Role of magnetic resonance imaging before initial biopsy: comparison of magnetic resonance imaging-targeted and systematic biopsy for significant prostate cancer detection

Detection of significant prostate cancer with magnetic resonance targeted biopsies--should transrectal ultrasound-magnetic resonance imaging fusion guided biopsies alone be a standard of care?

PURPOSE

Magnetic resonance imaging-transrectal ultrasound fusion targeted prostate biopsies were suggested to detect significant cancer with more accuracy than systematic biopsies. In this study we evaluate the pathological characteristics of multiparametric magnetic resonance imaging detected and undetected tumor foci on radical prostatectomy specimens.

MATERIALS AND METHODS

We selected 125 consecutive patients treated with radical prostatectomy for clinically localized prostate cancer diagnosed on magnetic resonance imaging-transrectal ultrasound targeted biopsy and/or systematic biopsy. On multiparametric magnetic resonance imaging each suspicious area was graded according to the PI-RADS score. On radical prostatectomy specimen, tumor foci with a Gleason score greater than 3+3 and/or tumor volume greater than 0.5 ml were considered significant. A correlation analysis between multiparametric magnetic resonance imaging and pathological findings was performed.

RESULTS

Pathological analysis of radical prostatectomy specimens detected 230 tumor foci. Of these, 137 were considered significant (Gleason score greater than 3+3 in 112) and were observed in 111 (89%) glands. A total of 95 individual tumor foci, including 14 significant foci, were missed with multiparametric magnetic resonance imaging. All of them were located in glands where another focus was detected with multiparametric magnetic resonance imaging. An additional 9 individual tumor foci, including 7 significant, were detected on multiparametric magnetic resonance imaging but missed with targeted biopsy, resulting in 5 (4%) significant cancers undetected with magnetic resonance imaging-transrectal ultrasound fusion targeted biopsy. The magnetic resonance imaging target largest diameter was associated with high volume (greater than 0.5 cc) foci detection, while PI-RADS score and cancer involvement on targeted biopsy were associated with significant foci detection.

CONCLUSIONS

In these series of men with suspicious prostate multiparametric magnetic resonance imaging findings, magnetic resonance imaging-transrectal ultrasound fusion guided targeted biopsy alone strategy would have resulted in the under detection of only 4% significant cancers.

Biopsy sampling and histopathological markers for diagnosis of prostate cancer

Prostate cancer is one of the most common malignant tumors and a leading cause of cancer-related morbidity and mortality. Irrespective of the method that allows for risk stratification of prostate cancer suspects, diagnosis relies on tissue sampling through prostate biopsy and subsequent histopathological evaluation. This provides critical information about disease aggressiveness, which is required for adequate patient management. Prostate biopsy methods have significantly evolved over the years, including the definition of indications, sampling schemes and use of imaging techniques (ultrasound and MRI) that allow for more accurate tissue sampling. In response to the challenges emerging from more precise collection of minute prostate tissue samples for analysis, histopathological assessment should include not only the observation of routinely stained sections, but also, and increasingly so, a series of ancillary techniques, especially immunohistochemistry, which increment the accuracy of prostate cancer diagnosis and may provide relevant information to guide patient management.

Negative predictive value of multiparametric MRI for prostate cancer detection: outcome of 5-year follow-up in men with negative findings on initial MRI studies

OBJECTIVE

To assess the clinical negative predictive value (NPV) of multiparametric MRI (mp-MRI) for prostate cancer in a 5-year follow-up.

MATERIALS AND METHODS

One hundred ninety-three men suspected of harboring prostate cancer with negative MRI findings were included. Patients with positive transrectal ultrasound (TRUS)-guided biopsy findings were defined as false-negative. Patients with negative initial TRUS-guided biopsy findings were followed up and only patients with negative findings by digital rectal examination, MRI, and repeat biopsy and no increase in PSA at 5-year follow-up were defined as "clinically negative". The clinical NPV of mp-MRI was calculated. For quantitative analysis, mean signal intensity on T2-weighted images and the mean apparent diffusion coefficient value on ADC maps of the initial MRI studies were compared between peripheral-zone (PZ) cancer and the normal PZ based on pathologic maps of patients who had undergone radical prostatectomy.

RESULTS

The clinical NPV of mp-MRI was 89.6% for significant prostate cancer. Small cancers, prostatitis, and benign prostatic hypertrophy masking prostate cancer returned false-negative results. Quantitative analysis showed that there was no significant difference between PZ cancer and the normal PZ.

CONCLUSION

The mp-MRI revealed a high clinical NPV and is a useful tool to rule out clinically significant prostate cancer before biopsy.

Can contemporary patients with biopsy Gleason score 3+4 be eligible for active surveillance?

INTRODUCTION

We analyzed whether expansion of existing active surveillance (AS) protocols to include men with biopsy Gleason score (GS) 3+4 prostate cancer (PCa) would significantly alter pathologic and biochemical outcomes of potential candidates of AS.

METHODS

Among patients who underwent radical prostatectomy at our center between 2006 and 2013, we identified 577 patients (group A) who preoperatively fulfilled at least one of 6 different AS criteria. Also, we identified 217 patients (group B) with biopsy GS 3+4 but fulfilled non-GS criteria from at least one of 6 AS criteria. Designating group C as expanded group incorporating all patients in group A and B, we compared risk of unfavorable disease (pathologic GS ≥ 4+3 and/or pathologic T stage ≥ pT3a) and biochemical recurrence (BCR)-free survival between groups.

RESULTS

Rates of unfavorable disease were not significantly different between patients of group A and C who met AS criteria from 5 institutions (all p>0.05), not including University of Toronto (p < 0.001). Also BCR-free survivals were not significantly different between patients in group A and C meeting each of 6 AS criteria (all p > 0.05). Among group B, PSAD > 0.15 ng/mL/cm3 (p = 0.011) and tumor length of biopsy GS 3+4 core > 4 mm (p = 0.007) were significant predictors of unfavorable disease. When these two criteria were newly applied in defining group B, rates of unfavorable disease in group A and B was 15.6% and 14.7%, respectively (p = 0.886).

CONCLUSION

Overall rate of pathologically aggressive PCa harbored by potential candidates for AS may not be increased significantly with expansion of criteria to biopsy GS 3+4 under most contemporary AS protocols. PSAD and tumor length of biopsy GS 3+4 core may be useful predictors of more aggressive disease among potential candidates for AS with biopsy GS 3+4.

