Magnetic Resonance Imaging-Ultrasound Fusion-Guided Prostate Biopsy: Review of Technology, Techniques, and Outcomes

Automatic MRI-TRUS Fusion Technique for Transperineal Biopsy Guidance: From Preoperative Planning to Intraoperative Navigation

BACKGROUND

Targeted and systematic transperineal biopsy of lesions guided by magnetic resonance imaging (MRI) and transrectal ultrasonography (TRUS) fusion technique may optimize the biopsy procedure and enhance the detection of prostate cancer. We described the transperineal biopsy guided by an automatic MRI-TRUS fusion technique, and evaluated the accuracy and feasibility of this method in a prospective single-center study.

METHODS

The proposed method focuses on automating the delineation of prostate contours in both the MRI and TRUS images, the registration and fusion of MRI and TRUS images, the generation and visualiztion of the systematic biopsy cores in their corresponding locations within the 2D and the 3D views, as well as the computation and visualiztion of needle trajectories from preoperative planning to intraoperative navigation. A total of 76 patients with clinically suspected prostate cancer underwent systematic (SBx) and targeted (TBx) biopsies, all performed by a single urologist with more than 10 years of experience. The detection rates of prostate cancer (PCa) and clinically significant prostate cancer (csPCa) were recorded. We also measured preoperative registration time, duration of the overall surgical procedure, and postoperative complication rates within the first week following the surgery. Descriptive analyses were presented in this study.

RESULTS

PCa was identified in 73.7% (56/76) of the subjects, while csPCa was identified in 61.8% (47/76). The preoperative registration time was 5.0 min (IQR: 4.4-6.0), while the overall surgery duration was 24.8 min (IQR: 23.2-27.2). Postoperatively, 12 patients experienced immediate hematuria, and one patient reported dysuria 1 day following surgery.

CONCLUSIONS

The automatic MRI-TRUS fusion technique for transperineal biopsy is feasible and safe, with preoperative planning to intraoperative navigation it offering convenient and efficient preoperative preparation and surgical procedure.

Prioritizing precision: detection of prostate cancer using mri guided fusion needle biopsy across the pennsylvania urologic regional collaborative

PURPOSE

Targeted prostate biopsies are increasingly being performed by urologists in the United States including those in the Pennsylvania Urologic Regional Collaborative, a physician-led data-sharing and quality improvement collaborative. To evaluate the performance of MRI guided fusion needle prostate biopsies in the collaborative, we analyzed the variability by practice in rates of detection of clinically significant prostate cancer and patient characteristics associated with detection of clinically significant prostate cancer.

METHODS

We analyzed 857 first-time MRI fusion biopsy procedures performed at five practices (minimum 20 procedures) between 2015 and 2019. We used chi-square analysis for baseline patient characteristics and Grade Group (GG) ≥ 3 tumor detection rates by practice. Multivariable logistic regression was used to estimate the odds of clinically significant cancer detection when adjusting for baseline patient characteristics.

RESULTS

Approximately 15% of men undergoing targeted MRI guided biopsy were ≤ 59 years old. Median prostate specific antigen (PSA) was 6.8 ng/ml. Detection rates for GG ≥ 3 tumors ranged from 14.3% to 28.3% (P = 0.02) across practices. However, the odds of GG ≥ 3 tumor detection did not differ significantly between practices after adjusting for clinical and radiographic factors. Overall, increased likelihood of detecting a GG ≥ 3 tumor was associated with increased age, DRE abnormalities, higher PSA, smaller gland volume and PI-RADS ≥ 4 MRI lesions. There was an 81% concordance rate between PI-RADS ≥ 4 and Gleason grade ≥ 3 prostate cancer.

CONCLUSION

We demonstrate the value of obtaining pre-biopsy MRI given high concordance between presence of suspicious lesions and MRI-targeted biopsy detection of clinically significant prostate cancer. Variability of baseline patient characteristics among practices may account for the observed differences in clinically significant cancer detection rates. These findings can aid standardization and quality improvement efforts within the collaborative.

Introduction of Androgen Receptor Targeting shRNA Inhibits Tumor Growth in Patient-Derived Prostate Cancer Xenografts

Patient-derived xenograft (PDX) models have been established as important preclinical cancer models, overcoming some of the limitations associated with the use of cancer cell lines. The utility of prostate cancer PDX models has been limited by an inability to genetically manipulate them in vivo and difficulties sustaining PDX-derived cancer cells in culture. Viable, short-term propagation of PDX models would allow in vitro transfection with traceable reporters or manipulation of gene expression relevant to different studies within the prostate cancer field. Here, we report an organoid culture system that supports the growth of prostate cancer PDX cells in vitro and permits genetic manipulation, substantially increasing the scope to use PDXs to study the pathobiology of prostate cancer and define potential therapeutic targets. We have established a short-term PDX-derived in vitro cell culture system which enables genetic manipulation of prostate cancer PDXs LuCaP35 and BM18. Genetically manipulated cells could be re-established as viable xenografts when re-implanted subcutaneously in immunocompromised mice and were able to be serially passaged. Tumor growth of the androgen-dependent LuCaP35 PDX was significantly inhibited following depletion of the androgen receptor (AR) in vivo. Taken together, this system provides a method to generate novel preclinical models to assess the impact of controlled genetic perturbations and allows for targeting specific genes of interest in the complex biological setting of solid tumors.

Molecular basis and therapeutic targets in prostate cancer: A comprehensive review

Prostate cancer is one of the most significant causes of morbidity and mortality in male patients. The incidence increases with age, and it is higher among African Americans. The occurrence of prostate cancer is associated with many risk factors, including genetic and hereditary predisposition. The most common genetic syndromes associated with prostate cancer risk are BRCA-associated hereditary breast and ovarian cancer (HBOC) and Lynch syndrome. Local-regional therapy, i.e., surgery is beneficial in early-stage prostate cancer management. Advanced and metastatic prostate cancers require systemic therapies, including hormonal inhibition, chemotherapy, and targeted agents. Most prostate cancers can be treated by targeting the androgen-receptor pathway and decreasing androgen production or binding to androgen receptors (AR). Castration-resistant prostate cancer (CRPC) usually involves the PI3K/AKT/mTOR pathway and requires targeted therapy. Specific molecular therapy can target mutated cell lines in which DNA defect repair is altered, caused by mutations of BRCA2, partner and localizer of BRCA2 (PALB2), and phosphatase and tensin homolog (PTEN) or the transmembrane protease serine 2-ERG (TMPRSS2-ERG) fusion. Most benefits were demonstrated in cyclin dependent-kinase 12 (CDK12) mutated cell lines when treated with anti-programmed cell death protein 1 (PD1) therapy. Therapies targeting p53 and AKT are the subject of ongoing clinical trials. Many genetic defects are listed as diagnostic, prognostic, and clinically actionable markers in prostate cancer. Androgen receptor splice variant 7 (AR-V7) is an important oncogenic driver and an early diagnostic and prognostic marker, as well as a therapeutic target in hormone-resistant CRPC. This review summarizes the pathophysiological mechanisms and available targeted therapies for prostate cancer.

Ultrasound Frame-to-Volume Registration via Deep Learning for Interventional Guidance

Fusing intraoperative 2-D ultrasound (US) frames with preoperative 3-D magnetic resonance (MR) images for guiding interventions has become the clinical gold standard in image-guided prostate cancer biopsy. However, developing an automatic image registration system for this application is challenging because of the modality gap between US/MR and the dimensionality gap between 2-D/3-D data. To overcome these challenges, we propose a novel US frame-to-volume registration (FVReg) pipeline to bridge the dimensionality gap between 2-D US frames and 3-D US volume. The developed pipeline is implemented using deep neural networks, which are fully automatic without requiring external tracking devices. The framework consists of three major components, including one) a frame-to-frame registration network (Frame2Frame) that estimates the current frame's 3-D spatial position based on previous video context, two) a frame-to-slice correction network (Frame2Slice) adjusting the estimated frame position using the 3-D US volumetric information, and three) a similarity filtering (SF) mechanism selecting the frame with the highest image similarity with the query frame. We validated our method on a clinical dataset with 618 subjects and tested its potential on real-time 2-D-US to 3-D-MR fusion navigation tasks. The proposed FVReg achieved an average target navigation error of 1.93 mm at 5-14 fps. Our source code is publicly available at https://github.com/DIAL-RPI/Frame-to-Volume-Registration.

Ultrasound/MRI-targeted biopsy versus saturated trans-rectal ultrasound guided biopsy of prostate in patients with primary negative conventional biopsy and still elevated PSA: a prospective randomized clinical trial

INTRODUCTION

To evaluate and compare the rate of cancer detection by two methods Saturated TRUS guided biopsy and ultrasound/magnetic resonance imaging (US/MRI)-targeted biopsy in patients with primary negative prostate cancer in standard 12 cores biopsy evaluation but still have elevated prostate specific antigen (PSA).

