Are 3D Image Guidance Systems Ready for Use? A Comparative Analysis of 3D Image Guidance Implementations in Minimally Invasive Partial Nephrectomy

Introduction: Three-dimensional image-guided surgical (3D-IGS) systems for minimally invasive partial nephrectomy (MIPN) can potentially improve the efficiency and accuracy of intraoperative anatomical localization and tumor resection. This review seeks to analyze the current state of research regarding 3D-IGS, including the evaluation of clinical outcomes, system functionality, and qualitative insights regarding 3D-IGS's impact on surgical procedures. Methods: We have systematically reviewed the clinical literature pertaining to 3D-IGS deployed for MIPN. For inclusion, studies must produce a patient-specific 3D anatomical model from two-dimensional imaging. Data extracted from the studies include clinical results, registration (alignment of the 3D model to the surgical scene) method used, limitations, and data types reported. A subset of studies was qualitatively analyzed through an inductive coding approach to identify major themes and subthemes across the studies. Results: Twenty-five studies were included in the review. Eight (32%) studies reported clinical results that point to 3D-IGS improving multiple surgical outcomes. Manual registration was the most utilized (48%). Soft tissue deformation was the most cited limitation among the included studies. Many studies reported qualitative statements regarding surgeon accuracy improvement, but quantitative surgeon accuracy data were not reported. During the qualitative analysis, six major themes emerged across the nine applicable studies. They are as follows: 3D-IGS is necessary, 3D-IGS improved surgical outcomes, researcher/surgeon confidence in 3D-IGS system, enhanced surgeon ability/accuracy, anatomical explanation for qualitative assessment, and claims without data or reference to support. Conclusions: Currently, clinical outcomes are the main source of quantitative data available to point to 3D-IGS's efficacy. However, the literature qualitatively suggests the benefit of accurate 3D-IGS for robotic partial nephrectomy.

Unified Robot and Inertial Sensor Self-Calibration

Robots and inertial measurement units (IMUs) are typically calibrated independently. IMUs are placed in purpose-built, expensive automated test rigs. Robot poses are typically measured using highly accurate (and thus expensive) tracking systems. In this paper, we present a quick, easy, and inexpensive new approach to calibrate both simultaneously, simply by attaching the IMU anywhere on the robot's end effector and moving the robot continuously through space. Our approach provides a fast and inexpensive alternative to both robot and IMU calibration, without any external measurement systems. We accomplish this using continuous-time batch estimation, providing statistically optimal solutions. Under Gaussian assumptions, we show that this becomes a nonlinear least squares problem and analyze the structure of the associated Jacobian. Our methods are validated both numerically and experimentally and compared to standard individual robot and IMU calibration methods.

A Safe Framework for Quantitative In Vivo Human Evaluation of Image Guidance

Goal: We present a new framework for in vivo image guidance evaluation and provide a case study on robotic partial nephrectomy. Methods: This framework (called the "bystander protocol") involves two surgeons, one who solely performs the therapeutic process without image guidance, and another who solely periodically collects data to evaluate image guidance. This isolates the evaluation from the therapy, so that in-development image guidance systems can be tested without risk of negatively impacting the standard of care. We provide a case study applying this protocol in clinical cases during robotic partial nephrectomy surgery. Results: The bystander protocol was performed successfully in 6 patient cases. We find average lesion centroid localization error with our IGS system to be 6.5 mm in vivo compared to our prior result of 3.0 mm in phantoms. Conclusions: The bystander protocol is a safe, effective method for testing in-development image guidance systems in human subjects.

Carbon Dioxide Pyelography: A Convenient and Safe Alternative to Both Room Air and Iodinated Contrast Pyelography During Endourologic Procedures

Introduction/Background: There are increasing reports of serious complications related to the air pyelography technique, which raise concerns about the safety of room air (RA) injection into the renal collecting system. Carbon dioxide (CO2) is much more soluble in blood than nitrogen and oxygen and thus considerably less likely to cause gas emboli. Iodinated contrast medium (ICM) is expensive, and supplies may not be as reliable as previously assumed. CO2 pyelography (CO2-P) techniques using standard fluoroscopy and digital subtraction fluoroscopy (CO2 digital subtraction pyelography [CO2-DSP]) are described. Materials and Methods: During the endourologic stone cases, 15 to 20 mL of CO2 gas was typically injected into the renal pelvis through a catheter or sheath. Imaging was usually obtained with endovascular CO2 digital subtraction angiography settings using either a traditional fluoroscopy system (TFS) or robotic arm multiplanar fluoroscopy system (RMPFS) (Artis Zeego Care+Clear®; Siemens). Results: CO2-P was performed in 22 endoscopic stone treatment cases between March 2021 and August 2022, primarily using digital subtraction settings in 20 cases. CO2-DSP overall provided higher quality images of the renal pelvis and collecting system than CO2-P, but with a relatively higher radiation dose. Following a quality intervention, fluoroscopy doses for CO2-DSP cases were decreased by 81% overall. The use of CO2-P avoided fluoroscopic or intraoperative CT (ICT) artifacts seen with intraluminal ICM. Conclusions: CO2-P allows the urologist to obtain imaging of the renal collecting system without ICM and with much lower risk of air embolism compared with RA pyelography. CO2 is a nearly cost-free alternative to ICM. Because CO2 is widely available and the technique is easy to perform, we propose that CO2-P should be favored over traditional air pyelography to improve patient safety.

