Feasibility and accuracy of computational robot-assisted partial nephrectomy planning by virtual partial nephrectomy analysis

Preoperative three-dimensional modelling and virtual reality planning aids nephron sparing surgery in a child with bilateral Wilms tumour

Bilateral Wilms tumour (BWT) is a surgically challenging condition. Virtual reality (VR) reconstruction aids surgeons to foresee the anatomy ahead of Nephron Sparing Surgery (NSS). Three-dimensional (3D) visualisation improves the anatomical orientation of surgeons performing NSS. We herewith report a case of BWT where VR planning and 3D printing were used to aid NSS. Conventional imaging is often found to be inadequate while assessing the tumour-organ-vascular anatomy. Advances like VR and 3D printing help surgeons plan better for complex surgeries like bilateral NSS. Next-generation extended reality tools will likely aid robotic-assisted precision NSS and improve patient outcomes.

Patient-specific simulations and navigation systems for partial nephrectomy

Partial nephrectomy (PN) is the standard treatment for T1 renal cell carcinoma. PN is affected more by surgical variations and requires greater surgical experience than radical nephrectomy. Patient-specific simulations and navigation systems may help to reduce the surgical experience required for PN. Recent advances in three-dimensional (3D) virtual reality (VR) imaging and 3D printing technology have allowed accurate patient-specific simulations and navigation systems. We reviewed previous studies about patient-specific simulations and navigation systems for PN. Recently, image reconstruction technology has developed, and commercial software that converts two-dimensional images into 3D images has become available. Many urologists are now able to view 3DVR images when preparing for PN. Surgical simulations based on 3DVR images can change surgical plans and improve surgical outcomes, and are useful during patient consultations. Patient-specific simulators that are capable of simulating surgical procedures, the gold-standard form of patient-specific simulations, have also been reported. Besides VR, 3D printing is also useful for understanding patient-specific information. Some studies have reported simulation and navigation systems for PN based on solid 3D models. Patient-specific simulations are a form of preoperative preparation, whereas patient-specific navigation is used intraoperatively. Navigation-assisted PN procedures using 3DVR images have become increasingly common, especially in robotic surgery. Some studies found that these systems produced improvements in surgical outcomes. Once its accuracy has been confirmed, it is hoped that this technology will spread further and become more generalized.

Robot-assisted partial nephrectomy for T1b renal cell carcinoma with complete situs inversus totalis with pre- and intraoperative three-dimensional virtual imaging

Complete Situs Inversus Totalis (SIT) is a rare congenital anomaly characterized by the transposition of organs to a totally inverted position. We present a case of Robot-Assisted Partial Nephrectomy (RAPN) for T1b renal hilum tumor (RENAL score 9) with SIT. All procedures were performed safely using preoperative three-dimensional (3D) virtual image assistance. There were no intraoperative complications, and the patient was discharged uneventfully. Pathological diagnosis confirmed papillary renal cell carcinoma type1. In patients who have renal cancer with SIT, RAPN can be performed safely, and 3D virtual imaging could provide successful surgical outcomes.

A hybrid approach to full-scale reconstruction of renal arterial network

The renal vasculature, acting as a resource distribution network, plays an important role in both the physiology and pathophysiology of the kidney. However, no imaging techniques allow an assessment of the structure and function of the renal vasculature due to limited spatial and temporal resolution. To develop realistic computer simulations of renal function, and to develop new image-based diagnostic methods based on artificial intelligence, it is necessary to have a realistic full-scale model of the renal vasculature. We propose a hybrid framework to build subject-specific models of the renal vascular network by using semi-automated segmentation of large arteries and estimation of cortex area from a micro-CT scan as a starting point, and by adopting the Global Constructive Optimization algorithm for generating smaller vessels. Our results show a close agreement between the reconstructed vasculature and existing anatomical data obtained from a rat kidney with respect to morphometric and hemodynamic parameters.

