Real-Time Transrectal Ultrasound Guidance During Laparoscopic Radical Prostatectomy: Impact on Surgical Margins

Nerve Visualization using Phenoxazine-Based Near-Infrared Fluorophores to Guide Prostatectomy

Fluorescence-guided surgery (FGS) is poised to revolutionize surgical medicine through near-infrared (NIR) fluorophores for tissue- and disease-specific contrast. Clinical open and laparoscopic FGS vision systems operate nearly exclusively at NIR wavelengths. However, tissue-specific NIR contrast agents compatible with clinically available imaging systems are lacking, leaving nerve tissue identification during prostatectomy a persistent challenge. Here, it is shown that combining drug-like molecular design concepts and fluorophore chemistry enabled the production of a library of NIR phenoxazine-based fluorophores for intraoperative nerve-specific imaging. The lead candidate readily delineated prostatic nerves in the canine and iliac plexus in the swine using the clinical da Vinci Surgical System that has been popularized for minimally invasive prostatectomy procedures. These results demonstrate the feasibility of molecular engineering of NIR nerve-binding fluorophores for ready integration into the existing surgical workflow, paving the path for clinical translation to reduce morbidity from nerve injury for prostate cancer patients.

Arc-to-line frame registration method for ultrasound and photoacoustic image-guided intraoperative robot-assisted laparoscopic prostatectomy

PURPOSE

To achieve effective robot-assisted laparoscopic prostatectomy, the integration of transrectal ultrasound (TRUS) imaging system which is the most widely used imaging modality in prostate imaging is essential. However, manual manipulation of the ultrasound transducer during the procedure will significantly interfere with the surgery. Therefore, we propose an image co-registration algorithm based on a photoacoustic marker (PM) method, where the ultrasound/photoacoustic (US/PA) images can be registered to the endoscopic camera images to ultimately enable the TRUS transducer to automatically track the surgical instrument.

METHODS

An optimization-based algorithm is proposed to co-register the images from the two different imaging modalities. The principle of light propagation and an uncertainty in PM detection were assumed in this algorithm to improve the stability and accuracy of the algorithm. The algorithm is validated using the previously developed US/PA image-guided system with a da Vinci surgical robot.

RESULTS

The target-registration-error (TRE) is measured to evaluate the proposed algorithm. In both simulation and experimental demonstration, the proposed algorithm achieved a sub-centimeter accuracy which is acceptable in practical clinics (i.e., 1.15 ± 0.29 mm from the experimental evaluation). The result is also comparable with our previous approach (i.e., 1.05 ± 0.37 mm), and the proposed method can be implemented with a normal white light stereo camera and does not require highly accurate localization of the PM.

CONCLUSION

The proposed frame registration algorithm enabled a simple yet efficient integration of commercial US/PA imaging system into laparoscopic surgical setting by leveraging the characteristic properties of acoustic wave propagation and laser excitation, contributing to automated US/PA image-guided surgical intervention applications.

Real-time intraoperative surgical guidance system in the da Vinci surgical robot based on transrectal ultrasound/photoacoustic imaging with photoacoustic markers: an ex vivo demonstration

This paper introduces the first integrated real-time intraoperative surgical guidance system, in which an endoscope camera of da Vinci surgical robot and a transrectal ultrasound (TRUS) transducer are co-registered using photoacoustic markers that are detected in both fluorescence (FL) and photoacoustic (PA) imaging. The co-registered system enables the TRUS transducer to track the laser spot illuminated by a pulsed-laser-diode attached to the surgical instrument, providing both FL and PA images of the surgical region-of-interest (ROI). As a result, the generated photoacoustic marker is visualized and localized in the da Vinci endoscopic FL images, and the corresponding tracking can be conducted by rotating the TRUS transducer to display the PA image of the marker. A quantitative evaluation revealed that the average registration and tracking errors were 0.84 mm and 1.16°, respectively. This study shows that the co-registered photoacoustic marker tracking can be effectively deployed intraoperatively using TRUS+PA imaging providing functional guidance of the surgical ROI.

Intraoperative 3D-US-mpMRI Elastic Fusion Imaging-Guided Robotic Radical Prostatectomy: A Pilot Study

INTRODUCTION

When performing a nerve-sparing (NS) robotic radical prostatectomy (RARP), cancer location based on multiparametric MRI (mpMRI) is essential, as well as the location of positive biopsy cores outside mpMRI targets. The aim of this pilot study was to assess the feasibility of intraoperative 3D-TRUS-mpMRI elastic fusion imaging to guide RARP and to evaluate its impact on the surgical strategy.

METHODS

We prospectively enrolled 11 patients with organ-confined mpMRI-visible prostate cancer (PCa), histologically confirmed at transperineal fusion biopsy using Koelis Trinity. Before surgery, the 3D model of the prostate generated at biopsy was updated, showing both mpMRI lesions and positive biopsy cores, and was displayed on the Da Vinci robotic console using TilePro™ function.

RESULTS

Intraoperative 3D modeling was feasible in all patients (median of 6 min). The use of 3D models led to a major change in surgical strategy in six cases (54%), allowing bilateral instead of monolateral NS, or monolateral NS instead of non-NS, to be performed. At pathologic examination, no positive surgical margins (PSMs) were reported. Bilateral PCa presence was detected in one (9%), four (36%), and nine (81%) patients after mpMRI, biopsy, and RARP, respectively. Extracapsular extension was found in two patients (18%) even if it was not suspected at MRI.

CONCLUSIONS

Intraoperative 3D-TRUS-mpMRI modeling with Koelis Trinity is feasible and reliable, helping the surgeon to maximize functional outcomes without increasing the risk of positive surgical margins. The location of positive biopsy cores must be registered in 3D models, given the rates of bilateral involvement not seen at mpMRI.

Virtual reality of three-dimensional surgical field for surgical planning and intraoperative management

PURPOSE

To investigate the impact of virtual reality (VR) technologies on urological surgeries, specifically in the management of prostate cancer and renal cancer.

