa, endorectal coil use, and MP-MRI for indications other than cancer detection. INTERVENTION: Patients underwent MRGB of MP-MRI CSRs. MEASUREMENTS: (Clinically significant) MRGB cancer-detection rates were determined. Clinically significant cancer was defined by accepted (i.a. Epstein and d'Amico) criteria based on PSA, Gleason score, stage, and tumour volume. Follow-up PSA and histopathology were collected. Sensitivity analysis was performed for patients with MP-MRI CSRs without MRGB. RESULTS AND LIMITATIONS: In a total of 117 patients, cancer was detected with MRGB (n=108) or after negative MRGB (n=9). PCa was detected in 108 of 438 patients (25%) and in 41% (108 of 265) of MRGB patients. The majority of detected cancers (87%) were clinically significant. Clinically significant cancers were detected in seven of nine (78%) negative MRGB patients in whom PCa was detected during follow-up. Sensitivity analysis resulted in increased cancer detection (47-56%). Complications occurred in 0.2% of patients (5 of 265). CONCLUSIONS: In patients with elevated PSA and one or more negative TRUS-biopsy sessions, MRGB of MP-MRI CSRs had a PCa-detection rate of 41%. The majority of detected cancers were clinically significant (87%).

Feasibility of 3T dynamic contrast-enhanced magnetic resonance-guided biopsy in localizing local recurrence of prostate cancer after external beam radiation therapy.

OBJECTIVES: The objective of this study was to assess the feasibility of the combination of magnetic resonance (MR)-guided biopsy (MRGB) and diagnostic 3T MR imaging in the localization of local recurrence of prostate cancer (PCa) after external beam radiation therapy (EBRT). MATERIALS AND METHODS: Twenty-four consecutive men with biochemical failure suspected of local recurrence after initial EBRT were enrolled prospectively in this study. All patients underwent a diagnostic 3T MR examination of the prostate. T2-weighted and dynamic contrast-enhanced MR images (DCE-MRI) were acquired. Two radiologists evaluated the MR images in consensus for tumor suspicious regions (TSRs) for local recurrence. Subsequently, these TSRs were biopsied under MR-guidance and histopathologically evaluated for the presence of recurrent PCa. Descriptive statistical analysis was applied. RESULTS: Tissue sampling was successful in all patients and all TSRs. The positive predictive value on a per patient basis was 75% (15/20) and on a per TSR basis 68% (26/38). The median number of biopsies taken per patient was 3, and the duration of an MRGB session was 31 minutes. No intervention-related complications occurred. CONCLUSIONS: The combination of MRGB and diagnostic MR imaging of the prostate was a feasible technique to localize PCa recurrence after EBRT using a low number of cores in a clinically acceptable time.

[Multiparametric MRI for prostate cancer screening]. / Multiparametrische MRI bij prostaatkankerscreening.

Two recent studies on prostate cancer screening gave conflicting results about the effects of screening on prostate cancer mortality. The current screening method of PSA determination in combination with transrectal ultrasonic biopsy leads to a large number of false positive results and overtreatment. A screening test is needed that reduces the number of unnecessary prostate biopsies and which discriminates between more and less aggressive forms of prostate cancer. Multiparametric MRI has a high specificity for prostate cancer detection and provides information about prostate cancer aggressiveness. PSA in combination with multiparametric MRI performed at 1.5 Tesla appears to be a fairly accurate screening test. Due to its high costs and limited availability, multiparametric MRI is not suitable as a primary screening test. However, it could serve as a subsequent screening test if the PSA has increased above threshold values. Using multiparametric MRI as a follow-up test during screening would provide more accurate biopsies, prevent unnecessary prostate biopsies and improve the characterization of prostate cancer.