Magnetic resonance imaging does not improve the prediction of misclassification of prostate cancer patients eligible for active surveillance when the most stringent selection criteria are based on the saturation biopsy scheme

Fuzzy C-Means Clustering Algorithm-Based Magnetic Resonance Imaging Image Segmentation for Analyzing the Effect of Edaravone on the Vascular Endothelial Function in Patients with Acute Cerebral Infarction

This paper aimed to discuss the denoising ability of magnetic resonance imaging (MRI) images based on fuzzy C-means clustering (FCM) algorithm and the influence of Butylphthalide combined with Edaravone treatment on nerve function and vascular endothelial function in patients with acute cerebral infarction (ACI). Based on FCM algorithm, Markov Random Field (MRF) model algorithm was introduced to obtain a novel algorithm (NFCM), which was compared with FCM and MRF algorithm in terms of misclassification rate (MCR) and difference of Kappa index (KI). 90 patients with ACI diagnosed in hospital from December 2018 to December 2019 were selected as subjects, who were divided into combined treatment group (conventional treatment + Edaravone + Butylphthalide) and Edaravone group (conventional treatment + Edaravone) randomly, each consisting of 45 cases. The National Institutes of Health Stroke Scale (NIHSS) score and endothelial function index level such as plasma nitric oxide (NO), human endothelin-1 (ET-1), and vascular endothelial cell growth factor (VEGF) were compared before and after treatment between the two groups. The results showed that the MCR of NFCM was evidently inferior to FCM and MRF, and the KI was notably higher relative to the other two algorithms. After treatment, the NIHSS score of the combined treatment group was (9.09 ± 1.86) points and that of Edaravone group was (14.97 ± 3.44) points, with evident difference between the two groups (P < 0.05). After treatment, the NO of the combined treatment was (54.63 ± 4.85), and that of Edaravone group was (41.54 ± 5.27), which was considerably different (P < 0.01), and the VEGF and ET-1 of combined treatment group were greatly inferior to Edaravone group (P < 0.01). It was revealed that the novel algorithm based on FCM can obtain more favorable quality and segmentation accuracy of MRI images. Moreover, Butylphthalide combined with Edaravone treatment can effectively improve nerve function, vascular endothelial function, and short-term prognosis in ACI, which was safe and worthy of clinical adoption.

MRI to guide biopsies or avoid biopsies?

PURPOSE OF REVIEW

To discuss contemporary data on the value of multiparametric MRI (mpMRI) for guiding the decision to biopsy men at risk for prostate cancer, as well as its utility in active surveillance programs.

RECENT FINDINGS

Although a systematic 12-core biopsy is the current standard of care for men with increased suspicion for prostate cancer, MRI with or without targeted biopsy has been shown to reliably improve the detection of clinically significant disease following a prior negative biopsy. At the same time, there is a growing body of evidence to support the use of MRI for diagnostic purposes in biopsy-naive patients, as well for enrolling and monitoring men on active surveillance programs.

SUMMARY

mpMRI is an evolving technology with great promise for altering our approach to prostate cancer diagnosis and surveillance. In conjunction with targeted biopsies, MRI offers greater specificity for the detection of clinically significant cancer and therefore may help to reduce overdetection of indolent disease while minimizing the risks and limitations of systematic biopsies.

MRI in active surveillance: a critical review

INTRODUCTION

Recent technological advancements and the introduction of modern anatomical and functional sequences have led to a growing role for multiparametric magnetic resonance imaging (mpMRI) in the detection, risk assessment and monitoring of early prostate cancer. This includes men who have been diagnosed with lower-risk prostate cancer and are looking at the option of active surveillance (AS). The purpose of this paper is to review the recent evidence supporting the use of mpMRI at different time points in AS, as well as to discuss some of its potential pitfalls.

METHODS

A combination of electronic and manual searching methods were used to identify recent, important papers investigating the role of mpMRI in AS.

RESULTS

The high negative predictive value of mpMRI can be exploited for the selection of AS candidates. In addition, mpMRI can be efficiently used to detect higher risk disease in patients already on surveillance.

CONCLUSION

Although there is an ongoing debate regarding the precise nature of its optimal implementation, mpMRI is a promising risk stratification tool and should be considered for men on AS.

[Pathology findings after radical prostatectomy for prostate cancer in patients eligible for active surveillance: Contribution of multiparametric MRI to treatment decision]

OBJECTIVES

To analyze, in patients with prostate cancer (PC) potentially eligible for active surveillance (AS), whether multiparametric-MRI (mp-MRI) predicts presence of clinically significant cancer on radical prostatectomy (RP) specimen.