METHODS

A non-systematic review of the literature was performed. Medline, Pubmed, and the Cochrane Database were screened for studies regarding the use of VR technologies in the management of prostate and renal cancer.

RESULTS

In the management of prostate cancer, VR technologies have been increasingly applied for diagnosis with magnetic resonance imaging/ultrasound fusion biopsy, surgical training using a simulator, surgical navigation in robot-assisted radical prostatectomy, and targeted focal therapy. In partial nephrectomy, surgical simulation and intra-surgical guidance with three-dimensional VR have been used for better understanding of the hilar vascular information, tumor location, and positional relationships of the tumor-feeding vessel and pyelocaliceal system.

CONCLUSIONS

VR contributes to the education, training, and simulation of surgical procedures as well as helping the surgeons to tailor surgical planning on each patient. Further prospective studies are needed to assess the beneficial impacts of this technology for both the physician and patient by objective parameters.

The evolution of image guidance in robotic-assisted laparoscopic prostatectomy (RALP): a glimpse into the future

OBJECTIVES

To describe the innovative intraoperative technologies emerging to aid surgeons during minimally invasive robotic-assisted laparoscopic prostatectomy.

METHODS

We searched multiple electronic databases reporting on intraoperative imaging and navigation technologies, robotic surgery in combination with 3D modeling and 3D printing used during laparoscopic or robotic-assisted laparoscopic prostatectomy. Additional searches were conducted for articles that considered the role of artificial intelligence and machine learning and their application to robotic surgery. We excluded studies using intraoperative navigation technologies during open radical prostatectomy and studies considering technology to visualize lymph nodes. Intraoperative imaging using either transrectal ultrasonography or augmented reality was associated with a potential decrease in positive surgical margins rates. Improvements in detecting capsular involvement may be seen with augmented reality. The benefit, feasibility and applications of other imaging modalities such as 3D-printed models and optical imaging are discussed.

CONCLUSION

The application of image-guided surgery and robotics has led to the development of promising new intraoperative imaging technologies such as augmented reality, fluorescence imaging, optical coherence tomography, confocal laser endomicroscopy and 3D printing. Currently challenges regarding tissue deformation and automatic tracking of prostate movements remain and there is a paucity in the literature supporting the use of these technologies. Urologic surgeons are encouraged to improve and test these advanced technologies in the clinical arena, preferably with comparative, randomized, trials.

Near-infrared nerve-binding fluorophores for buried nerve tissue imaging

Nerve-binding fluorophores with near-infrared (NIR; 650 to 900 nm) emission could reduce iatrogenic nerve injury rates by providing surgeons precise, real-time visualization of the peripheral nervous system. Unfortunately, current systemically administered nerve contrast agents predominantly emit at visible wavelengths and show nonspecific uptake in surrounding tissues such as adipose, muscle, and facia, thus limiting detection to surgically exposed surface-level nerves. Here, a focused NIR fluorophore library was synthesized and screened through multi-tiered optical and pharmacological assays to identify nerve-binding fluorophore candidates for clinical translation. NIR nerve probes enabled micrometer-scale nerve visualization at the greatest reported tissue depths (~2 to 3 mm), a feat unachievable with previous visibly emissive contrast agents. Laparoscopic fluorescent surgical navigation delineated deep lumbar and iliac nerves in swine, most of which were invisible in conventional white-light endoscopy. Critically, NIR oxazines generated contrast against all key surgical tissue classes (muscle, adipose, vasculature, and fascia) with nerve signal-to-background ratios ranging from ~2 (2- to 3-mm depth) to 25 (exposed nerve). Clinical translation of NIR nerve-specific agents will substantially reduce comorbidities associated with surgical nerve damage.

Fluorescence Image-Guided Surgery - a Perspective on Contrast Agent Development

In the past several decades, a number of novel fluorescence image-guided surgery (FGS) contrast agents have been under development, with many in clinical translation and undergoing clinical trials. In this review, we have identified and summarized the contrast agents currently undergoing clinical translation. In total, 39 novel FGS contrast agents are being studied in 85 clinical trials. Four FGS contrast agents are currently being studied in phase III clinical trials and are poised to reach FDA approval within the next two to three years. Among all novel FGS contrast agents, a wide variety of probe types, targeting mechanisms, and fluorescence properties exists. Clinically available FGS imaging systems have been developed for FDA approved FGS contrast agents, and thus further clinical development is required to yield FGS imaging systems tuned for the variety of contrast agents in the clinical pipeline. Additionally, study of current FGS contrast agents for additional disease types and development of anatomy specific contrast agents is required to provide surgeons FGS tools for all surgical specialties and associated comorbidities. The work reviewed here represents a significant effort from many groups and further development of this promising technology will have an enormous impact on surgical outcomes across all specialties.

A partial augmented reality system with live ultrasound and registered preoperative MRI for guiding robot-assisted radical prostatectomy

We propose an image guidance system for robot assisted laparoscopic radical prostatectomy (RALRP). A virtual 3D reconstruction of the surgery scene is displayed underneath the endoscope's feed on the surgeon's console. This scene consists of an annotated preoperative Magnetic Resonance Image (MRI) registered to intraoperative 3D Trans-rectal Ultrasound (TRUS) as well as real-time sagittal 2D TRUS images of the prostate, 3D models of the prostate, the surgical instrument and the TRUS transducer. We display these components with accurate real-time coordinates with respect to the robot system. Since the scene is rendered from the viewpoint of the endoscope, given correct parameters of the camera, an augmented scene can be overlaid on the video output. The surgeon can rotate the ultrasound transducer and determine the position of the projected axial plane in the MRI using one of the registered da Vinci instruments. This system was tested in the laboratory on custom-made agar prostate phantoms. We achieved an average total registration accuracy of 3.2  ±  1.3 mm. We also report on the successful application of this system in the operating room in 12 patients. The average registration error between the TRUS and the da Vinci system for the last 8 patients was 1.4  ±  0.3 mm and average target registration error of 2.1  ±  0.8 mm, resulting in an in vivo overall robot system to MRI mean registration error of 3.5 mm or less, which is consistent with our laboratory studies.