Comparison of robot-assisted partial nephrectomy with soft coagulation and double-layer technique for complex and non-complex tumors

OBJECTIVES

To compare the postoperative outcomes of robot-assisted partial nephrectomy when only the inner layer is sutured (single-layer technique with soft coagulation) with those when sutures are placed in the inner and outer layers (double-layer technique) in patients with and without complex renal tumors.

METHODS

This retrospective three-institution study included 371 patients with renal tumors who underwent robot-assisted partial nephrectomy with a double-layer technique or a single-layer technique with soft coagulation. Tumors that were cT1b, completely embedded, located in the renal portal, or had a RENAL score of ≥10 were considered complex. Relevant data were collected from hospital records. Propensity score matching was performed to minimize selection bias.

RESULTS

Propensity score matching created 83 patient pairs with non-complex tumors and 32 with complex tumors. Regardless of tumor complexity, there was no significant difference in operation time, console time, warm ischemia time, positive surgical margin rate, or length of hospital stay between the double-layer and single-layer groups. Although Clavien-Dindo grade I-II urinomas not requiring intervention were significantly more common in the single-layer group regardless of tumor complexity, there was no significant between-group difference in the rate of decline in renal function or grade III-IV complications.

CONCLUSION

Single-layer suturing with soft coagulation achieves renal function and perioperative outcomes comparable to those of double-layer suturing regardless of complexity.

A Novel Three-dimensional Planning Tool for Selective Clamping During Partial Nephrectomy: Validation of a Perfusion Zone Algorithm

BACKGROUND

Selective clamping during robot-assisted partial nephrectomy (RAPN) requires extensive knowledge on patient-specific renal vasculature, obtained through imaging.

OBJECTIVE

To validate an in-house developed perfusion zone algorithm that provides patient-specific three-dimensional (3D) renal perfusion information.

DESIGN, SETTING, AND PARTICIPANTS

Between October 2020 and June 2022, 25 patients undergoing RAPN at Ghent University Hospital were included. Three-dimensional models, based on preoperative computed tomography (CT) scans, showed the clamped artery's ischemic zone, as calculated by the algorithm.

SURGICAL PROCEDURE

All patients underwent selective clamping during RAPN. Indocyanine green (ICG) was administered to visualize the true ischemic zone perioperatively. Surgery was recorded for a postoperative analysis.

MEASUREMENTS

The true ischemic zone of the clamped artery was compared with the ischemic zone predicted by the algorithm through two metrics: (1) total ischemic zone overlap and (2) tumor ischemic zone overlap. Six urologists assessed metric 1; metric 2 was assessed objectively by the authors.

RESULTS AND LIMITATIONS

In 92% of the cases, the algorithm was sufficiently accurate to plan a selective clamping strategy. Metric 1 showed an average score of 4.28 out of 5. Metric 2 showed an average score of 4.14 out of 5. A first limitation is that ICG can be evaluated only at the kidney surface. A second limitation is that mainly patients with impaired renal function are expected to benefit from this technology, but contrast-enhanced CT is required at present.

CONCLUSIONS

The proposed new tool demonstrated high accuracy when planning selective clamping for RAPN. A follow-up prospective study is needed to determine the tool's clinical added value.

PATIENT SUMMARY

In partial nephrectomy, the surgeon has no information on which specific arterial branches perfuse the kidney tumor. We developed a surgeon support system that visualizes the perfusion zones of all arteries on a three-dimensional model and indicates the correct arteries to clamp. In this study, we validate this tool.

Robotic partial nephrectomy in 3D virtual reconstructions era: is the paradigm changed?

CONTEXT

The development of a tailored, patient-specific medical and surgical approach is becoming object of intense research. In kidney oncologic surgery, where a clear understanding of case-specific surgical anatomy is considered a key point to optimize the perioperative outcomes, such philosophy gained increasing importance. Recently, important advances in 3D virtual modeling technologies have fueled the interest for their application in the field of robotic minimally invasive surgery for kidney tumors.