Single cell analysis of cribriform prostate cancer reveals cell intrinsic and tumor microenvironmental pathways of aggressive disease

Cribriform prostate cancer, found in both invasive cribriform carcinoma (ICC) and intraductal carcinoma (IDC), is an aggressive histological subtype that is associated with progression to lethal disease. To delineate the molecular and cellular underpinnings of ICC/IDC aggressiveness, this study examines paired ICC/IDC and benign prostate surgical samples by single-cell RNA-sequencing, TCR sequencing, and histology. ICC/IDC cancer cells express genes associated with metastasis and targets with potential for therapeutic intervention. Pathway analyses and ligand/receptor status model cellular interactions among ICC/IDC and the tumor microenvironment (TME) including JAG1/NOTCH. The ICC/IDC TME is hallmarked by increased angiogenesis and immunosuppressive fibroblasts (CTHRC1⁺ASPN⁺FAP⁺ENG⁺) along with fewer T cells, elevated T cell dysfunction, and increased C1QB⁺TREM2⁺APOE⁺-M2 macrophages. These findings support that cancer cell intrinsic pathways and a complex immunosuppressive TME contribute to the aggressive phenotype of ICC/IDC. These data highlight potential therapeutic opportunities to restore immune signaling in patients with ICC/IDC that may afford better outcomes.

Patient-specific, touch-based registration during robotic, image-guided partial nephrectomy

Image-guidance during partial nephrectomy enables navigation within the operative field alongside a 3-dimensional roadmap of renal anatomy generated from patient-specific imaging. Once a process is performed by the human mind, the technology will allow standardization of the task for the benefit of all patients undergoing robot-assisted partial nephrectomy. Any surgeon will be able to visualize the kidney and key subsurface landmarks in real-time within a 3-dimensional simulation, with the goals of improving operative efficiency, decreasing surgical complications, and improving oncologic outcomes. For similar purposes, image-guidance has already been adopted as a standard of care in other surgical fields; we are now at the brink of this in urology. This review summarizes touch-based approaches to image-guidance during partial nephrectomy, as the technology begins to enter in vivo human evaluation. The processes of segmentation, localization, registration, and re-registration are all described with seamless integration into the da Vinci surgical system; this will facilitate clinical adoption sooner.

Differential effect of body mass index by gender on oncological outcomes in patients with renal cell carcinoma

Objectives

To investigate the relationship between gender, body mass index (BMI), and prognosis in renal cell carcinoma (RCC) patients.

Materials and Methods

We retrospectively reviewed 1353 patients with RCC who underwent a partial or radical nephrectomy between 1988 and 2015. The association among sex, BMI, stage, grade, overall survival (OS), and recurrence-free survival (RFS) was analyzed.

Results

The median age of the patients was 59.4 ± 11.9 years. Female patients had proportionally lower grade tumors than male patients (Grade I-II in 75.5% vs. 69.3% in women and men, respectively, P = 0.022). There was no relationship between Fuhrman grade and BMI when substratified by gender (p > 0.05). There was a nonsignificant trend toward more localized disease in female patients (p = 0.058). There was no relationship between T stage and BMI when stratified by gender (p > 0.05). Patients with higher BMI had significantly better OS (p = 0.0004 and P = 0.0003) and RFS (P = 0.0209 and P =0.0082) whether broken out by lower 33^rd or 25^th percentile. Male patients with higher BMI had significantly better OS and RFS rates. However, there was no relationship between BMI and OS or RFS for female patients (P > 0.05). Multivariate analysis of the entire cohort demonstrated that a BMI in the lower quartile independently predicts OS (hazard ratio 1.604 [95% confidence interval: 1.07-2.408], P = 0.022) but not RFS (P > 0.05). When stratified by gender, there was no relationship between BMI and either OS or RFS (P > 0.05).

Conclusions

Increasing BMI was associated with RCC prognosis. However, the clinical association between BMI and oncologic outcomes may be different between men and women.

Transurethral Anastomosis after Transurethral Radical Prostatectomy: A Phantom Study on Intraluminal Suturing With Concentric Tube Robots

Current surgical approaches to radical prostatectomy are associated with high rates of erectile dysfunction and incontinence. These complications occur secondary to the disruption of surrounding healthy tissue, which is required to expose the prostate. The urethra offers the least invasive access to the prostate, and feasibility has been demonstrated of enucleating the prostate with an endoscope using Holmium laser, which can itself be aimed by concentric tube robots. However, the transurethral approach to radical prostatectomy has thus far been limited by the lack of a suitable means to perform an anastomosis of the urethra to the bladder after prostate removal. Only a few intraluminal anastomotic devices currently exist, and none are small enough to pass through the urethra. In this paper we describe a new way to perform an anastomosis in the small luminal space of the urethra, harnessing the dexterity and customizability of concentric tube manipulators. We demonstrate a successful initial proof-of-concept anastomosis in an anthropomorphic phantom of the urethra and bladder.

Mechatronic Design of a Two-Arm Concentric Tube Robot System for Rigid Neuroendoscopy

Open surgical approaches are still often employed in neurosurgery, despite the availability of neuroendoscopic approaches that reduce invasiveness. The challenge of maneuvering instruments at the tip of the endoscope makes neuroendoscopy demanding for the physician. The only way to aim tools passed through endoscope ports is to tilt the entire endoscope; but, tilting compresses brain tissue through which the endoscope passes and can damage it. Concentric tube robots can provide necessary dexterity without endoscope tilting, while passing through existing ports in the endoscope and carrying surgical tools in their inner lumen. In this paper we describe the mechatronic design of a new concentric tube robot that can deploy two concentric tube manipulators through a standard neuroendoscope. The robot uses a compact differential drive and features embedded motor control electronics and redundant position sensors for safety. In addition to the mechatronic design of this system, this paper contributes experimental validation in the context of colloid cyst removal, comparing our new robotic system to standard manual endoscopy in a brain phantom. The robotic approach essentially eliminated endoscope tilt during the procedure (17.09° for the manual approach vs. 1.16° for the robotic system). The robotic system also enables a single surgeon to perform the procedure - typically in a manual approach one surgeon aims the endoscope and another operates the tools delivered through its ports.