Standards for prostate biopsy

PURPOSE OF REVIEW

A variety of techniques have emerged for the optimization of prostate biopsy. In this review, we summarize and critically discuss the most recent developments regarding the optimal systematic biopsy and sampling labeling along with multiparametric MRI and magnetic resonance-targeted biopsies.

RECENT FINDINGS

The use of 10-12-core-extended sampling protocols increases cancer detection rates compared with traditional sextant sampling and reduces the likelihood that patients will require a repeat biopsy, ultimately allowing more accurate risk stratification without increasing the likelihood of detecting insignificant cancers. As the number of cores increases above 12 cores, the increase in diagnostic yield becomes marginal. However, the limitations of this technique include undersampling, oversampling, and the need for repetitive biopsy. MRI and magnetic resonance-targeted biopsies have demonstrated superiority over systematic biopsies for the detection of clinically significant disease and representation of disease burden, while deploying fewer cores and may have applications in men undergoing initial or repeat biopsy and those with low-risk cancer on or considering active surveillance.

SUMMARY

A 12-core systematic biopsy that incorporates apical and far-lateral cores in the template distribution allows maximal cancer detection, avoidance of a repeat biopsy while minimizing the detection of insignificant prostate cancers. MRI-guided prostate biopsy has an evolving role in both initial and repeat prostate biopsy strategies, as well as active surveillance, potentially improving sampling efficiency, increasing the detection of clinically significant cancers, and reducing the detection of insignificant cancers.

Multiparametric magnetic resonance imaging in the management and diagnosis of prostate cancer: current applications and strategies

Magnetic resonance imaging (MRI) has become increasingly used worldwide in the diagnosis and management of prostate cancer. With advances in multiparametric MRI (mpMRI) technology, such as the use of dynamic contrast-enhanced and diffusion-weighted imaging sequences, observational studies have evaluated the utility for mpMRI in the continuum of prostate cancer management, from improving the detection of clinically significant prostate cancer, to planning radical prostatectomy and radiation therapy and the early detection of local recurrence. Furthermore, the potential for advanced imaging to reduce the burden of routine serial prostate needle biopsies for men on active surveillance is a promising area of research. MRI technology continues to evolve, and the potential applications in the management of prostate cancer care will require well-designed multi-institutional prospective clinical trials and rigorous efforts to standardize reporting and improve dissemination of expertise across institutions.

Role of multiparametric magnetic resonance imaging in the diagnosis of prostate cancer

Prostate cancer is the most common solid-organ malignancy among American men. It is currently most commonly diagnosed on random systematic biopsies prompted by elevated serum PSA levels. Multi-parametric MRI (MP-MRI) of the prostate has emerged as an anatomic and functional imaging modality, which offers accurate detection, localization and staging of prostate cancer. Recently, MP-MRI has gained an increasing role in guiding biopsies to sites of abnormality and in monitoring patients on active surveillance. Here, we discuss the historical development, current role, and potential future directions of MP-MRI in the diagnosis of prostate cancer.

Transperineal in-bore 3-T MR imaging-guided prostate biopsy: a prospective clinical observational study

PURPOSE

To determine the detection rate, clinical relevance, Gleason grade, and location of prostate cancer ( PCa prostate cancer ) diagnosed with and the safety of an in-bore transperineal 3-T magnetic resonance (MR) imaging-guided prostate biopsy in a clinically heterogeneous patient population.

MATERIALS AND METHODS

This prospective retrospectively analyzed study was HIPAA compliant and institutional review board approved, and informed consent was obtained. Eighty-seven men (mean age, 66.2 years ± 6.9) underwent multiparametric endorectal prostate MR imaging at 3 T and transperineal MR imaging-guided biopsy. Three subgroups of patients with at least one lesion suspicious for cancer were included: men with no prior PCa prostate cancer diagnosis, men with PCa prostate cancer who were undergoing active surveillance, and men with treated PCa prostate cancer and suspected recurrence. Exclusion criteria were prior prostatectomy and/or contraindication to 3-T MR imaging. The transperineal MR imaging-guided biopsy was performed in a 70-cm wide-bore 3-T device. Overall patient biopsy outcomes, cancer detection rates, Gleason grade, and location for each subgroup were evaluated and statistically compared by using χ(2) and one-way analysis of variance followed by Tukey honestly significant difference post hoc comparisons.

RESULTS

Ninety biopsy procedures were performed with no serious adverse events, with a mean of 3.7 targets sampled per gland. Cancer was detected in 51 (56.7%) men: 48.1% (25 of 52) with no prior PCa prostate cancer , 61.5% (eight of 13) under active surveillance, and 72.0% (18 of 25) in whom recurrence was suspected. Gleason pattern 4 or higher was diagnosed in 78.1% (25 of 32) in the no prior PCa prostate cancer and active surveillance groups. Gleason scores were not assigned in the suspected recurrence group. MR targets located in the anterior prostate had the highest cancer yield (40 of 64, 62.5%) compared with those for the other parts of the prostate (P < .001).

CONCLUSION

In-bore 3-T transperineal MR imaging-guided biopsy, with a mean of 3.7 targets per gland, allowed detection of many clinically relevant cancers, many of which were located anteriorly.

Optimization of prostate biopsy: the role of magnetic resonance imaging targeted biopsy in detection, localization and risk assessment

PURPOSE

Optimization of prostate biopsy requires addressing the shortcomings of standard systematic transrectal ultrasound guided biopsy, including false-negative rates, incorrect risk stratification, detection of clinically insignificant disease and the need for repeat biopsy. Magnetic resonance imaging is an evolving noninvasive imaging modality that increases the accurate localization of prostate cancer at the time of biopsy, and thereby enhances clinical risk assessment and improves the ability to appropriately counsel patients regarding therapy. In this review we 1) summarize the various sequences that comprise a prostate multiparametric magnetic resonance imaging examination along with its performance characteristics in cancer detection, localization and reporting standards; 2) evaluate potential applications of magnetic resonance imaging targeting in prostate biopsy among men with no previous biopsy, a negative previous biopsy and those with low stage cancer; and 3) describe the techniques of magnetic resonance imaging targeted biopsy and comparative study outcomes.

MATERIALS AND METHODS

A bibliographic search covering the period up to October 2013 was conducted using MEDLINE®/PubMed®. Articles were reviewed and categorized based on which of the 3 objectives of this review was addressed. Data were extracted, analyzed and summarized.