METHODS

We identified 77 men with PC eligible for AS (PSA≤15ng/mL, stage≤T2a, Gleason score≤6, up to 3 positive cores, maximal cancer core length≤5mm) who underwent RP between 01/2008 and 08/2015. All patients had prebiopsy mp-MRI followed by systematic±targeted biopsies. For each patient, the likelihood of the presence of cancer on mp-MRI was assigned using Likert scale (1 to 5). The predictive factors for the presence of significant cancer on RP specimen (Gleason score≥7 and/or tumoral maximal diameter>10mm) were evaluated using logistic regression.

RESULTS

Median age was 61 and median PSA was 6.7ng/mL. Overall, 49 (64%) patients had a positive mp-MRI (score≥3). Clinically significant cancer on RP specimen was found in 45 (58%) patients (69% in MRI-positive patients vs 39% in MRI-negative patients). In multivariate analysis, a positive MRI was a predictive factor for the presence of significant cancer on the surgical specimen (OR=3.0; CI95% [1.01-8.88]; P=0.04), as was age (OR=1.17; CI95% [1.05-1.31]; P=0.004) and PSAD (OR=1.10; CI95% [1.01-1.20]; P=0.02).

CONCLUSION

Mp-MRI is a useful exam for selecting patients eligible for AS even if the situation remains unclear after prostate biopsies including targeted biopsies. Upon confirmation by further studies, mp-MRI should be considered as an independent criterion before entering an AS program.

LEVEL OF EVIDENCE

4.

Multiparametric Magnetic-Resonance to Confirm Eligibility to an Active Surveillance Program for Low-Risk Prostate Cancer: Intermediate Time Results of a Third Referral High Volume Centre Active Surveillance Protocol

BACKGROUND

To evaluate the role of confirmatory multiparametric magnetic resonance imaging (mpMRI) of the prostate at the time of Active Surveillance (AS) enrollment to reduce disease misclassification.

MATERIALS

From 2012 to 2016, 383 patients with low-risk disease respecting Prostate Cancer Research International AS criteria underwent confirmatory 1.5-T mpMRI. AS was proposed to patients with Prostate Imaging and Report and Data System (PI-RADS) score ≤3 and no extraprostatic extension (EPE), whereas patients with PI-RADS score ≥4 and/or EPE were treated actively. Kaplan-Meier analyses quantified progression-free survival (PFS) in patients enrolled in the AS program. Logistic regression analyses tested the association between confirmatory mpMRI and clinically significant prostate cancer (csPCa) at radical prostatectomy (RP). Diagnostic performance of mpMRI was calculated in patients submitted to immediate RP.

RESULTS

PFS rate was 99, 90 and 86% at 1, 2 and 3 years respectively. At multivariable analysis, PI-RADS 3, PI-RADS 4, PI-RADS 5 and EPE increased the probability of having csPCa at immediate RP (PI-RADS 3 [OR] 1.2, p = 0.26; PI-RADS 4 [OR] 5.1, p = 0.02; PI-RADS 5 [OR] 6.7; p = 0.009; EPE [OR] 11.8, p < 0.001). Confirmatory mpMRI showed sensibility, specificity, positive predictive value and negative predictive value of 85, 55, 68 and 76% respectively.

CONCLUSIONS

MpMRI at the time of AS enrollment reduces the misclassification rate of csPCa. We suggest to perform target biopsies in patients with PI-RADS score 3 and 4 lesions.

Magnetic Resonance Imaging-Based Prostate-Specific Antigen Density for Prediction of Gleason Score Upgrade in Patients With Low-Risk Prostate Cancer on Initial Biopsy

OBJECTIVE

The aim of this study was to assess the utility of prostate-specific antigen density (PSAD) calculated using magnetic resonance imaging for predicting Gleason score (GS) upgrade in patients with low-risk prostate cancer on biopsy.

METHODS

Seventy-three patients were divided into 2 groups according to the concordance between biopsy and prostatectomy GS: group 1 (6/6) and group 2 (6/≥7). Magnetic resonance imaging-based PSAD, prostate volume, prostate-specific antigen (PSA), and age were compared between the 2 groups. Logistic regression and receiver operating characteristic curve analysis were performed.

RESULTS

Gleason score was upgraded in 40 patients. Patients in group 2 had significantly higher PSAD and PSA values and smaller prostate volume than did those in group 1. Prostate-specific antigen density of 0.26 ng/mL per cm or higher, PSA of 7.63 ng/mL or higher, and prostate volume of 25.1 cm or less were related to GS upgrade, with area-under-the-curve values of 0.765, 0.721, and 0.639, respectively.