A Concentric Tube Robot System for Rigid Bronchoscopy: A Feasibility Study on Central Airway Obstruction Removal

New robotic systems have recently emerged to assist with peripheral lung access, but a robotic system for rigid bronchoscopy has yet to be developed. We describe a new robotic system that can deliver thin robotic manipulators through the ports of standard rigid bronchoscopes. The manipulators bend and elongate to provide maneuverability of surgical tools at the endoscope tip, without endoscope motion. We describe an initial feasibility study on the use of this system to bronchoscopically treat a central airway obstruction (CAO). CAO is prevalent and can be life-threatening in patients with large tumors, and conventional rigid bronchoscopic treatments place patients at risk of complications including broken teeth, neck trauma and damage to oropharyngeal structures due to significant forces induced by bronchoscope tilting and manipulation. In this study, we used an ex vivo ovine airway model to demonstrate the ability of a physician using the robotic system to efficiently remove tissue and restore the airway. Pre- and post-operative CT scans showed that the robot was able to reduce the degree of airway obstruction stenosis from 75 to 14% on average for five CAO resections performed in an ex vivo animal model. Using cadaver experiments, we demonstrated the potential of the robotic system to substantially reduce the intraoperative forces applied to the patient's head and neck (from 80.6 to 4.1 N). These preliminary results illustrate that CAO removal is feasible with our new rigid bronchoscopy robot system, and that this approach has the potential to reduce forces applied to the patient due to bronchoscope angulation, and thereby reduce the risk of complications encountered during CAO surgery.

Opiate Exposure and Predictors of Increased Opiate Use After Ureteroscopy

Objective: Kidney stone formers are at risk for opioid dependence. The aim of this study is to describe opiate exposure and determine predictors of prolonged opiate use among kidney stone formers after surgery. Materials and Methods: A retrospective review was performed among patients who underwent ureteroscopy for upper tract stone disease. Prescription data were ascertained from a statewide prescribing database. Demographic data and surgical factors were collected from the electronic medical record. Predictors of additional postsurgery prescriptions filled within 30 days and persistent opiate use 60 days after ureteroscopy were determined. Results: Among 208 patients, 127 (61%) had received preoperative opiate prescriptions within 30 days before surgery. Overall, 12% (n = 25) of patients required an additional opiate prescription within 30 days after ureteroscopy, and 7% (n = 14) of patients continued to use opiate medications more than 60 days postoperatively. Patients continuing to use opiates long-term were not chronic opiate users. For both outcomes, preoperative opiate exposure, including number of prescriptions, days prescribed, and unique providers had significant associations (all p < 0.05). Additionally, younger age (p = 0.049) was associated with obtaining an additional opiate prescription within 30 days. Lower BMI (p = 0.02) and higher ASA score (p = 0.03) were predictors of continued opiate use more than 60 days after ureteroscopy. Conclusions: The majority of stone formers have had opiate exposure before surgery, often from multiple providers. Approximately 1 in 8 stone formers who undergo ureteroscopy require additional opiate prescriptions within 30 days. A small but significant population receive opiates beyond the immediate postoperative period.

A Hand-Held Non-Robotic Surgical Tool With a Wrist and an Elbow

OBJECTIVE

This paper describes a surgical device that provides both wrist and elbow dexterity without motors or electronics. The device provides dexterity advantages in minimally invasive surgery typically associated with robotic systems, but does so with many fewer components. Fully mechanical designs of this type promise to deliver "robot-like dexterity" at a lower financial cost than current surgical robotic systems.

METHODS

Most non-robotic articulated surgical tools developed to date feature one or two degrees-of-freedom (DOF) close to the tool tip (i.e., a "wrist"). In this paper, we describe a new tool that not only features a two-DOF wrist, but also augments its dexterity with a two-DOF "elbow" consisting of a multi-backbone design seen previously only in robotic systems. Such an elbow offers high stiffness in a thin form factor. This elbow requires static balancing, which we accomplish with springs in the handle, so that the surgeon can benefit from the stiffness without feeling it while using the device.

RESULTS

We report the overall tool design and experiments evaluating how well our static balance mechanism compensates for the multi-backbone elbow's intrinsic stiffness.

CONCLUSION

We demonstrate the use of a multi-backbone elbow in a manual tool for the first time and show how to combine the elbow with a pin joint wrist in a fully mechanical (i.e., non-robotic) tool.

SIGNIFICANCE

This paper is a step toward high dexterity, low-cost surgical instruments that bring some benefits of surgical robotic systems to patients and surgeons at a lower cost.

Predictors of spontaneous ureteral stone passage in the presence of an indwelling ureteral stent

Patients presenting acutely with obstructing stones often have a ureteral stent placed as a temporizing solution. Ureteroscopy is then commonly performed in a staged fashion, but occasionally the stone is found to have passed. We aimed to identify the frequency and predictors of ureteral stone passage with a stent in place. Records were reviewed to identify patients who had a stent placed for a single ureteral stone. Subsequent ureteroscopy or CT scan was used to ascertain stone passage. Effect of age, gender, BMI, stone diameter, alpha blocker use, urinary tract infection, hydronephrosis, and stent duration on stone passage was assessed. Inclusion and exclusion criteria were met in 209 patients. Mean maximum stone diameter was 6.5 ± 2.5 mm. Passage rates for stones < 3 mm, 3-4.9 mm, 5-6.9 mm, and ≥ 7 mm were 50%, 13%, 10%, and 0%, respectively. The overall rate of passage was 8%. Stone passage was associated with smaller maximum stone diameter, more distal stone location, and longer duration of stent before ureteroscopy/CT on univariate analysis (p < 0.01). Stone diameter and stent duration remained significantly associated on multivariable analysis (p = 0.001 and p = 0.05, respectively). Our findings suggest ureteral stone passage with a concurrent ureteral stent is not a rare event as it occurred in 14% of stones less then 7 mm in maximum diameter. Stone size and duration of stent before ureteroscopy or CT were found to be independent predictors of passage. Select patients with small ureteral stones who have been stented should be considered for a trial of urine straining or repeat imaging before subsequent ureteroscopy.