Augmented-reality robot-assisted radical prostatectomy using hyper-accuracy three-dimensional reconstruction (HA3D™) technology: a radiological and pathological study

OBJECTIVES

To assess the use of hyper-accuracy three-dimensional (HA3D™; MEDICS, Moncalieri, Turin, Italy) reconstruction based on multiparametric magnetic resonance imaging (mpMRI) and superimposed imaging during augmented-reality robot-assisted radical prostatectomy (AR-RARP).

PATIENTS AND METHODS

Patients with prostate cancer (clinical stages cT1-3, cN0, cM0) undergoing RARP at our Centre, from June 2017 to April 2018, were enrolled. In all cases, cancer was diagnosed with targeted biopsy at the level of index lesion based on high-resolution (1-mm slices) mpMRI. HA3D reconstruction was created by dedicated software to obtain the 3D virtual model of the prostate and surrounding structures. A specific system was used to overlay virtual data on the endoscopic video displayed by the remote da Vinci® surgical console (Intuitive Surgical Inc., Sunnyvale, CA, USA), and the virtual images were superimposed by the surgeon by the means of the TilePro™ multi-input display technology (Intuitive Surgical Inc.). The AR technology was used in four standardised key steps during RARP. The procedures were modulated differently in cases of prostate cancer without extracapsular extension (ECE) at mpMRI (Group A) or in cases of prostate cancer with ECE (Group B) at mpMRI. In Group A, the virtual image of the prostate was overlaid on the endoscopic view and the intraprostatic lesion was marked on the prostate surface by a metallic clip at the level of the suspicious lesion as identified by the 3D virtual AR image. In Group B, the same step was performed; moreover, a metallic clip was placed at the level of the suspicious ECE on the neurovascular bundles (NVBs) according to the virtual images. Finally, selective biopsies were taken from the NVBs at this level, and then, the entire NVBs were removed for final pathological examination, according to standard clinical indications. For Group A, the pathologist performed a targeted needle biopsy at the level of the metallic clip on the surface of prostate before the sample reduction. For Group B, the presence of tumour was evaluated during the reduction phase, at the level of metallic clip on the prostate surface and at the level of NVBs, sent separately. Finally, an image 3D scanner (Kinect, Microsoft) was used to perform a dimensional comparison between the mpMRI-based 3D virtual reconstruction and the whole-mount specimen.

RESULTS

In all, 30 patients were enrolled in the present study, 11 (36.6%) included in Group A and 19 (63.4%) in Group B. In all cases (30/30), final pathology confirmed the location of the index lesion, as cancer was found at the level of the metallic clip. The suspected ECE was confirmed on final pathology in 15/19 cases (79%). The AR-guided selective biopsies at the level of the NVBs confirmed the ECE location, with 11/15 (73.3%) biopsies at the level of NVBs positive for cancer. The mismatch between the 3D virtual reconstruction and the prostate 3D scanning based on the whole-mount specimen was <3 mm in >85% of the gland.

CONCLUSION

Our results suggest that a HA3D virtual reconstruction of the prostate based on mpMRI data and real-time superimposed imaging allow performance of an effective AR-RARP. Potentially, this approach translates into better outcomes, as the surgeon can tailor the procedure for each patient.

Prior knowledge snake segmentation of ultrasound images denoised by J-divergence anisotropy diffusion

BACKGROUND

Applying transrectal ultrasound to robot-assisted laparoscopic radical prostatectomy has attracted attention in recent years, and it is considered as a proper method to provide real-time subsurface anatomic features. A precise registration between the ultrasound equipment and robotic surgical system is necessary, which usually requires a fast and accurate recognition of the registration tool in the ultrasound image.

METHODS

Tissue forceps are chosen as the registration tool. J-divergence anisotropy diffusion and prior knowledge snake segmentation are proposed for the automatic recognition of forceps in ultrasound images.

RESULTS

Simulation, gel tissue phantom experiments and in vitro experiments are carried out. Several evaluation indices are calculated to compare results under different methods.

CONCLUSIONS

The proposed methods are proved to be practicable, reliable and superior to existing ones, with reduced calculation time and higher accuracy.

Visualization of prostatic nerves by polarization-sensitive optical coherence tomography

Preservation of prostatic nerves is critical to recovery of a man's sexual potency after radical prostatectomy. A real-time imaging method of prostatic nerves will be helpful for nerve-sparing radical prostatectomy (NSRP). Polarization-sensitive optical coherence tomography (PS-OCT), which provides both structural and birefringent information of tissue, was applied for detection of prostatic nerves in both rat and human prostate specimens, ex vivo. PS-OCT imaging of rat prostate specimens visualized highly scattering and birefringent fibrous structures superficially, and these birefringent structures were confirmed to be nerves by histology or multiphoton microscopy (MPM). PS-OCT could easily distinguish these birefringent structures from surrounding other tissue compartments such as prostatic glands and fats. PS-OCT imaging of human prostatectomy specimens visualized two different birefringent structures, appearing fibrous and sheet-like. The fibrous ones were confirmed to be nerves by histology, and the sheet-like ones were considered to be fascias surrounding the human prostate. PS-OCT imaging of human prostatectomy specimens along the perimeter showed spatial variation in the amount of birefringent fibrous structures which was consistent with anatomy. These results demonstrate the feasibility of PS-OCT for detection of prostatic nerves, and this study will provide a basis for intraoperative use of PS-OCT.

Advances in laparoscopic urologic surgery techniques

The last two decades witnessed the inception and exponential implementation of key technological advancements in laparoscopic urology. While some of these technologies thrived and became part of daily practice, others are still hindered by major challenges. This review was conducted through a comprehensive literature search in order to highlight some of the most promising technologies in laparoscopic visualization, augmented reality, and insufflation. Additionally, this review will provide an update regarding the current status of single-site and natural orifice surgery in urology.

