Robotic transperineal prostate biopsy: pilot clinical study

TransVFS: A spatio-temporal local-global transformer for vision-based force sensing during ultrasound-guided prostate biopsy

Robot-assisted prostate biopsy is a new technology to diagnose prostate cancer, but its safety is influenced by the inability of robots to sense the tool-tissue interaction force accurately during biopsy. Recently, vision based force sensing (VFS) provides a potential solution to this issue by utilizing image sequences to infer the interaction force. However, the existing mainstream VFS methods cannot realize the accurate force sensing due to the adoption of convolutional or recurrent neural network to learn deformation from the optical images and some of these methods are not efficient especially when the recurrent convolutional operations are involved. This paper has presented a Transformer based VFS (TransVFS) method by leveraging ultrasound volume sequences acquired during prostate biopsy. The TransVFS method uses a spatio-temporal local-global Transformer to capture the local image details and the global dependency simultaneously to learn prostate deformations for force estimation. Distinctively, our method explores both the spatial and temporal attention mechanisms for image feature learning, thereby addressing the influence of the low ultrasound image resolution and the unclear prostate boundary on the accurate force estimation. Meanwhile, the two efficient local-global attention modules are introduced to reduce 4D spatio-temporal computation burden by utilizing the factorized spatio-temporal processing strategy, thereby facilitating the fast force estimation. Experiments on prostate phantom and beagle dogs show that our method significantly outperforms existing VFS methods and other spatio-temporal Transformer models. The TransVFS method surpasses the most competitive compared method ResNet3dGRU by providing the mean absolute errors of force estimation, i.e., 70.4 ± 60.0 millinewton (mN) vs 123.7 ± 95.6 mN, on the transabdominal ultrasound dataset of dogs.

The learning curve for robotic-assisted transperineal MRI/US fusion-guided prostate biopsy

Transperineal fusion prostate biopsy has a considerable learning curve (LC). Robotic-assisted transperineal MRI/Ultrasound fusion-guided biopsy (RA-TP-FBx) may have an easier LC due to automatization. We aimed to assess the LC of RA-TP-FBx and analyze its most difficult steps. We prospectively analyzed cases randomized to a biopsy-naïve urology resident, the chief resident, and an expert urologist in RA-TP-FBx (controls). We also analyzed consecutive cases in the LC of the expert. The LC was defined by procedure time, PCa detection rate (including stratification by PI-RADS), entrustable professional activities (EPA) assessment scores, and the NASA task load index. We collectively performed 246 RA-TP-FBx with the Mona Lisa device. Procedure time for residents decreased steeply from maximum 53 min to minimum 10 min, while the mean procedure time for the expert was 9 min (range 17-5 min). PCa detection for PI-RADS-4 lesions was 57% for the naïve resident, 61% for the chief resident and 62% for the expert. There was also no difference in Pca detection for PI-RADS-4 lesions when comparing the first and second half of the experts' biopsies (p = 0.8). Maximum EPA score was registered after 22 cases. Workload steeply declined. Proficient RA-TP-FBx performance appears feasible after 22 cases regardless of previous experience.

Shifting to transperineal prostate biopsy: A narrative review

To address the limitations and challenges associated with transrectal (TR) biopsy and to present transperineal (TP) biopsy as a viable and potentially safer alternative to TR biopsy. Prostate cancer (PCa) is a significant global health concern. The prevalence of advanced-stage prostate cancer in Asia is higher than that in the United States, emphasizing the need for effective screening and diagnosis methods. The gold standard of diagnosis is a TR biopsy. However, it has limitations due to the risk of infection and potential complications, such as injury to the rectal artery. Efforts have been made to address issues such as false-negative biopsies, under-sampling, and over-sampling through MRI-guided biopsies. However, the TR approach makes it difficult to access the apical and anterior regions of the prostate. TP biopsy has emerged as an alternative to address the limitations of TR biopsy. Nevertheless, a TP biopsy is a painful procedure, requiring the use of general anesthesia and expensive equipment. As a result, it has been perceived as costly and time-consuming. In addition, it requires a steep learning curve. The introduction of local anesthesia such as pudendal nerve block and the adoption of freehand techniques have contributed to the feasibility of performing TP biopsy. Recent research indicates that freehand TP biopsy can yield comparable diagnostic results to template-guided approaches. The diagnostic performance, cancer detection rates, and complication rates of TP biopsy have demonstrated its potential as a safe and effective diagnostic method.

