Endorectal Magnetic Resonance Research Articles

Multiparametric magnetic resonance imaging for the assessment of extracapsular invasion and other staging parameters in patients with prostate cancer candidates for radical prostatectomy

IntroductionThe proper evaluation of the extracapsular extension (ECE), the invasion of seminal vesicles and regional lymph nodes are necessary to plan the treatment of localized prostate cancer. A model that assesses the risk of ECE in the specimen considering the clinical, histological and imaging findings is defined. Material and methodsProspective study in 85 patients with prostate cancer treated with radical prostatectomy. Prostate biopsy was performed 4 weeks before multiparametric study (mpMRI). mpMRI included T2-weighted endorectal magnetic resonance imaging (T2W-MRI), diffusion-weighted magnetic resonance imaging (DW-MRI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The apparent diffusion coefficient (ADC) was also measured. A study of consistency (k) was assessed comparing receiver operating characteristic (ROC) curve and area under the curve (AUC), which were obtained in each case (Z). Finally, a regression model was performed to predict ECE. ResultsThe mean age was 63.7±6.9 years and the mean value of PSA 12.6±13.8. In 31.7% of cases, digital rectal examination was suspicious for malignancy. Prostatectomy specimen showed pT2a in 12 cases (14%), pT2b in 3 (3%), pT2c in 37 (43%), pT3a in 19 (22%) and pT3b 14 cases (17%). ECE was evidenced in 33 (39%) of the specimens, seminal vesicle invasion in 14 (16.5%) and pelvic node involvement in 5 patients (6%). The consistency in the evaluation of ECE (image and pathological studies) was .35 for MRI (sensitivity .33, specificity .96) and .62 for mpMRI (sensitivity .58, specificity .98). Mean value of ADC was .76±.2 in patients with ECE. This value was not associated with Gleason score (p=.2) or with PSA value (p=.6). AUC value as predictor of ECE was of 65% for MRI, 78% for mpMRI and 50% ADC (Z=.008). Univariate analysis demonstrated that ECE probability increases with each Gleason score point, whilst this probability increases 1.06 times with each PSA point, and decreases .3 times with each point of ADC. Multivariate analysis confirmed that ADC value is a slight protective factor against ECE (OR=.01; CI 95% .002–.14). The consistency in the evaluation of seminal vesicles was .43 for MRI and .67 for mpMRI. AUC was 69% and 82% respectively (Z=.02). The consistency in the evaluation of positive lymph nodes was .4 for MRI and .7 for mpMRI. AUC was 68% and 88% respectively (Z=.36). ConclusionsMultiparametric study allows to carry out a more proper preoperative evaluation of ECE than convectional MRI. The most reliable predictors of ECE are DW-MRI combined with DCE-MRI, ADC coefficient and Gleason score. The superiority of mpMRI is also demonstrated for the detection of seminal vesicles invasion, but not for the evaluation of lymph nodes invasion.

Value of Endorectal Magnetic Resonance Imaging at 3T for the Local Staging of Prostate Cancer

To assess the accuracy of endorectal 3 T magnetic resonance imaging (MRI) in detecting extracapsular extension (ECE) and seminal vesicle invasion (SVI) of prostate cancer (PCa). 38 consecutive patients with biopsy-proven PCa underwent multiparametric endorectal MRI at 3 T prior to prostatectomy. Two readers (A with nine years of experience and B with four) used established criteria for ECE and SVI to diagnose the extent of local disease in six regions (apical, dorsolateral, basal; left and right each) with the highest chance of ECE. The standard of reference was provided by intraoperative frozen section analysis and prostatectomy specimens. Histopathology revealed ECE in 15 of the 222 regions (10 of 37 patients) and SVI in 8 of 74 potential regions (5 of 37 patients). The sensitivity, specificity, and accuracy in detecting ECE for reader A/B were 93%/67%, 92%/95% and 92%/93% per region and 90%/80%, 74%/82% and 78%/81% per patient, respectively. The corresponding values for the detection of SVI were 80%/100%, 96%/99% and 95%/97%, respectively. Endorectal 3 T MRI is a highly reliable noninvasive technique for the local staging of PCa. ► Endorectal 3 T MRI provided high accuracy for the local staging of prostate cancer. ► The sensitivity in detecting extracapsular tumor growth per patient was 80% or higher. ► The specificity in detecting extracapsular extension (pT3 stage) was good.