Symptomatic Urinary Tract Infections in Renal Transplant Recipients after Cystoscopy for Ureteral Stent Removal

INTRODUCTION

Symptomatic urinary tract infection (UTI) is a known complication of cystoscopy with ureteral stent removal. However, little is known about the incidence and risk factors for post-cystoscopy UTI in renal transplant recipients, who likely represent a high-risk cohort. Our aim was to determine the infection rate following cystoscopy with stent removal in this population and identify opportunities for care improvement.

METHODS

We performed a retrospective cohort study of office cystoscopies with stent removal in renal transplant recipients performed at a single institution from April 2012 through May 2014. Strict criteria were used to determine presence of symptomatic UTI within one month of the procedure. Fisher's exact tests were completed to examine associations between patient characteristics and post-transplant outcomes with UTI.

RESULTS

A total of 324 patients were included. Mean age was 50.0 (SD 13.1) years, and 187 (57.7%) patients were male. Within this group,165 (52.5%) patients received a pre-procedural oral fluoroquinolone antibiotic dose prior to the procedure. Nine patients had symptomatic UTIs (2.8%), of which three infections (33.3%) were due to quinolone-resistant organisms. Female sex (P =0.04), but no other patient or post-operative characteristic was associated with symptomatic UTI, including the use of peri-procedural antibiotics.

CONCLUSIONS

The incidence of symptomatic UTI after cystoscopy with ureteral stent removal in renal transplant recipients is less than three percent and comparable to post-cystoscopy UTI risk in the general population. Female sex is associated with symptomatic UTI. Further investigation is needed to identify groups most at risk for UTI and other complications.

Lubriglide Sequential Ureteral Dilators®: A Safe and Effective Method of Ureteral Dilation

INTRODUCTION

During ureteroscopy (URS), ureteral dilation may be required to increase the likelihood of accessing the ureter to complete the procedure. Thus, we sought to assess the safety and efficacy of using Lubriglide sequential ureteral dilators^® (Boston Scientific) to promote primary URS, without need for prestenting.

PATIENTS AND METHODS

Retrospective review was performed of a consecutive series of patients undergoing primary URS by a single surgeon (N.L.M.) from 2011 to 2013. The primary outcomes were to characterize the use, safety, and efficacy of sequential ureteral dilators to promote stone treatment during URS.

RESULTS

A total of 316 nonprestented cases of primary URS were attempted over the study period. Use of sequential ureteral dilators to promote ureteral access was performed in 109 (34.5%) cases and was effective to allow completion of the procedure in 102 (93.6%) cases. No intraoperative complications occurred while performing sequential ureteral dilation. Fourteen patients (4.3%) required ureteral stent placement for passive ureteral dilation, with definitive stone treatment at a later date. Postoperative radiographic follow-up was available for 272 (86.1%) cases, and no ureteral strictures were detected in the ureteral dilation group. On multivariate analysis, both a history of prior extracorporeal shockwave lithotripsy [odds ratio (OR) 0.45, confidence interval (CI) 0.25, 0.81, p = 0.008] and prior URS (OR 0.42, CI 0.25, 0.70, p = 0.001) were inversely associated with need to perform ureteral dilation.

CONCLUSIONS

Approximately 1/3 of nonprestented patients may require ureteral dilation for effective completion of primary URS. Use of sequential ureteral dilators may significantly decrease the need for prestenting and a secondary procedure to complete stone treatment. Thus, we conclude that sequential ureteral dilators represent a safe and effective method to perform ureteral dilation to promote ureteral access and allow for effective stone treatment in one setting.

Characterization of Urolithiasis in Patients Following Lower Urinary Tract Reconstruction with Intestinal Segments

PURPOSE

Urinary diversion and augmentation cystoplasty are associated with long-term complications, including metabolic derangements, infectious complications, and urolithiasis. The aim of this series was to characterize upper and lower urinary tract (LUT) calculi in this population.

METHODS

A retrospective chart review was performed on all patients with a history of urinary diversion or augmentation cystoplasty who subsequently underwent treatment for urolithiasis between January 1998 and May 2015. Data collected included demographics, perioperative characteristics, type of reconstructive procedure, urine culture, stone analysis, and metabolic evaluation. A statistical analysis was performed.

RESULTS

Ninety-nine patients were identified with a history of urolithiasis and incontinent urinary diversion (28), neobladder (21), continent cutaneous diversion (12), and augmentation cystoplasty (38). LUT stones were more common than upper tract stones in all except for incontinent diversions, which only had one lower tract stone (p = 0.0001). Twenty-three percent of stones were metabolic. Several metabolic derangements were noted, including hypocitraturia (100%), elevated urine pH (100%), low urine volume (70%), and hyperoxaluria (35%). There was a 44% rate of recurrent urolithiasis.

CONCLUSIONS

Given the high rate of stone recurrence among patients with a history of urinary diversion and augmentation cystoplasty, all measures should be taken to prevent recurrent stones. In addition to actions aimed to prevent infectious stones such as bladder and pouch irrigation, we recommend these patients undergo a full metabolic workup with targeted dietary changes and medical therapies.