CONCLUSIONS

Magnetic resonance imaging-based PSAD could help in predicting postoperative GS upgrade in patients with low-risk prostate cancer.

Low-risk Prostate Cancer: Identification, Management, and Outcomes

CONTEXT

The incidence of low-risk prostate cancer (PCa) has increased as a consequence of prostate-specific antigen testing.

OBJECTIVE

In this collaborative review article, we examine recent literature regarding low-risk PCa and the available prognostic and therapeutic options.

EVIDENCE ACQUISITION

We performed a literature review of the Medline, Embase, and Web of Science databases. The search strategy included the terms: prostate cancer, low risk, active surveillance, focal therapy, radical prostatectomy, watchful waiting, biomarker, magnetic resonance imaging, alone or in combination.

EVIDENCE SYNTHESIS

Prospective randomized trials have failed to show an impact of radical treatments on cancer-specific survival in low-risk PCa patients. Several series have reported the risk of adverse pathologic outcomes at radical prostatectomy. However, it is not clear if these patients are at higher risk of death from PCa. Long-term follow-up indicates the feasibility of active surveillance in low-risk PCa patients, although approximately 30% of men starting active surveillance undergo treatment within 5 yr. Considering focal therapies, robust data investigating its impact on long-term survival outcomes are still required and therefore should be considered experimental. Magnetic resonance imaging and tissue biomarkers may help to predict clinically significant PCa in men initially diagnosed with low-risk disease.

CONCLUSIONS

The incidence of low-risk PCa has increased in recent years. Only a small proportion of men with low-risk PCa progress to clinical symptoms, metastases, or death and prospective trials have not shown a benefit for immediate radical treatments. Tissue biomarkers, magnetic resonance imaging, and ongoing surveillance may help to identify those men with low-risk PCa who harbor more clinically significant disease.

PATIENT SUMMARY

Low-risk prostate cancer is very common. Active surveillance has excellent long-term results, while randomized trials have failed to show a beneficial impact of immediate radical treatments on survival. Biomarkers and magnetic resonance imaging may help to identify which men may benefit from early treatment.

Prostate MRI: a national survey of Urologist's attitudes and perceptions

Introduction

The use of multi-parametric (MP) MRI to diagnose prostate cancer has been the subject of intense research, with many studies showing positive results. The purpose of our study is to better understand the accessibility, role, and perceived accuracy of MP-MRI in practice by surveying practicing urologists.

Materials and Methods

Surveys were sent to 7,400 practicing American Urological Association member physicians with a current email address. The survey asked demographic information and addressed access, accuracy, cost, and role of prostate MRI in clinical practice.

Results

Our survey elicited 276 responses. Respondents felt that limited access and prohibitive cost of MP-MRI limits its use, 72% and 59% respectively. Academic urologists ordered more MP-MRI studies per year than those in private practice (43.3% vs. 21.1%; p<0.001). Urologists who performed more than 30 prostatectomies a year were more likely to feel that an MP-MRI would change their surgical approach (37.5% vs. 19.6%, p-value=0.002). Only 25% of respondents agreed or strongly agreed that MP-MRI should be used in active surveillance. For patients with negative biopsies and elevated PSA, 39% reported MP-MRI to be very useful.

Conclusions

Our study found that MP-MRI use is most prominent among practitioners who are oncology fellowship-trained, practice at academic centers, and perform more than 30 prostatectomies per year. Limited access and prohibitive cost of MP-MRI may limit its utility in practice. Additionally, study participants perceive a lack of accuracy of MP-MRI, which is contrary to the recent literature.

Integration of multiparametric MRI into active surveillance of prostate cancer

Prostate cancer is the most common noncutaneous cancer in men though many men will not die of this disease and may not require definitive treatment. Active surveillance (AS) is an increasingly utilized potential solution to the issue of overtreatment of prostate cancer. Traditionally, prostate cancer patients have been stratified into risk groups based on clinical stage on digital rectal examination, prostate-specific antigen and biopsy Gleason score, though each of these variables has significant limitations. This review will discuss the potential role for prostate multiparametric MRI and targeted biopsy techniques incorporating MRI in the selection of candidates for AS, monitoring patients on AS and as triggers for definitive treatment.

Multiparametric magnetic resonance imaging for pre-treatment local staging of prostate cancer: A Cancer Care Ontario clinical practice guideline

INTRODUCTION

The utility of T2-weighted magnetic resonance imaging (MRI) in the local staging of prostate cancer is controversial. Due to the success of multiparametric MRI in cancer localization, there is renewed interested in MRI (± functional sequences) for local staging. Guidance on pre-treatment local staging of prostate cancer by MRI was developed using systematic review methodology and expert consultation.

