Stanley Duke Herrell

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.

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.

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.

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

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.

Narcotic Use and Postoperative Doctor Shopping by Patients with Nephrolithiasis Requiring Operative Intervention: Implications for Patient Safety

PURPOSE We sought to determine perioperative patterns of narcotic use and the prevalence of postoperative doctor shopping among patients with nephrolithiasis requiring operative management. MATERIALS AND METHODS We retrospectively reviewed the records of consecutive patients residing in Tennessee who required ureteroscopy with laser lithotripsy for nephrolithiasis at a single institution from January to December 2013. Using the Tennessee CSMD (Controlled Substances Medication Database) patients were categorized by the number of postoperative narcotic providers. Doctor shopping behavior was identified as any patient seeking more than 1 narcotic provider within 3 months of surgery. Demographic and clinical characteristics associated with doctor shopping behavior were identified. RESULTS During the study period 200 eligible patients underwent ureteroscopy with laser lithotripsy for nephrolithiasis, of whom 48 (24%) were prescribed narcotics by more than 1 provider after surgery. Compared to those receiving narcotics from a single provider, patients with multiple narcotic providers were younger (48.1 vs 54.2 years, p <0.001), less educated (high school education or less in 83.3% vs 58.7%, p = 0.014), more likely to have a history of mental illness (37.5% vs 16%, p <0.01) and more likely to have undergone prior stone procedures (66% vs 42%, p <0.01). Additionally, these patients demonstrated more frequent preoperative narcotic use (87.5% vs 63.2%), longer postoperative narcotic use (39.1 vs 6.0 days) and a higher morphine equivalent dose per prescription (44.7 vs 35.2 dose per day, each p <0.001). CONCLUSIONS Postoperative doctor shopping is common among patients with nephrolithiasis who require operative management. Urologists should be aware of available registry data to decrease the likelihood of redundant narcotic prescribing.

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.