Image-guided prostate biopsy robots: A review

At present, the incidence of prostate cancer (PCa) in men is increasing year by year. So, the early diagnosis of PCa is of great significance. Transrectal ultrasonography (TRUS)-guided biopsy is a common method for diagnosing PCa. The biopsy process is performed manually by urologists but the diagnostic rate is only 20%-30% and its reliability and accuracy can no longer meet clinical needs. The image-guided prostate biopsy robot has the advantages of a high degree of automation, does not rely on the skills and experience of operators, reduces the work intensity and operation time of urologists and so on. Capable of delivering biopsy needles to pre-defined biopsy locations with minimal needle placement errors, it makes up for the shortcomings of traditional free-hand biopsy and improves the reliability and accuracy of biopsy. The integration of medical imaging technology and the robotic system is an important means for accurate tumor location, biopsy puncture path planning and visualization. This paper mainly reviews image-guided prostate biopsy robots. According to the existing literature, guidance modalities are divided into magnetic resonance imaging (MRI), ultrasound (US) and fusion image. First, the robot structure research by different guided methods is the main line and the actuators and material research of these guided modalities is the auxiliary line to introduce and compare. Second, the robot image-guided localization technology is discussed. Finally, the image-guided prostate biopsy robot is summarized and suggestions for future development are provided.

Robot-Assisted Magnetic Resonance Imaging-Targeted versus Systematic Prostate Biopsy; Systematic Review and Meta-Analysis

INTRODUCTION

Robot-assisted devices have been recently developed for use in prostate biopsy. However, it is possible advantages over standard biopsy remain unclear. We aimed to assess the diagnostic performance and safety of robot-assisted targeted (RA-TB) and systematic prostate biopsies (RA-SB).

METHODS

A systematic literature search was performed in MEDLINE and Scopus databases. The detailed search strategy is available at Prospero (CRD42021269290). The primary outcome was the clinically significant prostate cancer (PCa) detection rate. The secondary outcomes included the overall detection rate of PCa, cancer detection rate per core, and complications.

RESULTS

The clinically significant cancer detection rate, overall cancer detection rate, and "per patient" did not significantly differ between RA-TB and RA-SB [OR = 1.02 (95% CI 0.83; 1.26), p = 0.05, I² = 62% and OR = 0.95 (95% CI 0.78; 1.17), p = 0.17, I² = 40%, respectively]. There were no differences in the clinically insignificant cancer detection rate "per patient" between RA-TB and RA-SB [OR = 0.81 (95% CI 0.54; 1.21), p = 0.31, I² = 0%]. RA-TB had a significantly higher cancer detection rate "per core" [OR = 3.01 (95% CI 2.77; 3.27), p < 0.0001, I² = 96%].

CONCLUSION

RA-TB and RA-SB are both technically feasible and have comparable clinical significance and overall PCa detection rates.

Landmarks in the evolution of prostate biopsy

Approaches and techniques used for diagnostic prostate biopsy have undergone considerable evolution over the past few decades: from the original finger-guided techniques to the latest MRI-directed strategies, from aspiration cytology to tissue core sampling, and from transrectal to transperineal approaches. In particular, increased adoption of transperineal biopsy approaches have led to reduced infectious complications and improved antibiotic stewardship. Furthermore, as image fusion has become integral, these novel techniques could be incorporated into prostate biopsy methods in the future, enabling 3D-ultrasonography fusion reconstruction, molecular targeting based on PET imaging and autonomous robotic-assisted biopsy.

Reducing the number of systematic biopsy cores in the era of MRI targeted biopsy-implications on clinically-significant prostate cancer detection and relevance to focal therapy planning

BACKGROUND

The optimal number of systematic biopsy cores in the era of multi-parametric MRI targeted biopsy remains unclear, especially on its impact of focal therapy planning. Our objective is to investigate the impact of reducing the number of systematic cores on prostate cancer detection in the era of MRI-US fusion targeted biopsy and as well as its relevance in template planning for focal therapy.

MATERIALS AND METHODS

A retrospective analysis of 398 consecutive men who underwent both systematic saturation (~24 cores) and MRI-US fusion targeted biopsy was performed. Four reduced-core systematic biopsy strategies (two-thirds, half, one-third and one-quarter systematic cores) were modelled and the detection rates of clinically-significant prostate cancer (csPCa defined as grade group ≥2) were compared to that of a full systematic biopsy using McNemar's test. Focal therapy treatment plans were made based on positive cores on combined (targeted and systematic) biopsy and the various reduced-cores strategies to compare the proportion who had a change in treatment plan.

RESULTS

csPCa was detected in 42% (168/398) of this patient cohort. Non-targeted systematic saturation biopsy had a 21% (83/398) csPCa detection rate. Our four strategies reduced the mean number of non-targeted systematic cores from 21.8 to 14.5, 10.9, 7.3 and 5.4 cores and their csPCa detection rates were significantly decreased to 16%, 13%, 9% and 8% respectively (all p < 0.05). Compared to the reduced-core strategies, a full systematic saturation biopsy resulted in change to the focal therapy treatment plan in 12% (2/3 cores), 19% (1/2 cores), 24% (1/3 cores) and 29% (1/4 cores) of the time (p = 0.0434).