Evaluación de la invasión extracapsular y otros parámetros de estadificación mediante resonancia nuclear magnética multiparamétrica en pacientes con cáncer de próstata candidatos a prostatectomía radical

Introductionthe proper evaluation of the extracapsular extension (ECE), the invasion of seminal vesicles and regional lymph nodes are necessary to plan the treatment of localized prostate cancer. A model that assesses the risk of ECE in the specimen considering the clinical, histological and imaging findings is defined. Material and methodsprospective study in 85 patients with prostate cancer treated with radical prostatectomy. Prostate biopsy was performed 4 weeks before multiparametric study (mpMRI). mpMRI included T2-weighted endorectal magnetic resonance imaging (T2W-MRI), diffusion-weighted magnetic resonance imaging (DW-MRI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The apparent diffusion coefficient (ADC) was also measured. A study of consistency (k) was assessed comparing receiver operating characteristic (ROC) curve and area under the curve (AUC), which were obtained in each case (Z). Finally, a regression model was performed to predict ECE. Resultsthe mean age was 63.7±6.9 years and the mean value of PSA 12.6±13.8. In 31.7% of cases, digital rectal examination was suspicious for malignancy. Prostatectomy specimen showed pT2a in 12 cases (14%), pT2b in 3 (3%), pT2c in 37 (43%), pT3a in 19(22%) and pT3b 14 cases (17%). ECE was evidenced in 33 (39%) of the specimens, seminal vesicle invasion in 14 (16.5%) and pelvic node involvement in 5 patients (6%). The consistency in the evaluation of ECE (image and pathological studies) was .35 for MRI (sensitivity .33, specificity .96) and .62 for mpMRI (sensitivity .58, specificity .98). Mean value of ADC was .76±.2 in patients with ECE. This value was not associated with Gleason score (P=.2) or with PSA value (P=.6). AUC value as predictor of ECE was of 65% for MRI, 78% for mpMRI and 50% ADC (Z=.008). Univariate analysis demonstrated that ECE probability increases with each Gleason score point, whilst this probability increases 1.06 times with each PSA point, and decreases .3 times with each point of ADC. Multivariate analysis confirmed that ADC value is a slight protective factor against ECE (OR=.01; CI 95% .002-.14). The consistency in the evaluation of seminal vesicles was .43 for MRI and .67 for mpMRI. AUC was 69% and 82% respectively (Z=.02). The consistency in the evaluation of positive lymph nodes was .4 for MRI and .7 for mpMRI. AUC was 68% and 88% respectively (Z=.36). Conclusionsmultiparametric study allows to carry out a more proper preoperative evaluation of ECE than convectional MRI. The most reliable predictors of ECE are DW-MRI combined with DCE-MRI, ADC coefficient and Gleason score. The superiority of mpMRI is also demonstrated for detection of seminal vesicles invasion, but not for the evaluation of lymph nodes invasion.

Salvage Low-Dose-Rate Brachytherapy for Prostate Cancer Local Recurrence after Radical Prostatectomy: Our First three Patients

To present our initial experience with brachytherapy (BT) as a primary salvage procedure for the treatment of prostate cancer (PCa) local recurrence following radical retropubic prostatectomy (RRP). From December 2009 to May 2010, three patients underwent salvage BT due to local recurrences of high risk PCa after extrafascial RRP without additional adjuvant therapies. Local recurrence was confirmed by prostate biopsy and the relapse was well defined by endorectal ultrasonography and magnetic resonance imaging. Metastatic screening was negative. The patients were followed-up according to the American Brachytherapy Society guidelines. The median dose delivered to 90% of the local relapse (D90) was 115 Gy. The three patients reached a prostate specific antigen (PSA) nadir value within the first year that remained stable at a mean follow-up of 32 months. As regards morbidity, moderate de novo urgency was reported by only one patient. We think that our data confirms the feasibility and safety of salvage BT as a possible alternative option to external beam radiotherapy (EBRT) for the treatment of locally recurrent PCa in selected patients when performed by experienced centers. However, larger series of patients with longer follow-ups are needed to define the oncologic role of this procedure.

Seminal Vesicle Invasion: Accuracy and Analysis of Infiltration Patterns with High-Spatial Resolution T2-Weighted Sequences on Endorectal Magnetic Resonance Imaging

Objective: To evaluate the accuracy of high-spatial resolution T2-weighted endorectal magnetic resonance imaging (eMRI) for detection and pattern depiction of seminal vesicle invasion (SVI) in patients with prostate cancer (PCa). Methods: 376 patients were included who underwent eMRI for staging before radical open prostatectomy at 1.5 T with an endorectal coil. Statistical accuracy for detection of SVI was calculated. MR images of patients with SVI were further evaluated by two radiologists according to the classification by Wheeler and Ohori. Results: In the cohort, 35 patients had SVI after histopathological evaluation of the prostatectomy specimen (stage pT3b). Sensitivity and specificity for detection of SVI were 48.6 and 97.7%, respectively. Negative and positive predictive values and overall accuracy were 94.9, 68.0, and 93.1%, respectively. Infiltration pattern analysis showed that type I invasion was most common with 48.6 followed by type IIa (31.4%) and IIb (20%). Type III was not present. There was no statistical significant difference between the three groups regarding Gleason score, age, and prostate-specific antigen level. Conclusions: eMRI with high-spatial resolution T2-weighted imaging is accurate for assessment of SVI. Depiction of different infiltration types of SVI is feasible. By adding information about the extent of SVI, diagnostic reporting and risk stratification could be improved.