OBJECTIVE

To provide a synthesis of current applications of 3D virtual models for robot-assisted partial nephrectomy.

EVIDENCE ACQUISITION

Medline, PubMed, the Cochrane Database, and Embase were screened for Literature regarding the use of 3D virtual models for robot-assisted partial nephrectomy (RAPN).

EVIDENCE SYNTHESIS

The use of 3D virtual models for RAPN has been tested in different settings, including surgical indication and planning, intraoperative guidance, and training. Currently, several studies are available on the application of this technology for surgical planning, demonstrating impact on clinical outcomes such as renal function recovery, whilst experiences concerning their intraoperative application for navigation are still experimental. One of the latest innovations in this field is represented by the development of dedicated softwares able to automatically overlap the 3D virtual models to the real anatomy, to perform augmented reality procedures.

CONCLUSIONS

The available Literature suggests a potentially crucial role of 3D virtual reconstructions during RAPN. Encouraging results concerning surgical planning and indication, intraoperative navigation, and surgical training are available. In the future, artificial intelligence may represent the key to further improve the 3D virtual modeling technology during RAPN.

Virtual Resection: A New Tool for Preparing for Nephron-Sparing Surgery in Wilms Tumor Patients

Nephron-sparing surgery (NSS) in Wilms tumor (WT) patients is a surgically challenging procedure used in highly selective cases only. Virtual resections can be used for preoperative planning of NSS to estimate the remnant renal volume (RRV) and to virtually mimic radical tumor resection. In this single-center evaluation study, virtual resection for NSS planning and the user experience were evaluated. Virtual resection was performed in nine WT patient cases by two pediatric surgeons and one pediatric urologist. Pre- and postoperative MRI scans were used for 3D visualization. The virtual RRV was acquired after performing virtual resection and a questionnaire was used to assess the ease of use. The actual RRV was derived from the postoperative 3D visualization and compared with the derived virtual RRV. Virtual resection resulted in virtual RRVs that matched nearly perfectly with the actual RRVs. According to the questionnaire, virtual resection appeared to be straightforward and was not considered to be difficult. This study demonstrated the potential of virtual resection as a new planning tool to estimate the RRV after NSS in WT patients. Future research should further evaluate the clinical relevance of virtual resection by relating it to surgical outcome.

Trends and safety of robot-assisted partial nephrectomy during the initial 2-year period after government approval in Japan: A nationwide database study from 2016 to 2018

OBJECTIVES

To evaluate the trends and safety of robot-assisted partial nephrectomy during the initial 2-year period after government approval for this type of procedure in April 2016.

METHODS

This nationwide retrospective study included 3722 received robot-assisted partial nephrectomy cases carried out from April 2016 to March 2018 in 124 participating institutions. The institutions were divided into lower- and higher-volume institutions according to the median of 19 robot-assisted partial nephrectomy cases during the study period. Surgical outcomes between 616 cases from lower-volume institutions and 3106 cases from higher-volume institutions were compared using propensity score matching.

RESULTS

During the study period, both the number of robot-assisted partial nephrectomy surgeries and the number of institutions in which the surgery was carried out steadily increased. Overall, the median anesthesia time was 217 min, the median postoperative length of stay was 9 days, and the proportion of blood transfusions, complications and readmissions were 0.8%, 5.1% and 1.0%, respectively. There were no significant differences in anesthesia time, incidence of blood transfusions, and complication rates between the lower-volume and higher-volume institutions. However, a slightly, but significantly, longer postoperative length of stay and a lower incidence of readmission were observed in lower-volume institutions both before and after propensity score matching.

CONCLUSIONS

Robot-assisted partial nephrectomy has become widespread during the initial 2-year period after government approval with an acceptable safety profile, regardless of the institutional caseloads. This technique has become a standard of care for stage 1 renal cancer patients in Japan.

Superselective Ischemia in Robotic Partial Nephrectomy Does Not Provide Better Long-term Renal Function than Renal Artery Clamping in a Randomized Controlled Trial (EMERALD): Should We Take the Risk?