Intraoperative Ultrasonography During Transoral Robotic Surgery

OBJECTIVE

This study describes the potential application of intraoperative ultrasound imaging during transoral robotic surgery (TORS).

METHODS

Ultrasound imaging was performed during transoral robotic resection of oropharyngeal tumors in 10 patients at a tertiary academic center. Ultrasound imaging was utilized to identify large-caliber vessels adjacent to the surgical site. Measurements were also taken on the ultrasound of tumor thickness to determine the deep margin. Following resection, the tumor was sectioned, and a gross measurement of the tumor thickness was obtained.

RESULTS

Intraoperative ultrasound use led to the identification of larger-caliber blood vessels within the operative field prior to encountering them visually. Ultrasound could also aid in defining deep tumor margins; the tumor thickness measured via ultrasound was found to be accurate within 1 to 2 mm of the grossly measured tumor thickness. This allowed for focused, careful dissection to protect and avoid blood vessels during dissection as well as improved tumor resection.

CONCLUSIONS

The use of intraoperative ultrasound provides additional information to the head and neck surgeon during TORS. This may be used to identify blood vessels and assess tumor margins, thereby improving the safety and efficacy of TORS.

Image-based monitoring of targeted biopsy-proven prostate cancer on active surveillance: 11-year experience

PURPOSE

To report our 11-year experience of Active Surveillance (AS) program focusing on modern transrectal ultrasound (TRUS)-based monitoring of targeted biopsy-proven cancer lesion.

METHODS

Consecutive patients on AS, who had targeted biopsy-proven lesion followed by at least a repeat surveillance biopsy and three times TRUS monitoring of the identical visible lesion, were included. Doppler grade of blood flow signal within the lesion was classified from grade 0 to 3. Biopsy-proven progression was defined as upgrade of Gleason score or 25% or greater increase in cancer core involvement.

RESULTS

Fifty patients were included in this study. Clinical variables (median) included age (61 years), clinical stage (T1c, 42;T2, 8), PSA (4.6 ng/ml), and Gleason score (3 + 3, n = 41;3 + 4, n = 9). Of the 50 patients, 34 demonstrated pathological progression at a median follow-up of 4.4 years. In comparing between without (n = 16) and with (n = 34) pathological progression, there were significant differences in cancer core involvement at entry (p = 0.003), the major axis diameter (p = 0.001) and minor axis diameter (p = 0.001) of the visible lesion at entry, increase in the major axis diameter (p = 0.005) and minor axis diameter (p = 0.013), and upgrade of Doppler grade (p < 0.0001). In multivariate analysis for predicting pathological progression, the increase (≥25%) in diameter of biopsy-proven lesion (hazard ratio, 15.314; p = 0.023) and upgrade of Doppler grade (hazard ratio, 37.409; p = 0.019) were significant risk factors.

CONCLUSIONS

Longitudinal monitoring of the TRUS-visible biopsy-proven cancer provides a new opportunity to perform per-lesion-based AS. The increase in diameter and upgrade of Doppler grade of the lesion were significant risk factors for biopsy-proven progression on AS.

Navigation surgery using an augmented reality for pancreatectomy

AIM

The aim of this study was to evaluate the utility of navigation surgery using augmented reality technology (AR-based NS) for pancreatectomy.

METHODS

The 3D reconstructed images from CT were created by segmentation. The initial registration was performed by using the optical location sensor. The reconstructed images were superimposed onto the real organs in the monitor display. Of the 19 patients who had undergone hepatobiliary and pancreatic surgery using AR-based NS, the accuracy, visualization ability, and utility of our system were assessed in five cases with pancreatectomy.

RESULTS

The position of each organ in the surface-rendering image corresponded almost to that of the actual organ. Reference to the display image allowed for safe dissection while preserving the adjacent vessels or organs. The locations of the lesions and resection line on the targeted organ were overlaid on the operating field. The initial mean registration error was improved to approximately 5 mm by our refinements. However, several problems such as registration accuracy, portability and cost still remain.

CONCLUSION

AR-based NS contributed to accurate and effective surgical resection in pancreatectomy. The pancreas appears to be a suitable organ for further investigations. This technology is promising to improve surgical quality, training, and education.

Using imaging biomarkers to improve the planning of radical prostatectomies

OBJECTIVES

This exploratory pilot study aimed to evaluate whether adding imaging biomarkers to conventional staging improves complete excision rates after undergoing radical prostatectomy (RP) in the United Kingdom for patients who have not undergone population prostate specific antigen screening. We primarily considered estimates of lesion volume and location based on computer-aided analysis of ultrasound (US) raw radiofrequency (RF) data acquired during trans-rectal ultrasound. The imaging analysis device used had been shown to accurately detect tumor loci within the prostate in previous studies.

METHODS AND MATERIALS

US raw RF data were collected from motorized trans-rectal ultrasound of 68 consecutive men with operable prostate cancer. In this cohort (group 1), locations and volume measurements of lesions suspected of harboring cancer on US raw RF data analysis by prostate HistoScanning, were added to conventional presurgical staging.The unexposed control group comprised 100 men who underwent conventional presurgical staging only (group 2): 50 were operated before and 50 operated after group 1 recruitment. Changes to pre-operative surgical planning and positive lateral margins of RP prostate pathological specimens were the primary outcomes. Data were collected using a Microsoft Excel database and analyzed using Stata.

RESULTS

Baseline demographics were comparable. In group 1, consideration of the additional imaging biomarkers led to changes in 27 (19.9%) operative surgical plans. Absolute rate reduction of a positive surgical margin (PSM) attributable to the imaging-biomarkers was 13.3% (P = 0.029). For stage pT3, PSM rate was reduced from 45.8% (n = 44) to 21.2% (n = 11) (P = 0.0028).