RESULTS

Multiparametric magnetic resonance imaging consists of anatomical T2-weighted imaging coupled with at least 2 functional imaging techniques. It has demonstrated improved prostate cancer detection sensitivity up to 80% in the peripheral zone and 81% in the transition zone. A prostate cancer magnetic resonance imaging suspicion score has been developed, and is depicted using the Likert or PI-RADS (Prostate Imaging Reporting and Data System) scale for better standardization of magnetic resonance imaging interpretation and reporting. Among men with no previous biopsy, magnetic resonance imaging increases the frequency of significant cancer detection to 50% in low risk and 71% in high risk patients. In low risk men the negative predictive value of a combination of negative magnetic resonance imaging with prostate volume parameters is nearly 98%, suggesting a potential role in avoiding biopsy and reducing over detection/overtreatment. Among men with a previous negative biopsy 72% to 87% of cancers detected by magnetic resonance imaging guidance are clinically significant. Among men with a known low risk cancer, repeat biopsy using magnetic resonance targeting demonstrates a high likelihood of confirming low risk disease in low suspicion score lesions and of upgrading in high suspicion score lesions. Techniques of magnetic resonance imaging targeted biopsy include visual estimation transrectal ultrasound guided biopsy; software co-registered magnetic resonance imaging-ultrasound, transrectal ultrasound guided biopsy; and in-bore magnetic resonance imaging guided biopsy. Although the improvement in accuracy and efficiency of visual estimation biopsy compared to systematic appears limited, co-registered magnetic resonance imaging-ultrasound biopsy as well as in-bore magnetic resonance imaging guided biopsy appear to increase cancer detection rates in conjunction with increasing suspicion score.

CONCLUSIONS

Use of magnetic resonance imaging for targeting prostate biopsies has the potential to reduce the sampling error associated with conventional biopsy by providing better disease localization and sampling. More accurate risk stratification through improved cancer sampling may impact therapeutic decision making. Optimal clinical application of magnetic resonance imaging targeted biopsy remains under investigation.

Multiparametric MRI in the PSA screening era

Prostate cancer remains significant public health concern amid growing controversies regarding prostate specific antigen (PSA) based screening. The utility of PSA has been brought into question, and alternative measures are investigated to remedy the overdetection of indolent disease and safeguard patients from the potential harms resulting from an elevated PSA. Multiparametric MRI of the prostate has shown promise in identifying patients at risk for clinically significant disease but its role within the current diagnostic and treatment paradigm remains in question. The current review focuses on recent applications of MRI in this pathway.

Multiparametric magnetic resonance imaging of the prostate: technical aspects and role in clinical management

The heterogeneity and largely indolent nature of prostate cancer require better tools to avoid overdetection of low-risk disease and improve diagnostic accuracy in high-risk patients. During the last 3 decades, magnetic resonance imaging (MRI) has evolved to become the most accurate imaging technique for prostate cancer detection and staging, with a promising role in risk stratification. Because each MRI technique has advantages and limitations, state of the art of the so-called multiparametric MRI of the prostate is achieved combining anatomical T2-weighted imaging integrated with other techniques in which image contrast is related to the pathophysiology of the disease, such as diffusion-weighted imaging, dynamic contrast-enhanced imaging, and MR spectroscopy. After reviewing this article, readers will understand the clinical challenges in the management of patients with confirmed or suspected prostate cancer, when and how multiparametric MRI of the prostate can provide meaningful information, and how to perform and interpret it.

Evaluation of the PI-RADS scoring system for mpMRI of the prostate: a whole-mount step-section analysis

PURPOSE

Evaluation of the Prostate Imaging Reporting and Data System (PI-RADS) scoring system for classifying multi-parametric magnetic resonance imaging findings of the prostate using whole-mount step-section slides as reference standard.

MATERIALS AND METHODS

Prospective inclusion of 50 consecutive patients with biopsy-proven prostate cancer (PCa). All patients received a multi-parametric MRI of the prostate, consisting of T2-weighted, diffusion-weighted, and dynamic contrast-enhanced MRI. After prostatectomy, all prostates were prepared as whole-mount step-section slides. For each patient, six lesions were predefined on whole-mount step-sections according to a distinct scheme and the corresponding regions were identified on MRI. Each lesion then was scored on MRI according to PI-RADS by an experienced blinded uro-radiologist and compared with histopathological findings.

RESULTS

PCa received significant (p < 0.01) higher overall PI-RADS scores (4.10 ± 0.75) compared with benign changes (2.00 ± 0.74). In the peripheral zone, each single modality score showed good diagnostic accuracy for PCa detection (area under the curve [AUC] > 0.90). When combining all single modality scores, an even higher discriminative ability of PCa detection (AUC = 0.97, 95 % CI 0.95-0.99) could be achieved. In contrast, in the transitional zone, dynamic contrast-enhanced MRI (DCE) showed very low diagnostic accuracy (AUC = 0.60). Regarding tumor malignancy, no high-grade PCa (Gleason >7a) was present at PI-RADS scores <4 and no Gleason 6 PCa at a PI-RADS score of 5.

CONCLUSION

The PI-RADS scoring system showed good diagnostic accuracy: Only PI-RADS 4 and 5 showed high-grade PCa. However, it seems necessary to revise the PI-RADS scoring system concerning DCE in the transitional zone.

Comparative analysis of transperineal template saturation prostate biopsy versus magnetic resonance imaging targeted biopsy with magnetic resonance imaging-ultrasound fusion guidance

PURPOSE

Multiparametric magnetic resonance imaging and magnetic resonance imaging targeted biopsy may improve the detection of clinically significant prostate cancer. However, standardized prospective evaluation is limited.

MATERIALS AND METHODS

A total of 294 consecutive men with suspicion of prostate cancer (186 primary, 108 repeat biopsies) enrolled in 2013 underwent 3T multiparametric magnetic resonance imaging (T2-weighted, diffusion weighted, dynamic contrast enhanced) without endorectal coil and systematic transperineal cores (median 24) independently of magnetic resonance imaging suspicion and magnetic resonance imaging targeted cores with software registration (median 4). The highest Gleason score from each biopsy method was compared. McNemar's tests were used to evaluate detection rates. Predictors of Gleason score 7 or greater disease were assessed using logistic regression.