Kinematic and experimental investigation of manual resection tools for transurethral bladder tumor resection

BACKGROUND

Transurethral Resection of Bladder Tumors (TURBT) is a challenging procedure partly due to resectoscope limitations. To date, manual resection performance has not been fully characterized. This work characterizes manual resection performance in the bladder while analyzing the effect of resection location on accuracy.

METHODS

Kinematic simulations are used to assess kinematic measures of resection dexterity. An experimental protocol for manual resection accuracy assessment is developed. Cross correlations between the theoretical performance measures and the observed experimental accuracy are investigated.

RESULTS

Tangential accuracy correlates relatively strongly with normal singular value and moderately with tangential kinematic conditioning index and tangential minimum singular value. Simulations also clarified difficulties in resecting close to the bladder neck.

CONCLUSIONS

Measures to evaluate accuracy and dexterity of TURBT from a kinematic viewpoint are presented to provide a currently missing quantified dexterity baseline in manual TURBT. Limitations in various bladder regions are illustrated. Copyright © 2016 John Wiley & Sons, Ltd.

A novel method for texture-mapping conoscopic surfaces for minimally invasive image-guided kidney surgery

PURPOSE

Organ-level registration is critical to image-guided therapy in soft tissue. This is especially important in organs such as the kidney which can freely move. We have developed a method for registration that combines three-dimensional locations from a holographic conoscope with an endoscopically obtained textured surface. By combining these data sources clear decisions as to the tissue from which the points arise can be made.

METHODS

By localizing the conoscope's laser dot in the endoscopic space, we register the textured surface to the cloud of conoscopic points. This allows the cloud of points to be filtered for only those arising from the kidney surface. Once a valid cloud is obtained we can use standard surface registration techniques to perform the image-space to physical-space registration. Since our methods use two distinct data sources we test for spatial accuracy and characterize temporal effects in phantoms, ex vivo porcine and human kidneys. In addition we use an industrial robot to provide controlled motion and positioning for characterizing temporal effects.

RESULTS

Our initial surface acquisitions are hand-held. This means that we take approximately 55 s to acquire a surface. At that rate we see no temporal effects due to acquisition synchronization or probe speed. Our surface registrations were able to find applied targets with submillimeter target registration errors.

CONCLUSION

The results showed that the textured surfaces could be reconstructed with submillimetric mean registration errors. While this paper focuses on kidney applications, this method could be applied to any anatomical structures where a line of sight can be created via open or minimally invasive surgical techniques.

Use of Contrasted Computerized Tomography as a Surrogate for Nuclear Medicine Renogram to Categorize Renal Function in the Setting of Ureteropelvic Junction Obstruction

OBJECTIVE

To use basic measurements on contrasted computerized tomography (CT) to reliably determine whether a kidney with ureteropelvic junction obstruction (UPJO) is definitively functional (≥30% differential renal function [DRF]) or nonfunctional (≤10% DRF), obviating the need for nuclear medicine renogram (RG) to determine DRF.

METHODS

This is a single institution, retrospective cohort of patients diagnosed with UPJO who underwent either pyeloplasty or nephrectomy between December 2004 and December 2014. Included patients had both preoperative mercaptoacetyltriglycine RG and contrasted CT within 180 days of each other. Patients with stents or nephrostomy tubes were excluded.

RESULTS

A total of 49 patients were included. The strongest correlation between differential CT measurements and DRF on RG existed by multiplying the cortical area by the average cortical Hounsfield units (Pearson's r = 0.90, P < .001). Using an equation derived from linear regression and cutoff values generated by receiver operator curve (ROC) analysis, CT equation-estimated DRF values of ≥40% and ≤10% correlated with "definitively functional" RG values of ≥30% (100% specificity) and with "definitively nonfunctional" RG values of ≤10% (100% specificity), respectively. In 30 out of 49 cases, CT could have replaced RG.

CONCLUSION

RG is the gold standard in determining quantitative DRF. However, the treatment algorithm for a kidney with symptomatic UPJO hinges on categorized function: "functional" (repair) or "nonfunctional" (remove). Appropriate measurements on contrasted CT can categorize definitively functional or nonfunctional kidneys with UPJO, negating the need for RG to obtain DRF in a majority of cases. This study design favors real-world application with potential to reduce medical expenditure and delay in definitive treatment.

Toward Improving Transurethral Prostate Surgery: Development and Initial Experiments with a Prototype Concentric Tube Robotic Platform

INTRODUCTION

Despite the potential clinical advantages of holmium laser enucleation of the prostate (HoLEP), there has been reluctance of the urologic community to adopt the procedure, as a result of a perceived steep learning curve. Thus, we sought to design and develop a transurethral endoscopic robotic platform for HoLEP.

MATERIALS AND METHODS

We developed a novel transurethral, concentric tube robotic platform for HoLEP. We conducted magnetic tracking experiments to compare movements of the end effectors of the robot with those of a rigid endoscope. Additionally, we tested the robot on an HoLEP simulator and with a human cadaveric prostate to assess its ability to maneuver within a small working space.

RESULTS

In the prostate scanning experiment, the area reached by the robot represents a 65% improvement vs the area accessible by a rigid endoscope without tissue deformation. Additionally, the robot performed well within the confines of the prostatic urethra and was able to successfully complete prostate lobe enucleation, on both the HoLEP simulator and with a human cadaveric prostate.

CONCLUSIONS

We have developed a concentric tube robotic platform that is passed through a standard endoscope that is capable of producing complex movements of the end effectors. We have shown that these movements of the concentric tube manipulators are capable of performing tasks that may eventually translate into improved ease of performing HoLEP.