CONCLUSIONS

Reducing the number of systematic biopsies when performing an MRI-targeted biopsy leads to reduced detection of csPCa and alter the treatment plans for focal therapy, possibly limiting its oncological efficacy.

Hundred years of transperineal prostate biopsy

The earliest recorded efforts to biopsy prostate, in the early 20th century, were made through transperineal (TP) approach, with open perineal prostate biopsy (PBx) being considered the gold standard for prostate cancer (PCa) diagnosis in that era. Later, to minimize morbidity and increase diagnostic accuracy, several technical modifications and transrectal ultrasound (TRUS) assistance were incorporated. However, in the 1980s, the transrectal (TR) approach became the predominant PBx method following the introduction of TRUS-TR PBx with sextant sampling, providing a convenient and efficacious method for prostate sampling. With modernization of PCa diagnosis, a recent resurgence of the TP PBx has been observed, driven primarily by TR drawbacks of infectious complications and sampling limitations. TP PBx is rapidly emerging as the new PBx standard, being officially recommended as the initial approach for biopsy in Europe and is increasingly being conducted and studied in the United States. The modern era of TP PBx is based on the improvements in local anesthesia techniques, TP access systems, and robotic assistance. These modifications and advancements have improved the ease of use, patient comfort, and diagnostic outcomes with TP PBx. Herein, we present a history of the evolution of TP PBx spanning over 100 years and explore the basis of the technique that merits future utilization.

Limitations of overlapping cores in systematic and MRI-US fusion biopsy

OBJECTIVES

To evaluate the clinically-significant prostate cancer (csCaP) detection rate of systematic (SBx) vs. targeted biopsy (TBx), after accounting for the overlapping systematic cores within the MRI regions of interest.

MATERIALS AND METHODS

We identified 398 consecutive men who underwent both transperineal systematic and targeted biopsy between January 2015 to January 2019. We reclassified overlapping systematic cores in the MRI regions of interest as target cores. The detection rates of SBx and TBx were compared using McNemar's test.

RESULTS

Detection rate of csCaP (grade group ≥2) was 42% (168/398). Median number of systematic and targeted cores were 23 (IQR 19-29) and 9 (IQR 6-12) respectively. A median of 3 (IQR 2-4) overlapping systematic cores were reclassified as targeted cores. After accounting for overlap, csPC detection rate on SBx decreased from 37% and 21% while the csCaP detection rate of TBx increased from 34% to 39% (both P < 0.001), with TBx having a better detection rate (39% vs. 21%, P < 0.001). A previous negative biopsy was associated with a lower risk of having csCaP on non-targeted SBx (OR 0.27, 95% CI: 0.12 - 0.58, P = 0.001). Only 5% (13/243) of those who had no cancer detected on TBx had csCaP on non-targeted SBx compared to 45% (70/155) of those who had csCaP on TBx (P< 0.001).

CONCLUSIONS

The utility of SBx in detecting csCaP decreases after accounting for overlap into the MRI region of interest, especially in men with a prior negative biopsy. Overlapping systematic cores improve the csCaP detection rate on TBx.

Techniques and Outcomes of MRI-TRUS Fusion Prostate Biopsy

PURPOSE OF REVIEW

The goal of this study is to review recent findings and evaluate the utility of MRI transrectal ultrasound fusion biopsy (FBx) techniques and discuss future directions.

RECENT FINDINGS

FBx detects significantly higher rates of clinically significant prostate cancer (csPCa) than ultrasound-guided systematic prostate biopsy (SBx), particularly in repeat biopsy settings. FBx has also been shown to detect significantly lower rates of clinically insignificant prostate cancer. In addition, a dedicated prostate MRI can assist in more accurately predicting the Gleason score and provide further information regarding the index cancer location, prostate volume, and clinical stage. The ability to accurately evaluate specific lesions is vital to both focal therapy and active surveillance, for treatment selection, planning, and adequate follow-up. FBx has been demonstrated in multiple high-quality studies to have improved performance in diagnosis of csPCa compared to SBx. The combination of FBx with novel technologies including radiomics, prostate-specific membrane antigen positron emission tomography (PSMA PET), and high-resolution micro-ultrasound may have the potential to further enhance this performance.

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.