RESULTS

Overall 150 cancers and 86 Gleason score 7 or greater cancers were diagnosed. Systematic, transperineal biopsy missed 18 Gleason score 7 or greater tumors (20.9%) while targeted biopsy did not detect 11 (12.8%). Targeted biopsy of PI-RADS 2-5 alone overlooked 43.8% of Gleason score 6 tumors. McNemar's tests for detection of Gleason score 7 or greater cancers in both modalities were not statistically significant but showed a trend of superiority for targeted primary biopsies (p=0.08). Sampling efficiency was in favor of magnetic resonance imaging targeted prostate biopsy with 46.0% of targeted biopsy vs 7.5% of systematic, transperineal biopsy cores detecting Gleason score 7 or greater cancers. To diagnose 1 Gleason score 7 or greater cancer, 3.4 targeted and 7.4 systematic biopsies were needed. Limiting biopsy to men with PI-RADS 3-5 would have missed 17 Gleason score 7 or greater tumors (19.8%), demonstrating limited magnetic resonance imaging sensitivity. PI-RADS scores, digital rectal examination findings and prostate specific antigen greater than 20 ng/ml were predictors of Gleason score 7 or greater disease.

CONCLUSIONS

Compared to systematic, transperineal biopsy as a reference test, magnetic resonance imaging targeted biopsy alone detected as many Gleason score 7 or greater tumors while simultaneously mitigating the detection of lower grade disease. The gold standard for cancer detection in primary biopsy is a combination of systematic and targeted cores.

TRUS-MRI image registration: a paradigm shift in the diagnosis of significant prostate cancer

Accuracy of multiparametric MRI has greatly improved the ability of localizing tumor foci of prostate cancer. This property can be used to perform a TRUS-MR image registration, new technological advance, which allows for an overlay of an MRI onto a TRUS image to target a prostate biopsy toward a suspicious area Three types of registration have been developed: cognitive-based, sensor-based, and organ-based registration. Cognitive registration consists of aiming a suspicious area during biopsy with the knowledge of the lesion location identified on multiparametric MRI. Sensor-based registration consists of tracking in real time the TRUS probe with a magnetic device, achieving a global positioning system which overlays in real-time prostate image on both modalities. Its main limitation is that it does not take into account prostate and patient motion during biopsy. Two systems (Artemis and Uronav) have been developed to partially circumvent this drawback. Organ-based registration (Koelis) does not aim to track the TRUS probe, but the prostate itself to compute in a 3D acquisition the TRUS prostate shape, allowing for a registration with the corresponding 3D MRI shape. This system is not limited by prostate/patient motion and allows for a deformation of the organ during registration. Pros and cons of each technique and the rationale for a targeted biopsy only policy are discussed.

Multiparametric MRI in biopsy guidance for prostate cancer: fusion-guided

Prostate cancer (PCa) is the most common solid-organ malignancy among American men and the second most deadly. Current guidelines recommend a 12-core systematic biopsy following the finding of an elevated serum prostate-specific antigen (PSA). However, this strategy fails to detect an unacceptably high percentage of clinically significant cancers, leading researchers to develop new, innovative methods to improve the effectiveness of prostate biopsies. Multiparametric-MRI (MP-MRI) has emerged as a promising instrument in identifying suspicious regions within the prostate that require special attention on subsequent biopsy. Fusion platforms, which incorporate the MP-MRI into the biopsy itself and provide active targets within real-time imaging, have shown encouraging results in improving the detection rate of significant cancer. Broader applications of this technology, including MRI-guided focal therapy for prostate cancer, are in early phase trials.

Prebiopsy multiparametric 3T prostate MRI in patients with elevated PSA, normal digital rectal examination, and no previous biopsy

PURPOSE

To find the diagnostic accuracy of 3T multiparametric magnetic resonance imaging (mpMRI) and mpMRI targeted transrectal ultrasound (TRUS)-guided biopsy using visual coregistration (TB) in patients with elevated prostate-specific antigen (PSA), normal digital rectal examination, and no previous biopsy.

MATERIALS AND METHODS

Fifty-five patients at two institutions underwent mpMRI, consisting of anatomical T2 -weighted imaging (T2 W), diffusion-weighted imaging (DWI), proton magnetic resonance spectroscopy ((1) H-MRS), and dynamic contrast-enhanced MRI (DCE-MRI), followed by TB in addition to 12 core systematic TRUS-guided biopsy (SB). Histopathological scorings of biopsy (n = 38) and prostatectomy (n = 17) specimens were used as the reference standard for calculation of diagnostic accuracy values. Clinically significant prostate cancer (SPCa) was defined as 3 mm core length of Gleason score 3+3 or any Gleason grade 4.

RESULTS

The sensitivity, specificity, accuracy, and area under the curve (AUC) values for the detection of SPCa on the sextant level for T2 W+DWI+(1) H-MRS+DCE-MRI were 72%, 89%, 85%, and 0.81, respectively. The corresponding values for T2 wi+DWI were 61%, 96%, 87%, and 0.79, respectively. The overall PCa detection rate per core in 53 patients was 21% (138 of 648 cores) for SB and 43% (33 of 77 cores) for TB (P < 0.001).

CONCLUSION

Prebiopsy mpMRI is an accurate tool for PCa detection and biopsy targeting in patients with elevated PSA.

Multiparametric MRI followed by targeted prostate biopsy for men with suspected prostate cancer: a clinical decision analysis

OBJECTIVE

To compare the diagnostic outcomes of the current approach of transrectal ultrasound (TRUS)-guided biopsy in men with suspected prostate cancer to an alternative approach using multiparametric MRI (mpMRI), followed by MRI-targeted biopsy if positive.

DESIGN

Clinical decision analysis was used to synthesise data from recently emerging evidence in a format that is relevant for clinical decision making.

POPULATION

A hypothetical cohort of 1000 men with suspected prostate cancer.

INTERVENTIONS

mpMRI and, if positive, MRI-targeted biopsy compared with TRUS-guided biopsy in all men.

OUTCOME MEASURES

We report the number of men expected to undergo a biopsy as well as the numbers of correctly identified patients with or without prostate cancer. A probabilistic sensitivity analysis was carried out using Monte Carlo simulation to explore the impact of statistical uncertainty in the diagnostic parameters.

RESULTS

In 1000 men, mpMRI followed by MRI-targeted biopsy 'clinically dominates' TRUS-guided biopsy as it results in fewer expected biopsies (600 vs 1000), more men being correctly identified as having clinically significant cancer (320 vs 250), and fewer men being falsely identified (20 vs 50). The mpMRI-based strategy dominated TRUS-guided biopsy in 86% of the simulations in the probabilistic sensitivity analysis.

CONCLUSIONS

Our analysis suggests that mpMRI followed by MRI-targeted biopsy is likely to result in fewer and better biopsies than TRUS-guided biopsy. Future research in prostate cancer should focus on providing precise estimates of key diagnostic parameters.