Comparing a Mechanical Analogue With the Da Vinci User Interface: Suturing at Challenging Angles

The da Vinci Surgical System offers a natural user interface and wrist articulation, which enable suturing and other complex surgical actions in confined spaces. However, both the one-time cost of the system and the recurring cost of the limited-use instruments remain high. This has motivated the development of several hand-held alternatives-some partially motorized, some fully mechanical-in recent years. While a few of these have been commercialized, none have yet met with broad commercial success comparable to the da Vinci robot. In this letter, we suggest a user interface-based explanation for this, and describe a new mechanical instrument that provides wrist articulation with a novel user interface. We provide results of a single-user pilot study with an experienced laparoscopic surgeon to compare the new device with a traditional wristless laparoscopic tool, a prior commercial wristed mechanical tool (the RealHand), and the da Vinci robot, in the context of suturing at challenging angles. We observe better targeting of desired suture needle entry and exit points with the new device in comparison to prior wristed and wristless mechanical instruments, with the da Vinci only slightly outperforming the new tool.

Hand-held transendoscopic robotic manipulators: A transurethral laser prostate surgery case study

Natural orifice endoscopic surgery can enable incisionless approaches, but a major challenge is the lack of small and dexterous instrumentation. Surgical robots have the potential to meet this need yet often disrupt the clinical workflow. Hand-held robots that combine thin manipulators and endoscopes have the potential to address this by integrating seamlessly into the clinical workflow and enhancing dexterity. As a case study illustrating the potential of this approach, we describe a hand-held robotic system that passes two concentric tube manipulators through a 5 mm port in a rigid endoscope for transurethral laser prostate surgery. This system is intended to catalyze the use of a clinically superior, yet rarely attempted, procedure for benign prostatic hyperplasia. This paper describes system design and experiments to evaluate the surgeon's functional workspace and accuracy using the robot. Phantom and cadaver experiments demonstrate successful completion of the target procedure via prostate lobe resection.

Renal cell cancer histological subtype distribution differs by race and sex

OBJECTIVES

To examine racial differences in the distribution of histological subtypes of renal cell carcinoma (RCC) and associations with established RCC risk factors by subtype.

MATERIALS AND METHODS

Tumours from 1532 consecutive patients with RCC who underwent nephrectomy at Vanderbilt University Medical Center (1998-2012) were classified as clear-cell, papillary, chromophobe and other subtypes. In pairwise comparisons, we used multivariate logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between race, sex, age, end-stage renal disease (ESRD) and body mass index at diagnosis according to histological subtype.

RESULTS

The RCC subtype distribution was significantly different in black people from that in white people (P < 0.001), with a substantially higher proportion of patients with papillary RCC among black people than white people (35.7 vs 13.8%). In multivariate analyses, compared with clear-cell RCC, people with papillary RCC were significantly more likely to be black (OR 4.15; 95% CI 2.64-6.52) and less likely to be female (OR 0.60; 95% CI 0.43-0.83). People with chromophobe RCC were significantly more likely to be female (OR 2.32; 95% CI 1.44-3.74). Both people with papillary RCC (OR 6.26; 95% CI 2.75-14.24) and those with chromophobe RCC (OR 7.07; 95% CI 2.13-23.46) were strongly and significantly more likely to have ESRD, compared with those with clear-cell RCC.

CONCLUSION

We observed marked racial differences in the proportional subtype distribution of RCCs diagnosed at a large tertiary care academic centre. To our knowledge, no previous study has examined racial differences in the distribution of RCC histologies while adjusting for ESRD, which was the factor most strongly associated with papillary and chromophobe RCC compared with clear-cell RCC.

Future robotic platforms in urologic surgery: recent developments

PURPOSE OF REVIEW

To review recent developments at Vanderbilt University of new robotic technologies and platforms designed for minimally invasive urologic surgery and their design rationale and potential roles in advancing current urologic surgical practice.

RECENT FINDINGS

Emerging robotic platforms are being developed to improve performance of a wider variety of urologic interventions beyond the standard minimally invasive robotic urologic surgeries conducted currently with the da Vinci platform. These newer platforms are designed to incorporate significant advantages of robotics to improve the safety and outcomes of transurethral bladder surgery and surveillance, further decrease the invasiveness of interventions by advancing LESS surgery, and to allow for previously impossible needle access and ablation delivery.

SUMMARY

Three new robotic surgical technologies that have been developed at Vanderbilt University are reviewed, including a robotic transurethral system to enhance bladder surveillance and transurethral bladder tumor, a purpose-specific robotic system for LESS, and a needle-sized robot that can be used as either a steerable needle or small surgeon-controlled micro-laparoscopic manipulator.

An individualized weight-based goal urine volume model significantly improves expected calcium concentrations relative to a 2-L goal urine volume

Increased urinary volume decreases recurrence rates of nephrolithiasis. Current recommendations for goal volumes are not adjusted to reflect individual risk factors, such as obesity. Our intent was to develop and evaluate a goal urine volume for stone prevention based on predictive calcium modeling. Stone formers with a 24-h urine study (6/2001-9/2010) were identified. Patients with inadequate collections or non-calcium stones were excluded. Multivariate and univariate predictive models for daily calcium were evaluated and a univariate (weight) model was selected. A target calcium concentration constant (2.5 mM) was determined from current recommendations. Individualized weight-based goal urine volumes (WGUV) were calculated. Measured calcium concentration and expected calcium concentrations using a 2-L goal volume and WGUV were compared. 185 of 399 patients met inclusion criteria. Body weight was a strong predictor of calcium excretion in each model (p < 0.0001). While a 2-L goal urine volume would be expected to improve mean calcium concentrations for the cohort from 3.53 to 2.96 mM, the benefit is unequal between subsets with nearly twofold expected concentration for the highest weight quartile (3.98 vs. 2.10 mM) and higher expected concentration for males (3.35 vs. 2.59 mM). By contrast, a WGUV model improves expected concentrations for all subsets to <2.9 mM and the overall cohort to 2.50 mM. This study demonstrates a strong relationship between body weight and urinary calcium excretion in stone formers. We introduce the novel concept of individualized goal urine output using statistical modeling, which may be preferable to current recommendations.