CONCLUSIONS

Obtaining quantitative measurements of preoperative imaging biomarkers appears to improve PSM rates of patients undergoing RP. The greatest PSM rate reduction was observed for pT3 tumors.

Significance and management of positive surgical margins at the time of radical prostatectomy

Positive surgical margins (PSM) at the time of radical prostatectomy (RP) result in an increased risk of biochemical recurrence (BCR) and secondary treatment. We review current literature with a focus on stratifying the characteristics of the PSM that may define its significance, the impact of modern imaging and surgical approaches in avoidance of PSM, and management strategies when PSM do occur. We performed a review of the available literature to identify factors associated with PSM and their management. PSM have been repeatedly demonstrated to be associated with an increased risk of BCR following RP. The specific characteristics (size, number, location, Gleason score at the margin) of the PSM may influence the risk of recurrence. Novel imaging and surgical approaches are being investigated and may allow for reductions of PSM in the future. The use of adjuvant treatment for a PSM remains controversial and should be decided on an individual basis after a discussion about the risks and benefits. The goal of RP is complete resection of the tumor. PSM are associated with increased risk of BCR and secondary treatments. Of the risk factors associated with BCR after RP, a PSM is directly influenced by surgical technique.

Predictive value of magnetic resonance imaging determined tumor contact length for extracapsular extension of prostate cancer

PURPOSE

Tumor contact length is defined as the amount of prostate cancer in contact with the prostatic capsule. We evaluated the ability of magnetic resonance imaging determined tumor contact length to predict microscopic extracapsular extension compared to existing predictors of extracapsular extension.

MATERIALS AND METHODS

We retrospectively analyzed the records of 111 consecutive patients with magnetic resonance imaging/ultrasound fusion targeted, biopsy proven prostate cancer who underwent radical prostatectomy from January 2010 to July 2013. Median patient age was 64 years and median prostate specific antigen was 8.9 ng/ml. Clinical stage was cT1 in 93 cases (84%) and cT2 in 18 (16%). Postoperative pathological analysis confirmed pT2 in 71 patients (64%) and pT3 in 40 (36%). We evaluated 1) in the radical prostatectomy specimen the correlation of microscopic extracapsular extension with pathological cancer volume, pathological tumor contact length and Gleason score, 2) the correlation between microscopic extracapsular extension and magnetic resonance imaging tumor contact length, and 3) the ability of preoperative variables to predict microscopic extracapsular extension.

RESULTS

Logistic regression analysis revealed that pathological tumor contact length correlated better with microscopic extracapsular extension than the predictive power of pathological cancer volume (0.821 vs 0.685). The Spearman correlation between pathological and magnetic resonance imaging tumor contact length was r = 0.839 (p <0.0001). ROC AUC analysis revealed that magnetic resonance imaging tumor contact length outperformed cancer core involvement on targeted biopsy and the Partin tables to predict microscopic extracapsular extension (0.88 vs 0.70 and 0.63, respectively). At a magnetic resonance imaging tumor contact length threshold of 20 mm the accuracy for diagnosing microscopic extracapsular extension was superior to that of conventional magnetic resonance imaging criteria (82% vs 67%, p = 0.015). We developed a predicted probability plot curve of extracapsular extension according to magnetic resonance imaging tumor contact length.

CONCLUSIONS

Magnetic resonance imaging determined tumor contact length could be a promising quantitative predictor of microscopic extracapsular extension.

Clinical application of navigation surgery using augmented reality in the abdominal field

This article presents general principles and recent advancements in the clinical application of augmented reality-based navigation surgery (AR based NS) for abdominal procedures and includes a description of our clinical trial and subsequent outcomes. Moreover, current problems and future aspects are discussed. The development of AR-based NS in the abdomen is delayed compared with another field because of the problem of intraoperative organ deformations or the existence of established modalities. Although there are a few reports on the clinical use of AR-based NS for digestive surgery, sophisticated technologies in urology have often been reported. However, the rapid widespread use of video- or robot assisted surgeries requires this technology. We have worked to develop a system of AR-based NS for hepatobiliary and pancreatic surgery. Then we developed a short rigid scope that enables surgeons to obtain 3D view. We recently focused on pancreatic surgery, because intraoperative organ shifting is minimal. The position of each organ in overlaid image almost corresponded with that of the actual organ with about 5 mm of mean registration errors. Intraoperative information generated from this system provided us with useful navigation. However, AR-based NS has several problems to overcome such as organ deformity, evaluation of utility, portability or cost.

Intraoperative ultrasonography with a surgeon-manipulated microtransducer during robotic radical prostatectomy

Intraoperative transrectal ultrasonography during laparoscopic radical prostatectomy has been reported to lead to a reduction in surgical margin rates. However, the use of a surgeon-controlled ultrasound probe that allows for precise manipulation and direct interpretation of the image by a console surgeon has yet to be studied. The aim of the present study was to show initial feasibility using the microtransducer with 9-mm scan length controlled by the console surgeon during robot-assisted radical prostatectomy in 10 patients. The transducer is designed as a drop-in probe with a flexible cord for insertion through a laparoscopic port, and is controlled by a robotic arm with the ultrasonographic image shown as a console Tile-pro display. Intraoperative localization of the biopsy-proven cancerous hypoechoic lesion was feasible in four out of four cases. The microtransducer facilitated identification of the bladder neck as well as the appropriate level of neurovascular bundle release. Negative surgical margin was achieved in all 10 cases (100%), even though five of 10 patients (50%) had extraprostatic (pT3) disease. Recovery of erectile function and continence was encouraging. In conclusion, intraoperative ultrasound navigation using a drop-type microtransducer is a novel technique that could enhance the incremental value of the standard information.

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.