Localized Prostate Cancer Detection with18F FACBC PET/CT: Comparison with MR Imaging and Histopathologic Analysis

To characterize uptake of 1-amino-3-fluorine 18-fluorocyclobutane-1-carboxylic acid ((18)F FACBC) in patients with localized prostate cancer, benign prostatic hyperplasia (BPH), and normal prostate tissue and to evaluate its potential utility in delineation of intraprostatic cancers in histopathologically confirmed localized prostate cancer in comparison with magnetic resonance (MR) imaging. Institutional review board approval and written informed consent were obtained for this HIPAA-compliant prospective study. Twenty-one men underwent dynamic and static abdominopelvic (18)F FACBC combined positron emission tomography (PET) and computed tomography (CT) and multiparametric (MP) 3-T endorectal MR imaging before robotic-assisted prostatectomy. PET/CT and MR images were coregistered by using pelvic bones as fiducial markers; this was followed by manual adjustments. Whole-mount histopathologic specimens were sliced with an MR-based patient-specific mold. (18)F FACBC PET standardized uptake values (SUVs) were compared with those at MR imaging and histopathologic analysis for lesion- and sector-based (20 sectors per patient) analysis. Positive and negative predictive values for each modality were estimated by using generalized estimating equations with logit link function and working independence correlation structure. (18)F FACBC tumor uptake was rapid but reversible. It peaked 3.6 minutes after injection and reached a relative plateau at 15-20 minutes (SUVmax[15-20min]). Mean prostate tumor SUVmax(15-20min) was significantly higher than that of the normal prostate (4.5 ± 0.5 vs 2.7 ± 0.5) (P < .001); however, it was not significantly different from that of BPH (4.3 ± 0.6) (P = .27). Sector-based comparison with histopathologic analysis, including all tumors, revealed sensitivity and specificity of 67% and 66%, respectively, for (18)F FACBC PET/CT and 73% and 79%, respectively, for T2-weighted MR imaging. (18)F FACBC PET/CT and MP MR imaging were used to localize dominant tumors (sensitivity of 90% for both). Combined (18)F FACBC and MR imaging yielded positive predictive value of 82% for tumor localization, which was higher than that with either modality alone (P < .001). (18)F FACBC PET/CT shows higher uptake in intraprostatic tumor foci than in normal prostate tissue; however, (18)F FACBC uptake in tumors is similar to that in BPH nodules. Thus, it is not specific for prostate cancer. Nevertheless, combined (18)F FACBC PET/CT and T2-weighted MR imaging enable more accurate localization of prostate cancer lesions than either modality alone.

Transition Zone Prostate Cancer: Incremental Value of Diffusion-weighted Endorectal MR Imaging in Tumor Detection and Assessment of Aggressiveness

To evaluate the incremental value of using diffusion-weighted magnetic resonance (MR) imaging in addition to T2-weighted imaging for the detection of prostate cancer in the transition zone and the assessment of tumor aggressiveness. This retrospective HIPAA-compliant institutional review board-approved study included 156 consecutive patients (median age, 59.2 years) who underwent MR imaging before radical prostatectomy. Two readers who were blinded to patient data independently recorded their levels of suspicion on a five-point scale of the presence of transition zone tumors on the basis of T2-weighted imaging alone and then, 4 weeks later, diffusion-weighted imaging and T2-weighted imaging together. Apparent diffusion coefficients (ADCs) were measured in transition zone cancers and glandular and stromal benign prostatic hyperplasia. Areas under the receiver operating characteristic curves were used to evaluate detection accuracy, and generalized linear models were used to test ADC differences between benign and malignant prostate regions. Whole-mount step-section histopathologic examination was the reference standard. In overall tumor detection, addition of diffusion-weighted imaging to T2-weighted imaging improved the areas under the receiver operating characteristic curves for readers 1 and 2 from 0.60 and 0.60 to 0.75 and 0.71, respectively, at the patient level (P = .004 for reader 1 and P = .027 for reader 2) and from 0.64 and 0.63 to 0.73 and 0.68, respectively, at the sextant level (P = .001 for reader 1 and P = .100 for reader 2). Least squares mean ADCs (× 10(-3) mm(2)/sec) in glandular and stromal benign prostatic hyperplasia were 1.44 and 1.09, respectively. Mean ADCs were inversely associated with tumor Gleason scores (1.10, 0.98, 0.87, and 0.75 for Gleason scores of 3 + 3, 3 + 4, 4 + 3, and ≥ 4 + 4, respectively). Use of diffusion-weighted imaging in addition to T2-weighted imaging improved detection of prostate cancer in the transition zone, and tumor ADCs were inversely associated with tumor Gleason scores in the transition zone.