Recent Advances and Current Role of Transperineal Prostate Biopsy

"Approximately 1 million prostate biopsies are performed each year in the United States. This procedure has traditionally been performed using a transrectal approach, which is associated with a significant risk of infectious complications including sepsis. In recent years, transperineal prostate biopsy has been increasingly adopted due to its lower associated infectious risk. In this review, we explore the benefits of the transperineal approach for performing prostate biopsy and detail technical advancements that have allowed for this procedure to now be routinely performed in the outpatient settings under local anesthesia."

Multiparametric MRI-ultrasonography software fusion prostate biopsy: initial results using a stereotactic robotic-assisted transperineal prostate biopsy platform comparing systematic vs targeted biopsy

OBJECTIVE

To compare the detection rates of prostate cancer between systematic biopsy and targeted biopsy using a stereotactic robot-assisted transperineal prostate platform.

MATERIALS AND METHODS

We identified consecutive patients with suspicious lesion(s) on multiparametric magnetic resonance imaging (mpMRI), who underwent both systematic and MRI-transrectal ultrasonography (US) fusion targeted biopsy using our proprietary transperineal robot-assisted prostate biopsy platform between January 2015 and January 2019 at our institution, for retrospective analysis. Comparative analysis was performed between systematic and targeted biopsy using McNemar's test, and the cohort was further stratified by prior biopsy status and Prostate Imaging Reporting and Data System (PI-RADS) v2.0 score. International Society of Urological Pathology (ISUP) grade group (GG) ≥2 cancers (previously known as Gleason grade ≥7) were considered to be clinically significant.

RESULTS

A total of 500 patients were included in our final analysis, of whom 67 (13%) were patients with low-risk cancer on active surveillance. Of the 433 patients without prior diagnosis of cancer, 288 (67%) were biopsy-naïve. A total of 248 (57%) were diagnosed with prostate cancer, with 199 (46%) having clinically significant prostate cancer (ISUP GG ≥2). There were no statistically significant differences in the overall prostate cancer and clinically significant prostate cancer detection rate between systematic and targeted biopsy (51% vs 49% and 40% vs 38% respectively; P = 0.306 and P = 0.609). Of the 248 prostate cancers detected, 75% (187/248) were detected on both systematic and targeted biopsy, 14% (35/248) were detected on systematic biopsy alone and 11% (26/248) were detected on targeted biopsy alone. Of the 199 clinically significant cancers detected, 69% (138/199) were detected on both systematic and targeted biopsy, 17% (33/199) on systematic biopsy alone and 14% (28/199) on targeted biopsy alone. There were no statistically significant differences in the detection rate between systematic and targeted biopsy for both overall and clinically significant prostate cancer, even when the cohort was stratified by prior biopsy status and PI-RADS score. Targeted biopsy has greater sampling efficiency compared to systematic biopsy for both overall and clinically significant prostate cancer (23.2% vs 9.8%, P < 0.001 and 14.8% vs 5.6%, P < 0.001).

CONCLUSIONS

Using our robot-assisted transperineal prostate platform, combined MRI-US targeted biopsy with concurrent systematic prostate systematic biopsy probably represents the optimal method for the detection of clinically significant prostate cancer.

Robotic-assisted magnetic resonance imaging ultrasound fusion results in higher significant cancer detection compared to cognitive prostate targeting in biopsy naive men

Background

To determine differences in cancer detection rates (CDRs) of regions of interest (ROI) on magnetic resonance imaging (MRI) with robotic-assisted (RA) targeted biopsies (RA-TB) compared to cognitive targeted biopsies (C-TB).

Methods

In a two-centre, retrospective outcome study, a total of 92 consecutive men who had a pre-biopsy MRI, were biopsy naïve and had a transperineal (TP) prostate biopsy between 9/2015 and 7/2017 were included. The primary analysis consists of 39 men who had C-TB and 53 men who had RA-TB. Outcomes from targeted biopsies were reported as CDR for clinically significant prostate cancer (csPC) and for any cancer.

Results

Targeted csCDR was higher in RA-TB vs. C-TB (32.1% vs. 10.3%, P=0.014). Targeted CDR of any cancer with Prostate Imaging Reporting and Data System (PI-RADS) 3-5 ROIs was also significantly higher in RA-TB compared to C-TB (47.2% vs. 12.8%, P=0.001). On multivariable analysis significant factors which affected the CDR for csPC was prostate volume only [odds ratio (OR) 1.04, 95% confidence interval (CI): 1.01-1.07]. For any cancer, the CDR was related to prostate volume (OR 1.03, 95% CI: 1.01-1.06) and RA-TB (OR 5.97, 95% CI: 1.69-21.07). RA biopsy results in less acute urinary retention (1.9% vs. 12.8%, P=0.03), less prolonged haematuria (7.5% vs. 38.5%, P<0.01) and shortened biopsy times (24 vs. 32 min, P<0.001).