BACKGROUND

Superselective clamping of tumor-targeted arteries aims to eliminate ischemia of the remnant kidney while keeping tumor bed bloodless during excision.

OBJECTIVE

To evaluate the impact of superselective clamping on long-term renal function, compared with renal artery early unclamping.

DESIGN, SETTING, AND PARTICIPANTS

A randomized monocentric single-blind trial (1:1) was conducted from February 2018 to August 2019. Patients with a single renal tumor were candidates for a robot-assisted partial nephrectomy (RAPN) in a referral center. EMERALD (NCT03679572) was powered to include 50 patients with an interim analysis after 30 cases.

INTERVENTION

Superselective RAPN (SS-RAPN) with near-infrared fluorescence (NIRF) or conventional RAPN with renal artery early unclamping.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was the percent change of estimated glomerular filtration rate (eGFR) in the operated kidney after 6 mo (combination of eGFR and relative function on ^99mTc-DMSA scintigraphy). Secondary endpoints assessed feasibility and safety of the technique.

RESULTS AND LIMITATIONS

Relative eGFR reduction in the operated kidney at 6 mo did not differ significantly (-21.4% vs -23.4%, p=0.66). This absence of difference remained after adjusting on percentage of kidney volume preserved, which was an independent predictor of functional preservation. There were no significant differences in terms of blood loss, change in hemoglobin, postoperative complications, transfusion, and conversion to radical nephrectomy (two vs zero) or to open surgery (one vs zero). Despite a good accrual, the steering committee interrupted the trial after the interim analysis for futility given the absence of trend in favor of SS-RAPN.

CONCLUSIONS

SS-RAPN using NIRF does not provide better renal function preservation than renal artery clamping, questioning the interest of this technique at a higher risk of bleeding.

PATIENT SUMMARY

In this randomized controlled trial, superselective clamping of tumor feeding arteries did not show any advantage in terms of long-term renal function compared with conventional artery clamping.

Clinical advantages of robot-assisted partial nephrectomy versus laparoscopic partial nephrectomy in terms of global and split renal functions: A propensity score-matched comparative analysis

OBJECTIVES

To identify predictors of renal function preservation, and to compare the global and split renal function outcomes of robot-assisted partial nephrectomy and laparoscopic partial nephrectomy.

METHODS

Demographic, operative and pathological data, as well as renal function outcomes, of 251 patients who underwent laparoscopic (n = 104) and robot-assisted (n = 147) partial nephrectomy between 2008 and 2018 were retrospectively analyzed. Propensity score matching (1:1) was carried out to adjust for potential baseline confounders. Functional outcomes were assessed based on the estimated glomerular filtration rate and dynamic renal scintigraphy (using ^99m Tc-mercaptoacetyltriglycine), including renal volumetric analysis.

RESULTS

A total of 98 patients were allocated to each partial nephrectomy group. Ischemic (laparoscopic vs robot-assisted partial nephrectomy: 29 vs 15 min, P < 0.001) and operative times (181 vs 100 min, P < 0.001) were shorter in robot-assisted partial nephrectomy. The preservation ratio of global renal function at 3 months (88.3% vs 91.4%, P = 0.040) and 12 months (87.8% vs 91.5%, P = 0.010) postoperatively, and the renal function of the operated kidney (80.3% vs 88.2%, P < 0.001) were greater after robot-assisted partial nephrectomy. In robot-assisted partial nephrectomy, the volume of resected parenchyma was significantly smaller (27.2 vs 15.5 mL, P < 0.001), resulting in greater postoperative normal parenchymal volumes (120 vs 132 mL, P < 0.001) and a greater parenchymal preservation ratio (81.1% vs 90.1%, P < 0.001). The parenchymal preservation ratio was the strongest predictor of renal function preservation after surgery (P < 0.001, odds ratio 6.02).