MATERIALS AND METHODS

From 105 patients who met our inclusion criteria, 53 patients underwent US/MRI-targeted biopsy and 52 remaining patients underwent Saturated 20 core TRUS guided biopsy in a prospective randomized clinical trial.

RESULTS

The mean age (±SD) was 62.2 (±8.2) year. The mean PSA (±SD) was 11.8 (±7.5) ng/ml. The mean prostate volume was 56.1 (±24.8) ml. Adenocarcinoma of prostate was detected in 9/52 (17.3%) patients in groups saturated biopsy and 14/53 (26.4%) patients in US/MRI-targeted biopsy group and there was no difference in cancer detection rate between 2 groups (P=0.252). except four patients with fever (two in each group), there was no other serious complication (Clavien grade 3 or higher) occurred in the patients. In the multivariate analysis, higher pre-procedure PSA, lower size of the prostate, pathology of ASAP and presence of nodule in DRE were independent predictors for cancer detection in second biopsy (P=0.036, P<0.001, P=0.013 and P=0.031, respectively).

CONCLUSION

We didn't find any superiority in cancer detection rate and any different in complication rate between these two methods saturated TRUS guided biopsy and US/MRI-targeted biopsy.

Safety and efficacy of software-assisted MRI-TRUS fusion-guided transperineal prostate biopsy in an outpatient setting using local anaesthesia

PURPOSE

To evaluate diagnostic accuracy, safety, and efficiency of an MRI-TRUS fusion-guided transperineal prostate biopsy method in an outpatient setting under local anaesthesia.

METHODS

Patients undergoing transperineal prostate biopsy were included from March 2021 to May 2022. Biopsies were performed under local anaesthesia in an outpatient setting, using specialised fusion software. Primary outcome was (clinically significant) cancer detection rate. Secondary outcomes were procedure time, patient discomfort during the procedure and complication rate.

RESULTS

We included 203 male patients (69 years +-SD 8.2) with PI-RADS score > 2. In total 223 suspicious lesions were targeted. Overall cancer detection rate and clinically significant cancer detection rate were 73.5% and 60.1%, respectively. (Clinically significant) cancer detection rates in PI-RADS 3, 4 and 5 lesions were 46.4% (23.2%), 78.5% (66.1%) and 93.5% (89.1%), respectively. Mean duration of the procedure including fusion, targeted and systematic biopsies was 22.5 min. Patients rated injection of local anaesthesia on a numeric pain rating scale on average 3.7/10 (SD 2.09) and biopsy core sampling 1.6/10 (SD 1.65). No patient presented with acute urinary retention on follow-up consultation. Two (1%) patients presented with infectious complications. Four (2%) patients experienced a vasovagal reaction.

CONCLUSION

Transperineal targeted biopsy with MRI-TRUS fusion software has high overall and clinically significant cancer detection rates. The method is well tolerated under local anaesthesia and in an outpatient setting.

Kinematic and mechanical modelling of a novel 4-DOF robotic needle guide for MRI-guided prostate intervention

Traditionally ultrasound-guided biopsy has been used to diagnose prostate cancer despite of its poor soft tissue contrast and frequent false negative results. Magnetic Resonance Imaging (MRI) has the advantage of excellent soft tissue contrast for guiding and monitoring prostate biopsy. However, its working area and access in the confined MRI bore space limit the use of interventional guide devices including robotic systems. To provide robotic precision, greater access, and compact design, we designed a novel robotic mechanism that can provide four degrees of freedom (DOF) manipulation in a compact form comparable to size of manual templates. To develop the mechanism, we established a mathematical model of inverse and forward kinematics and prototyped a proof-of-concept needle guide for MRI guided prostate biopsy. The mechanism was materialized using four discs that house small passive spherical joints that can be moved by rotating the discs consisting of grooved profile. With an initial needle insertion angle range of ±15°, we identified mathematical and kinematic parameters for the mechanism design and fabricated the first prototype that has dimension of 40 × 110 × 180 mm3. The prototype demonstrated that the unique robotic manipulation can physically be delivered and could provide precise needle guidance including angulated needle insertion with higher structural rigidity.

Application of Multiple Ultrasonic Techniques in the Diagnosis of Prostate Cancer

Methods for diagnosing prostate cancer (PCa) are developing in the direction of imaging. Advanced ultrasound examination modes include micro-Doppler, computerized-transrectal ultrasound, elastography, contrast-enhanced ultrasound and microultrasound. When two or more of these modes are used in PCa diagnosis, the combined technique is called multiparameter ultrasound (mp-US). Mp-US provides complementary information to multiparameter magnetic resonance imaging (mp-MRI) for diagnosing PCa. At present, no study has attempted to combine the characteristics of different ultrasound modes with advanced classification systems similar to the PIRADS system in mpMRI for the diagnosis of PCa. As an imaging method, mp-US has great potential in the diagnosis of PCa.

Prostate MRI using a rigid two-channel phased-array endorectal coil: comparison with phased array coil acquisition at 3 T

Background

To compare image quality, lesion detection and patient comfort of 3T prostate MRI using a combined rigid two-channel phased-array endorectal coil and an external phased-array coil (ERC-PAC) compared to external PAC acquisition in the same patients.

Methods

Thirty three men (mean age 65.3y) with suspected (n = 15) or biopsy-proven prostate cancer (PCa, n = 18) were prospectively enrolled in this exploratory study. 3T prostate MRI including T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) was performed using an ERC-PAC versus PAC alone, in random order. Image quality, lesion detection and characterization (biparametric PI-RADSv2.1) were evaluated by 2 independent observers. Estimated signal-to-noise ratio (eSNR) was measured in identified lesions and the peripheral zone (PZ). Patient comfort was assessed using a questionnaire. Data were compared between sequences and acquisitions. Inter/intra-observer agreement for PI-RADS scores was evaluated.

Results

Twenty four prostate lesions (22 PCa) were identified in 20/33 men. Superior image quality was found for ERC-PAC compared to PAC for T2WI for one observer (Obs.1, p < 0.03) and high b-value DWI for both observers (p < 0.05). The sensitivity of PI-RADS for lesion detection for ERC-PAC and PAC acquisitions was 79.2 and 75% for Obs.1, and 79.1 and 66.7%, for Obs.2, without significant difference for each observer (McNemar p-values ≥0.08). Inter−/intra-observer agreement for PI-RADS scores was moderate-to-substantial (kappa = 0.52–0.84). Higher eSNR was observed for lesions and PZ for T2WI and PZ for DWI using ERC-PAC (p < 0.013). Most patients (21/33) reported discomfort at ERC insertion.

Conclusion

Despite improved image quality and eSNR using the rigid ERC-PAC combination, no significant improvement in lesion detection was observed, therefore not supporting the routine use of ERC for prostate MRI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40644-022-00453-7.

Comparison of prostate cancer detection rates in patients undergoing MRI/TRUS fusion prostate biopsy with two different software-based systems

BACKGROUND

Magnetic resonance imaging (MRI)-targeted prostate biopsy is a routinely used diagnostic tool for prostate cancer (PCa) detection. However, a clear superiority of the optimal approach for software-based MRI processing during biopsy procedures is still unanswered. To investigate the impact of robotic approach and software-based image processing (rigid vs. elastic) during MRI/transrectal ultrasound (TRUS) fusion prostate biopsy (FBx) on overall and clinically significant (cs) PCa detection.

METHODS

The study relied on the instructional retrospective biopsy data collected data between September 2013 and August 2017. Overall, 241 men with at least one suspicious lesion (PI-RADS ≥ 3) on multiparametric MRI underwent FBx. The study protocol contains a systematic 12-core sextant biopsy plus 2 cores per targeted lesion. One experienced urologist performed 1048 targeted biopsy cores; 467 (45%) cores were obtained using rigid processing, while the remaining 581 (55%) cores relied on elastic image processing. CsPCa was defined as International Society of Urological Pathology (ISUP) grade ≥ 2. The effect of rigid versus elastic FBx on overall and csPCa detection rates was determined. Propensity score weighting and multivariable regression models were used to account for potential biases inherent to the retrospective study design.

RESULTS

In multivariable regression analyses, age, prostate-specific antigen (PSA), and PIRADS ≥ 3 lesion were related to higher odds of finding csPCa. Elastic software-based image processing was independently associated with a higher overall PCa (odds ratio [OR] = 3.6 [2.2-6.1], p < 0.001) and csPCa (OR = 4.8 [2.6-8.8], p < 0.001) detection, respectively.

CONCLUSIONS

Contrary to existing literature, our results suggest that the robotic-driven software registration with elastic fusion might have a substantial effect on PCa detection.

Evolution of Focal Therapy in Prostate Cancer: Past, Present, and Future

Organ sparing approaches for the management of localized prostate cancer were developed in part to overcome the morbidity associated with standard, whole gland treatment options. The first description of focal therapy was now over two decades ago and since that time much has changed. The evolution of patient selection, the approach to ablation, and surveillance after focal therapy have mirrored the technologic advancements in the field as well as the improved understanding of the biology of low-grade, low-risk prostate cancer. This review presents the evidence for the basis of focal therapy from the past to the present and future endeavors.