Conclusions

RA targeted biopsy results in higher CDR for clinically significant cancers and any cancer. It also suffers lower complications compared to cognitive directed TP biopsy. The ease of use and standardisation of the robotic procedure may reduce the learning curve and increase biopsy accuracy.

Beyond transrectal ultrasound-guided prostate biopsies: available techniques and approaches

OBJECTIVES

Recent advances have led to the use of magnetic resonance imaging (MRI) alone or with fusion to transrectal ultrasound (TRUS) images for guiding biopsy of the prostate. Our group sought to develop consensus recommendations regarding MRI-guided prostate biopsy based on currently available literature and expert opinion.

METHODS

The published literature on the subject of MRI-guided prostate biopsy was reviewed using standard search terms and synthesized and analyzed by four different subgroups from among the authors. The literature was grouped into four categories-MRI-guided biopsy platforms, robotic MRI-TRUS fusion biopsy, template mapping biopsy and transrectal MRI-TRUS fusion biopsy. Consensus recommendations were developed using the Oxford Center for Evidence Based Medicine criteria.

RESULTS

There is limited high level evidence available on the subject of MRI-guided prostate biopsy. MRI guidance with or without TRUS fusion can lead to fewer unnecessary biopsies, help identify high-risk (Gleason ≥ 3 + 4) cancers that might have been missed on standard TRUS biopsy and identify cancers in the anterior prostate. There is no apparent significant difference between MRI biopsy platforms. Template mapping biopsy is perhaps the most accurate method of assessing volume and grade of tumor but is accompanied by higher incidence of side effects compared to TRUS biopsy.

CONCLUSIONS

Magnetic resonance imaging-guided biopsies are feasible and better than traditional ultrasound-guided biopsies for detecting high-risk prostate cancer and anterior lesions. Judicious use of MRI-guided biopsy could enhance diagnosis of clinically significant prostate cancer while limiting diagnosis of insignificant cancer.

[MRI/TRUS fusion-guided prostate biopsy : Value in the context of focal therapy]

BACKGROUND

Several systems for MRI/TRUS fusion-guided biopsy of the prostate are commercially available. Many studies have shown superiority of fusion systems for tumor detection and diagnostic quality compared to random biopsy. The benefit of fusion systems in focal therapy of prostate cancer (PC) is less clear.

OBJECTIVES

Critical considerations of fusion systems for planning and monitoring of focal therapy of PC were investigated.

MATERIALS AND METHODS

A systematic literature review of available fusion systems for the period 2013-5/2016 was performed. A checklist of technical details, suitability for special anatomic situations and suitability for focal therapy was established by the German working group for focal therapy (Arbeitskreis fokale und Mikrotherapie).

RESULTS

Eight fusion systems were considered (Artemis™, BioJet, BiopSee®, iSR´obot™ Mona Lisa, Hitachi HI-RVS, UroNav and Urostation®). Differences were found for biopsy mode (transrectal, perineal, both), fusion mode (elastic or rigid), navigation (image-based, electromagnetic sensor-based or mechanical sensor-based) and space requirements.

DISCUSSION

Several consensus groups recommend fusion systems for focal therapy. Useful features are "needle tracking" and compatibility between fusion system and treatment device (available for Artemis™, BiopSee® and Urostation® with Focal One®; BiopSee®, Hitachi HI-RVS with NanoKnife®; BioJet, BiopSee® with cryoablation, brachytherapy).

CONCLUSIONS

There are a few studies for treatment planning. However, studies on treatment monitoring after focal therapy are missing.

Outcomes of combination MRI-targeted and transperineal template biopsy in restaging low-risk prostate cancer for active surveillance

Objective

Active surveillance (AS) offers a strategy to reduce overtreatment and now is a widely accepted treatment option for low-risk prostate cancer. An ideal tool for risk-stratification would detect aggressive cancers and exclude such men from taking up AS in the first place. We evaluate if a combination of transperineal template biopsy with magnetic resonance imaging (MRI)-targeted biopsy identifies significant prostate cancer amongst men initially diagnosed with low-risk prostate cancer.

Methods

This prospective, single-blinded study included men with low-risk prostate cancer (D'Amico's Criteria) diagnosed on conventional transrectal ultrasound-guided biopsy. Patients first underwent multiparametric MRI of the prostate ≥6 weeks after initial biopsy. Each suspicious lesion is mapped and assigned a Prostate Imaging Reporting and Data System (PIRADS) score. Template biopsy is first performed with the surgeon blinded to MRI findings followed by MRI-targeted biopsy using a robotic transperineal biopsy platform.