Recent advances in urologic laparoscopic surgeries: laparoendoscopic single-site surgery, natural orifice transluminal endoscopic surgery, robotics and navigation

Laparoscopic surgery was developed at the end of the 1980s and has been utilized in almost all urologic surgical procedures. It offers the benefits of less invasiveness and earlier recovery than open surgery. The introduction of laparoendoscopic single-site surgery has offered reduced pain and improved cosmetic satisfaction to patients. Scarless nephrectomy has been realized with transvaginal natural orifice transluminal endoscopic surgery in women. The development of surgical robots has decreased the technical difficulty of complicated procedures, shortened the learning curve, and improved perioperative outcomes relative to laparoscopic surgery. Surgical navigation using real-time sonography, augmented reality, fluorescence, or radioisotope images will improve the quality of these surgeries.

Ultrasound elastography as a tool for imaging guidance during prostatectomy: initial experience

BACKGROUND

During laparoscopic or robotic assisted laparoscopic prostatectomy, the surgeon lacks tactile feedback which can help him tailor the size of the excision. Ultrasound elastography (USE) is an emerging imaging technology which maps the stiffness of tissue. In the paper we are evaluating USE as a palpation equivalent tool for intraoperative image guided robotic assisted laparoscopic prostatectomy.

MATERIAL/METHODS

Two studies were performed: 1) A laparoscopic ultrasound probe was used in a comparative study of manual palpation versus USE in detecting tumor surrogates in synthetic and ex-vivo tissue phantoms; N=25 participants (students) were asked to provide the presence, size and depth of these simulated lesions, and 2) A standard ultrasound probe was used for the evaluation of USE on ex-vivo human prostate specimens (N=10 lesions in N=6 specimens) to differentiate hard versus soft lesions with pathology correlation. Results were validated by pathology findings, and also by in-vivo and ex-vivo MR imaging correlation.

RESULTS

In the comparative study, USE displayed higher accuracy and specificity in tumor detection (sensitivity=84%, specificity=74%). Tumor diameters and depths were better estimated using USE versus with manual palpation. USE also proved consistent in identification of lesions in ex-vivo prostate specimens; hard and soft, malignant and benign, central and peripheral.

CONCLUSIONS

USE is a strong candidate for assisting surgeons by providing palpation equivalent evaluation of the tumor location, boundaries and extra-capsular extension. The results encourage us to pursue further testing in the robotic laparoscopic environment.

Registration of 3D ultrasound through an air-tissue boundary

In this study we evaluated a new method for registering three-dimensional ultrasound (3DUS) data to external coordinate systems. First, 3DUS was registered to the stereo endoscope of a da Vinci Surgical System by placing a registration tool against an air-tissue boundary so that the 3DUS could image ultrasound fiducials while the stereo endoscope could image camera markers on the same tool. The common points were used to solve the registration between the 3DUS and camera coordinate systems. The target registration error (TRE) when imaging through a PVC tissue phantom ranged from 3.85 1.76 mm to 1.82 1.03 mm using one to four registration tool positions. TRE when imaging through an ex-vivo liver tissue sample ranged from 2.36 1.01 mm to 1.51 0.70 mm using one to four registration tool positions. Second, using a similar method, 3DUS was registered to the kinematic coordinate system of a da Vinci Surgical System by using the da Vinci surgical manipulators to identify common points on an air-tissue boundary. TRE when imaging through a PVC tissue phantom was 0.95 0.38 mm. This registration method is simpler and potentially more accurate than methods using commercial motion tracking systems. This method may be useful in the future in augmented reality systems for laparoscopic and robotic-assisted surgery.

Real-time robotic transrectal ultrasound navigation during robotic radical prostatectomy: initial clinical experience

OBJECTIVE

To describe a novel robotic transrectal ultrasound platform for real-time navigation during robot-assisted laparoscopic radical prostatectomy (RALP) and to report its early clinical application.

METHODS

Five men undergoing RALPs at our Institution agreed to participate in this Institutional Review Board-approved pilot study. All of them were eligible for a bilateral nerve sparing procedure. Before docking the da Vinci robot, a transrectal ultrasound tri-plane side-fire probe was placed. A modified ViKY Endoscope Holder was used during RALPs to move the probe thanks to a remote control placed under the console surgeon's control during RALPs. During each procedure, attempt was made to estimate prostate volume, define 12 reference points, and to precisely identify location of the neurovascular bundles using Doppler ultrasound. The TilePro was used during the procedures to allow real-time ultrasound imaging to guide robotic instruments during dissection.

RESULTS

Median robotic transrectal ultrasound probe holder (R-TRUS) setup time was 11 minutes (interquartile range [IQR], 10-14). Prostate volume calculation, reference point definition, neurovascular bundle identification, and instrument tip visualization were successful in all men. In 1 patient with a large prostate (120 mL), R-TRUS was withdrawn during recto-prostatic dissection. There were no rectal injuries.

CONCLUSION

R-TRUS during RALPs is feasible and safe. It allows real-time TRUS navigation and guidance. Further studies are needed to evaluate its impact on oncological and functional outcomes.

Robotic transrectal ultrasonography during robot-assisted radical prostatectomy

We evaluate the use of robotically manipulated transrectal ultrasound (TRUS) for real-time monitoring of prostate and periprostatic anatomy during robot-assisted prostatectomy (RAP). Ten patients with clinically organ-confined prostate cancer undergoing RAP underwent preoperative and real-time intraoperative biplanar TRUS evaluation using a robotically manipulated TRUS device (ViKY System; EndoControl Medical, Grenoble, France). Median patient age was 66 yr (range: 54-88), baseline prostate-specific antigen (PSA) was 5.3 (range: 1.3-17.9), and four patients (40%) had clinical high-grade and high-stage disease. Bilateral or unilateral nerve sparing was performed in nine patients (90%). Median time for ViKY System setup to insertion of the TRUS probe was 7 min (range: 4-12). Complete robotic TRUS evaluation was successful in all patients. Five patients (50%) had TRUS-visible hypoechoic lesions, confirmed cancerous on preoperative biopsy. Relevant intraoperative TRUS findings were relayed in real time to the robotic surgeon, particularly during dissection of the bladder neck and prostatic apex, during neurovascular bundle preservation, and when hypoechoic prostate lesions approximated nerve-preserving dissection. Negative margins were achieved in nine patients (90%), including cases where significant intraprostatic lesions abutted or extended through the prostate capsule. No complications occurred. We concluded that real-time robotic TRUS guidance during RAP is feasible and safe. Robotic TRUS can provide the console surgeon with valuable anatomic information, thus maximizing functional preservation and oncologic success.