Systematic biopsy should not be omitted in the era of combined magnetic resonance imaging/ultrasound fusion-guided biopsies of the prostate

PURPOSE

To evaluate prostate cancer detection rates with classical trans-rectal ultrasound-guided systematic 10-core biopsies (SB), targeted biopsies (TB) guided by magnetic resonance (MR)/US fusion imaging and their combination in biopsy-naïve and patients with previously negative prostate biopsies. We compared pathology results after radical prostatectomy with biopsy findings.

METHODS

Consecutive patients with prostate imaging-reporting and data system lesions grade ≥ 3 submitted to MRI/US-guided TB and subsequent standard 10-core SB between December 2015 and June 2019 were analyzed.

RESULTS

Detection rate (TB- or SB-positive) in 563 included patients (192 naïve, 371 with previous biopsies) was 56.7% (67.7% for the first, 50.9% for repeated biopsies). With TB (disregarding SB), the rates were 41.4%, 52.1% and 35.8%, respectively. With SB (disregarding TB), the rates were 49.1%, 63.0% and 41.8%, respectively. Eventually, 118 patients underwent surgery and clinically significant cancer was found in 111 (94.1%) specimens. Of those, 23 (20.7%) would have been missed had we relied upon a negative TB and 14 (12.6%) would have been missed had we relied upon a negative SB, disregarding a positive finding on the alternative biopsy template.

CONCLUSION

SB should not be omitted since TB and SB combination have higher detection rate of clinically relevant prostate cancer than either procedure alone.

Applications of artificial intelligence in prostate cancer imaging

PURPOSE OF REVIEW

The purpose of this review was to identify the most recent lines of research focusing on the application of artificial intelligence (AI) in the diagnosis and staging of prostate cancer (PCa) with imaging.

RECENT FINDINGS

The majority of studies focused on the improvement in the interpretation of bi-parametric and multiparametric magnetic resonance imaging, and in the planning of image guided biopsy. These initial studies showed that AI methods based on convolutional neural networks could achieve a diagnostic performance close to that of radiologists. In addition, these methods could improve segmentation and reduce inter-reader variability. Methods based on both clinical and imaging findings could help in the identification of high-grade PCa and more aggressive disease, thus guiding treatment decisions. Though these initial results are promising, only few studies addressed the repeatability and reproducibility of the investigated AI tools. Further, large-scale validation studies are missing and no diagnostic phase III or higher studies proving improved outcomes regarding clinical decision making have been conducted.

SUMMARY

AI techniques have the potential to significantly improve and simplify diagnosis, risk stratification and staging of PCa. Larger studies with a focus on quality standards are needed to allow a widespread introduction of AI in clinical practice.

PET- and SPECT-based navigation strategies to advance procedural accuracy in interventional radiology and image-guided surgery

INTRODUCTION

Nuclear medicine has a crucial role in interventional strategies where a combination between the increasing use of targeted radiotracers and intraprocedural detection modalities enable novel, but often complex, targeted procedures in both the fields of interventional radiology and surgery. 3D navigation approaches could assist the interventional radiologist or surgeon in such complex procedures.

EVIDENCE ACQUISITION

This review aimed to provide a comprehensive overview of the current application of computer-assisted navigation strategies based on nuclear imaging to assist in interventional radiology and image-guided surgery. This work starts with a brief overview of the typical navigation workflow from a technical perspective, which is followed by the different clinical applications organized based on their anatomical organ of interest.

EVIDENCE SYNTHESIS

Although many studies have proven the feasibility of PET- and SPECT-based navigation strategies for various clinical applications in both interventional radiology and surgery, the strategies are spread widely in both navigation workflows and clinical indications, evaluated in small patient groups. Hence, no golden standard has yet been established.

CONCLUSIONS

Despite that the clinical outcome is yet to be determined in large patient cohorts, navigation seems to be a promising technology to translate nuclear medicine findings, provided by PET- and SPECT-based molecular imaging, to the intervention and operating room. Interventional Nuclear Medicine (iNM) has an exciting future to come using both PET- and SPECT-based navigation.

Voxel-level Classification of Prostate Cancer on Magnetic Resonance Imaging: Improving Accuracy Using Four-Compartment Restriction Spectrum Imaging

BACKGROUND

Diffusion magnetic resonance imaging (MRI) is integral to detection of prostate cancer (PCa), but conventional apparent diffusion coefficient (ADC) cannot capture the complexity of prostate tissues and tends to yield noisy images that do not distinctly highlight cancer. A four-compartment restriction spectrum imaging (RSI₄ ) model was recently found to optimally characterize pelvic diffusion signals, and the model coefficient for the slowest diffusion compartment, RSI₄ -C₁ , yielded greatest tumor conspicuity.

PURPOSE

To evaluate the slowest diffusion compartment of a four-compartment spectrum imaging model (RSI₄ -C₁ ) as a quantitative voxel-level classifier of PCa.

STUDY TYPE

Retrospective.

SUBJECTS

Forty-six men who underwent an extended MRI acquisition protocol for suspected PCa. Twenty-three men had benign prostates, and the other 23 men had PCa.

FIELD STRENGTH/SEQUENCE

A 3 T, multishell diffusion-weighted and axial T2-weighted sequences.

ASSESSMENT

High-confidence cancer voxels were delineated by expert consensus, using imaging data and biopsy results. The entire prostate was considered benign in patients with no detectable cancer. Diffusion images were used to calculate RSI₄ -C₁ and conventional ADC. Classifier images were also generated.

STATISTICAL TESTS

Voxel-level discrimination of PCa from benign prostate tissue was assessed via receiver operating characteristic (ROC) curves generated by bootstrapping with patient-level case resampling. RSI₄ -C₁ was compared to conventional ADC for two metrics: area under the ROC curve (AUC) and false-positive rate for a sensitivity of 90% (FPR₉₀ ). Statistical significance was assessed using bootstrap difference with two-sided α = 0.05.

RESULTS

RSI₄ -C₁ outperformed conventional ADC, with greater AUC (mean 0.977 [95% CI: 0.951-0.991] vs. 0.922 [0.878-0.948]) and lower FPR₉₀ (0.032 [0.009-0.082] vs. 0.201 [0.132-0.290]). These improvements were statistically significant (P < 0.05).

DATA CONCLUSION

RSI₄ -C₁ yielded a quantitative, voxel-level classifier of PCa that was superior to conventional ADC. RSI classifier images with a low false-positive rate might improve PCa detection and facilitate clinical applications like targeted biopsy and treatment planning.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Magnetic resonance imaging-guided prostate biopsy-A review of literature

Objective

Multiparametric magnetic resonance imaging (MP-MRI) helps to identify lesion of prostate with reasonable accuracy. We aim to describe the various uses of MP-MRI for prostate biopsy comparing different techniques of MP-MRI guided biopsy.

Materials and methods

A literature search was performed for "multiparametric MRI", "MRI fusion biopsy", "MRI guided biopsy", "prostate biopsy", "MRI cognitive biopsy", "MRI fusion biopsy systems", "prostate biopsy" and "cost analysis". The search operation was performed using the operator "OR" and "AND" with the above key words. All relevant systematic reviews, original articles, case series, and case reports were selected for this review.

Results

The sensitivity of MRI targeted biopsy (MRI-TB) is between 91%-93%, and the specificity is between 36%-41% in various studies. It also has a high negative predictive value (NPV) of 89%-92% and a positive predictive value (PPV) of 51%-52%. The yield of MRI fusion biopsy (MRI-FB) is similar, if not superior to MR cognitive biopsy. In-bore MRI-TB had better detection rates compared to MR cognitive biopsy, but were similar to MR fusion biopsy.

Conclusions

The use of MRI guidance in prostate biopsy is inevitable, subject to availability, cost, and experience. Any one of the three modalities (i.e. MRI cognitive, MRI fusion and MRI in-bore approach) can be used. MRI-FB has a fine balance with regards to accuracy, practicality and affordability.

A 3D-2D Hybrid U-Net Convolutional Neural Network Approach to Prostate Organ Segmentation of Multiparametric MRI

OBJECTIVE

Prostate cancer is the most commonly diagnosed cancer in men in the United States with more than 200,000 new cases in 2018. Multiparametric MRI (mpMRI) is increasingly used for prostate cancer evaluation. Prostate organ segmentation is an essential step of surgical planning for prostate fusion biopsies. Deep learning convolutional neural networks (CNNs) are the predominant method of machine learning for medical image recognition. In this study, we describe a deep learning approach, a subset of artificial intelligence, for automatic localization and segmentation of prostates from mpMRI.