Results

The age of the 19 men included is 65.4 ± 4.9 years (mean ± SD). Prostate specific antigen (PSA) at diagnosis and at the time of transperineal biopsy were comparable (7.3 ± 1.7 ng/mL and 7.0 ± 1.8 ng/mL, p = 0.67), so were prostate volumes (34.2 ± 8.9 mL and 32.1 ± 13.4 mL, p = 0.28). MRI-targeted biopsy had a higher percentage of cancer detection per core compared to template biopsy (11.7% vs. 6.5%, p = 0.02), this was more than 3 times superior for Gleason 7 disease (5.9% vs. 1.6%, p < 0.01). Four of 18 (22.2%) patients with MRI lesions had significant disease with MRI-targeted biopsy alone. Three of 19 patients (15.8%) had significant disease with template biopsy alone. In combination, both techniques upclassified five patients (26.3%), all of whom underwent radical prostatectomy. Whole mount histology confirmed tumour location and grade. All six patients with PIRADS 5 lesions had cancer detected (66.6% significant disease).

Conclusion

A combination of MRI-targeted and template biopsy may optimally risk-classify “low-risk” patients diagnosed on initial conventional transrectal ultrasonography (TRUS) prostate biopsy.

Transperineal vs. transrectal biopsy in MRI targeting

Prostate biopsy is typically performed via either the transrectal or transperineal approach. MRI-targeted biopsy, whether using any of the three options of cognitive fusion, MRI-ultrasound fusion software, or in-bore MRI-guided biopsy, can also be performed via either transrectal or transperineal approaches. As an extension of traditional random prostate biopsy, the transrectal approach is far more commonly used for MRI-targeted biopsy due to its convenience. However, in the context of today’s increasing multi-drug resistance of rectal flora, the transperineal approach is being used more often due to its lack of septic complications. In addition, only a first-generation cephalosporin, not a fluoroquinolone, is required as antibiotic prophylaxis. Evidence shows excellent detection rates of significant prostate cancer using magnetic resonance imaging (MRI)-targeted and/or systematic transperineal biopsy (TPB). However, there are no head-to-head studies comparing the different MRI-targeted methods within TPB. To provide truly patient-centred care, the biopsy technique using the safest method with the highest detection rate of significant cancer should be used. Depending on healthcare context and hospital resource utilization, MRI-targeted TPB is an excellent option and should be performed wherever available and feasible. Whilst building capacity for TPB in one’s practice, the routine use of rectal culture swabs prior to any transrectal biopsies is strongly encouraged. Independent of biopsy route, the addition of systematic cores needs to be discussed with the patient weighing maximal detection of significant cancer against increased detection of insignificant lesions.

Development and Phantom Validation of a 3-D-Ultrasound-Guided System for Targeting MRI-Visible Lesions During Transrectal Prostate Biopsy

OBJECTIVE

Three- and four-dimensional transrectal ultrasound transducers are now available from most major ultrasound equipment manufacturers, but currently are incorporated into only one commercial prostate biopsy guidance system. Such transducers offer the benefits of rapid volumetric imaging, but can cause substantial measurement distortion in electromagnetic tracking sensors, which are commonly used to enable 3-D navigation. In this paper, we describe the design, development, and validation of a 3-D-ultrasound-guided transrectal prostate biopsy system that employs high-accuracy optical tracking to localize the ultrasound probe and prostate targets in 3-D physical space.

METHODS

The accuracy of the system was validated by evaluating the targeted needle placement error after inserting a biopsy needle to sample planned targets in a phantom using standard 2-D ultrasound guidance versus real-time 3-D guidance provided by the new system.

RESULTS

The overall mean needle-segment-to-target distance error was 3.6 ± 4.0 mm and mean needle-to-target distance was 3.2 ± 2.4 mm.

CONCLUSION

A significant increase in needle placement accuracy was observed when using the 3-D guidance system compared with visual targeting of invisible (virtual) lesions using a standard B-mode ultrasound-guided biopsy technique.

Systematic 12- and 13-core transrectal ultrasound- or magnetic resonance imaging-guided biopsies significantly improve prostate cancer detection rate: A single-center 13-year experience

The aim of the present study was to evaluate the value of systematic 12- and 13-core biopsies, guided by transrectal ultrasound (TRUS) or magnetic resonance imaging (MRI), with regard to the prostate cancer detection rate (PCDR). Between July 1999 and June 2012, 2,707 patients were recruited to the Department of Urology, The First Affiliated Hospital of Nanjing Medical University (Nanjing, China). Prostate biopsies were performed via systematic 12- or 13-core biopsy and guided by either TRUS or MRI. The PCDR was established by retrospectively analyzing the distribution of positive cores, and it was assumed that all patients had undergone four biopsy schemes: Medial 6-core, lateral 6-core, 12-core and entire 13-core. In addition, the positive rate of the biopsies with the extra 13th core and the mean positive rate of systematic 12-core biopsies were compared. The PCDR of an entire 13-core biopsy was significantly higher than that of a lateral 6-core biopsy. The positive rate of the extra 13th core, which identified abnormal TRUS or MRI findings, was significantly higher when compared with that of the mean positive rate of the systematic 12-core biopsy. The results of the present study demonstrated that the entire 13-core biopsy was superior to the 6-core biopsy with regard to the PCDR. Therefore, the systematic 12-core biopsy with an extra 13th core is considered to be beneficial towards improving the PCDR.