Dose-adapted salvage radiotherapy after radical prostatectomy based on an erMRI target definition model: Toxicity analysis

Background. To assess treatment tolerance by patients treated with a dose-adapted salvage radiotherapy (SRT) protocol based on an multiparametric endorectal magnetic resonance imaging (erMRI) failure definition model after radical prostatectomy (RP). Material and methods. A total of 171 prostate cancer patients recurring after RP undergoing erMRI before SRT were analyzed. A median dose of 64 Gy was delivered to the prostatic bed (PB) with, in addition, a boost of 10 Gy to the suspected relapse as visualized on erMRI in 131 patients (76.6%). Genitourinary (GU) and gastrointestinal (GI) toxicities were scored using the RTOG scale. Results. Grade ≥ 3 GU and GI acute toxicity were observed in three and zero patients, respectively. The four-year grade ≥ 2 and ≥ 3 late GU and GI toxicity-free survival rates (109 patients with at least two years of follow-up) were 83.9 ± 4.7% and 87.1 ± 4.2%, and 92.1 ± 3.6% and 97.5 ± 1.7%, respectively. Boost (p = 0.048) and grade ≥ 2 acute GU toxicity (p = 0.008) were independently correlated with grade ≥ 2 late GU toxicity on multivariate analysis. Conclusions. A dose-adapted, erMRI-based SRT approach treating the PB with a boost to the suspected local recurrence may potentially improve the therapeutic ratio by selecting patients that are most likely expected to benefit from SRT doses above 70 Gy as well as by reducing the size of the highest-dose target volume. Further prospective trials are needed to investigate the use of erMRI in SRT as well as the role of dose-adapted protocols and the best fractionation schedule.

Transition Zone Prostate Cancer: Incremental Value of Diffusion-weighted Endorectal MR Imaging in Tumor Detection and Assessment of Aggressiveness

To evaluate the incremental value of using diffusion-weighted magnetic resonance (MR) imaging in addition to T2-weighted imaging for the detection of prostate cancer in the transition zone and the assessment of tumor aggressiveness. This retrospective HIPAA-compliant institutional review board-approved study included 156 consecutive patients (median age, 59.2 years) who underwent MR imaging before radical prostatectomy. Two readers who were blinded to patient data independently recorded their levels of suspicion on a five-point scale of the presence of transition zone tumors on the basis of T2-weighted imaging alone and then, 4 weeks later, diffusion-weighted imaging and T2-weighted imaging together. Apparent diffusion coefficients (ADCs) were measured in transition zone cancers and glandular and stromal benign prostatic hyperplasia. Areas under the receiver operating characteristic curves were used to evaluate detection accuracy, and generalized linear models were used to test ADC differences between benign and malignant prostate regions. Whole-mount step-section histopathologic examination was the reference standard. In overall tumor detection, addition of diffusion-weighted imaging to T2-weighted imaging improved the areas under the receiver operating characteristic curves for readers 1 and 2 from 0.60 and 0.60 to 0.75 and 0.71, respectively, at the patient level (P = .004 for reader 1 and P = .027 for reader 2) and from 0.64 and 0.63 to 0.73 and 0.68, respectively, at the sextant level (P = .001 for reader 1 and P = .100 for reader 2). Least squares mean ADCs (× 10(-3) mm(2)/sec) in glandular and stromal benign prostatic hyperplasia were 1.44 and 1.09, respectively. Mean ADCs were inversely associated with tumor Gleason scores (1.10, 0.98, 0.87, and 0.75 for Gleason scores of 3 + 3, 3 + 4, 4 + 3, and ≥ 4 + 4, respectively). Use of diffusion-weighted imaging in addition to T2-weighted imaging improved detection of prostate cancer in the transition zone, and tumor ADCs were inversely associated with tumor Gleason scores in the transition zone.