MATERIALS AND METHODS

This retrospective study included patients who underwent prostate MRI and ultrasound-MRI fusion transrectal biopsy between September 2014 and December 2016. Axial T2-weighted images were manually segmented by two abdominal radiologists, which served as ground truth. These manually segmented images were used for training on a customized hybrid 3D-2D U-Net CNN architecture in a fivefold cross-validation paradigm for neural network training and validation. The Dice score, a measure of overlap between manually segmented and automatically derived segmentations, and Pearson linear correlation coefficient of prostate volume were used for statistical evaluation.

RESULTS

The CNN was trained on 299 MRI examinations (total number of MR images = 7774) of 287 patients. The customized hybrid 3D-2D U-Net had a mean Dice score of 0.898 (range, 0.890-0.908) and a Pearson correlation coefficient for prostate volume of 0.974.

CONCLUSION

A deep learning CNN can automatically segment the prostate organ from clinical MR images. Further studies should examine developing pattern recognition for lesion localization and quantification.

Software-assisted US/MRI fusion-targeted biopsy for prostate cancer

BACKGROUND

Prostate cancer is the first cancer diagnosis in men. European Association of Urology  (EAU) Guidelines for Prostate Cancer underline the importance of screening, performed through PSA testing on all men with more than 50 years of age and before on men with risk factors. The diagnosis is still histopathologic, and it is done on the basis of the findings on biopsy samples.

MATERIALS AND METHODS

Fusion biopsy is a relatively new technique that allows the operator to perform the biopsies in office instead of the MRI gantry, without losing the detection capability of MRI. The  T2-wighted images obtained during a previous mpMRI are merged with the real-time ones of the TRUS.

RESULTS

Fusion biopsy in comparison with the systematic standard biopsy has a better detection rate of clinically significant cancers and of any cancers.

CONCLUSION

EAU 2020 guidelines still do offer a list of indications of when the biopsy should be performed, but it still appeared to be overperformed. The aim of our study is to underline how, in accordance with the recent literature result,  fusion biopsy has showed a better detection rate of any cancer and clinically significant disease with a reduced numbers of samplings, and no substantial difference between the multiple software.

A Comparison of Cancer Detection Rates Between Template Systematic Biopsies Obtained Using Magnetic Resonance Imaging-Ultrasound Fusion Machine and Freehand Transrectal Ultrasound-Guided Systematic Biopsies

Introduction: There are reports that the 12-core template systematic biopsies (SBx) obtained by using software registration machines (e.g., Artemis) have higher cancer detection rates (CDRs) of prostate cancer (PCa) than the standard, freehand 12-core transrectal ultrasound (TRUS)-guided biopsies. The goal of our study is to compare the clinically significant (CS) CDRs of SBx in two independent cohorts who underwent freehand TRUS-SBx alone (Cohort A) or machine-guided SBx as part of a combined MRI-ultrasound (MRI-US) fusion biopsy (FBx) (Cohort B). Materials and Methods: A retrospective review of all patients undergoing prostate biopsies over a 4-year period at the University of Cincinnati Medical Center was performed. CS cancer was defined as having a Gleason score ≥7. MRI-US FBx were obtained by using an Artemis software registration device (ARTEMIS™, Eigen, Inc., Grass Valley, CA). Statistical significance was considered at p < 0.05. Results: Nine hundred and thirty men underwent SBx (Cohort A: 474, Cohort B: 456). There were no statistical differences between cohort A and B in CS CDRs in the overall population (39.3% vs 33.8%; p = 0.093), biopsy naive patients (40.4% vs 39.8%; p = 0.951), or patients with a prior negative biopsy (22.7% vs 25.0%; p = 0.910). Multivariate logistic regression controlling for age, race, prostate-specific antigen level, prostate volume, abnormal digital rectal exam, and family history of PCa demonstrated comparable CS CDRs, which was maintained when further stratified by prior biopsy history (all patients: odds ratio [OR] 0.99, 95% confidence interval [CI] 0.71-1.38, p = 0.958; biopsy naive: OR 0.79, 95% CI 0.51-1.22, p = 0.291; prior negative biopsy: OR 0.64, 95% CI 0.21-1.75, p = 0.403). Conclusions: Our study did not find a significant difference in the CS CDRs of machine-guided SBx compared with the freehand TRUS-SBx. Unless the SBx is done at the time of FBx, the use of these machines for obtaining SBx only is unlikely to result in any increase of CS CDRs.

A systematic review and meta-analysis of magnetic resonance imaging and ultrasound guided fusion biopsy of prostate for cancer detection-Comparing transrectal with transperineal approaches

Targeted biopsy using multiparametric magnetic resonance imaging increases the detection rate of clinically significant prostate cancer (csCaP). In this meta-analysis, we compare the diagnostic accuracy of transrectal (TR) vs transperineal (TP) approaches for MRI-guided software fusion biopsy (FB) in the detection of csCaP. A literature search was performed in PubMed, Cochrane and Embase electronic databases up until July 2019 following the preferred reporting items for systematic review and meta-analysis system. The pooled sensitivity and specificity of either approach was evaluated using radical prostatectomy or systematic biopsies with ≥24 biopsy cores to be the reference standard. Fourteen papers with a total of 2002 patients were selected. Seven hundred and sixty-five patients underwent TR FB, while 1,387 underwent TP FB. One hundred and fifty of the patients underwent both TR and TP approaches. Both approaches were similar in terms of sensitivity (TR vs. TP: 0.81 vs 0.80) and specificity (TR vs. TP: 0.99 vs 0.95). In terms of likelihood ratios and diagnostic odds ratio, TR performed better than TP approach. The area under the receiving operator curve for both approaches was similar (0.91 vs 0.88 respectively). However, there was substantial heterogeneity across the studies for both approaches. TP and TR approaches to software-based FB yield similar diagnostic performance for the detection of csCaP. When deciding on the approach, physicians should consider other inherent features of either technique that suit their practice.

Functionalized NIR-II Semiconducting Polymer Nanoparticles for Single-cell to Whole-Organ Imaging of PSMA-Positive Prostate Cancer

Development of molecular probes holds great promise for early diagnosis of aggressive prostate cancer. Here, 2-[3-(1,3-dicarboxypropyl) ureido] pentanedioic acid (DUPA)-conjugated ligand and bis-isoindigo-based polymer (BTII) are synthesized to formulate semiconducting polymer nanoparticles (BTII-DUPA SPN) as a prostate-specific membrane antigen (PSMA)-targeted probe for prostate cancer imaging in the NIR-II window. Insights into the interaction of the imaging probes with the biological targets from single cell to whole organ are obtained by transient absorption (TA) microscopy and photoacoustic (PA) tomography. At single-cell level, TA microscopy reveals the targeting efficiency, kinetics, and specificity of BTII-DUPA SPN to PSMA-positive prostate cancer. At organ level, PA tomographic imaging of BTII-DUPA SPN in the NIR-II window demonstrates superior imaging depth and contrast. By intravenous administration, BTII-DUPA SPN demonstrates selective accumulation and retention in the PSMA-positive tumor, allowing noninvasive PA detection of PSMA overexpressing prostate tumors in vivo. The distribution of nanoparticles inside the tumor tissue is further analyzed through TA microscopy. These results collectively demonstrate BTII-DUPA SPN as a promising probe for prostate cancer diagnosis by PA tomography.

Automatic segmentation of prostate MRI using convolutional neural networks: Investigating the impact of network architecture on the accuracy of volume measurement and MRI-ultrasound registration

Convolutional neural networks (CNNs) have recently led to significant advances in automatic segmentations of anatomical structures in medical images, and a wide variety of network architectures are now available to the research community. For applications such as segmentation of the prostate in magnetic resonance images (MRI), the results of the PROMISE12 online algorithm evaluation platform have demonstrated differences between the best-performing segmentation algorithms in terms of numerical accuracy using standard metrics such as the Dice score and boundary distance. These small differences in the segmented regions/boundaries outputted by different algorithms may potentially have an unsubstantial impact on the results of downstream image analysis tasks, such as estimating organ volume and multimodal image registration, which inform clinical decisions. This impact has not been previously investigated. In this work, we quantified the accuracy of six different CNNs in segmenting the prostate in 3D patient T2-weighted MRI scans and compared the accuracy of organ volume estimation and MRI-ultrasound (US) registration errors using the prostate segmentations produced by different networks. Networks were trained and tested using a set of 232 patient MRIs with labels provided by experienced clinicians. A statistically significant difference was found among the Dice scores and boundary distances produced by these networks in a non-parametric analysis of variance (p < 0.001 and p < 0.001, respectively), where the following multiple comparison tests revealed that the statistically significant difference in segmentation errors were caused by at least one tested network. Gland volume errors (GVEs) and target registration errors (TREs) were then estimated using the CNN-generated segmentations. Interestingly, there was no statistical difference found in either GVEs or TREs among different networks, (p = 0.34 and p = 0.26, respectively). This result provides a real-world example that these networks with different segmentation performances may potentially provide indistinguishably adequate registration accuracies to assist prostate cancer imaging applications. We conclude by recommending that the differences in the accuracy of downstream image analysis tasks that make use of data output by automatic segmentation methods, such as CNNs, within a clinical pipeline should be taken into account when selecting between different network architectures, in addition to reporting the segmentation accuracy.