Robotic ultrasound and needle guidance for prostate cancer management: review of the contemporary literature

PURPOSE OF REVIEW

To present the recent advances in needle guidance and robotic ultrasound technology which are used for prostate cancer (PCa) diagnosis and management.

RECENT FINDINGS

Prostate biopsy technology has remained relatively unchanged. Improved needle localization and precision would allow for better management of this common disease. Robotic ultrasound and needle guidance is one strategy to improve needle localization and diagnostic accuracy of PCa. This review focuses on the recent advances in robotic ultrasound and needle guidance technologies, and their potential impact on PCa diagnosis and management.

SUMMARY

The use of robotic ultrasound and robotic-assisted needle guidance has the potential to improve PCa diagnosis and management.

MRI-safe robot for targeted transrectal prostate biopsy: animal experiments

OBJECTIVES

To study the feasibility and safety of using a magnetic resonance imaging (MRI)-safe robot for assisting MRI-guided transrectal needle placement and biopsy in the prostate, using a canine model. To determine the accuracy and precision afforded by the use of the robot while targeting a desired location in the organ.

MATERIALS AND METHODS

In a study approved by the Institutional Animal Care and Use Committee, six healthy adult male beagles with prostates of at least 15 × 15 mm in size at the largest transverse section were chosen for the procedure. The probe portion of the robot was placed into the rectum of the dog, images were acquired and image-to-robot registration was performed. Images acquired after placement of the robot were reviewed and a radiologist selected targets for needle placement in the gland. Depending on the size of the prostate, up to a maximum of six needle placements were performed on each dog. After needle placement, robot-assisted core biopsies were performed on four dogs that had larger prostate volumes and extracted cores were analysed for potential diagnostic value.

RESULTS

Robot-assisted MRI-guided needle placements were performed to target a total of 30 locations in six dogs, achieving a targeting accuracy of 2.58 mm (mean) and precision of 1.31 mm (SD). All needle placements were successfully completed on the first attempt. The mean time required to select a desired target location in the prostate, align the needle guide to that point, insert the needle and perform the biopsy was ∼ 3 min. For this targeting accuracy study, the inserted needle was also imaged after its placement in the prostate, which took an additional 6-8 min. Signal-to-noise ratio analysis indicated that the presence of the robot within the scanner bore had minimal impact on the quality of the images acquired. Analysis of intact biopsy core samples indicated that the samples contained prostatic tissues, appropriate for making a potential diagnosis. Dogs used in the study did not experience device- or procedure-related complications.

CONCLUSIONS

Results from this preclinical pilot animal study suggest that MRI-targeted transrectal biopsies are feasible to perform and this procedure may be safely assisted by an MRI-safe robotic device.

Transperineal biopsy of the prostate--is this the future?

Transperineal prostate biopsy is re-emerging after decades of being an underused alternative to transrectal biopsy guided by transrectal ultrasonography (TRUS). Factors driving this change include possible improved cancer detection rates, improved sampling of the anteroapical regions of the prostate, a reduced risk of false negative results and a reduced risk of underestimating disease volume and grade. The increasing incidence of antimicrobial resistance and patients with diabetes mellitus who are at high risk of sepsis also favours transperineal biopsy as a sterile alternative to standard TRUS-guided biopsy. Factors limiting its use include increased time, training and financial constraints as well as the need for high-grade anaesthesia. Furthermore, the necessary equipment for transperineal biopsy is not widely available. However, the expansion of transperineal biopsy has been propagated by the increase in multiparametric MRI-guided biopsies, which often use the transperineal approach. Used with MRI imaging, transperineal biopsy has led to improvements in cancer detection rates, more-accurate grading of cancer severity and reduced risk of diagnosing clinically insignificant disease. Targeted biopsy under MRI guidance can reduce the number of cores required, reducing the risk of complications from needle biopsy.