Analysis of the correlation between endorectal MRI response to neoadjuvant chemotherapy and biochemical recurrence in patients with high-risk localized prostate cancer

Intermediate end points are desirable to expedite the integration of neoadjuvant systemic therapy into the treatment strategy for high-risk localized prostate cancer. Endorectal magnetic resonance imaging at 1.5 Tesla (1.5T erMRI) response has been utilized as an end point in neoadjuvant trials but has not been correlated with clinical outcomes. Data were pooled from two trials exploring neoadjuvant chemotherapy in high-risk localized prostate cancer. Trial 1 explored docetaxel for 6 months and Trial 2 explored docetaxel plus bevacizumab for 4.5 months, both before radical prostatectomy. erMRI was done at baseline and end of chemotherapy. 1.5T erMRI response, based upon T2W sequences, was recorded. Multivariable Cox regression was undertaken to evaluate the association between clinical parameters and biochemical recurrence. There were 53 evaluable patients in the combined analysis: 20 (33%) achieved a PSA response, 16 (27%) achieved an erMRI partial response and 24 (40%) achieved an erMRI minor response. Median follow-up was 4.2 years, and 33 of 53 evaluable (62%) patients developed biochemical recurrence. On multivariable analysis, PSA response did not correlate with biochemical recurrence (hazard ratio=0.58, 95% confidence interval (CI) 0.25-1.33) and paradoxically erMRI response was associated with a significantly shorter time to biochemical recurrence (hazard ratio=2.47, 95% CI 1.00-6.13). Response by 1.5T erMRI does not correlate with a decreased likelihood of biochemical recurrence in patients with high-risk localized prostate cancer treated with neoadjuvant docetaxel and may be associated with inferior outcomes. These data do not support the use of 1.5T erMRI response as a primary end point in neoadjuvant chemotherapy trials.

Endorectal MRI and MR spectroscopic imaging of prostate cancer: Developing selection criteria for MR‐guided focal therapy

To investigate criteria that can identify dominant treatable prostate cancer foci with high certainty at endorectal magnetic resonance imaging (MRI) and MR spectroscopic (MRS) imaging, and thus facilitate selection of patients who are radiological candidates for MR-guided focal therapy. We retrospectively identified 88 patients with biopsy-proven prostate cancer who underwent endorectal MRI and MRS imaging prior to radical prostatectomy with creation of histopathological tumor maps. Two independent readers noted the largest tumor foci at MRI, if visible, and the volume of concordant abnormal tissue at MRS imaging, if present. A logistic random intercept model was used to determine the association between clinical and MR findings and correct identification of treatable (over 0.5 cm3) dominant intraprostatic tumor foci. Readers 1 and 2 identified dominant tumor foci in 50 (57%) and 58 (65%) of 88 patients; 42 (84%) and 48 (83%) of these were dominant treatable lesions at histopathology, respectively. Within the statistical model, the volume of concordant spectroscopic abnormality was the only factor that predicted correct identification of a dominant treatable lesion on T2-weighted images (odds ratio=1.75; 95% confidence interval=1.08 to 2.82; P value=0.02). In particular, all visible lesions on T2-weighted imaging associated with at least 0.54 cm3 of concordant spectroscopic abnormality were correctly identified dominant treatable tumor foci. Patients with dominant intraprostatic tumor foci seen on T2-weighted MRI and associated with at least 0.54 cm3 of concordant MRS imaging abnormality may be radiological candidates for MR-guided focal therapy.

Clarifying the role of salvage radiotherapy

In this issue of CUAJ, the Genito-Urinary Radiation Oncologists of Canada (GUROC) group addresses several very important issues relating to salvage radiotherapy following biochemical relapse after radical prostatectomy.1 With the published results from the EORTC (European Organisation for Research and Treatment of Cancer) 229112 and SWOG (Southwest Oncology Group) 8794 (NCIC PR-2)3 studies and the recent update of the latter trial showing metastasis-free and overall survival benefit for adjuvant radiotherapy for pT3 disease,4 the questions relating to salvage radiotherapy deserve more discussion. A fundamental issue is the attitude of urologists toward the use of local salvage radiotherapy. There is a wide range of opinions among practitioners in various countries about whether radiotherapy should be recommended for prostate-specific antigen (PSA) relapse after radical prostatectomy, with those in favour ranging from 13% to 91%. A safe assumption is that the Canadian position is more moderate and intermediate. The dichotomy in practice pattern stems largely from the lack of evidence from randomized controlled trials. The GUROC consensus meeting included a discussion on 2 retrospective multi-institutional analyses by Stephenson and colleagues5,6 that revealed some surprising results. The 6-year progression-free probability was 32% for all participants, and even the most unfavourable group (those with a Gleason score of 8–10, negative margins or a serum PSA level doubling time of < 10 mo, i.e., those with a high probability of distant metastatic disease) had a 1 in 5 chance of achieving sustained progression-free response provided the local salvage radiotherapy was delivered when the serum PSA level was less than 2.0 μg/L. Remarkably, when such patients were treated when the serum PSA level was less than 0.5 μg/L, 41% were disease-free at 6 years. These findings have led to the very reasonable recommendation by the GUROC for much earlier referral for salvage radiation consideration, even for patients with high-risk features. Another potential consequence of earlier radiotherapy may be obviation or deferral of androgen ablation (demonstrated in the SWOG 8794, NCIC PR-2 adjuvant radiotherapy trial3,4), with the inherent benefits of avoiding hormonal therapy. Although multivariable analysis from the retrospective multicentre study suggested a benefit for neoadjuvant androgen ablation6 the role of adjunctive hormonal therapy with salvage radiotherapy remains unsettled. The upcoming MRC (Medical Research Council) (NCIC PR-13) study hopes to answer some of the questions, including the timing and duration of hormonal therapy. The trial design appears somewhat complicated and imposing at first glance, but is in fact very logical and straightforward, and by providing an opportunity for most radical prostatectomy patients to participate at some point in the variable clinical course, the MRC will hopefully maximize accrual and eventually provide some valuable answers. Sia and colleagues referred to the potential role of endorectal magnetic resonance imaging in guiding and planning salvage radiotherapy. Another imaging modality is the ProstaScint (Cytogen Corporation) capromab pendetide scan.7 More promising would be the fusion or coregistration of ProstaScint with another imaging modality such as CT.8,9 Ongoing studies with newer imaging techniques will assist radiation oncologist with making decisions about and fine-tuning salvage radiotherapy for the patient with biochemical relapse after radical prostatectomy. The recommendations by GUROC, with acceptance and participation from urologists, should clarify the role of salvage radiotherapy after radical prostatectomy.