Comparison of image-guided targeted biopsies versus systematic randomized biopsies in the detection of prostate cancer: a systematic literature review of well-designed studies

OBJECTIVE

The clinical utility of image-targeted biopsies can only be judged by a comparison of the current standard of systematic 10-12 core biopsy schemes. The aim of this review was to gather the current evidence in favor of or against targeted biopsies in the detection of prostate cancer based on well-designed, controlled studies, in order to draw clinical relevant conclusions.

SUBJECTS/PATIENTS AND METHODS

A systematic literature review was performed addressing studies that compared the prostate cancer detection rates of targeted and systematic biopsy schemes using the imaging techniques of elastography, contrast-enhanced ultrasound, histoscanning and multiparametric MRI. Only well-designed, controlled studies were included and the results summarized.

RESULTS

All imaging techniques are associated with varying results regarding better or poorer detection rates relative to systematic biopsies. No technique provides a clear trend in favor of or against image-targeted biopsies. In almost all studies, the combination of targeted and systematic biopsies provided sometimes a substantial, increase in the detection rate relative to systematic biopsies alone. MRI-targeted biopsies show no advantage in the initial biopsy setting, whereas in the repeat biopsy setting improvements in the detection rates are often observed relative to systemic biopsies.

CONCLUSION

Based on well-designed, controlled studies no clear advantage of targeted biopsies over the current standard of systematic biopsies can be observed. Therefore, targeted biopsies cannot replace systematic biopsies in the diagnosis of prostate cancer. In all indications, the combination of systematic and targeted biopsy schemes provides the highest detection rate.

Optimization of prostate biopsy: review of technique and complications

A 12-core systematic biopsy that incorporates apical and far-lateral cores in the template distribution allows maximal cancer detection and avoidance of a repeat biopsy while minimizing the detection of insignificant prostate cancers. Magnetic resonance imaging-guided prostate biopsy has an evolving role in both initial and repeat prostate biopsy strategies, potentially improving sampling efficiency, increasing the detection of clinically significant cancers, and reducing the detection of insignificant cancers. Hematuria, hematospermia, and rectal bleeding are common complications of prostate needle biopsy, but are generally self-limiting and well tolerated. All men should receive antimicrobial prophylaxis before biopsy.

Prostate volume and biopsy tumor length are significant predictors for classical and redefined insignificant cancer on prostatectomy specimens in Japanese men with favorable pathologic features on biopsy

Background

Gleason pattern 3 less often has molecular abnormalities and often behaves indolent. It is controversial whether low grade small foci of prostate cancer (PCa) on biopsy could avoid immediate treatment or not, because substantial cases harbor unfavorable pathologic results on prostatectomy specimens. This study was designed to identify clinical predictors for classical and redefined insignificant cancer on prostatectomy specimens in Japanese men with favorable pathologic features on biopsy.

Methods

Retrospective review of 1040 PCa Japanese patients underwent radical prostatectomy between 2006 and 2013. Of those, 170 patients (16.3%) met the inclusion criteria of clinical stage ≤ cT2a, Gleason score (GS) ≤ 6, up to two positive biopsies, and no more than 50% of cancer involvement in any core. The associations between preoperative data and unfavorable pathologic results of prostatectomy specimens, and oncological outcome were analyzed. The definition of insignificant cancer consisted of pathologic stage ≤ pT2, GS ≤ 6, and an index tumor volume < 0.5 mL (classical) or 1.3 mL (redefined).

Results

Pathologic stage ≥ pT3, upgraded GS, index tumor volume ≥ 0.5 mL, and ≥ 1.3 mL were detected in 25 (14.7%), 77 (45.3%), 83 (48.8%), and 53 patients (31.2%), respectively. Less than half of cases had classical (41.2%) and redefined (47.6%) insignificant cancer. The 5-year recurrence-free survival was 86.8%, and the insignificant cancers essentially did not relapse regardless of the surgical margin status. MRI-estimated prostate volume, tumor length on biopsy, prostate-specific antigen density (PSAD), and findings of magnetic resonance imaging were associated with the presence of classical and redefined insignificant cancer. Large prostate volume and short tumor length on biopsy remained as independent predictors in multivariate analysis.

Conclusions

Favorable features of biopsy often are followed by adverse pathologic findings on prostatectomy specimens despite fulfilling the established criteria. The finding that prostate volume is important does not simply mirror many other studies showing PSAD is important, and the clinical criteria for risk assessment before definitive therapy or active surveillance should incorporate these significant factors other than clinical T-staging or PSAD to minimize under-estimation of cancer in Japanese patients with low-risk PCa.

Prospective evaluation of magnetic resonance imaging guided in-bore prostate biopsy versus systematic transrectal ultrasound guided prostate biopsy in biopsy naïve men with elevated prostate specific antigen

PURPOSE

Magnetic resonance imaging guided biopsy is increasingly performed to diagnose prostate cancer. However, there is a lack of well controlled, prospective trials to support this treatment method. We prospectively compared magnetic resonance imaging guided in-bore biopsy with standard systematic transrectal ultrasound guided biopsy in biopsy naïve men with increased prostate specific antigen.

MATERIALS AND METHODS

We performed a prospective study in 132 biopsy naïve men with increased prostate specific antigen (greater than 4 ng/ml). After 3 Tesla functional multiparametric magnetic resonance imaging patients were referred for magnetic resonance imaging guided in-bore biopsy of prostate lesions (maximum 3) followed by standard systematic transrectal ultrasound guided biopsy (12 cores). We analyzed the detection rates of prostate cancer and significant prostate cancer (greater than 5 mm total cancer length or any Gleason pattern greater than 3).

RESULTS

A total of 128 patients with a mean ± SD age of 66.1 ± 8.1 years met all study requirements. Median prostate specific antigen was 6.7 ng/ml (IQR 5.1-9.0). Transrectal ultrasound and magnetic resonance imaging guided biopsies provided the same 53.1% detection rate, including 79.4% and 85.3%, respectively, for significant prostate cancer. Magnetic resonance imaging and transrectal ultrasound guided biopsies missed 7.8% and 9.4% of clinically significant prostate cancers, respectively. Magnetic resonance imaging biopsy required significantly fewer cores and revealed a higher percent of cancer involvement per biopsy core (each p <0.01). Combining the 2 methods provided a 60.9% detection rate with an 82.1% rate for significant prostate cancer.