METHODS

MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and other databases were searched to identify studies comparing: (1) MRI staging vs. radical prostatectomy staging on diagnostic accuracy outcomes; and (2) MRI staging vs. routine clinical staging on clinical and patient outcomes. Studies meeting inclusion criteria were synthesized by outcome and sensitivity/specificity analysis by tumour location was performed. Evidence quality of included studies was assessed and considered in recommendation formulation.

RESULTS

The literature search identified 2510 citations; 62 studies were included. Analysis of MRI ≥1.5 T plus endorectal coil (ER) (± functional sequences) in the detection of extraprostatic extension or seminal vesicle invasion showed modest sensitivities (≥50%) and excellent specificities (>85%) among patients scheduled for radical prostatectomy. MRI upstaging was shown in 20/21 studies, with large variation in correctness (11-85%). Scarcity of clinical and patient outcomes among studies limited synthesis and evaluation. Quality assessment found non-trivial biases.

CONCLUSIONS

Modest imaging performance was shown for MRI (1.5 T + ER and 3 T ± ER) ± functional sequences in regards to sensitivity. Limitations in study design, reporting of clinical and patient outcomes, and the heterogeneous use of MRI tempered the strength of the recommendations.

Role of Multi-Parametric Magnetic Resonance Image and PIRADS Score in Patients with Prostate Cancer Eligible for Active Surveillance According PRIAS Criteria

OBJECTIVE

To evaluate the prognostic role of multiparametric-MRI (mp-MRI) in patients with clinically localized prostate cancer (PCa) eligible for active surveillance (AS) according to Prostate Cancer Research International: Active Surveillance (PRIAS) criteria.

PATIENTS AND METHODS

We analyzed prospectively 73 patients with PCa and PRIAS criteria for low-risk disease. All patients fitted criteria for AS but optioned surgery treatment. The mp-MRI was performed to define the likelihood of malignancy according to the Prostate Imaging Reporting and Data System (PIRADS) score (1-5). Patients were divided in 2 groups: non-visible cancer lesion on MRI (PIRADS 2-3) and visible cancer (PIRADS 4-5). Preoperative clinical data (age, body mass index, prostate specific antigen (PSA) level, positive core biopsy, PSA density (PSAD)) and definitive pathological findings (staging, upgrading, unfavorable disease) were compared between groups. PIRADS score was correlated with pathological data to evaluate the prognostic role of mp-MRI; and preoperative variables and definitive pathology (upgrading, upstaging and unfavorable disease) were also assessed.

RESULTS

PSAD (p = 0.04) and pathological stage (p = 0.03) were significantly associated with the presence of visible disease. Visible disease was significantly associated with upstaging (p = 0.03). Correlation between PIRADS 5 and unfavorable disease was statistically significant (p = 0.02). The mp-MRI had adequate sensibility in detecting upstaging (92%), intermediate for upgrading (76%) and unfavorable disease (76%). Negative predictive value was higher for upstaging than for upgrading or unfavorable disease (96 vs. 68% and 64%). Multivariate logistic regression revealed that PIRADS 5 was a significant predictor of upstaging (p = 0.05, OR 16.12) and unfavorable disease (p = 0.01, OR 6.53).

CONCLUSION

A visible lesion on mp-MRI strongly predicts significant PCa in patients eligible for AS according to PRIAS criteria, based on upstaging and unfavorable disease. We believe that mp-MRI is an important tool and should be added to clinical selection criteria for AS.

Use of mpMRI in active surveillance for localized prostate cancer

INTRODUCTION

In an effort to limit prostate cancer (PCa) overdiagnosis and overtreatment, which have occurred in response to widespread prostate specific antigen testing, numerous strategies aimed at improved risk stratification of patients with PCa have evolved. Multiparametric magnetic resonance imaging (MRI) is being used in concert with prostate specific antigen testing and prostate biopsies to improve sensitivity and specificity of these tests. There are limited data on how multiparametric MRI can be incorporated into active surveillance (AS) protocols.

EVIDENCE ACQUISITION

A PubMed literature search of available English language publications on PCa, AS, and MRI was conducted. Appropriate articles were selected and included for review. Bibliographies were also used to expand our search.

EVIDENCE SYNTHESIS

Data from 41 studies were reviewed. AS inclusion criteria and protocols varied among studies, as did indications for use of MRI. Technological improvements are briefly highlighted. Studies are broadly categorized and discussed according to the role of MRI in patient selection, disease staging, and monitoring in AS protocols.