CONCLUSIONS

Robot-assisted partial nephrectomy allows better preservation of split renal function than laparoscopic partial nephrectomy by increasing the parenchymal preservation ratio. This translates into better postoperative global renal function.

Precise estimation of renal vascular dominant regions using spatially aware fully convolutional networks, tensor-cut and Voronoi diagrams

This paper presents a new approach for precisely estimating the renal vascular dominant region using a Voronoi diagram. To provide computer-assisted diagnostics for the pre-surgical simulation of partial nephrectomy surgery, we must obtain information on the renal arteries and the renal vascular dominant regions. We propose a fully automatic segmentation method that combines a neural network and tensor-based graph-cut methods to precisely extract the kidney and renal arteries. First, we use a convolutional neural network to localize the kidney regions and extract tiny renal arteries with a tensor-based graph-cut method. Then we generate a Voronoi diagram to estimate the renal vascular dominant regions based on the segmented kidney and renal arteries. The accuracy of kidney segmentation in 27 cases with 8-fold cross validation reached a Dice score of 95%. The accuracy of renal artery segmentation in 8 cases obtained a centerline overlap ratio of 80%. Each partition region corresponds to a renal vascular dominant region. The final dominant-region estimation accuracy achieved a Dice coefficient of 80%. A clinical application showed the potential of our proposed estimation approach in a real clinical surgical environment. Further validation using large-scale database is our future work.

Is patient-specific pre-operative preparation feasible in a clinical environment? A systematic review and meta-analysis

Technical difficulty of an operation is associated with patient and disease characteristics, indicating the necessity for surgeons to exercise patient-specific preparation. Such methods have been shown to be effective in the simulation suite, however, application in a real clinical environment has been sporadic. This systematic review attempts to answer if patient-specific preparation in challenging surgical procedures is feasible. A systematic review of OvidMedline, Embase and all Evidence Based Medicine review databases, was conducted in search of studies who described surgical rehearsals in all specialties. Following the application of defined inclusion and exclusion criteria relevant data were extracted and summarised. Descriptive synthesis was performed for all included studies and meta-analysis of data was applied when possible. Of fourty-nine studies included, thirty-seven were case-series, ten were non-randomised comparative trials and two randomised controlled trials. Accuracy of applied methods ranged from 66.7 to 100% and a good outcome was seen in 60-100% of operations. Meta-analysis of studies comparing rehearsals to real procedures (same patients) showed that simulated procedures were significantly faster than real ones (SMD = -1.56 [-2.19, -0.93] p < 0.00001) but were similar in other outcomes (fluoroscopy time: SMD = -0.1 [-0.63, 0.42] p = 0.7, fluoroscopy volume: SMD = -0.43[-0.97, 0.11], p = 0.12). Meta-analysis of studies comparing pre-operative rehearsals to standard treatment (two distinct groups of patients), demonstrated that real procedures were performed quicker if pre-operative rehearsal took place (SMD = -0.47 [-0.79, -0.16], P  = 0.003) but the immediate clinical outcome was similar for practiced and not practiced operations (SMD =0.03[-0.23, 0.29], p = 0.82). Current evidence suggests that patient-specific pre-operative preparation is feasible and safe and decreases operational time.

Navigation of Intelligent/Interactive Qualitative and Quantitative Analysis Three-Dimensional Reconstruction Technique in Laparoscopic or Robotic Assisted Partial Nephrectomy for Renal Hilar Tumors