CONCLUSIONS

Magnetic resonance imaging guided in-bore and systematic transrectal ultrasound guided biopsies achieved equally high detection rates in biopsy naïve patients with increased prostate specific antigen. Magnetic resonance imaging guided in-bore biopsies required significantly fewer cores and revealed a significantly higher percent of cancer involvement per biopsy core.

Current status of magnetic resonance imaging (MRI) and ultrasonography fusion software platforms for guidance of prostate biopsies

Prostate MRI is currently the best diagnostic imaging method for detecting PCa. Magnetic resonance imaging (MRI)/ultrasonography (US) fusion allows the sensitivity and specificity of MRI to be combined with the real-time capabilities of transrectal ultrasonography (TRUS). Multiple approaches and techniques exist for MRI/US fusion and include direct 'in bore' MRI biopsies, cognitive fusion, and MRI/US fusion via software-based image coregistration platforms.

Multiparametric MRI in prostate cancer management

Prostate cancer is the second most common cancer in men worldwide. The clinical behaviour of prostate cancer ranges from low-grade indolent tumours that never develop into clinically significant disease to aggressive, invasive tumours that may progress rapidly to metastatic disease and death. Therefore, there is an urgent clinical need to detect high-grade cancers and to differentiate them from the indolent, slow-growing tumours. Conventional methods of cancer detection-such as levels of prostate-specific antigen (PSA) in serum, digital rectal examination, and random biopsies-are limited in their sensitivity, specificity, or both. The combination of conventional anatomical MRI and functional magnet resonance sequences-known as multiparametric MRI (mp-MRI)-is emerging as an accurate tool for identifying clinically relevant tumours owing to its ability to localize them. In this Review, we discuss the value of mp-MRI in localized and metastatic prostate cancer, highlighting its role in the detection, staging, and treatment planning of prostate cancer.

Management of low risk prostate cancer-active surveillance and focal therapy

Low-risk prostate cancer, defined as Gleason Score 6 or less with PSA <10 ng/ml, is diagnosed in about half of men undergoing screening. Approximately 30% of men diagnosed with low-risk disease harbour high-grade cancer that is unrepresented on the biopsy. Moreover, a small percentage of low-grade cancers have molecular alterations that result in progression to aggressive disease. Favourable-risk prostate cancer should be managed with close follow up. Active surveillance is appropriate for most patients with low-risk disease, and radical treatment should be reserved for cases in which higher-risk disease is identified. In turn, focal therapy aims to preserve tissue and function in men who have been diagnosed with localized disease, and should be offered to men with higher risk disease at baseline, as an alternative to whole-gland radiation or surgery, or when the patient transitions from low-risk to higher-risk disease. The two strategies should be viewed as complementary elements of care that can be applied in a risk-stratified manner. In this Review, we discuss the rationale and current status of active surveillance-which constitutes a standard of care in most evidence-based guidelines-and comment on whether and when focal therapy should complement it in those men wishing to continue a tissue-preserving strategy.

Prospective study of diagnostic accuracy comparing prostate cancer detection by transrectal ultrasound-guided biopsy versus magnetic resonance (MR) imaging with subsequent MR-guided biopsy in men without previous prostate biopsies

BACKGROUND

The current diagnosis of prostate cancer (PCa) uses transrectal ultrasound-guided biopsy (TRUSGB). TRUSGB leads to sampling errors causing delayed diagnosis, overdetection of indolent PCa, and misclassification. Advances in multiparametric magnetic resonance imaging (mpMRI) suggest that imaging and selective magnetic resonance (MR)-guided biopsy (MRGB) may be superior to TRUSGB.

OBJECTIVE

To compare the diagnostic efficacy of the magnetic resonance imaging (MRI) pathway with TRUSGB.

DESIGN, SETTING, AND PARTICIPANTS

A total of 223 consecutive biopsy-naive men referred to a urologist with elevated prostate-specific antigen participated in a single-institution, prospective, investigator-blinded, diagnostic study from July 2012 through January 2013.

INTERVENTION

All participants had mpMRI and TRUSGB. Men with equivocal or suspicious lesions on mpMRI also underwent MRGB.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary outcome was PCa detection. Secondary outcomes were histopathologic details of biopsy and radical prostatectomy specimens, adverse events, and MRI reader performance. Sensitivity, specificity, negative predictive values (NPVs), and positive predictive values were estimated and basic statistics presented by number (percentage) or median (interquartile range).

RESULTS AND LIMITATIONS

Of 223 men, 142 (63.7%) had PCa. TRUSGB detected 126 cases of PCa in 223 men (56.5%) including 47 (37.3%) classed as low risk. MRGB detected 99 cases of PCa in 142 men (69.7%) with equivocal or suspicious mpMRI, of which 6 (6.1%) were low risk. The MRGB pathway reduced the need for biopsy by 51%, decreased the diagnosis of low-risk PCa by 89.4%, and increased the detection of intermediate/high-risk PCa by 17.7%. The estimated NPVs of TRUSGB and MRGB for intermediate/high-risk disease were 71.9% and 96.9%, respectively. The main limitation is the lack of long follow-up.

CONCLUSIONS

We found that mpMRI/MRGB reduces the detection of low-risk PCa and reduces the number of men requiring biopsy while improving the overall rate of detection of intermediate/high-risk PCa.

PATIENT SUMMARY

We compared the results of standard prostate biopsies with a magnetic resonance (MR) image-based targeted biopsy diagnostic pathway in men with elevated prostate-specific antigen. Our results suggest patient benefits of the MR pathway. Follow-up of negative investigations is required.

Active surveillance for clinically localized prostate cancer--a systematic review

Active surveillance (AS) has been introduced as an observational strategy to delay or avoid curative treatment without compromising long-term cancer-specific survival. The 10 studies included in this review, published between 2008 and 2013, generally agreed upon patients selection for the AS strategy and how they should be managed within the program. However, uncertainties persists concerning optimal patient selection and reliable progression criteria, as well as the long-term safety of AS.

Current Ability of Multiparametric Prostate Magnetic Resonance Imaging and Targeted Biopsy to Improve the Detection of Prostate Cancer

INTRODUCTION

Recent advancements in imaging technology have significantly increased the diagnostic accuracy of magnetic resonance imaging for prostate cancer. However, tissue diagnosis and grading remain the gold standard for diagnosis and prognostication. Because transrectal ultrasound guided prostate biopsy performs poorly, extensive research has been conducted into biopsy techniques that are guided by magnetic resonance imaging, including direct in-bore, cognitive fusion and magnetic resonance imaging/ultrasound fusion guided biopsies.