Novel focal therapy treatment options for prostate cancer

PURPOSE OF REVIEW

Examine and discuss novel focal therapy treatment options for prostate cancer.

RECENT FINDINGS

With the widespread adoption of mpMRI-guided biopsies for prostate cancer, use of image-guided treatment of prostate cancer has increased. Focal therapies leading to partial gland ablation such as partial prostatectomy, focal laser ablation, irreversible electroporation, vascular targeted photodynamic therapy, and focal radiofrequency ablation have emerged and begun to be properly evaluated. This review covers published phase 1 and 2 trials of each treatment and discusses potential limitations of each modality.

SUMMARY

Focal therapy of prostate cancer is being actively investigated. On the basis of limited published data, the treatments appear to be well tolerated and have an acceptable side effect profile. Importantly, short-term oncologic control has been mixed and there are no long-term outcomes. The acquisition of more data is essential to evaluate these novel technology platforms.

Targeted biopsy: benefits and limitations

PURPOSE OF REVIEW

To review the current literature regarding the role of multiparametric MRI and fusion-guided biopsies in urologic practice.

RECENT FINDINGS

Fusion biopsies consistently show an increase in the detection of clinically significant cancers and decrease in low-risk disease that may be more suitable for active surveillance. Although, when to incorporate multiparametric MRI into workup is not clearly agreed upon, studies have shown a clear benefit in both biopsy naïve and those with prior negative biopsies in determining the appropriate treatment strategy. More recently, cost-analysis models have been published that show that upfront MRIs are more cost-effective when considering missed cancers and treatment courses.

SUMMARY

With improved accuracy over systematic biopsies, fusion biopsies are a superior method for detection of the true grade of cancer for both biopsy naïve and patients with prior negative biopsies, choosing appropriate candidates for active surveillance, and monitoring progression on active surveillance.

Computer-assisted surgery: virtual- and augmented-reality displays for navigation during urological interventions

PURPOSE OF REVIEW

To provide an overview of the developments made for virtual- and augmented-reality navigation procedures in urological interventions/surgery.

RECENT FINDINGS

Navigation efforts have demonstrated potential in the field of urology by supporting guidance for various disorders. The navigation approaches differ between the individual indications, but seem interchangeable to a certain extent. An increasing number of pre- and intra-operative imaging modalities has been used to create detailed surgical roadmaps, namely: (cone-beam) computed tomography, MRI, ultrasound, and single-photon emission computed tomography. Registration of these surgical roadmaps with the real-life surgical view has occurred in different forms (e.g. electromagnetic, mechanical, vision, or near-infrared optical-based), whereby the combination of approaches was suggested to provide superior outcome. Soft-tissue deformations demand the use of confirmatory interventional (imaging) modalities. This has resulted in the introduction of new intraoperative modalities such as drop-in US, transurethral US, (drop-in) gamma probes and fluorescence cameras. These noninvasive modalities provide an alternative to invasive technologies that expose the patients to X-ray doses. Whereas some reports have indicated navigation setups provide equal or better results than conventional approaches, most trials have been performed in relatively small patient groups and clear follow-up data are missing.

SUMMARY

The reported computer-assisted surgery research concepts provide a glimpse in to the future application of navigation technologies in the field of urology.

A comparison of magnetic resonance imaging techniques used to secure biopsies in prostate cancer patients

Introduction: Prostate cancer (PCa) is the most common diagnosed malignancy among the male population in the United States. The incidence is increasing with an estimated amount of 175.000 cases in 2019. Areas covered: Primarily, PCa is generally detected by an elevated or rising serum prostate-specific antigen (PSA) and digital rectal examination (DRE) followed by pathological examination. Histopathology ultimately confirms the presence of PCa and determines a Gleason score. However, PSA and DRE have low specificity and sensitivity, respectively. Subsequently, accurate assessment of the aggressiveness of PCa is essential to prevent overdiagnosis and thus overtreatment of low-risk or indolent cancers. By visualizing PCa suspicious lesions and sampling them during the targeted biopsy, it is likely that the diagnostic accuracy of significant PCa improves. This article reviews the current imaging techniques used to secure biopsies in patients with a suspicion of PCa. The advantages and limitations of each technique are described. Expert opinion: Multiparametric magnetic resonance imaging (mpMRI) and subsequent-targeted biopsy have improved the diagnostic accuracy of PCa detection in men with an elevated or rising serum PSA. Prostate lesions visible on mpMRI are easily targeted during either in-bore MRI-guided biopsy, cognitive fusion biopsy or MRI-TRUS fusion biopsy.

Photoacoustic tomography for imaging the prostate: a transurethral illumination probe design and application

In vivo imaging of prostate cancer with photoacoustic tomography is currently limited by the lack of sufficient local fluence for deep tissue penetration and the risk of over-irradiation near the laser-tissue contact surface. We propose the design of a transurethral illumination probe that addresses those limitations. A high energy of 50 mJ/pulse is coupled into a 1000-µm-core diameter multimode fiber. A 2 cm diffusing end is fabricated, which delivers light in radial illumination. The radial illumination is then reflected and reshaped by a parabolic cylindrical mirror to obtain nearly parallel side illumination with a doubled fluence. The fiber assembly is housed in a 25 Fr cystoscope sheath to provide protection of the fiber and maintain a minimal laser-tissue contact distance of 5 mm. A large laser-tissue contact surface area of 4 cm² is obtained and the fluence on the tissue surface is kept below the maximum permissible exposure. By imaging a prostate mimicking phantom, a penetration depth of 3.5 cm at 10 mJ/cm² fluence and 700 nm wavelength is demonstrated. The results indicate that photoacoustic tomography with the proposed transurethral probe has the potential to image the entire prostate while satisfying the fluence maximum permissible exposure and delivering a high power to the tissue.

Magnetic resonance imaging-transrectal ultrasound fusion image-guided prostate biopsy: Current status of the cancer detection and the prospects of tailor-made medicine of the prostate cancer

Multi-parametric magnetic resonance imaging (mpMRI) has been increasingly used to diagnose clinically significant prostate cancer (csPCa) because of its growing availability and its ability to combine anatomical and functional data. Magnetic resonance imaging (MRI)-transrectal ultrasound (TRUS) fusion imaging provides MRI information with TRUS images for prostate biopsies. This technique combines the superior sensitivity of MRI for targeting suspicious lesions with the practicality and familiarity of TRUS. MRI-TRUS fusion image-guided prostate biopsy is performed with different types of image registration (rigid vs. elastic) and needle tracking methods (electromagnetic tracking vs. mechanical position encoders vs. image-based software tracking). A systematic review and meta-analysis showed that MRI-targeted biopsy detected csPCa at a significantly higher rate than did TRUS-guided biopsy, while it detected significantly fewer cases of insignificant PCas. In addition to the high accuracy of MRI-targeted biopsy for csPCa, localization of csPCa is accurate. The ability to choose the route of biopsy (transperineal vs. transrectal) is required, depending on the patients' risk and the location and size of suspicious lesions on mpMRI. Fusion image-guided prostate biopsy has the potential to allow precise management of prostate cancer, including active surveillance, radical treatment, and focal therapy.

"Super-active surveillance": MRI ultrasound fusion biopsy and ablation for less invasive management of prostate cancer

Multiparametric magnetic resonance imaging (mpMRI) of the prostate has allowed clinicians to better visualize and target suspicious lesions during biopsy. Targeted prostate biopsies give a more accurate representation of the true cancer volume and stage so that appropriate treatment or active surveillance can be selected. Advances in technology have led to the development of MRI and ultrasound fusion platforms used for targeted biopsies, monitoring cancer progression, and more recently for the application of focal therapy. Lesions visualized on mpMRI can be targeted for ablation with a variety of energy sources employed under both local and general anesthesia. Focal ablation may offer an alternative option for treating prostate cancer as compared to the well-established interventions of whole-gland radiation or prostatectomy. Focal ablation may also be an option for patients on active surveillance who wish to be even more "active" in their surveillance. In this review, we describe the advancements and development of fusion biopsies, the rationale behind focal therapy, and introduce focal ablative techniques for indolent prostate cancers ("super-active surveillance"), including cryoablation and focal laser ablation (FLA) and the subsequent MRI/biopsy surveillance.

Prognostic Value of Neutrophil to Lymphocyte Ratio on Pathologic Findings of Transrectal Ultrasonography Guided Biopsy of Prostate

BACKGROUND AND OBJECTIVE

Prostate cancer is considered as one of the most common malignancies in males. Despite the decreasing trend during the past decade, the incidence continues to rise in adolescents worldwide. Recently, new emerging technologies beside TRUS-guided prostate biopsy were introduced and showed high potential in the diagnosis of prostate cancer. The current study aimed at investigating the role of blood cell count and its prognostic value on pathologic findings.