CONCLUSIONS

Although improvements in MRI technology have been useful for biopsy guidance and in the diagnosis and staging of PCa, this literature search demonstrates that more prospective research is needed, specifically regarding how this promising technology can be incorporated into AS protocols.

Nonvisible tumors on multiparametric magnetic resonance imaging does not predict low-risk prostate cancer

Purpose

To determine whether multiparametric MRI could help predict the diagnosis of low-risk prostate cancer (PCA).

Methods

We retrospectively analyzed consecutive 623 patients with PCA who underwent multiparametric MRI before radical prostatectomy(RP). High-resolution T1- and T2-weighted, diffusion-weighted, and dynamic precontrast and postcontrast image sequences were obtained for each patient. Of the 623 patients, 177(28.4%) exhibited non visible tumors on MRI of clinical stage T1c. The imaging results were compared with the pathological findings with respect to both stage and Gleason scores (GS).

Results

Of the 177 prostatectomy patients with non visible tumors on MRI, pathological findings resulted in the upgrading of 49(27.7%) patients to a sum of GS 7 or more. 101(57.1%) patients exhibited tumor volumes greater than 0.5cc. The biochemical recurrence rate was significantly higher in the pathological upgraded group compared with the nonupgraded group after a mean follow-up time of 29 months. In the multiple logistic analysis, non visible tumor on MRI was not a significant predictor of low-risk PCA.

Conclusions

Even though cancer foci were not visualized by postbiopsy MRI, the pathological tumor volumes and extent of GS upgrading were relatively high. Therefore, nonvisible tumors by multiparametric MRI do not appear to be predictive of low-risk PCA.

Predicting Pathological Features at Radical Prostatectomy in Patients with Prostate Cancer Eligible for Active Surveillance by Multiparametric Magnetic Resonance Imaging

PURPOSE

The aim of this study was to investigate the prognostic performance of multiparametric magnetic resonance imaging (mpMRI) and Prostate Imaging Reporting and Data System (PIRADS) score in predicting pathologic features in a cohort of patients eligible for active surveillance who underwent radical prostatectomy.

METHODS

A total of 223 patients who fulfilled the criteria for "Prostate Cancer Research International: Active Surveillance", were included. Mp-1.5 Tesla MRI examination staging with endorectal coil was performed at least 6-8 weeks after TRUS-guided biopsy. In all patients, the likelihood of the presence of cancer was assigned using PIRADS score between 1 and 5. Outcomes of interest were: Gleason score upgrading, extra capsular extension (ECE), unfavorable prognosis (occurrence of both upgrading and ECE), large tumor volume (≥ 0.5 ml), and seminal vesicle invasion (SVI). Receiver Operating Characteristic (ROC) curves and Decision Curve Analyses (DCA) were performed for models with and without inclusion of PIRADS score.

RESULTS

Multivariate analysis demonstrated the association of PIRADS score with upgrading (P < 0.0001), ECE (P < 0.0001), unfavorable prognosis (P < 0.0001), and large tumor volume (P = 0.002). ROC curves and DCA showed that models including PIRADS score resulted in greater net benefit for almost all the outcomes of interest, with the only exception of SVI.

CONCLUSIONS

mpMRI and PIRADS scoring are feasible tools in clinical setting and could be used as decision-support systems for a more accurate selection of patients eligible for AS.

Abnormal findings on multiparametric prostate magnetic resonance imaging predict subsequent biopsy upgrade in patients with low risk prostate cancer managed with active surveillance

PURPOSE

To determine the ability of multiparametric MR imaging to predict disease progression in patients with prostate cancer managed by active surveillance.

METHODS

Sixty-four men with biopsy-proven prostate cancer managed by active surveillance were included in this HIPPA compliant, IRB approved study. We reviewed baseline MR imaging scans for the presence of a suspicious findings on T2-weighted imaging, MR spectroscopic imaging (MRSI), and diffusion-weighted MR imaging (DWI). The Gleason grades at subsequent biopsy were recorded. A Cox proportional hazard model was used to determine the predictive value of MR imaging for Gleason grades, and the model performance was described using Harrell's C concordance statistic and 95% confidence intervals (CIs).

RESULTS

The Cox model that incorporated T2-weighted MR imaging, DWI, and MRSI showed that only T2-weighted MR imaging and DWI are independent predictors of biopsy upgrade (T2; HR = 2.46; 95% CI 1.36-4.46; P = 0.003-diffusion; HR = 2.76; 95% CI 1.13-6.71; P = 0.03; c statistic = 67.7%; 95% CI 61.1-74.3). There was an increasing rate of Gleason score upgrade with a greater number of concordant findings on multiple MR sequences (HR = 2.49; 95% CI 1.72-3.62; P < 0.001).