Purpose: To evaluate the feasibility and effectiveness of the navigation of intelligent/interactive qualitative and quantitative analysis (IQQA) three-dimensional (3D) reconstruction technique in laparoscopic or robotic assisted partial nephrectomy (LPN or RAPN) for renal hilar tumors. Patients and Methods: The study retrospectively reviewed 26 patients with hilar tumors from February 2016 to February 2018. IQQA 3D reconstruction technique was applied for the purpose of navigation and resection of the tumors. Relevant clinical parameters and surgical outcomes were recorded. Results: All 26 LPN or RAPN were effectively completed without conversion to a hand-assisted or an open approach. Under the navigation of IQQA, all tumors were found precisely at the first time during surgeries. The mean operative time was 142 minutes (142 ± 35), with a mean warm ischemia time of 24.3 minutes (24.3 ± 9.5). The estimated blood loss was 156 mL (156 ± 112). No intraoperative complications occurred. Two patients suffered from postoperative complications. All patients had negative margins on the final pathological examination. At a mean follow-up period of 3 months, the mean glomerular filtration rate is 22.5 mL/min (22.5 ± 7.1) without tumor recurrence. Conclusions: With peculiar features, such as accurate location, complete resection, and fewer perioperative complications, the navigation of IQQA 3D reconstruction technique in partial nephrectomy represents a safe and effective procedure for hilar tumors.

Preliminary Kidney Parenchymal Ligation Using Endoloop Ligatures-A Simple Method to Achieve a Trifecta in Laparoscopic Partial Nephrectomy Without Hilar Clamping for Polar Complex Tumors

OBJECTIVE

To describe a novel and simple technique of preliminary kidney parenchymal ligation using Endoloop ligatures during laparoscopic partial nephrectomy (PN) without hilar clamping for polar complex tumor cases.

METHODS

The subjects were 17 patients who had a renal mass with a R.E.N.A.L. nephrometry score ≥7 (7/8/9/10 in 3/6/6/2 patients, respectively) located in the pole of the kidney. Patient-specific 3D reconstructed kidney images were created for preoperative planning in all cases. The renal hilar vessels were meticulously dissected and definitive tumor feeders were sacrificed when the branches directly perfused the peri-tumor area. Following the vascular microdissection, a circumferential cortex-depth incision on the kidney was made all around the tumor. Consequently, several Endoloop ligatures were placed in the incised tumor base to ligate the parenchyma preliminarily. Step-by-step Endoloop tightening facilitated effective parenchymal dissection without the urinary tract. After confirming that the tumor base parenchyma was ligated sufficiently, tumor resection was completed. Neither inner- nor outer-layer renorrhaphy sutures were placed.

RESULTS

Perioperative outcomes were satisfactory and all patients had negative surgical margins with no damage in the tumor capsule. Urological complications and renal function lower than predicted at 3 months after surgery involved 1 and 3 cases, respectively. The rate of PN trifecta achievement was 82% (14/17) despite the complexity of the 17 tumors.

CONCLUSION

The current technique helped surgeons achieve the trifecta in patients with polar complex masses treated with laparoscopic PN. Use of this technique can provide surgeons with a bloodless operative field even during PN without hilar clamping.

Virtual and Augmented Reality Systems for Renal Interventions: A Systematic Review

PURPOSE

Many virtual and augmented reality systems have been proposed to support renal interventions. This paper reviews such systems employed in the treatment of renal cell carcinoma and renal stones.

METHODS

A systematic literature search was performed. Inclusion criteria were virtual and augmented reality systems for radical or partial nephrectomy and renal stone treatment, excluding systems solely developed or evaluated for training purposes.

RESULTS

In total, 52 research papers were identified and analyzed. Most of the identified literature (87%) deals with systems for renal cell carcinoma treatment. About 44% of the systems have already been employed in clinical practice, but only 20% in studies with ten or more patients. Main challenges remaining for future research include the consideration of organ movement and deformation, human factor issues, and the conduction of large clinical studies.

CONCLUSION

Augmented and virtual reality systems have the potential to improve safety and outcomes of renal interventions. In the last ten years, many technical advances have led to more sophisticated systems, which are already applied in clinical practice. Further research is required to cope with current limitations of virtual and augmented reality assistance in clinical environments.

Patient-specific mental rehearsal with interactive visual aids: a path worth exploring?

Background

Surgeons of today are faced with unprecedented challenges; necessitating a novel approach to pre-operative preparation which takes into account the specific tests each case poses. In this study, we examine patient-specific mental rehearsal for pre-surgical practice and assess whether this method has an additional effect when compared to generic mental rehearsal.