METHODS

The current prospective analysis was conducted on patients with abnormality from January 2013 to January 2016. A total of 168 CBC tests including absolute Neutrophil and lymphocyte counts were performed on males at the Department of Urology, Razi University Hospital (Guilan, Iran). Of these, all males had both CBCs and free:total (F/T) prostate-specific antigen (PSA) ratio.

RESULTS

Average age of patients was 63.5±7. It was observed that Neutrophil count and Neutrophil percentage was not significantly different among the groups with different pathologies. In comparison to biopsy findings none of the cell count had suitable specificity and sensitivity. In the multivariate analysis to predict malignancy, only age (B=0.1, S.E=0.04, EXP [B]) =1.1 and sig=0.00) and PSA level (B=0.1, S.E=0.04, EXP [B]) =1.1 and sig=0.00) were significant.

CONCLUSIONS

In comparison to biopsy findings, none of the cell counts (absolute or percent) had suitable specificity and sensitivity, and the cell count and percentage before biopsy were not different among the groups with different pathologies. Powerful and long-term studies are required to evaluate prognostic values of cell count on adenocarcinoma.

Analysis of histological findings obtained combining US/mp-MRI fusion-guided biopsies with systematic US biopsies: mp-MRI role in prostate cancer detection and false negative

AIMS AND OBJECTIVES

To evaluate the diagnostic accuracy of mp-MRI correlating US/mp-MRI fusion-guided biopsy with systematic random US-guided biopsy in prostate cancer diagnosis.

MATERIALS AND METHODS

137 suspected prostatic abnormalities were identified on mp-MRI (1.5T) in 96 patients and classified according to PI-RADS score v2. All target lesions underwent US/mp-MRI fusion biopsy and prostatic sampling was completed by US-guided systematic random 12-core biopsies. Histological analysis and Gleason score were established for all the samples, both target lesions defined by mp-MRI, and random biopsies. PI-RADS score was correlated with the histological results, divided in three groups (benign tissue, atypia and carcinoma) and with Gleason groups, divided in four categories considering the new Grading system of the ISUP 2014, using t test. Multivariate analysis was used to correlate PI-RADS and Gleason categories to PSA level and abnormalities axial diameter. When the random core biopsies showed carcinoma (mp-MRI false-negatives), PSA value and lesions Gleason median value were compared with those of carcinomas identified by mp-MRI (true-positives), using t test.

RESULTS

There was statistically significant difference between PI-RADS score in carcinoma, atypia and benign lesions groups (4.41, 3.61 and 3.24, respectively) and between PI-RADS score in Gleason < 7 group and Gleason > 7 group (4.14 and 4.79, respectively). mp-MRI performance was more accurate for lesions > 15 mm and in patients with PSA > 6 ng/ml. In systematic sampling, 130 (11.25%) mp-MRI false-negative were identified. There was no statistic difference in Gleason median value (7.0 vs 7.06) between this group and the mp-MRI true-positives, but a significant lower PSA median value was demonstrated (7.08 vs 7.53 ng/ml).

CONCLUSION

mp-MRI remains the imaging modality of choice to identify PCa lesions. Integrating US-guided random sampling with US/mp-MRI fusion target lesions sampling, 3.49% of false-negative were identified.

3-T multiparametric MRI characteristics of prostate cancer patients suspicious for biochemical recurrence after primary focal cryosurgery (hemiablation)

INTRODUCTION

We aimed to report on multiparametric MRI (mpMRI) characteristics of post-primary focal cryosurgery (PFC) patients suspected of biochemical recurrence (BCR) by the Phoenix criteria.

METHODS

We retrospectively reviewed all patients at our institution who had undergone PFC. Prostate-specific antigen nadir was determined using 2 or more post-PFC values. Suspicion of BCR was determined using the Phoenix criteria (nadir + 2 ng/ml). At the discretion of the physician, pre-and post-PFC 3-T mpMRIs were obtained and in a few cases biopsies were performed.

RESULTS

Ninety (58.4%) of 154 consecutive patients who underwent PFC were included in our analysis and had a median (range) age and prostate volume of 66.5 (48-82) years and 40.5 (16-175) ml, respectively. Of those suspected of BCR (37/90, 41.1%), with a median time to BCR of 19.9 (7.0-38.5) months, 27 patients (73.0%) underwent a post-PFC mpMRI. Twenty-two (81.5%) of these mpMRIs were found with 24 suspicious lesions. A considerable number (9/24, 37.5%) of these lesions were located in the central gland of the prostate. Seven of 24 lesions exhibited adverse mpMRI characteristic; 4 (16.7%) had capsular contact, 2 (8.2%) showed frank extracapsular extension, and 1 (4.2%) showed seminal vesicle invasion. Five (45.5%) of 11 patients with positive post-PFC mpMRIs were positive on biopsy (4/5, 80% were clinically significant prostate cancer).

CONCLUSION

Post-PFC mpMRI, at Phoenix suspicion of BCR, may help identify a significant number of patients failing post-PFC.

A critical comparison of techniques for MRI-targeted biopsy of the prostate

MRI-targeted biopsy is a promising technique that offers an improved detection of clinically significant prostate cancer over standard non-targeted biopsy. It is established that prostate MRI is of use in both the primary and repeat biopsy setting for the detection of significant prostate cancer. There are three approaches to targeting biopsies to areas of interest seen on prostate MRI. They each rely on the acquisition and reporting of a diagnostic quality multi-parametric MRI scan used to identify areas of interest, and the subsequent use of those diagnostic quality images in combination with real-time images of the prostate during the biopsy procedure. The three techniques are: visual registration of the MRI images with a real-time ultrasound image; software-assisted fusion of the MRI images and the real-time ultrasound images, and in-bore biopsy, which requires registration of a diagnostic quality MRI scan with a real time interventional MRI image. In this paper we compare the three techniques and evaluate those studies where there is a direct comparison of more than one MRI-targeting technique. PubMed was searched from inception to November 2016 using the search terms (cognitive registration OR visual registration OR fusion biopsy OR in-bore biopsy OR targeted biopsy) AND (prostate cancer OR prostate adenocarcinoma OR prostate carcinoma OR prostatic carcinoma OR prostatic adenocarcinoma) AND (MRI OR NMR OR magnetic resonance imaging OR mpMRI OR multiparametric MRI). The initial search included 731 abstracts. Eleven full text papers directly compared two or more techniques of MRI-targeting, and were selected for inclusion. The detection of clinically significant prostate cancer varied from 0% to 93.3% for visual registration, 23.2% to 100% for software-assisted registration and 29% to 80% for in-bore biopsy. Detection rates for clinically significant cancer are dependent on the prevalence of cancer within the population biopsied, which in turn is determined by the selection criteria [biopsy naïve, previous negative biopsy, prostate specific antigen (PSA) selection criteria, presence of a lesion on MRI]. Cancer detection rates varied more between study populations than between biopsy approaches. Currently there is no consensus on which type of MRI-targeted biopsy performs better in a given setting. Although there have been studies supporting each of the three techniques, substantial differences in methodology and reporting the findings make it difficult to reliably compare their outcomes.

Multiparametric MRI/ultrasound fusion-guided biopsy decreases detection of indolent cancer in African-American men

BACKGROUND

Analysis of systematic 12-core biopsies (SBx) has shown that African-American (AA) men tend to harbor higher risk prostate cancer (PCa) at presentation relative to other races. Multiparametric magnetic resonance imaging (mpMRI) and MRI-ultrasound fusion-guided biopsy (FBx) have been shown to diagnose more intermediate- and high-risk PCa in the general population; however, the efficacy in AA remains largely uncharacterized. We aim to evaluate the utility of FBx in an AA patient cohort.

METHODS

Men suspected of PCa underwent an mpMRI and FBx with concurrent SBx from 2007 to 2015 in this institutional review board-approved prospective cohort study. Patient demographics, imaging and fusion biopsy variables were collected. χ², Mann-Whitney U-test and McNemar's tests were performed to compare proportions, means and paired variables, respectively. Clinically significant PCa (CSPCa) was defined as Gleason score ⩾3+4.

RESULTS

Fusion biopsy demonstrated exact agreement with SBx risk categories in 64% of AA men. There was no statistically significant difference in the detection of CSPCa between FBx vs SBx (68 vs 62 cases, P=0.36). However, FBx detected 41% fewer cases of clinically insignificant PCa (CIPCa) compared with SBx (FBx 30 vs SBx 51 cases, P=0.0004). The combined FBx/SBx biopsy approach detected significantly more cases of CSPCa (FBx/SBx 80 vs SBx 62 cases, P=0.004) while detecting comparable number of cases of CIPCa (FBx/SBx 45 vs SBx 51 cases, P=0.37) compared with SBx alone. FBx/SBx also detected more CSPCa in patients with a history of prior negative SBx (FBx/SBx 28 vs 19 cases, P=0.003).