CONCLUSIONS

Abnormal results on multiparametric prostate MRI confer an increased risk for Gleason score upgrade at subsequent biopsy in men with localized prostate cancer managed by active surveillance. These results may be of help in appropriately selecting candidates for active surveillance.

Magnetic resonance imaging in active surveillance of prostate cancer: a systematic review

CONTEXT

There is great interest in using magnetic resonance imaging (MRI) for men on active surveillance for prostate cancer.

OBJECTIVE

To systematically review evidence regarding the use of MRI in men with low- or intermediate-risk prostate cancer suitable for active surveillance.

EVIDENCE ACQUISITION

Ovid Medline and Embase databases were searched for active surveillance, prostate cancer, and MRI from inception until April 25, 2014 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses process. Identified reports were critically appraised according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) criteria.

EVIDENCE SYNTHESIS

A lesion on MRI suspicious for prostate cancer (positive MRI) is seen in two-thirds of men otherwise suitable for active surveillance. A positive MRI makes the identification of clinically significant disease at repeat biopsy more likely, especially when biopsies are targeted to suspicious MRI lesions. Radical prostatectomy data show that positive MRI is more likely to be associated with upgrading (Gleason score>3+3) than a negative MRI (43% vs 27%). A positive MRI is not significantly more likely to be associated with upstaging at radical prostatectomy (>T2) than a negative MRI (10% vs 8%). Although MRI is of interest in the monitoring of men on active surveillance, robust data on the use of repeat MRI in active surveillance are lacking. Prospective studies with clear definitions of radiological significance and progression are needed before this approach can be adopted.

CONCLUSIONS

MRI is useful for detection of clinically significant disease at initial assessment of men considering active surveillance. To use MRI as a monitoring tool in surveillance, it will be necessary to define both radiological significance and radiological progression.

PATIENT SUMMARY

This review assesses evidence for the use of magnetic resonance imaging (MRI) in men on active surveillance for prostate cancer. MRI at the start of surveillance can detect clinically significant disease in one-third to half of men. There are few data to assess the use of MRI as a monitoring tool during surveillance, so there is a need to define significant disease on MRI and significant changes over time.

Magnetic resonance-invisible versus magnetic resonance-visible prostate cancer in active surveillance: a preliminary report on disease outcomes

OBJECTIVE

To assess the association between magnetic resonance (MR) appearance of prostate cancer on a baseline multiparametric prostate (MP) MR imaging (MRI) and biopsy outcome in men with favorable-risk prostate cancer managed with active surveillance (AS).

MATERIALS AND METHODS

Ninety-six consecutive men (mean age, 67.8 years) who had a baseline MP MRI within 1 year of AS enrollment were included in the study. MP MRI results were analyzed to identify men with MR-invisible tumor defined as no signal abnormality on T2-weighted images, no focal restricted diffusion, and no perfusion abnormality on dynamic contrast-enhanced images. Patients with (n = 84) or without (n = 12) MR-visible tumor were compared and the impact of MR-invisibility of tumor on the risk of adverse biopsy pathology based on the Epstein criteria was investigated with a median follow-up of 23 months.

RESULTS

Adverse biopsy pathology occurred in 36.5% (35 of 96) of patients. There was no significant difference in the fulfillment of AS criteria at enrollment, prostate-specific antigen level or density, prostate volume, and number of biopsies (total or after MRI) between the 2 groups of patients. A total of 8.3% (1 of 12) of men with MR-invisible tumor had adverse biopsy pathology as compared with 40.5% (34 of 84) of men with MR-visible tumors. The MR-invisibility of tumor was associated with a lower risk of adverse biopsy pathology (crude relative risk = 0.35; 95% confidence interval, 0.10-1.25; prostate-specific antigen density-adjusted relative risk = 0.21; 95% confidence interval, 0.03-1.32).

CONCLUSION

The MR-invisibility of tumor on MP MRI could be of prognostic significance in monitoring men in AS with potential benefit of tailoring the frequency of surveillance biopsies and reducing the number of unnecessary biopsies.

The role of magnetic resonance imaging in the diagnosis and management of prostate cancer

BACKGROUND

The diagnosis of prostate cancer has long been plagued by the absence of an imaging tool that reliably detects and localises significant tumours. Recent evidence suggests that multi-parametric MRI could improve the accuracy of diagnostic assessment in prostate cancer. This review serves as a background to a recent USANZ position statement. It aims to provide an overview of MRI techniques and to critically review the published literature on the clinical application of MRI in prostate cancer.