A study on the theoretical and practical accuracy of conoscopic holography-based surface measurements: toward image registration in minimally invasive surgery

BACKGROUND

Registered medical images can assist with surgical navigation and enable image-guided therapy delivery. In soft tissues, surface-based registration is often used and can be facilitated by laser surface scanning. Tracked conoscopic holography (which provides distance measurements) has been recently proposed as a minimally invasive way to obtain surface scans. Moving this technique from concept to clinical use requires a rigorous accuracy evaluation, which is the purpose of our paper.

METHODS

We adapt recent non-homogeneous and anisotropic point-based registration results to provide a theoretical framework for predicting the accuracy of tracked distance measurement systems. Experiments are conducted a complex objects of defined geometry, an anthropomorphic kidney phantom and a human cadaver kidney.

RESULTS

Experiments agree with model predictions, producing point RMS errors consistently < 1 mm, surface-based registration with mean closest point error < 1 mm in the phantom and a RMS target registration error of 0.8 mm in the human cadaver kidney.

CONCLUSIONS

Tracked conoscopic holography is clinically viable; it enables minimally invasive surface scan accuracy comparable to current clinical methods that require open surgery.

Follow-up for Clinically Localized Renal Neoplasms: AUA Guideline

PURPOSE

The purpose of this guideline is to provide a clinical framework for follow-up of clinically localized renal neoplasms undergoing active surveillance, or following definitive therapy.

MATERIALS AND METHODS

A systematic literature review identified published articles in the English literature between January 1999 and 2011 relevant to key questions specified by the Panel related to kidney neoplasms and their follow-up (imaging, renal function, markers, biopsy, prognosis). Study designs consisting of clinical trials (randomized or not), observational studies (cohort, case-control, case series) and systematic reviews were included.

RESULTS

Guideline statements provided guidance for ongoing evaluation of renal function, usefulness of renal biopsy, timing/type of radiographic imaging and formulation of future research initiatives. A lack of studies precluded risk stratification beyond tumor staging; therefore, for the purposes of postoperative surveillance guidelines, patients with localized renal cancers were grouped into strata of low- and moderate- to high-risk for disease recurrence based on pathological tumor stage.

CONCLUSIONS

Evaluation for patients on active surveillance and following definitive therapy for renal neoplasms should include physical examination, renal function, serum studies and imaging and should be tailored according to recurrence risk, comorbidities and monitoring for treatment sequelae. Expert opinion determined a judicious course of monitoring/surveillance that may change in intensity as surgical/ablative therapies evolve, renal biopsy accuracy improves and more long-term follow-up data are collected. The beneficial impact of careful follow-up will also need critical evaluation as further study is completed.

Design and performance evaluation of a minimally invasive telerobotic platform for transurethral surveillance and intervention

Bladder cancer, a significant cause of morbidity and mortality worldwide, presents a unique opportunity for aggressive treatment due to the ease of transurethral accessibility. While the location affords advantages, transurethral resection of bladder tumors can pose a difficult challenge for surgeons encumbered by current instrumentation or difficult anatomic tumor locations. This paper presents the design and evaluation of a telerobotic system for transurethral surveillance and surgical intervention. The implementation seeks to improve current procedures and enable development of new surgical techniques by providing a platform for intravesicular dexterity and integration of novel imaging and interventional instrumentation. The system includes a dexterous continuum robot with access channels for the parallel deployment of multiple visualization and surgical instruments. This paper first presents the clinical conditions imposed by transurethral access and the limitations of the current state-of-the-art instrumentation. Motivated by the clinical requirements, the design considerations for this system are discussed and the prototype system is presented. Telemanipulation evaluation demonstrates submillimetric RMS positioning accuracy and intravesicular dexterity suitable for improving transurethral surveillance and intervention.

Fine Tilt Tuning of a Laparoscopic Camera by Local Magnetic Actuation

Background. The magnetic surgical camera is an emerging technology having the potential to improve visualization without taking up port site space. However, tilting the point of view downward/upward can be done only by constantly applying a pressure on the abdomen. This study aims to test the hypothesis that the novel concept of local magnetic actuation (LMA) is able to increase the tilt range available for a magnetic camera without the need for deforming the abdominal wall. The hypothesis that 2-port laparoscopic nephrectomy in fresh tissue human cadavers could be performed by using the LMA camera is also tested. Methods. First, the 2 cameras were separately inserted, anchored, and moved inside the inflated abdomen. Tilting angles were quantified by image analysis while intra-abdominal pressure changes were monitored. Then, 5 two-port nephrectomies were performed by using the LMA camera while collecting quantitative outcomes. Results. The magnetic camera required a constant pressure on the magnetic handle to achieve an average ±20° tilt from the horizontal position, with an average of 7 mm Hg loss of intra-abdominal pressure. The LMA camera allowed for 75° of tilt from the horizontal position with a resolution of ±1°, without any need to deform the abdomen. All the nephrectomies were completed successfully within an average time of 11 minutes. Conclusion. LMA is an effective strategy to provide magnetic cameras with wide-range and high-resolution vertical motion without the need to deform the abdominal wall.

Salvage robotic assisted laparoscopic radical prostatectomy: a single institution, 5-year experience

PURPOSE

Salvage robotic assisted laparoscopic prostatectomy is a treatment option for certain patients with recurrent prostate cancer after primary therapy. Data regarding patient selection, complication rates and cancer outcomes are scarce. We report the largest, single institution series to date, to our knowledge, of salvage robotic assisted laparoscopic prostatectomy.

