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.

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.

Computer Vision Enabled Segmentation of Kidney Stones During Ureteroscopy and Laser Lithotripsy

Objective: To evaluate the performance of computer vision models for automated kidney stone segmentation during flexible ureteroscopy and laser lithotripsy. Materials and Methods: We collected 20 ureteroscopy videos of intrarenal kidney stone treatment and extracted frames (N = 578) from these videos. We manually annotated kidney stones on each frame. Eighty percent of the data were used to train three standard computer vision models (U-Net, U-Net++, and DenseNet) for automatic stone segmentation during flexible ureteroscopy. The remaining data (20%) were used to compare performance of the three models after optimization through Dice coefficients and binary cross entropy. We identified the highest performing model and evaluated automatic segmentation performance during ureteroscopy for both stone localization and treatment using a separate set of endoscopic videos. We evaluated performance of the pixel-based analysis using area under the receiver operating characteristic curve (AUC-ROC), accuracy, sensitivity, and positive predictive value both in previously recorded videos and in real time. Results: A computer vision model (U-Net++) was evaluated, trained, and optimized for kidney stone segmentation during ureteroscopy using 20 surgical videos (mean video duration of 22 seconds, standard deviation ±13 seconds). The model showed good performance for stone localization with both digital ureteroscopes (AUC-ROC: 0.98) and fiberoptic ureteroscopes (AUC-ROC: 0.93). Furthermore, the model was able to accurately segment stones and stone fragments <270 μm in diameter during laser fragmentation (AUC-ROC: 0.87) and dusting (AUC-ROC: 0.77). The model automatically annotated videos intraoperatively in three cases and could do so in real time at 30 frames per second (FPS). Conclusion: Computer vision models demonstrate strong performance for automatic stone segmentation during ureteroscopy. Automatically annotating new videos at 30 FPS demonstrate the feasibility of real-time application during surgery, which could facilitate tracking tools for stone treatment.

Patient-Reported Financial Toxicity Associated With Management of Nephrolithiasis

OBJECTIVE

To characterize stone-related financial burden among adults with nephrolithiasis through validated questionnaires for financial toxicity.

METHODS

We performed a cross-sectional survey of adults with history of nephrolithiasis at an outpatient clinic. The survey contained a measure of stone-related financial toxicity (COST score), and assessed demographics, stone event history, and burden of overall, ancillary, preventative, and insurance costs. A COST score ≤21 was classified as high financial toxicity. Multivariable logistic regression was used to evaluate associations with demographic variables and stone event history.

RESULTS

One hundred patients completed the survey (median age 57, IQR, 48-64). The median COST score was 30 (IQR, 23-37), and 19% reported high financial toxicity. Insurance status, household income, stone surgeries during lifetime and within the last 3 years were associated with financial toxicity on univariable analysis (P <.05). Burden of costs was significantly higher in all categories within the high financial toxicity cohort (each P <.05). On multivariable logistic regression, only income >$75,000 remained significant within the second model (OR: 0.22, 95% CI, 0.05-0.77, P = .02), however, this relationship did not persist on the final model. When asked whether providers should be mindful of their financial situation prior to making treatment recommendations, 39% responded "quite a bit" or "very much."

CONCLUSION

One in 5 patients seeking care for nephrolithiasis meet criteria for high financial toxicity. Financial toxicity was associated with household income, insurance, education, and frequency of stone events. Thirty-nine percent reported that their provider should be mindful of their financial situation when making recommendations.

Renal Forniceal Rupture in the Setting of Obstructing Ureteral Stones: An Analysis of Stone Characterization and Urologic Intervention Pattern

Introduction and Objective: Forniceal rupture due to obstructing ureterolithiasis (FROU) is a seldom encountered radiographic finding, but the impact of this diagnosis and influence on stone management has not been well studied in the literature. The purpose of the study is to examine stone characteristics and intervention patterns of patients with radiographic evidence of FROU. Materials and Methods: A retrospective analysis of all patients with radiographic evidence of FROU was compared with patients with obstructing ureteral stones without forniceal ruptures (noFROU). All patients presented to our Emergency Department from January 2015 until December 2018. Data analyzed included patient demographics, clinical presentation, stone characteristics, and management pattern. Primary outcome was need for hospital admission and surgical intervention. Results: Thirty-two patients with FROU (mean age = 45) were compared with 50 patients with noFROU (mean age = 57). Univariate analysis revealed that age, history of diabetes mellitus, history of hypertension, days of symptoms, degree of hydronephrosis, and degree of perinephric stranding were associated with forniceal rupture (p ≤ 0.05). On multivariate analysis, only degree of perinephric stranding remained significant (p ≤ 0.05). Average maximum axial stone diameter in the FROU group was 5.1 mm vs 4.7 mm in the noFROU group (p = 0.66). Overall, 68.8% of stones were located within the distal ureter in the FROU group vs 48.8% in the noFROU group (p = 0.09). There was no difference in hospital admission (FROU 37.5% vs noFROU 44%, p = 0.56) and need for surgical intervention (FROU 50% vs noFROU 48%, p = 0.86). There were no 30-day complications in patients with FROU. Conclusions: Ureteral stone location and size does not seem to impact the presence of FROU. FROU may be an alarming reported finding but its presence does not appear to impact clinical outcomes or affect urological management, including admission or need for urologic intervention.

Devices for penile traction: the long and winding road to treating Peyronie's disease

INTRODUCTION

Penile traction therapy (PTT) is increasingly being recognized as a viable nonsurgical approach to Peyronie's disease (PD). The goal of this article is to review the current literature on PTT with attention to traction protocols, devices, and outcomes.

AREAS COVERED

Literature on the pathophysiology of PD, PTT as primary and adjunctive treatment for PD, perioperative use of PTT, and vacuum erection devices are all reviewed. Pertinent literature was obtained from the PubMed database. The key words 'penile traction,' 'mechanotransduction,' and 'Peyronie's disease' were searched and results were narrowed down based on relevance to the review.

EXPERT COMMENTARY

PTT appears beneficial but the true magnitude of effect is difficult to discern. Most studies are not randomized, have small sample sizes, lack control arms, or have varying traction protocols. Patient compliance is critical and new devices and traction protocols are needed to maximize the benefit of PTT.