Accuracy of Endorectal Magnetic Resonance/Transrectal Ultrasound Fusion for Detection of Prostate Cancer During Brachytherapy

To evaluate the effectiveness of 3 Tesla endorectal magnetic resonance imaging (erMRI) with fusion to real-time transrectal ultrasound to detect a dominant cancer focus within the prostate gland. The safety and effectiveness of identifying suspicious lesions using erMRI was assessed in men undergoing brachytherapy perineal implants. Suspicious lesions identified on erMRI fused to real-time transrectal ultrasound were biopsied at brachytherapy seed placement. In addition, a biopsy was also obtained from an area identified as negative for cancer. This prospective study was performed for 30 patients who had previously provided consent for brachytherapy. Eligible patients had to have a lesion on erMRI that was≥1.0 cm× 1.0 cm. Their mean prostate-specific antigen level was 7.3 ng/mL, mean Gleason score 6.75, and mean percentage of positive diagnostic core biopsies was 29%. Cancer was detected in a suspicious area in 53% of the patients. In 9 of these patients, the cancer was Gleason score 3+ 3, in 6, Gleason score 3+ 4, and in 1, Gleason score 4+ 3. Cancer was detected in unsuspected areas in 10% of patients; all Gleason score 3+ 3 in<10% of the core. No adverse events from the biopsy were reported. Although biopsy of lesions identified by erMRI is safe and more effective than would be expected by blind biopsy, a significant "miss" rate was still found. However, the negative predictive (10%) value of this technique might be useful for determining which regions of the gland might not need treatment in the setting of focal therapy.

Seminal Vesicle Invasion in Prostate Cancer: Evaluation by Using Multiparametric Endorectal MR Imaging

To retrospectively evaluate the diagnostic performance of multiparametric endorectal magnetic resonance (MR) imaging, including T2-weighted, diffusion-weighted (DW), and dynamic contrast material-enhanced (DCE) MR techniques, for the diagnosis of seminal vesicle invasion (SVI) and to determine the incremental value of DW MR and DCE MR images. This retrospective HIPAA-compliant study was approved by the institutional review board, with a waiver of informed consent. The study included 131 patients (mean age, 68 years; range, 43-75 years) who underwent endorectal MR imaging before radical prostatectomy between January 2007 and April 2010. Two radiologists (A: experienced, B: less experienced) estimated the likelihood of SVI by using a five-point ordinal scale in three image-viewing settings: T2-weighted images alone; T2-weighted and DW MR images; and T2-weighted, DW MR, and DCE MR images. Sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve (AUC) were calculated. Confidence intervals estimated with bootstrapping and the McNemar test or Fisher exact test were used to compare sensitivity, specificity, positive predictive value, and negative predictive value. Of the 131 patients, 23 (17.6%) had SVI identified after surgery. Review of T2-weighted MR images alone resulted in high specificity (93.1% and 93.6%, for radiologists A and B, respectively) and high negative predictive value (94.8% and 94.0%) but moderate sensitivity (59% and 52%) and positive predictive value (52% and 50%). Review of T2-weighted and DW MR images significantly improved specificity (96.6% [P = .02] and 98.3% [P = .003]) and positive predictive value (70% [P < .05] and 79% [P < .05]) without significantly improving AUC. Additional review of DCE MR images did not yield further incremental improvement. Additional review of DW MR images improves specificity and positive predictive value in SVI detection compared with reviewing T2-weighted images alone. Addition of DCE MR images to this combination, however, does not provide incremental value for diagnosis of SVI.