MATERIALS AND METHODS

We reviewed our database of 4,234 patients treated with robotic assisted laparoscopic prostatectomy at Vanderbilt University and identified 34 men who had surgery after the failure of prior definitive ablative therapy. Each patient had biopsy proven recurrent prostate cancer and no evidence of metastases. The primary outcome measure was biochemical failure.

RESULTS

Median time from primary therapy to salvage robotic assisted laparoscopic prostatectomy was 48.5 months with a median preoperative prostate specific antigen of 3.86 ng/ml. Most patients had Gleason scores of 7 or greater on preoperative biopsy, although 12 (35%) had Gleason 8 or greater disease. After a median followup of 16 months 18% of patients had biochemical failure. The positive margin rate was 26%, of which 33% had biochemical failure after surgery. On univariable analysis there was a significant association between prostate specific antigen doubling time and biochemical failure (HR 0.77, 95% CI 0.60-0.99, p = 0.049) as well as between Gleason score at original diagnosis and biochemical failure (HR 3.49, 95% CI 1.18-10.3, p = 0.023). There were 2 Clavien II-III complications, namely a pulmonary embolism and a rectal laceration. Postoperatively 39% of patients had excellent continence.

CONCLUSIONS

Salvage robotic assisted laparoscopic prostatectomy is safe, with many favorable outcomes compared to open salvage radical prostatectomy series. Advantages include superior visualization of the posterior prostatic plane, modest blood loss, low complication rates and short length of stay.

ABO blood group is a predictor of survival in patients undergoing surgery for renal cell carcinoma

What's known on the subject? and What does the study add? Some evidence suggests that ABO blood type may be a risk factor for cancer incidence and prognosis. For example, a large study recently discovered an increased incidence of pancreatic cancer in patients with non-O blood type; however, it is not known whether blood group correlates with outcomes in patients with RCC. We found a significant and independent association between ABO blood group and overall survival in patients undergoing surgery for locoregional RCC. Specifically, we identified non-O blood type as a predictor of mortality.

OBJECTIVE

• To determine whether ABO blood group is associated with survival after nephrectomy or partial nephrectomy for renal cell carcinoma (RCC).

PATIENTS AND METHODS

• We conducted a retrospective cohort study of 900 patients who underwent surgery for locoregional RCC between 1997 and 2008 at a single institution. • Covariates included age, gender, race, American Society of Anesthesiology Physical Status, preoperative anaemia and hypoalbuminemia, tumour characteristics, lymph node status, procedure performed, transfusion status and ABO blood group. • Primary outcomes were overall (OS) and disease-specific survival (DSS). • Univariable survival analyses were performed using the Kaplan-Meier and log-rank methods. Multivariable analysis was performed using a Cox proportional hazards model.

RESULTS

• The 3-year OS estimate was 75% (95%CI 70-79%) for O blood group and 68% (95% CI 63-73%) for non-O blood group (P= 0.072). The 3-year DSS was 81% (95% CI 76-85%) for O blood group and 76% (95%CI 71-80%) for non-O blood group (P= 0.053). • In the multivariable analysis for OS, non-O blood type was significantly associated with decreased OS (HR 1.68, 95%CI 1.18-2.39; P= 0.004) but not DSS (HR 1.53, 95%CI 0.97-2.41; P= 0.065).

CONCLUSION

• These data suggest that ABO blood group is independently associated with OS in patients undergoing surgery for locoregional RCC. ABO blood group has not been previously recognized as a predictor of survival in RCC.

Comparison study of intraoperative surface acquisition methods for surgical navigation

Soft-tissue image-guided interventions often require the digitization of organ surfaces for providing correspondence from medical images to the physical patient in the operating room. In this paper, the effect of several inexpensive surface acquisition techniques on target registration error and surface registration error (SRE) for soft tissue is investigated. A systematic approach is provided to compare image-to-physical registrations using three different methods of organ spatial digitization: 1) a tracked laser-range scanner (LRS), 2) a tracked pointer, and 3) a tracked conoscopic holography sensor (called a conoprobe). For each digitization method, surfaces of phantoms and biological tissues were acquired and registered to CT image volume counterparts. A comparison among these alignments demonstrated that registration errors were statistically smaller with the conoprobe than the tracked pointer and LRS (p<0.01). In all acquisitions, the conoprobe outperformed the LRS and tracked pointer: for example, the arithmetic means of the SRE over all data acquisitions with a porcine liver were 1.73 ± 0.77 mm, 3.25 ± 0.78 mm, and 4.44 ± 1.19 mm for the conoprobe, LRS, and tracked pointer, respectively. In a cadaveric kidney specimen, the arithmetic means of the SRE over all trials of the conoprobe and tracked pointer were 1.50 ± 0.50 mm and 3.51 ± 0.82 mm, respectively. Our results suggest that tissue displacements due to contact force and attempts to maintain contact with tissue, compromise registrations that are dependent on data acquired from a tracked surgical instrument and we provide an alternative method (tracked conoscopic holography) of digitizing surfaces for clinical usage. The tracked conoscopic holography device outperforms LRS acquisitions with respect to registration accuracy.

Image-Guided Abdominal Surgery and Therapy Delivery

Image-Guided Surgery has become the standard of care in intracranial neurosurgery providing more exact resections while minimizing damage to healthy tissue. Moving that process to abdominal organs presents additional challenges in the form of image segmentation, image to physical space registration, organ motion and deformation. In this paper, we present methodologies and results for addressing these challenges in two specific organs: the liver and the kidney.