Accuracy of Touch-Based Registration During Robotic Image-Guided Partial Nephrectomy Before and After Tumor Resection in Validated Phantoms.

Aim: Image-guided surgery (IGS) allows for accurate, real-time localization of subsurface critical structures during surgery. No prior IGS systems have described a feasible method of intraoperative reregistration after manipulation of the kidney during robotic partial nephrectomy (PN). We present a method for seamless reregistration during IGS and evaluate accuracy before and after tumor resection in two validated kidney phantoms. Materials and Methods: We performed robotic PN on two validated kidney phantoms-one with an endophytic tumor and one with an exophytic tumor-with our IGS system utilizing the da Vinci Xi robot. Intraoperatively, the kidney phantoms' surfaces were digitized with the da Vinci robotic manipulator via a touch-based method and registered to a three-dimensional segmented model created from cross-sectional CT imaging of the phantoms. Fiducial points were marked with a surgical marking pen and identified after the initial registration using the robotic manipulator. Segmented images were displayed via picture-in-picture in the surgeon console as tumor resection was performed. After resection, reregistration was performed by reidentifying the fiducial points. The accuracy of the initial registration and reregistration was compared. Results: The root mean square (RMS) averages of target registration error (TRE) were 2.53 and 4.88 mm for the endophytic and exophytic phantoms, respectively. IGS enabled resection along preplanned contours. Specifically, the RMS averages of the normal TRE over the entire resection surface were 0.75 and 2.15 mm for the endophytic and exophytic phantoms, respectively. Both tumors were resected with grossly negative margins. Point-based reregistration enabled instantaneous reregistration with minimal impact on RMS TRE compared with the initial registration (from 1.34 to 1.70 mm preresection and from 1.60 to 2.10 mm postresection). Conclusions: We present a novel and accurate registration and reregistration framework for use during IGS for PN with the da Vinci Xi surgical system. The technology is easily integrated into the surgical workflow and does not require additional hardware.

Comparing the accuracy of the da Vinci Xi and da Vinci Si for image guidance and automation.

BACKGROUND: Current laparoscopic surgical robots are teleoperated, which requires high fidelity differential motions but does not require absolute accuracy. Emerging applications, including image guidance and automation, require absolute accuracy. The absolute accuracy of the da Vinci Xi robot has not yet been characterized or compared to the Si system, which is now being phased out. This study compares the accuracy of the two. METHODS: We measure robot tip positions and encoder values assessing accuracy with and without robot calibration. RESULTS: The Si is accurate if the setup joints are not moved but loses accuracy otherwise. The Xi is always accurate. CONCLUSION: The Xi can achieve submillimetric average error. Calibration improves accuracy, but excellent baseline accuracy of the Xi means that calibration may not be needed for some applications. Importantly, the external tracking systems needed to account for setup joint error in the Si are no longer required with the Xi.

Preliminary Porcine In Vivo Evaluation of a Telerobotic System for Transurethral Bladder Tumor Resection and Surveillance.

INTRODUCTION: Transurethral resection of bladder tumors (TURBTs) can be a challenging procedure, primarily due to limitations in tooltip dexterity, visualization, and lack of tissue depth information. A transurethral robotic system was developed to revolutionize TURBTs by addressing some of these limitations. The results of three pilot in vivo porcine studies using the novel robotic system are presented and potential improvements are proposed based on experimental observations. MATERIALS AND METHODS: A transvesical endoscope with a mounted optically tracked camera was placed through the bladder of the swine under general anesthesia. Simulated bladder lesions were created by injecting HistoGel processing gel mixed with blue dye, transabdominally, into various locations in the bladder wall under endoscopic visualization. A 7-degree-of-freedom (DoF) robot was then used for transurethral resection/ablation of these simulated tumors. An independent 2-DoF distal laser arm (DLA) was deployed through the robot for laser ablation and was assisted by a manually controlled gripper for en bloc resection attempts. RESULTS: Lesions were created and ablated using our novel endoscopic robot in the swine bladder. Full accessibility of the bladder, including the bladder neck and dome, was demonstrated without requiring bladder deflation or pubic compression. Simulated lesions were ablated using the holmium laser. En bloc resection was demonstrated using the DLA and a manual grasper. CONCLUSION: Feasibility of robot-assisted en bloc resection was demonstrated. Main challenges were lack of depth perception and visual occlusion induced by the transvesical endoscope. Recommendations are given to enhance robot-assisted TURBTs. Lessons learned through these pilot swine studies verify the feasibility of robot-assisted TURBTs while informing designers about critical aspects needed for future clinical deployment.

TPX2 as a prognostic indicator and potential therapeutic target in clear cell renal cell carcinoma.