Methods

Sixteen medical students were trained how to perform a simulated laparoscopic cholecystectomy (SLC). After baseline assessments, they were randomised to two equal groups and asked to complete three SLCs involving different anatomical variants. Prior to each procedure, Group A practiced mental rehearsal with the use of a pre-prepared checklist and Group B mental rehearsal with the checklist combined with virtual models matching the anatomical variations of the SLCs. The performance of the two groups was compared using simulator provided metrics and competency assessment tool (CAT) scoring by two blinded assessors.

Results

The participants performed equally well when presented with a “straight-forward” anatomy [Group A vs. Group B—time sec: 445.5 vs. 496 p = 0.64—NOM: 437 vs. 413 p = 0.88—PL cm: 1317 vs. 1059 p = 0.32—per: 0.5 vs. 0 p = 0.22—NCB: 0 vs. 0 p = 0.71—DVS: 0 vs. 0 p = 0.2]; however, Group B performed significantly better [Group A vs. B Total CAT score—Short Cystic Duct (SCD): 20.5 vs. 26.31 p = 0.02 η² = 0.32—Double cystic Artery (DA): 24.75 vs. 30.5 p = 0.03 η² = 0.28] and committed less errors (Damage to Vital Structures—DVS, SCD: 4 vs. 0 p = 0.03 η²=0.34, DA: 0 vs. 1 p = 0.02 η² = 0.22). in the cases with more challenging anatomies.

Conclusion

These results suggest that patient-specific preparation with the combination of anatomical models and mental rehearsal may increase operative quality of complex procedures.

Automated renal cortical volume measurement for assessment of renal function in patients undergoing radical nephrectomy

BACKGROUND

Renal volume change greatly affects renal function after nephrectomy. Although various measuring techniques were reported, no standard measuring method is available. In this study, we examined the computational automated volumetric method, and evaluated the volumetric change to assess the functional outcome in patients undergoing radical nephrectomy. We developed the predictive equation for postoperative renal function from volume alternation and validated the performance.

METHODS

Thirty-two patients undergoing radical nephrectomy participated in this study. Renal volume was calculated using three different methods [ellipsoid method, conventional manual voxel count method for renal parenchyma (manual RPV), and automated voxel count method for renal cortex (automated RCV)] through newly developed imaging software. Statistical analysis was performed to evaluate the correlation between renal functional alternation 7 days after the nephrectomy and renal volumetric change. A simple predictive equation for the postoperative renal function by renal volume loss was developed and externally validated through another 12 cases.

RESULTS

The automated RCV method had the strongest correlation between renal function alternation and RCV change (R = 0.82), than manual RPV (R = 0.69) and ellipsoid method (R = 0.50). Subsequently, a simple equation for postoperative renal function by renal volume alternation was developed: predicted postoperative estimated glomerular filtration rate (eGFR) from renal volume change = preoperative eGFR × (postoperative renal volume / preoperative renal volume). In the external validation cohort, automated RCV demonstrated the predictive performance of the constructed equations for renal function (R = 0.77).

CONCLUSIONS

The computational automated RCV measurements is a simple estimation of renal functional outcome for patients undergoing radical nephrectomy.

The significance of predictable traumatic area by renorrhaphy in the prediction of postoperative ipsilateral renal function

Introduction

To determine the relationship between the actual renal function loss and volume loss in robot-assisted partial nephrectomy (RAPN) using a novel three-dimensional volume analyzer.

Material and methods

We respectively evaluated the medical records of 23 consecutive patients who underwent RAPN between January 2012 and March 2016 and the data on their kidney function and parenchymal mass specific to the operated kidney. Parenchymal volume was measured by computerized tomography and reconstructed with a Synapse Vincent volumetric analyzer. Using this system, we predicted the renal vascular territory and other trauma areas involved in renorrhaphy. All measurements were taken within 3 and 6 months pre- and postoperatively, respectively.