TECHNICAL ASPECTS

The combination of anatomical (T2-weighted) MRI with at least two of the three functional MRI parameters - which include diffusion-weighted imaging, dynamic contrast-enhanced imaging and spectroscopy - will detect greater than 90% of significant (moderate to high risk) tumours; however MRI is less reliable at detecting tumours that are small (<0.5 cc), low grade (Gleason score 6) or in the transitional zone. The higher anatomical resolution provided by 3-Tesla magnets and endorectal coils may improve the accuracy, particularly in primary tumour staging.

SCREENING

The use of mpMRI to determine which men with an elevated PSA should undergo biopsy is currently the subject of two large clinical trials in Australia. MRI should be used with caution in this setting and then only in centres with established uro-radiological expertise and quality control mechanisms in place. There is sufficient evidence to justify using MRI to determine the need for repeat biopsy and to guide areas in which to focus repeat biopsy.

IMAGE-DIRECTED BIOPSY

MRI-directed biopsy is an exciting concept supported by promising early results, but none of the three proposed techniques have so far been proven superior to standard biopsy protocols. Further evidence of superior accuracy and core-efficiency over standard biopsy is required, before their costs and complexities in use can be justified.

TREATMENT SELECTION AND PLANNING

When used for primary-tumour staging (T-staging), MRI has limited sensitivity for T3 disease, but its specificity of greater than 95% may be useful in men with intermediate-high risk disease to identify those with advanced T3 disease not suitable for nerve sparing or for surgery at all. MRI appears to be of value in planning dosimetry in men undergoing radiotherapy, and in guiding selection for and monitoring on active surveillance.

Performance characteristics of MR imaging in the evaluation of clinically low-risk prostate cancer: a prospective study

PURPOSE

To prospectively evaluate diagnostic performance of T2-weighted magnetic resonance (MR) imaging and MR spectroscopic imaging in detecting lesions stratified by pathologic volume and Gleason score in men with clinically determined low-risk prostate cancer.

MATERIALS AND METHODS

The institutional review board approved this prospective, HIPAA-compliant study. Written informed consent was obtained from 183 men with clinically low-risk prostate cancer (cT1-cT2a, Gleason score≤6 at biopsy, prostate-specific antigen [PSA] level<10 ng/mL [10 μg/L]) undergoing MR imaging before prostatectomy. By using a scale of 1-5 (score 1, definitely no tumor; score 5, definitely tumor), two radiologists independently scored likelihood of tumor per sextant on T2-weighted images. Two spectroscopists jointly recorded locations of lesions with metabolic features consistent with tumor on MR spectroscopic images. Whole-mount step-section histopathologic analysis constituted the reference standard. Diagnostic performance at sextant level (T2-weighted imaging) and detection sensitivities (T2-weighted imaging and MR spectroscopic imaging) for lesions of 0.5 cm3 or larger were calculated.

RESULTS

For T2-weighted imaging, areas under the receiver operating characteristic curves for sextant-level detection were 0.77 (reader 1) and 0.82 (reader 2). For lesions of ≥0.5 cm3 and, 1

CONCLUSION

In men with clinically low-risk prostate cancer, detection of lesions of <1 cm3 with T2-weighted imaging is significantly dependent on lesion Gleason score; detection of lesions of ≥1 cm3 is significantly better than detection of smaller lesions and is not affected by lesion Gleason score. The role of MR spectroscopic imaging alone in this population is limited.

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MESH Headings

• Adult
• Aged
• Humans
• Image Enhancement/methods
• Image Interpretation, Computer-Assisted/methods
• Male
• Middle Aged
• Preoperative Care/methods
• Prospective Studies
• Prostatic Neoplasms/pathology
• Reproducibility of Results
• Risk Factors
• Sensitivity and Specificity

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Grants

• R01 CA076423 NCI NIH HHS

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Affiliation(s)

Hebert Alberto Vargas Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, Room C-278, New York, NY 10065, USA
Oguz Akin
Amita Shukla-Dave
Jingbo Zhang
Kristen L Zakian
Junting Zheng
Kent Kanao
Debra A Goldman
Chaya S Moskowitz
Victor E Reuter
James A Eastham
Peter T Scardino
Hedvig Hricak

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Collaborators Collapse

Magnetic resonance imaging for predicting prostate biopsy findings in patients considered for active surveillance of clinically low risk prostate cancer

PURPOSE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Active surveillance in prostate cancer: patient selection and triggers for intervention

PURPOSE OF REVIEW

The long-term safety and effectiveness of active surveillance depends on our ability to select appropriate patients and trigger delayed treatment in those who need it, whereas avoiding intervention in those who do not. In this review, we will consider how recent advances have influenced patient selection for active surveillance and review the range of different intervention triggers that have been proposed.