Image-guided robotic surgery: update on research and potential applications in urologic surgery

PURPOSE OF REVIEW

New methods of imaging and image-guidance technology have the potential to provide surgeons with spatially accurate three-dimensional information about the location and anatomical relationships of critical subsurface structures and instrument position updated and displayed during the performance of surgery. Robotic platforms and technology in various forms continues to revolutionize surgery and will soon incorporate image guidance.

RECENT RESEARCH

Image-guided surgery (IGS) for abdominal and urologic interventions presents complex engineering and surgical challenges along with potential benefits to surgeons and patients. Key concepts such as registration, localization, accuracy, and targeting error are necessary for surgeons to understand and utilize the potential of IGS. Standard robotic surgeries, such as partial nephrectomy and radical prostatectomy may soon incorporate IGS.

SUMMARY

Research continues to explore the potential for combining image guidance and robotics to augment and improve a variety of surgical interventions.

Nerve mapping for prostatectomies: novel technologies under development

Prostatic neuroanatomy is difficult to visualize intraoperatively and can be extremely variable. Damage to these nerves during prostatectomies may lead to postoperative complications such as erectile dysfunction and incontinence. This review aims to discuss the prostatic neuroanatomy, sites of potential nerve damage during a prostatectomy, and nerve-mapping technologies being developed to prevent neural injury. These technologies include stimulation, dyes, and direct visualization. Nerve stimulation works by testing an area and observing a physiologic response but is limited by the long half-life for an erectile response; examples include CaverMap, ProPep, and optical nerve stimulation. Few nerve dyes have been approved by the Food and Drug Administration (FDA) because of the extensive testing required; examples of nerve dyes include compounds from Avelas and General Electric, fluorescent cholera toxin subunit B, indocyanine green, fluorescent inactivated herpes simplex 2, and Fluoro-Gold. Direct visualization techniques have a simpler FDA approval process; examples include optical coherence tomography, multiphoton microscopy, ultrasound, coherent anti-Stokes Raman scattering. Many researchers are developing several novel technologies that can be categorized as stimulation based, dye-based, or direct visualization. As of yet, none has shown clear evidence to improve surgical outcomes and consequently lack wide adoption. Further development of these technologies may lead to improved complication rates after prostatectomies. Clinically, some technologies have demonstrated utility in predicting the development of complications. By using that information, more aggressive rehabilitation programs may lead to improved long-term function. These technologies can also be applied for research to improve our knowledge of the neuroanatomy and physiology of erection and incontinence.

Water-filled laparoendoscopic surgery (WAFLES): feasibility study in porcine model

PURPOSE

Recent surgical techniques have been advancing under endoscopic view and insufflation of carbon dioxide gas to expand the abdominal cavity. Isotonic fluid could be one candidate for expanding cavities to facilitate surgical maneuvering. We tested the feasibility and drawbacks of replacement of irrigating materials using a porcine model (water-filled laparoendoscopic surgery [WAFLES]).

MATERIALS AND METHODS

Laparoscopic cholecystectomy was performed in two porcine models using instillation of sorbitol solution as irrigant. Solution irrigation was performed through one of four ports, with drainage via another port. Conventional forceps equipped with a monopolar electrode for electrocautery, laparoscope, video processor, ultrasound, and transducer for measuring intraabdominal pressure were used.

RESULTS

Laparoscopic cholecystectomy was successfully undertaken with the following benefits: (1) clear observation of the dissecting plane throughout maneuvering; (2) control of oozing and spilled bile by irrigation and suction; and (3) ultrasonographic and laparoscopic images can be obtained simultaneously without any restriction to probe location. However, two disadvantages should be noted: (1) difficulties in managing floating organs and (2) interruption of vision by blood.

CONCLUSIONS

WAFLES provides some benefits for endoscopic surgery with proper devices, including apparatuses for irrigation and suction. Efficient irrigation and selection of proper irrigant and apparatuses are required to establish an acceptable procedure.

Future perspectives in robotic surgery

• Robotics of the current day have advanced significantly from early computer-aided design/manufacturing systems to modern master-slave robotic systems that replicate the surgeon's exact movements onto robotic instruments in the patient. • Globally >300,000 robotic procedures were completed in 2010, including ≈98,000 robot-assisted radical prostatectomies. • Broadening applications of robotics for urological procedures are being investigated in both adult and paediatric urology. • The use of the current robotic system continues to be further refined. Increasing experience has optimized port placement reducing arm collisions to allow for more expedient surgery. Improved three-dimensional camera magnification provides improved intraoperative identification of structures. • Robotics has probably improved the learning curve of laparoscopic surgery while still maintaining its patient recovery advantages and outcomes. • The future of robotic surgery will take this current platform forward by improving haptic (touch) feedback, improving vision beyond even the magnified eye, improving robot accessibility with a reduction of entry ports and miniaturizing the slave robot. • Here, we focus on the possible advancements that may change the future landscape of robotic surgery.

Augmented reality visualization during laparoscopic radical prostatectomy

PURPOSE

We present an augmented reality (AR) navigation system that conveys virtual organ models generated from transrectal ultrasonography (TRUS) onto a real laparoscopic video during radical prostatectomy. By providing this additional information about the actual anatomy, we can support surgeons in their working decisions. This work reports the system's first in-vivo application.