RESULTS

The actual postoperative renal parenchymal volume was significantly correlated with the virtual predicted residual renal volume excluding the tumor and resected margin (r = 0.435, p <0.05). The ratio of split estimated glomerular filtration rate (eGFR) postoperative/preoperative) was significantly correlated with the virtual predicted residual renal volume excluding the resected margin and the traumatic area by renorrhaphy (r = 0.401, p <0.05).

Conclusions

When predicting the reduction of renal function of the diseased side following partial nephrectomy, adding the extent of the area traumatized by renorrhaphy might be useful for predicting the postoperative split renal function of the affected kidney.

Robot-assisted renal surgery: current status and future directions

This paper examines the current role of robot-assisted renal surgery as complex and partial nephrectomies, including vena cava thrombus, combined nephroureterectomies, living donor nephrectomy, autotransplantation, and difficult anatomy as in patients with obesity or adhesions. Indications for robot-assisted renal surgery are comparable to those of conventional laparoscopic approaches. A reduction in the learning curve leads to a stabilization of the procedure and further increases the number of minimally invasive procedures performed. A Medline literature search for publications on the field of robotic kidney surgery has been performed using the MeSH terms: robotic surgical procedures and kidney. Future directions include progress in robotic technology and instrumentation with further miniaturization of robotic procedures as laparoendoscopic single-site interventions and progress in image-guided robotic surgery.

Soft tissue deformation for surgical simulation: a position-based dynamics approach

PURPOSE

To assist the rehearsal and planning of robot-assisted partial nephrectomy, a real-time simulation platform is presented that allows surgeons to visualise and interact with rapidly constructed patient-specific biomechanical models of the anatomical regions of interest. Coupled to a framework for volumetric deformation, the platform furthermore simulates intracorporeal 2D ultrasound image acquisition, using preoperative imaging as the data source. This not only facilitates the planning of optimal transducer trajectories and viewpoints, but can also act as a validation context for manually operated freehand 3D acquisitions and reconstructions.

METHODS

The simulation platform was implemented within the GPU-accelerated NVIDIA FleX position-based dynamics framework. In order to validate the model and determine material properties and other simulation parameter values, a porcine kidney with embedded fiducial beads was CT-scanned and segmented. Acquisitions for the rest position and three different levels of probe-induced deformation were collected. Optimal values of the cluster stiffness coefficients were determined for a range of different particle radii, where the objective function comprised the mean distance error between real and simulated fiducial positions over the sequence of deformations.

RESULTS

The mean fiducial error at each deformation stage was found to be compatible with the level of ultrasound probe calibration error typically observed in clinical practice. Furthermore, the simulation exhibited unconditional stability on account of its use of clustered shape-matching constraints.

CONCLUSIONS

A novel position-based dynamics implementation of soft tissue deformation has been shown to facilitate several desirable simulation characteristics: real-time performance, unconditional stability, rapid model construction enabling patient-specific behaviour and accuracy with respect to reference CT images.

Laparoscopic upper-pole heminephrectomy for duplicated renal collecting system with superselective artery clamping using virtual partial nephrectomy analysis of Synapse Vincent: A case report

A 22-year-old woman was diagnosed with a duplicated renal collecting system with hydronephrosis and parenchymal loss in the upper pole of the left kidney. She underwent laparoscopic left upper-pole nephrectomy. Although a complex hilar vascular anatomy was identified during the operation, preoperative three-dimensional computed tomographic reconstruction using a three-dimensional image analysis device (Synapse Vincent; Fuji Medical Systems, Tokyo, Japan) greatly helped to accurately identify the anatomical renal hilum. For further detail, virtual partial nephrectomy analysis using a Voronoi decomposition was used to visualize the area supplied by a selected arterial branch including the atrophic cleavage line. We controlled the bleeding with selective clamping and safely carried out upper-pole heminephrectomy according to the preoperative plan.