Image-guided robotic interventions for prostate cancer

Robotic prostatectomy is a common surgical treatment for men with prostate cancer, with some studies estimating that 80% of prostatectomies now performed in the USA are done so robotically. Despite the technical advantages offered by robotic systems, functional and oncological outcomes of prostatectomy can still be improved further. Alternative minimally invasive treatments that have also adopted robotic platforms include brachytherapy and high-intensity focused ultrasonography (HIFU). These techniques require real-time image guidance--such as ultrasonography or MRI--to be truly effective; issues with software compatibility as well as image registration and tracking currently limit such technologies. However, image-guided robotics is a fast-growing area of research that combines the improved ergonomics of robotic systems with the improved visualization of modern imaging modalities. Although the benefits of a real-time image-guided robotic system to improve the precision of surgical interventions are being realized, the clinical usefulness of many of these systems remains to be seen.

Geometric evaluation of systematic transrectal ultrasound guided prostate biopsy

PURPOSE

Transrectal ultrasound guided prostate biopsy results rely on physician ability to target the gland according to the biopsy schema. However, to our knowledge it is unknown how accurately the freehand, transrectal ultrasound guided biopsy cores are placed in the prostate and how the geometric distribution of biopsy cores may affect the prostate cancer detection rate.

MATERIALS AND METHODS

To determine the geometric distribution of cores, we developed a biopsy simulation system with pelvic mock-ups and an optical tracking system. Mock-ups were biopsied in a freehand manner by 5 urologists and by our transrectal ultrasound robot, which can support and move the transrectal ultrasound probe. We compared 1) targeting errors, 2) the accuracy and precision of repeat biopsies, and 3) the estimated significant prostate cancer (0.5 cm(3) or greater) detection rate using a probability based model.

RESULTS

Urologists biopsied cores in clustered patterns and under sampled a significant portion of the prostate. The robot closely followed the predefined biopsy schema. The mean targeting error of the urologists and the robot was 9.0 and 1.0 mm, respectively. Robotic assistance significantly decreased repeat biopsy errors with improved accuracy and precision. The mean significant prostate cancer detection rate of the urologists and the robot was 36% and 43%, respectively (p <0.0001).

CONCLUSIONS

Systematic biopsy with freehand transrectal ultrasound guidance does not closely follow the sextant schema and may result in suboptimal sampling and cancer detection. Repeat freehand biopsy of the same target is challenging. Robotic assistance with optimized biopsy schemas can potentially improve targeting, precision and accuracy. A clinical trial is needed to confirm the additional benefits of robotic assistance.

Focal laser ablation of prostate cancer: definition, needs, and future

Current challenges and innovations in prostate cancer management concern the development of focal therapies that allow the treatment of only the cancer areas sparing the rest of the gland to minimize the potential morbidity. Among these techniques, focal laser ablation (FLA) appears as a potential candidate to reach the goal of focusing energy delivery on the identified targets. The aim of this study is to perform an up-to-date review of this new therapeutic modality. Relevant literature was identified using MEDLINE database with no language restrictions (entries: focal therapy, laser interstitial thermotherapy, prostate cancer, FLA) and by cross-referencing from previously identified studies. Precision, real-time monitoring, MRI compatibility, and low cost of integrated system are principal advantages of FLA. Feasibility and safety of this technique have been reported in phase I assays. FLA might eventually prove to be a middle ground between active surveillance and radical treatment. In conclusion, FLA may have found a role in the management of prostate cancer. However, further trials are required to demonstrate the oncologic effectiveness in the long term.

Robotic prostate biopsy and its relevance to focal therapy of prostate cancer

Focal therapy is an individualized treatment option for prostate cancer, which destroys localized cancerous tissue but not normal tissue, thus avoiding the morbidities associated with whole-gland therapy. Accurate cancer localization and precise ablation are integral to the success of focal therapy, which remains unproven owing to suboptimal patient selection. Currently, there are no clinical or biopsy features that can identify unifocal prostate cancer and no imaging modality that can accurately diagnose or localize prostate cancer. MRI diagnosis has the best accuracy but high cost and limited access hinder its widespread adoption. New management options, including focal therapy and active surveillance, require prostate biopsy to detect, localize and characterize the cancer. Transrectal prostate biopsy has a high false-negative detection rate, which might be related to an inability to biopsy the anterior and apical part of the prostate or interoperator variation. Transrectal biopsy is also associated with sepsis and bleeding. Robotic transperineal prostate biopsy can overcome the limitations of transrectal procedures. Robotic biopsy is automated with high accuracy, has improved access to the apex and anterior part of the prostate and has low risk of sepsis. Furthermore, it involves only two skin punctures, compared with template-based transperineal prostate biopsy, which can result in multiple wounds. Robotic prostate biopsy fulfills the fundamental needs of focal therapy and might be the platform for future treatment delivery for prostate cancer.