MATERIALS AND METHODS

The system uses custom-developed needles with colored heads that are inserted into the prostate as soon as the organ surface is uncovered. These navigation aids are once segmented in three-dimensional (3D) TRUS data that is acquired right after the placement of the needles and then continuously tracked in the laparoscopic video images by the surgical navigation system. The navigation system traces the navigation aids in real time and computes a registration between TRUS image and laparoscopic video based on the two-dimensional-three dimensional (2D-3D) point correspondences. With this registration, the system correctly superimposes TRUS-based 3D information on an additional AR monitor placed next to the normal laparoscopic screen. Surgical navigation guidance took place until the prostate was removed from the rectal wall. Finally, the navigation aids were removed together with the specimen inside the specimen bag.

RESULTS

The initial human in-vivo application of the surgical navigation system was successful. No complications occurred, the prostate was removed together with the navigation aids, and the system supported the surgeons as intended with an AR visualization in real time. In case of tissue deformations, changes in the spatial configuration of the navigation aids are detected, which preserves the system from erroneous navigation visualization.

CONCLUSIONS

Feasibility of the navigation system was shown in the first in-vivo application. TRUS information could be superimposed via AR in real time. To show the benefit for the patient, results obtained from a larger number of trials are needed.

Imaging guidance in minimally invasive prostatectomy

Minimally invasive prostatectomy, such as laparoscopic and robot-assisted prostatectomy, has become more popular, with similar short-term outcomes as open radical retropubic prostatectomy series. The purpose of this article is to review different imaging modalities that have been developed with a goal of further improving the surgical outcomes in minimally invasive prostatectomy.

Tandem-robot assisted laparoscopic radical prostatectomy to improve the neurovascular bundle visualization: a feasibility study

OBJECTIVES

To examine the feasibility of image-guided navigation using transrectal ultrasound (TRUS) to visualize the neurovascular bundle (NVB) during robot-assisted laparoscopic radical prostatectomy (RALP). The preservation of the NVB during radical prostatectomy improves the postoperative recovery of sexual potency. The accompanying blood vessels in the NVB can serve as a macroscopic landmark to localize the microscopic cavernous nerves in the NVB.

METHODS

A novel, robotic transrectal ultrasound probe manipulator (TRUS Robot) and three-dimensional (3-D) reconstruction software were developed and used concurrently with the daVinci surgical robot (Intuitive Surgical, Inc., Sunnyvale, CA) in a tandem-robot assisted laparoscopic radical prostatectomy (T-RALP).

RESULTS

After appropriate approval and informed consent were obtained, 3 subjects underwent T-RALP without associated complications. The TRUS Robot allowed a steady handling and remote manipulation of the TRUS probe during T-RALP. It also tracked the TRUS probe position accurately and allowed 3-D image reconstruction of the prostate and surrounding structures. Image navigation was performed by observing the tips of the daVinci surgical instruments in the live TRUS image. Blood vessels in the NVB were visualized using Doppler ultrasound.

CONCLUSIONS

Intraoperative 3-D image-guided navigation in T-RALP is feasible. The use of TRUS during radical prostatectomy can potentially improve the visualization and preservation of the NVB. Further studies are needed to assess the clinical benefit of T-RALP.

A comparative study between an improved novel air-cushion sensor and a wheeled probe for minimally invasive surgery

PURPOSE

We describe a comparative study between an enhanced air-cushion tactile sensor and a wheeled indentation probe. These laparoscopic tools are designed to rapidly locate soft-tissue abnormalities during minimally invasive surgery (MIS).

MATERIALS AND METHODS

The air-cushion tactile sensor consists of an optically based sensor with a 7.8 mm sphere "floating" on a cushion of air at the tip of a shaft. The wheeled indentation probe is a 10 mm wide and 5 mm in diameter wheel mounted to a force/torque sensor. A continuous rolling indentation technique is used to pass the sensors over the soft-tissue surfaces. The variations in stiffness of the viscoelastic materials that are detected during the rolling indentations are illustrated by stiffness maps that can be used for tissue diagnosis. The probes were tested by having to detect four embedded nodules in a silicone phantom. Each probe was attached to a robotic manipulator and rolled over the silicone phantom in parallel paths. The readings of each probe collected during the process of rolling indentation were used to achieve the final results.

RESULTS

The results show that both sensors reliably detected the areas of variable stiffness by accurately identifying the location of each nodule. These are illustrated in the form of two three-dimensional spatiomechanical maps.

CONCLUSIONS

These probes have the potential to be used in MIS because they could provide surgeons with information on the mechanical properties of soft tissue, consequently enhancing the reduction in haptic feedback.

Radical prostatectomy: does surgical technique influence margin control?

The goal of radical prostatectomy (RP) is complete removal of the prostate and seminal vesicles with negative surgical margins. Regardless of approach, the occurrence of positive surgical margins (PSMs) remains a risk associated with RP. In addition, PSMs can adversely affect biochemical and cause-specific survival. With the advent of PSA screening and introduction of new RP approaches, surgical technique has become increasingly debated in relationship to margin positivity. The issue, however, is controversial, as underlying clinical and pathologic characteristics of prostate cancer also influence margin control. This article evaluates the impact of surgical technique on margin control during RP. In addition, we evaluate the influence that stage migration, the individual surgeon, new technologic adjuncts, and specimen handling have had on margin control.

Imaging in percutaneous nephrolithotomy

Image guidance is a critical factor for the performance of urologic interventions. Percutaneous minimally invasive procedures have been developed and are being used with constantly increasing frequency. Procedures such as percutaneous nephrolithotomy (PCNL) are not performed without any image guidance. Recent developments in medical imaging, such as three-dimensional radiographic fluoroscopy, CT, and magnetic resonance (MR) fluoroscopy, four-dimensional ultrasonography, and image fusion techniques, propose a new generation of image-guidance tools that promise to improve patient care. These developments have been used or have the potential to be used in PCNL and other urologic interventional procedures. Moreover, advanced needles and needle guidance systems provide a new perspective for the nephrolithotomy suite of the future. The current review presents existing imaging technology in PCNL and interventional urology as well as advanced imaging techniques that are being or are expected to be evaluated in PCNL practice.