CONCLUSIONS

FBx when used in combination with SBx detected more cases of CSPCa while not significantly increasing the diagnosis of CIPCa in AA men. Future multicenter studies will be needed to validate ultimately the clinical implications of FBx in AA patients.

Ultrasound-Guided Biopsies of Bone Lesions Without Cortical Disruption Using Fusion Imaging and Needle Tracking: Proof of Concept

OBJECTIVE

To assess the technical feasibility and safety of combined fusion imaging and needle tracking under ultrasound guidance to target bone lesions without cortical disruption.

MATERIALS AND METHODS

Between January 2016 and March 2016, seven patients underwent US-guided biopsy of bone lesions without cortical disruption. Targeted bone lesions were measuring more than 1.5 cm with a thin cortex, a trans-osseous pathway not exceeding 2 cm and without any adjacent vulnerable structures. First three procedures were performed in the CT suite to aid the needle tracking where necessary (group 1), the remaining four procedures were performed in the US suite (group 2). In group 1, deviation from the real position of the bone trocar (estimated on CT) was compared to the virtual position (estimated on the fusion CT-US images). In both group, procedure data and histopathological results were collected, and compared to the suspected diagnosis and follow-up.

RESULTS

Mean procedure duration was 44 min. Total number of synchronisation points for combined fusion imaging were 3.3 on average. In group 1, mean deviation between the virtual and real CT coordinates was 5.3 mm on average. All biopsies yielded adequate quality analysable bone sample. Histopathological analysis revealed malignancy in three cases, non-specific inflammation in two cases, and normal bone in two cases. The four benign results were confirmed as true negative results. There were no immediate or post-procedural complications.

CONCLUSION

The use of combined fusion imaging and needle tracking ultrasound guidance to target bone lesions without cortical disruption seems technically feasible, provided the patient and lesion selection is appropriate.

Indications for a second prostate biopsy in patients suspected with prostate cancer after an initial negative prostate biopsy

BACKGROUND

The present study aimed to evaluate the indications for a second prostate biopsy in patients suspected with prostate cancer after an initial negative prostate biopsy.

METHODS

The present study included 421 patients who underwent repeat prostate biopsy between January 2007 and December 2015 at three hospitals. Clinicopathological data, including patient age, body mass index, history of prostate biopsy, prostate volume, prostate-specific antigen (PSA) level, PSA density, PSA velocity, and PSA fluctuation patterns, were analyzed. The patients were stratified into two groups based on the first PSA pattern (increase/decrease) within 1 year after the initial negative prostate biopsy.

RESULTS

Prostate cancer was detected in 100 (23.8%) of the 421 patients at the second prostate biopsy. In patients with a PSA decrease at the first follow-up, prostate volume and number of increases in the PSA level from the initial prostate biopsy were predictors for prostate cancer diagnosis at the second prostate biopsy. In patients with a steady PSA increase after the initial prostate biopsy, prostate volume and number of biopsy cores were predictors for prostate cancer diagnosis at the second prostate biopsy.

CONCLUSION

The indications for a second prostate biopsy are a low prostate volume and a high number of increases in the PSA level among patients with a PSA decrease at the first follow-up and a low prostate volume and a high number of biopsy cores among patients with a PSA increase at the first follow-up.

Accuracy of real-time magnetic resonance imaging-transrectal ultrasound fusion image-guided transperineal target biopsy with needle tracking with a mechanical position-encoded stepper in detecting significant prostate cancer in biopsy-naïve men

OBJECTIVE

To evaluate the accuracy of real-time elastic fusion image-guided transperineal prostate biopsy with needle tracking involving a mechanical position-encoded stepper in detecting clinically significant prostate cancer for biopsy-naïve men.

METHODS

We prospectively recruited patients with serum prostate-specific antigen levels of 4.0-20 ng/mL and suspicious of prostate cancer on multiparametric magnetic resonance imaging. They underwent targeted biopsies for cancer-suspicious lesions and 12-core systematic biopsies. Pathological findings from biopsy cores and whole-mount specimens (for those who underwent radical prostatectomy) were analyzed.

RESULTS

A total of 250 patients were included, in whom targeted and systematic biopsies detected significant cancers in 55% and 25%, respectively (P < 0.001). The targeted biopsy cores (n = 527) showed significantly greater biopsy-proven significant cancer detection rates (P < 0.001), cancer core length (P < 0.0001), cancer core percentage (P < 0.001) and Gleason scores (P < 0.001) than did the systematic biopsies. The significant cancer detection rate for targeted lesions (those with Prostate Imaging and Reporting and Data System classification scores of 5) was 80%. Biopsy-proven significant cancer detection rates for targeted lesions ≤10 mm and >10 mm were similar for Prostate Imaging and Reporting and Data System scores of 4 (P = 0.707) and 5 (P = 0.386). In whole-mount specimens (n = 30), locations for 95% of significant cancers were diagnosed preoperatively. Targeted biopsies alone diagnosed 79% of significant cancers.

CONCLUSIONS

Although targeted biopsies are superior to systematic biopsies in detecting significant cancers, systematic biopsies maintain an important role in the diagnosis of prostate cancer in biopsy-naïve men.

Multiparametric Magnetic Resonance/Ultrasound Fusion Prostate Biopsy: Number and Spatial Distribution of Cores for Better Index Tumor Detection and Characterization

PURPOSE

We evaluated the minimum core number for better index tumor detection to determine the best core site as well as biopsy Gleason score heterogeneity in the same index lesion. The aim was to optimize the highest Gleason score detection.

MATERIALS AND METHODS

A total of 327 patients with negative digital rectal examination underwent magnetic resonance imaging/transrectal ultrasound fusion targeted biopsy for elevated/rising prostate specific antigen and/or 1 or more detectable lesions on multiparametric magnetic resonance imaging after a previous negative standard biopsy. Depending on the diameter of each index lesion (8 or less, or greater than 8 mm) 4 or 6 cores, respectively, were taken according to a well determined sequence.

RESULTS

Of the patients 166 (50.7%) had prostate cancer, including 79 (47.6%) with an 8 mm or less index lesion and 87 (52.4%) with a greater than 8 mm index lesion. Of patients with an index tumor 8 mm or less 7 (8.9%) had 1, 31 (39.2%) had 2, 27 (34.2%) had 3 and 14 (17.7%) had 4 positive cores. Similarly, of patients with a lesion greater than 8 mm 8 (9.2%) had 1, 30 (34.5%) had 2, 13 (14.9%) had 3, 14 (16.1%) had 4, 12 (13.8%) had 5 and 10 (11.5%) had 6 positive cores. The major prevalence of positive cores was observed in the center of the target. Gleason score heterogeneity was found in 12.6% of those with an 8 mm or less target vs 26.4% with a target greater than 8 mm. In the center of the target there was a slight prevalence of Gleason pattern 4 or greater, or a lesser pattern.

CONCLUSIONS

Approaching magnetic resonance imaging/transrectal ultrasound fusion targeted biopsy with a single core might be inadequate. Rather, taking 2 cores in the center of the index lesion may provide more accurate cancer detection and optimize the chances of finding the highest Gleason pattern.

Current beliefs and practice patterns among urologists regarding prostate magnetic resonance imaging and magnetic resonance-targeted biopsy

INTRODUCTION AND OBJECTIVE

Multiparametric magnetic resonance imaging (MRI) and magnetic resonance (MR) -targeted biopsy have a growing role in the screening and evaluation of prostate cancer. We aim to evaluate the current knowledge, attitude, and practice patterns of urologists regarding this new technique.

METHODS

An anonymous online questionnaire was designed to collect information on urologists' beliefs and use of prostate multiparametric MRI and MR-targeted biopsy. The survey was sent to members of the Society of Urologic Oncology, the Endourological Society, and European Association of Urology. Multivariate logistic regression analysis was performed to determine predictors for use of prostate MRI and MR-targeted biopsy.

RESULTS

A total of 302 responses were received (Endourological Society: 175, European Association of Urology: 23, and Society of Urologic Oncology: 104). Most respondents (83.6%) believe MR-targeted biopsy to be moderately to extremely beneficial in the evaluation of prostate cancer. Overall, 85.7% of responders use prostate MRI in their practice, and 63.0% use MR-targeted biopsy. The 2 most common settings for use of MR-targeted biopsy include patients with history of prior negative biopsy result (96.3%) and monitoring patients on active surveillance (72.5%). In those who do not use MR-targeted biopsy, the principal reasons were lack of necessary infrastructure (64.1%) and prohibitive costs (48.1%). On multivariate logistic regression analysis, practice in an academic setting (1.86 [1.02-3.40], P = 0.043) and performing greater than 25 radical prostatectomies per year (2.32 [1.18-4.56], P = 0.015) remained independent predictors for using MR-targeted biopsy.

CONCLUSIONS

Most respondents of our survey look favorably on use of prostate MRI and MR-targeted biopsy in clinical practice. Over time, reduction in fixed costs and easier access to equipment may lead to further dissemination of this novel and potentially transformative technology.