Commentary on “Endorectal magnetic resonance imaging for predicting pathologic T3 disease in Gleason score 7 prostate cancer: Implications for prostate brachytherapy”

Commentary on “Endorectal magnetic resonance imaging for predicting pathologic T3 disease in Gleason score 7 prostate cancer: Implications for prostate brachytherapy”

Increased rate of positive biopsies using a combination of MR-Tomography, spectroscopy and diffusion-weighted magnetic resonance imaging prior to prostate biopsies in patients with persistent elevated prostate-specific antigen values: A retrospective analysis

Purpose:Persistently elevated prostate-specific antigen (PSA) values following negative biopsies result in a diagnostic dilemma. In order to improve detection rates in patients with former negative biopsies and persistently elevated PSA values, magnetic resonance tomography (MRT), magnetic resonance spectroscopy (MRS), and diffusion-weighted magnetic resonance imaging (DW-MRI) were performed prior to prostate rebiopsies.Materials and Methods:Over a 14-month period, 67 patients (mean age of 66 years) with a history of 1-5 negative biopsies underwent endorectal magnetic resonance imaging (MRI) using T2-weighted MRT MRS and DW-MRI before an additional prostate biopsy was performed. Subsequently, 5 contrast-enhanced transrectal ultrasound-guided biopsies were performed according to a 10-core systematic scheme. Out of the 67 men, 25 patients had positive biopsies and opted for radical prostatectomy. Histological evaluation of cancer localization, PSA, diameters of primary tumors, numbers and diameters of satellite tumors, prostate volume, and staging pathology was performed. These findings were compared with MRI and MRS results.Results:Serum PSA levels ranged from 3.1 to 19.5 g/ml (median level of 7.96 ng/ml). After the 25 patients underwent radical prostatectomy, analysis of 20 whole-mount sections of 25 radical retropubic prostatectomy (RPE) specimens presented results agreeing with the tumor location from MRI and MRS data.Conclusions:The aim of image-guided diagnostics should be to provide more critical information prior to biopsy. Furthermore, the acquisition of such data is important for better risk stratification in therapeutic decisions.

Transition Zone Prostate Cancer: Detection and Localization with 3-T Multiparametric MR Imaging

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. 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. 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). 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. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120281/-/DC1.

A Bayesian nonrigid registration method to enhance intraoperative target definition in image-guided prostate procedures through uncertainty characterization.

This study introduces a probabilistic nonrigid registration method for use in image-guided prostate brachytherapy. Intraoperative imaging for prostate procedures, usually transrectal ultrasound (TRUS), is typically inferior to diagnostic-quality imaging of the pelvis such as endorectal magnetic resonance imaging (MRI). MR images contain superior detail of the prostate boundaries and provide substructure features not otherwise visible. Previous efforts to register diagnostic prostate images with the intraoperative coordinate system have been deterministic and did not offer a measure of the registration uncertainty. The authors developed a Bayesian registration method to estimate the posterior distribution on deformations and provide a case-specific measure of the associated registration uncertainty. The authors adapted a biomechanical-based probabilistic nonrigid method to register diagnostic to intraoperative images by aligning a physician's segmentations of the prostate in the two images. The posterior distribution was characterized with a Markov Chain Monte Carlo method; the maximum a posteriori deformation and the associated uncertainty were estimated from the collection of deformation samples drawn from the posterior distribution. The authors validated the registration method using a dataset created from ten patients with MRI-guided prostate biopsies who had both diagnostic and intraprocedural 3 Tesla MRI scans. The accuracy and precision of the estimated posterior distribution on deformations were evaluated from two predictive distance distributions: between the deformed central zone-peripheral zone (CZ-PZ) interface and the physician-labeled interface, and based on physician-defined landmarks. Geometric margins on the registration of the prostate's peripheral zone were determined from the posterior predictive distance to the CZ-PZ interface separately for the base, mid-gland, and apical regions of the prostate. The authors observed variation in the shape and volume of the segmented prostate in diagnostic and intraprocedural images. The probabilistic method allowed us to convey registration results in terms of posterior distributions, with the dispersion providing a patient-specific estimate of the registration uncertainty. The median of the predictive distance distribution between the deformed prostate boundary and the segmented boundary was ≤3 mm (95th percentiles within ±4 mm) for all ten patients. The accuracy and precision of the internal deformation was evaluated by comparing the posterior predictive distance distribution for the CZ-PZ interface for each patient, with the median distance ranging from -0.6 to 2.4 mm. Posterior predictive distances between naturally occurring landmarks showed registration errors of ≤5 mm in any direction. The uncertainty was not a global measure, but instead was local and varied throughout the registration region. Registration uncertainties were largest in the apical region of the prostate. Using a Bayesian nonrigid registration method, the authors determined the posterior distribution on deformations between diagnostic and intraprocedural MR images and quantified the uncertainty in the registration results. The feasibility of this approach was tested and results were positive. The probabilistic framework allows us to evaluate both patient-specific and location-specific estimates of the uncertainty in the registration result. Although the framework was tested on MR-guided procedures, the preliminary results suggest that it may be applied to TRUS-guided procedures as well, where the addition of diagnostic MR information may have a larger impact on target definition and clinical guidance.