METHODS

The PubMed® database was searched from inception until January 15, 2014 for criteria pertaining to targeted prostate biopsy.

RESULTS

Initial studies of the 3 types of targeted prostate biopsy yielded similar results. Most importantly, targeted biopsy detects a greater amount of clinically significant prostate cancer than does transrectal ultrasound guided biopsy. Magnetic resonance imaging/ultrasound fusion guided biopsy has generated the most interest, as it is an office based procedure that does not require a significant change from the current workflow of transrectal prostate biopsy. These techniques hold great promise in the areas of patient selection for definitive treatment, appropriate screening, active surveillance and focal therapy for prostate cancer.

CONCLUSIONS

Targeted prostate biopsy has the potential to significantly improve the way patients are screened, treated and monitored in the setting of prostate cancer. These techniques allow for an individualized approach to each patient, which is a substantial improvement over the current practice of effectively random prostate biopsies. Large, multicenter studies are necessary to determine whether targeted prostate biopsy will become a definitive standard of care.

Performance of multiparametric MRI in men at risk of prostate cancer before the first biopsy: a paired validating cohort study using template prostate mapping biopsies as the reference standard

BACKGROUND

Multiparametric magnetic resonance imaging (mpMRI) has the potential to serve as a non-invasive triage test for men at risk of prostate cancer. Our objective was to determine the performance characteristics of mpMRI in men at risk before the first biopsy using 5 mm template prostate mapping (TPM) as the reference standard.

METHODS

One hundred and twenty-nine consecutive men with clinical suspicion of prostate cancer, who had no prior biopsy, underwent mpMRI (T1/T2-weighted, diffusion-weighting, dynamic contrast enhancement) followed by TPM. The primary analysis used were as follows: (a) radiological scores of suspicion of ≥3 attributed from a five-point ordinal scale, (b) a target condition on TPM of any Gleason pattern ≥4 and/or a maximum cancer core length of ≥4 mm and (c) two sectors of analysis per prostate (right and left prostate halves). Secondary analyses evaluated the impact of changing the mpMRI score threshold to ≥4 and varying the target definition for clinical significance.

RESULTS

One hundred and forty-one out of 258 (55%) sectors of analysis showed 'any cancer' and 77/258 (30%) had the target histological condition for the purpose of deriving the primary outcome. Median (with range) for age, PSA, gland volume and number of biopsies taken were 62 years (41-82), 5.8 ng ml(-1) (1.2-20), 40 ml (16-137) and 41 cores (20-93), respectively. For the primary outcome sensitivity, specificity, positive and negative predictive values and area under the receiver-operating curve (with 95% confidence intervals) were 94% (88-99%), 23% (17-29%), 34% (28-40%), 89% (79-98%) and 0.72 (0.65-0.79), respectively.

CONCLUSIONS

MpMRI demonstrated encouraging diagnostic performance characteristics in detecting and ruling out clinically significant prostate cancer in men at risk, who were biopsy naive.

Magnetic resonance imaging‑directed biopsy improves the prediction of prostate cancer aggressiveness compared with a 12‑core transrectal ultrasound‑guided prostate biopsy

The Gleason grading system is a fundamental indicator of the aggressive nature of prostate cancer (PCa). Diffusion-weighted imaging (DWI) and magnetic resonance (MR) spectroscopy (MRS) are methods for the assessment of PCa aggressiveness. The present study was designed to prospectively investigate whether transrectal ultrasound (TRUS)-guided MR imaging (MRI)-directed biopsies (TRUS‑MR‑Dbs) improve the prediction of PCa aggressiveness in comparison with 12-core TRUS-guided biopsies (TRUS‑Gbs). A total of 518 patients underwent pre-biopsy multi-parametric MRI to identify the clinically suspicious PCa regions. TRUS‑MR‑Dbs were performed on patients with suspected PCa by MRI in addition to TRUS‑Gbs. Only patients who underwent radical prostatectomy (RP) were included in the comparative analysis. TRUS‑biopsy was directed to those areas within suspicious regions with a minimum apparent diffusion coefficient obtained by DWI or with a maximum (choline + creatine)/citrate ratio obtained by MRS. The highest Gleason grades (HGGs) and the Gleason scores (GSs) of specimens were identified. The biopsies and RP results were evaluated using a McNemar test or χ2 analyses using Fisher' exact tests. MRI results were positive in 254 (49.0%) of the 518 patients. TRUS‑MR‑Db detected 165/254 (65.0%) cancer cases and TRUS‑Gb detected 190/518 (36.7%) cancer cases. Forty patients underwent RP. The TRUS‑MR‑Dbs method demonstrated a higher concordance rate (CR) with RP (89.6%) than TRUS‑Gbs (72.9%, P=0.008) for the overall HGG. The CRs with RP for TRUS‑MR‑Dbs vs. those for TRUS‑Gbs were 100 vs. 85.7% (P=0.5), 87.5 vs. 68.8% (P=0.031) and 50 vs. 50% (P=1) for HGG3, HGG4 and HGG5, respectively. The HGG CRs with RP for DWI‑directed biopsies (DWI-Dbs) vs. MRS-directed biopsies (MRS-Dbs) were 77.1 vs. 50.0% (P=0.015) for the overall tumors, 80.0 vs. 40.0% (P=0.003) for peripheral zone tumors and 69.2 vs. 76.9% (P=1) for transition zone tumors. A total of 37 (77.1%) and 25 (52.1%; P=0.007) tumors were assigned accurate GS for TRUS‑MR‑Dbs and TRUS‑Gbs, respectively. The results revealed that TRUS‑MR‑Dbs improved the prediction of PCa aggressiveness and that DWI-Dbs had a superior performance when compared with MRS‑Dbs in the peripheral zone.

Complications of prostate biopsy

Biopsy of the prostate is a common procedure with minor complications that are usually self-limited. However, if one considers that millions of men undergo biopsy worldwide, one realizes that although complication rate is low, the number of patients suffering from biopsy complications should not be underestimated and can be a clinically relevant problem for healthcare professionals. In this review, the authors present diagnosis and management of postbiopsy of prostate complications. Bleeding is the most common complication observed after prostate biopsy, but the use of aspirin or nonsteroidal anti-inflammatory drugs is not an absolute contraindication to prostate biopsy. Emerging resistance to ciprofloxacin is the most probable cause of the increasing risk of infectious complications after prostate biopsy. Even though extremely rare, fatal complications are possible and were described in case reports.