Magnetic Resonance Imaging-Transrectal Ultrasound Guided Fusion Biopsy to Detect Progression in Patients with Existing Lesions on Active Surveillance for Low and Intermediate Risk Prostate Cancer

PURPOSE

Active surveillance is an established option for men with low risk prostate cancer. Multiparametric magnetic resonance imaging with magnetic resonance imaging-transrectal ultrasound fusion guided biopsy may better identify patients for active surveillance compared to systematic 12-core biopsy due to improved risk stratification. To our knowledge the performance of multiparametric magnetic resonance imaging in following men on active surveillance with visible lesions is unknown. We evaluated multiparametric magnetic resonance imaging and magnetic resonance imaging-transrectal ultrasound fusion guided biopsy to monitor men on active surveillance.

MATERIALS AND METHODS

This retrospective review included men from 2007 to 2015 with prostate cancer on active surveillance in whom magnetic resonance imaging visible lesions were monitored by multiparametric magnetic resonance imaging and fusion guided biopsy. Progression was defined by ISUP (International Society of Urological Pathology) grade group 1 to 2 and ISUP grade group 2 to 3. Significance was considered at p ≤0.05.

RESULTS

A total of 166 patients on active surveillance with 2 or more fusion guided biopsies were included in analysis. Mean followup was 25.5 months. Of the patients 29.5% had pathological progression. Targeted biopsy alone identified 44.9% of patients who progressed compared to 30.6% identified by systematic 12-core biopsy alone (p = 0.03). Fusion guided biopsy detected 26% more cases of pathological progression on surveillance biopsy compared to systematic 12-core biopsy. Progression on multiparametric magnetic resonance imaging was the sole predictor of pathological progression at surveillance biopsy (p = 0.013). Multiparametric magnetic resonance imaging progression in the entire cohort had 81% negative predictive value, 35% positive predictive value, 77.6% sensitivity and 40.5% specificity in detecting pathological progression.

CONCLUSIONS

Multiparametric magnetic resonance imaging progression predicts the risk of pathological progression. Patients with stable multiparametric magnetic resonance imaging findings have a low rate of progression. Incorporating fusion guided biopsy in active surveillance nearly doubled our detection of pathological progression compared to systematic 12-core biopsy.

Transperineal Versus Transrectal MRI/TRUS Fusion Targeted Biopsy: Detection Rate of Clinically Significant Prostate Cancer

INTRODUCTION

To evaluate the detection rate for clinically significant prostate cancer (PCa) of transperineal (TP) versus transrectal (TR) multiparametric (mp) magnetic resonance imaging (MRI)/transrectal ultrasound-guided (TRUS) fusion targeted biopsy.

PATIENTS AND METHODS

From January 2015 to January 2016, a total of 200 men (median age, 61 years) with negative digital rectal examination findings underwent repeat saturation TP prostate biopsy (SPBx; median 30 cores) for increasing or persistent elevated prostate-specific antigen values. Ten day before SPBx, all patients underwent 3.0 T pelvic mpMRI (Achieva 3T; Philips Healthcare Best, Netherlands). In the presence of mpMRI lesions suggestive of cancer (Prostate Imaging-Reporting and Data System [PI-RADS] score 4/5), targeted mpMRI/TRUS TR fusion guided biopsies (4 cores) and TP cognitive biopsies (4 cores) were added to SPBx.

RESULTS

Median prostate-specific antigen was 8.6 ng/mL, and mpMRI revealed a suspicious lesion in 95 (47.5%) of 200 cases. Overall, in 60 (30%) of 200 men, a clinically significant PCa was found, and in all cases, mpMRI was positive. SPBx, TR fusion, and mpMRI/TRUS TP cognitive targeted biopsy diagnosed 59 (98.3%), 40 (78.3%), and 56 (93.3%) clinically significant PCa, respectively. TR fusion versus TP targeted biopsy missed 12 versus 1 (P = .001) cancers of the anterior zone and 8 versus 3 (P = .12) cancers of the peripheric gland, respectively; moreover, PCa diagnosed by TR fusion versus TP targeted biopsy had a mpMRI lesion diameter and percentage of positive cores equal to 13 versus 10 mm and 33% versus 58% (P = .001), respectively.

CONCLUSION

mpMRI/TRUS TP cognitive targeted biopsy found a greater percentage of clinically significant PCa of the anterior zone compared to the mpMRI/TRUS TR fusion approach (93.3% vs. 25%; P = .0001).

Diagnosis and Monitoring of Prostatic Lesions: A Comparison of Three Modalities: Multiparametric MRI, Fusion MRI/Transrectal Ultrasound (TRUS), and Traditional TRUS

PURPOSE

 Transrectal ultrasound (TRUS) has been the gold standard of imaging for diagnosing prostate cancer for decades but is plagued by user error and undersampling. We aim to explore imaging modalities that are now being used in combination or alone for screening, diagnosis, and/or active surveillance of prostate cancer.

METHODS

A PubMed literature search was performed to include articles published up to April 2016. Data were extracted and analyzed.

RESULTS

Several large-scale studies have found an increased cancer detection rate in MRI-targeted lesions with an improved ability to target anterior lesions as well as an increased cancer detection in high-risk cancers using fusion platforms vs TRUS alone.

CONCLUSIONS

To date, there have been few head-to-head trials to directly compare the use of multiparametric MRI (mpMRI), transrectal ultrasound, and MRI-ultrasound fusion modalities for accurate and reliable detection, active surveillance, or biopsy procedure success rates. Further investigation utilizing these modalities are needed before they can be relied upon in active surveillance management, although mpMRI appears to be currently the most reliable in monitoring and diagnosing prostate lesions.

Risk stratification of prostate cancer: integrating multiparametric MRI, nomograms and biomarkers

Accurate risk stratification of prostate cancer is achieved with a number of existing tools to ensure the identification of at-risk patients, characterization of disease aggressiveness, prediction of cancer burden and extrapolation of treatment outcomes for appropriate management of the disease. Statistical tables and nomograms using classic clinicopathological variables have long been the standard of care. However, the introduction of multiparametric MRI, along with fusion-guided targeted prostate biopsy and novel biomarkers, are being assimilated into clinical practice. The majority of studies to date present the outcomes of each in isolation. The current review offers a critical and objective assessment regarding the integration of multiparametric MRI and fusion-guided prostate biopsy with novel biomarkers and predictive nomograms in contemporary clinical practice.

Midline lesions of the prostate: role of MRI/TRUS fusion biopsy and implications in Gleason risk stratification

PURPOSE

MRI-TRUS fusion biopsy (FBx) has proven efficacy in targeting suspicious areas that are traditionally missed by systematic 12-core biopsy (SBx). Midline prostate lesions are undersampled during SBx, as traditional approaches aim laterally during TRUS biopsy. The aim of our study was to determine the utility of FBx for targeting midline lesions identified on multiparametric MRI (mpMRI).

METHODS

A review was performed of a prospectively maintained database of patients undergoing mpMRI followed by FBx and SBx from 2007 to 2015. Midline location was defined as any lesion crossing the midline on axial imaging and involving both prostatic lobes. Index lesion was defined as lesion with highest Gleason score on biopsy. Patient demographic, imaging, and histopathologic data were collected. Multivariate logistic regression was conducted to determine independent predictors of having clinically significant (CS) cancer (Gleason ≥ 7) in midline lesions.

RESULTS

Out of 1266 patients, we identified 202 suspicious midline lesions in 190 patients [median (IQR) age 63 (10) years; PSA 7.6 (6.6)]. Eighty-eight (46.3 %) patients had cancer detection on FBx of midline lesion. A midline target represented the index lesion of the prostate in 63/190 (33.2 %) patients. Risk category upgrading based on FBx of a midline lesion compared to SBx occurred in 45/190 patients (23.7 %). On multivariate analysis, higher PSA (p = .001), lower MRI-derived prostate volume (p < .001), and moderate-high or high suspicion on mpMRI (p = .014) predicted CS cancer in midline lesions.

CONCLUSIONS

MRI-TRUS FBx facilitates sampling of midline lesions. Integration of mpMRI and FBx for targeting of midline lesions improves detection of CS prostate cancer.

A urologist's perspective on prostate cancer imaging: past, present, and future

Prostate cancer is unique in that unlike other solid organ malignancies, only recently has imaging been employed to routinely detect and localize disease. The introduction of transrectal ultrasound was a significant development, transitioning digitally guided prostate biopsies to ultrasound guidance. The arrival of multiparametric MRI has become the next major step, transforming the way Urologist's diagnose, stage, and treat prostate cancer. Recent recommendations against PSA screening have changed the landscape of urologic oncology with the changing needs being reflected in the initiation of additional robust imaging techniques at different time points in prostate cancer care. The current review aims to provide a clinical perspective in the history, current standard of care, and novel imaging modalities in the evaluation of prostate cancer.