OBJECTIVES: Our aims were to determine if targeting protein for Xklp2 (TPX2) is correlated with clear cell renal cell carcinoma (ccRCC) histology and oncologic outcomes using The Cancer Genome Atlas (TCGA) and an institutional tissue microarray (TMA). METHODS: Clinicopathological data obtained from the TCGA consisted of 415 samples diagnosed with ccRCC. A TMA was constructed from tumors of 207 patients who underwent radical nephrectomy for ccRCC. TPX2 expression by immunohistochemistry on TMA was assessed by a genitourinary pathologist. Clinical data were extracted and linked to TMA cores. TPX2 and Aurora-A mRNA coexpression were evaluated in the TCGA cohort. Overall survival (OS), cancer-specific survival, and recurrence-free survival (RFS) were analyzed using the Kaplan-Meier method and log-rank statistics. Univariate and multivariate analyses were conducted using Cox proportional hazard models. RESULTS: Median follow-up time for the TCGA cohort was 3.07 years. Aurora-A and TPX2 mRNA coexpression were significantly correlated (Pearson correlation = 0.918). High TPX2 mRNA expression was associated with advanced stage, metastasis, poor OS, and RFS. Median follow-up time for the TMA cohort was 5.3 years. Elevated TPX2 protein expression, defined as greater than 75th percentile staining intensity, was identified in 47/207 (22.7%) patients. Increased TPX2 immunostaining was associated with poor OS (P = 0.0327, 53% 5-year mortality), cancer-specific survival (P<0.01, 47.8% 5-year cancer-specific mortality), RFS (P = 0.0313, 73.6%, 5-year recurrence rate), grade, T stage, and metastasis. Multivariate analysis demonstrated elevated expression served as an independent predictor of RFS (hazard ratio = 3.62 (1.13-11.55), P = 0.029). CONCLUSIONS: We show TPX2, a regulator of Aurora-A, is associated with high grade and stage of ccRCC, and is an independent predictor of recurrence. Future studies are warranted testing its role in ccRCC biology, and its potential as a therapeutic target.

Ectopic Ureteral Insertion into the Seminal Vesicle Causing Recurrent Epididymitis in a 24-Year-Old.

A 24-year-old male was found to have recurrent epididymitis secondary to ectopic ureteral insertion to the seminal vesicle. His ipsilateral kidney was atrophic and ectopic in the pelvis, suggesting a complex failure of embryological development. He was successfully treated with robot-assisted laparoscopic nephroureterectomy.

Kidney deformation and intraprocedural registration: a study of elements of image-guided kidney surgery.

INTRODUCTION: Central to any image-guided surgical procedure is the alignment of image and physical coordinate spaces, or registration. We explored the task of registration in the kidney through in vivo and ex vivo porcine animal models and a human study of minimally invasive kidney surgery. METHODS: A set of (n = 6) ex vivo porcine kidney models was utilized to study the effect of perfusion and loss of turgor caused by incision. Computed tomography (CT) and laser range scanner localizations of the porcine kidneys were performed before and after renal vessel clamping and after capsular incision. The da Vinci robotic surgery system was used for kidney surface acquisition and registration during robot-assisted laparoscopic partial nephrectomy. The surgeon acquired the physical surface data points with a tracked robotic instrument. These data points were aligned to preoperative CT for surface-based registrations. In addition, two biomechanical elastic computer models (isotropic and anisotropic) were constructed to simulate deformations in one of the kidneys to assess predictive capabilities. RESULTS: The mean displacement at the surface fiducials (glass beads) in six porcine kidneys was 4.4 ± 2.1 mm (range 3.4-6.7 mm), with a maximum displacement range of 6.1 to 11.2 mm. Surface-based registrations using the da Vinci robotic instrument in robot-assisted laparoscopic partial nephrectomy yielded mean and standard deviation closest point distances of 1.4 and 1.1 mm. With respect to computer model predictive capability, the target registration error was on average 6.7 mm without using the model and 3.2 mm with using the model. The maximum target error reduced from 11.4 to 6.2 mm. The anisotropic biomechanical model yielded better performance but was not statistically better. CONCLUSIONS: An initial point-based alignment followed by an iterative closest point registration is a feasible method of registering preoperative image (CT) space to intraoperative physical (robot) space. Although rigid registration provides utility for image-guidance, local deformations in regions of resection may be more significant. Computer models may be useful for prediction of such deformations, but more investigation is needed to establish the necessity of such compensation.

Analysis of 24-hour urine parameters as it relates to age of onset of cystine stone formation.

INTRODUCTION: Cystinuria is an inherited disorder characterized by the impaired reabsorption of the dibasic amino acid, cystine, in the proximal tubule of the nephron. Cystine stones most frequently occur in the first through third decades of life with a decreased incidence in old age. We hypothesize that patients presenting with first stone event at an older age would have more favorable 24-hour urine parameters compared with those patients who present early. PATIENTS: This is a retrospective review of 94 patients with cystinuria and cystine stones who underwent a 24-hour urine test. The patients were divided into four groups based on age at first clinical stone event: group 1, children aged <18 years (n = 37); group 2, 18 to 32 years (n = 19); group 3, 33 to 50 years (n = 19); and group 4, >50 years (n = 19). All 24-hour urines were collected prior to any medical therapy. Statistical analysis was performed using analysis of variance and Tukey pairwise comparison test. RESULTS: There was a significant increase in cystine supersaturation (SS) for the young adults (group 2) as opposed to older adults (groups 3 and 4) though cystine excretion was not different among the groups. A higher urine volume appeared to account for the lower cystine SS in the older adults. The children were found to have cystine SS similar to the young adults. DISCUSSION: In this retrospective study, a correlation was found between the age of onset of cystine stones and 24-hour urine parameters. Cystinuric patients presenting with first stone event at an older age have lower cystine SS and increased urinary volume compared with patients presenting earlier, likely conferring a protective effect.