Preoperative 3-Tesla Multiparametric Endorectal Magnetic Resonance Imaging Findings and the Odds of Upgrading and Upstaging at Radical Prostatectomy in Men With Clinically Localized Prostate Cancer

To investigate whether 3-T esla (3T) multiparametric endorectal MRI (erMRI) can add information to established predictors regarding occult extraprostatic or high-grade prostate cancer (PC) in men with clinically localized PC. At a single academic medical center, this retrospective study's cohort included 118 men with clinically localized PC who underwent 3T multiparametric erMRI followed by radical prostatectomy, from 2008 to 2011. Multivariable logistic regression analyses in all men and in 100 with favorable-risk PC addressed whether erMRI evidence of T3 disease was associated with prostatectomy T3 or Gleason score (GS) 8-10 (in patients with biopsy GS ≤7) PC, adjusting for age, prostate-specific antigen level, clinical T category, biopsy GS, and percent positive biopsies. The accuracy of erMRI prediction of extracapsular extension and seminal vesicle invasion was 75% and 95%, respectively. For all men, erMRI evidence of a T3 lesion versus T2 was associated with an increased odds of having pT3 disease (adjusted odds ratio [AOR] 4.81, 95% confidence interval [CI] 1.36-16.98, P=.015) and pGS 8-10 (AOR 5.56, 95% CI 1.10-28.18, P=.038). In the favorable-risk population, these results were AOR 4.14 (95% CI 1.03-16.56), P=.045 and AOR 7.71 (95% CI 1.36-43.62), P=.021, respectively. Three-Tesla multiparametric erMRI in men with favorable-risk PC provides information beyond that contained in known preoperative predictors about the presence of occult extraprostatic and/or high-grade PC. If validated in additional studies, this information can be used to counsel men planning to undergo radical prostatectomy or radiation therapy about the possible need for adjuvant radiation therapy or the utility of adding hormone therapy, respectively.

Magnetic Resonance Imaging for Predicting Prostate Biopsy Findings in Patients Considered for Active Surveillance of Clinically Low Risk Prostate Cancer

A barrier to the acceptance of active surveillance for men with prostate cancer is the risk of underestimating the cancer burden on initial biopsy. We assessed the value of endorectal magnetic resonance imaging in predicting upgrading on confirmatory biopsy in men with low risk prostate cancer. A total of 388 consecutive men (mean age 60.6 years, range 33 to 89) with clinically low risk prostate cancer (initial biopsy Gleason score 6 or less, prostate specific antigen less than 10 ng/ml, clinical stage T2a or less) underwent endorectal magnetic resonance imaging before confirmatory biopsy. Three radiologists independently and retrospectively scored tumor visibility on endorectal magnetic resonance imaging using a 5-point scale (1-definitely no tumor to 5-definitely tumor). Inter-reader agreement was assessed with weighted kappa statistics. Associations between magnetic resonance imaging scores and confirmatory biopsy findings were evaluated using measures of diagnostic performance and multivariate logistic regression. On confirmatory biopsy, Gleason score was upgraded in 79 of 388 (20%) patients. Magnetic resonance imaging scores of 2 or less had a high negative predictive value (0.96-1.0) and specificity (0.95-1.0) for upgrading on confirmatory biopsy. A magnetic resonance imaging score of 5 was highly sensitive for upgrading on confirmatory biopsy (0.87-0.98). At multivariate analysis patients with higher magnetic resonance imaging scores were more likely to have disease upgraded on confirmatory biopsy (odds ratio 2.16-3.97). Inter-reader agreement and diagnostic performance were higher for the more experienced readers (kappa 0.41-0.61, AUC 0.76-0.79) than for the least experienced reader (kappa 0.15-0.39, AUC 0.61-0.69). Magnetic resonance imaging performed similarly in predicting low risk and very low risk (Gleason score 6, less than 3 positive cores, less than 50% involvement in all cores) prostate cancer. Adding endorectal magnetic resonance imaging to the initial clinical evaluation of men with clinically low risk prostate cancer helps predict findings on confirmatory biopsy and assess eligibility for active surveillance.