RECENT FINDINGS

Several large surveillance cohort studies have been reported recently showing excellent medium-term outcomes in well selected patients, with approximately a third of patients going on to have deferred treatment. Debate continues on the most appropriate eligibility criteria for active surveillance and what triggers for intervention should be used. There is growing interest in the role of transperineal template biopsies and multiparametric MRI, both for patient selection and in identifying triggers for intervention.

SUMMARY

Active surveillance is a well tolerated treatment option in well selected groups of patients. There is no 'one size fits all' set of criteria for patient selection or triggers for intervention but decisions can be guided by information from histology, prostate-specific antigen kinetics and imaging.

Impact of multiparametric endorectal coil prostate magnetic resonance imaging on disease reclassification among active surveillance candidates: a prospective cohort study

PURPOSE

We report magnetic resonance imaging findings among unselected men with low risk prostate cancer before active surveillance.

MATERIALS AND METHODS

We prospectively enrolled men with low grade, low risk, localized prostate cancer. All patients underwent multiparametric endorectal coil magnetic resonance imaging and were offered confirmatory biopsy within 1 year of imaging. The primary outcome was the impact of magnetic resonance imaging on identifying patients who were reclassified by confirmatory biopsy as no longer fulfilling active surveillance criteria. We further identified clinical parameters associated with reclassification. The cohort was stratified as patients with 1) normal magnetic resonance imaging, 2) cancer on magnetic resonance imaging concordant with initial biopsy (less than 1 cm) and 3) cancer on magnetic resonance imaging larger than 1 cm. We performed univariate analysis to assess differences in clinical parameters among the groups.

RESULTS

Magnetic resonance imaging did not detect cancer in 23 cases (38%) while magnetic resonance imaging and initial biopsy were concordant in 24 (40%). Magnetic resonance imaging detected a 1 cm or larger lesion in 13 patients (22%). Of the cases 18 (32.14%) were reclassified. When no cancer was identified on magnetic resonance imaging, only 2 cases (3.5%) were reclassified. The positive and negative predictive values for magnetic resonance imaging predicting reclassification were 83% (95% CI 73-93) and 81% (95% CI 71-91), respectively. Prostate specific antigen density was increased in patients with lesions larger than 1 cm on magnetic resonance imaging compared to those with no cancer on imaging (median 0.15 vs 0.07 ng/ml/cc, p=0.016).

CONCLUSIONS

Magnetic resonance imaging appears to have a high yield for predicting reclassification among men who elect active surveillance. Upon confirmation of our results magnetic resonance imaging may be used to better select and guide patients before active surveillance.

The contemporary concept of significant versus insignificant prostate cancer

CONTEXT

The notion of insignificant prostate cancer (Ins-PCa) has progressively emerged in the past two decades. The clinical relevance of such a definition was based on the fact that low-grade, small-volume, and organ-confined prostate cancer (PCa) may be indolent and unlikely to progress to biologic significance in the absence of treatment.

OBJECTIVE

To review the definition of Ins-PCa, its incidence, and the clinical impact of Ins-PCa on the contemporary management of PCa.

EVIDENCE ACQUISITION

A review of the literature was performed using the Medline, Scopus, and Web of Science databases with no restriction on language up to September 2010. The literature search used the following terms: insignificant, indolent, minute, microfocal, minimal, low volume, low risk, and prostate cancer.

EVIDENCE SYNTHESIS

The most commonly used criteria to define Ins-PCa are based on the pathologic assessment of the radical prostatectomy specimen: (1) Gleason score ≤ 6 without Gleason pattern 4 or 5, (2) organ-confined disease, and (3) tumour volume<0.5 cm(3). Several preoperative criteria and prognostication tools for predicting Ins-PCa have been suggested. Nomograms are best placed to estimate the risk of progression on an individualised basis, but a substantial proportion of men with a high probability of harbouring Ins-PCa are at risk for pathologic understaging and/or undergrading. Thus, there is an ongoing need for identifying novel and more accurate predictors of Ins-PCa to improve the distinction between insignificant versus significant disease and thus to promote the adequate management of PCa patients at low risk for progression.

CONCLUSIONS

The exciting challenge of obtaining the pretreatment diagnostic tools that can really distinguish insignificant from significant PCa should be one of the main objectives of urologists in the following years to decrease the risk of overtreatment of Ins-PCa.