Imaging and Markers as Novel Diagnostic Tools in Detecting Insignificant Prostate Cancer: A Critical Overview

Recent therapeutic advances for managing low-risk prostate cancer include the active surveillance and focal treatment. However, locating a tumor and detecting its volume by adequate sampling is still problematic. Development of predictive biomarkers guiding individual therapeutic choices remains an ongoing challenge. At the same time, prostate cancer magnetic resonance imaging is gaining increasing importance for prostate diagnostics. The high morphological resolution of T2-weighted imaging and functional MRI methods may increase the specificity and sensitivity of diagnostics. Also, recent studies founded an ability of novel biomarkers to identify clinically insignificant prostate cancer, risk of progression, and association with poor differentiation and, therefore, with clinical significance. Probably, the above mentioned methods would improve tumor characterization in terms of its volume, aggressiveness, and focality. In this review, we attempted to evaluate the applications of novel imaging techniques and biomarkers in assessing the significance of the prostate cancer.

Improving detection of clinically significant prostate cancer: magnetic resonance imaging/transrectal ultrasound fusion guided prostate biopsy

PURPOSE

Given the limitations of prostate specific antigen and standard biopsies for detecting prostate cancer, we evaluated the cancer detection rate and external validity of a magnetic resonance imaging/transrectal ultrasound fusion guided prostate biopsy system used at the National Institutes of Health.

MATERIALS AND METHODS

We performed a phase III trial of a magnetic resonance imaging/transrectal ultrasound fusion guided prostate biopsy system with participants enrolled between 2012 and 2013. A total of 153 men consented to the study and underwent 3 Tesla multiparametric magnetic resonance imaging with an endorectal coil for clinical suspicion of prostate cancer. Lesions were classified as low or moderate/high risk for prostate cancer. Magnetic resonance imaging/transrectal ultrasound fusion guided biopsy and standard 12-core prostate biopsy were performed and 105 men were eligible for analysis.

RESULTS

Mean patient age was 65.8 years and mean prostate specific antigen was 9.5 ng/ml. The overall cancer detection rate was 62.9% (66 of 105 patients). The cancer detection rate in those with moderate/high risk on imaging was 72.3% (47 of 65) vs 47.5% (19 of 40) in those classified as low risk for prostate cancer (p<0.05). Mean tumor core length was 4.6 and 3.7 mm for fusion biopsy and standard 12-core biopsy, respectively (p<0.05). Magnetic resonance imaging/transrectal ultrasound fusion guided biopsy detected prostate cancer that was missed by standard 12-core biopsy in 14.3% of cases (15 of 105), of which 86.7% (13 of 15) were clinically significant. This biopsy upgraded 23.5% of cancers (4 of 17) deemed clinically insignificant on 12-core biopsy to clinically significant prostate cancer necessitating treatment.

CONCLUSIONS

Magnetic resonance imaging/transrectal ultrasound fusion guided biopsy can improve prostate cancer detection. The results of this trial support the external validity of this platform and may be the next step in the evolution of prostate cancer management.

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.

Target detection: magnetic resonance imaging-ultrasound fusion-guided prostate biopsy

Recent advances in multiparametric magnetic resonance imaging (MRI) have enabled image-guided detection of prostate cancer. Fusion of MRI with real-time ultrasound (US) allows the information from MRI to be used to direct biopsy needles under US guidance in an office-based procedure. Fusion can be performed either cognitively or electronically, using a fusion device. Fusion devices allow superimposition (coregistration) of stored MRI images on real-time US images; areas of suspicion found on MRI can then serve as targets during US-guided biopsy. Currently available fusion devices use a variety of technologies to perform coregistration: robotic tracking via a mechanical arm with built-in encoders (Artemis/Eigen, BioJet/Geoscan); electromagnetic tracking (UroNav/Philips-Invivo, Hi-RVS/Hitachi); or tracking with a 3D US probe (Urostation/Koelis). Targeted fusion biopsy has been shown to identify more clinically significant cancers and fewer insignificant cancers than conventional biopsy. Fusion biopsy appears to be a major advancement over conventional biopsy because it allows (1) direct targeting of suspicious areas not seen on US and (2) follow-up biopsy of specific cancerous sites in men undergoing active surveillance.

A prospective, blinded comparison of magnetic resonance (MR) imaging-ultrasound fusion and visual estimation in the performance of MR-targeted prostate biopsy: the PROFUS trial

BACKGROUND

Increasing evidence supports the use of magnetic resonance (MR)-targeted prostate biopsy. The optimal method for such biopsy remains undefined, however.

OBJECTIVE

To prospectively compare targeted biopsy outcomes between MR imaging (MRI)-ultrasound fusion and visual targeting.

DESIGN, SETTING, AND PARTICIPANTS

From June 2012 to March 2013, prospective targeted biopsy was performed in 125 consecutive men with suspicious regions identified on prebiopsy 3-T MRI consisting of T2-weighted, diffusion-weighted, and dynamic-contrast enhanced sequences.

INTERVENTION

Two MRI-ultrasound fusion targeted cores per target were performed by one operator using the ei-Nav|Artemis system. Targets were then blinded, and a second operator took two visually targeted cores and a 12-core biopsy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Biopsy information yield was compared between targeting techniques and to 12-core biopsy. Results were analyzed using the McNemar test. Multivariate analysis was performed using binomial logistic regression.

RESULTS AND LIMITATIONS

Among 172 targets, fusion biopsy detected 55 (32.0%) cancers and 35 (20.3%) Gleason sum ≥7 cancers compared with 46 (26.7%) and 26 (15.1%), respectively, using visual targeting (p=0.1374, p=0.0523). Fusion biopsy provided informative nonbenign histology in 77 targets compared with 60 by visual (p=0.0104). Targeted biopsy detected 75.0% of all clinically significant cancers and 86.4% of Gleason sum ≥7 cancers detected on standard biopsy. On multivariate analysis, fusion performed best among smaller targets. The study is limited by lack of comparison with whole-gland specimens and sample size. Furthermore, cancer detection on visual targeting is likely higher than in community settings, where experience with this technique may be limited.

CONCLUSIONS

Fusion biopsy was more often histologically informative than visual targeting but did not increase cancer detection. A trend toward increased detection with fusion biopsy was observed across all study subsets, suggesting a need for a larger study size. Fusion targeting improved accuracy for smaller lesions. Its use may reduce the learning curve necessary for visual targeting and improve community adoption of MR-targeted biopsy.