Publications by authors named "Rachel Melnyk"

18 Publications

  • Page 1 of 1

Comparison of Multi-Parametric MRI of the Prostate to 3D Prostate Computer Aided Designs and 3D-Printed Prostate Models for Pre-Operative Planning of Radical Prostatectomies: A Pilot Study.

Urology 2021 Sep 5. Epub 2021 Sep 5.

University of Rochester Medical Center, Department of Urology, Simulation Innovation Laboratory, Rochester, New York. Electronic address:

Objective: To evaluate the use of 3D computed aided designs and 3D-printed models as pre-operative planning tools for urologists, in addition to radiologist interpreted mp-MRIS, prior to radical prostatectomy procedures.

Methods: Ten patients with biopsy-positive lesions detected on mp-MRI were retrospectively selected. Radiologists identified lesion locations using a Prostate Imaging-Reporting and Data System (PI-RADS) map and segmented the prostate, lesion(s), and surrounding anatomy to create 3D-CADs and 3D-printed models for each patient. Six uro-oncologists randomly reviewed three modalities (mp-MRI, 3D-CAD, and 3D-printed models) for each patient and identified lesion locations which were graded for accuracy against the radiologists' answers. Questionnaires assessed decision confidence, ease-of-interpretation, and usefulness for preoperative planning for each modality.

Results: Using 3D-CADs and 3D-printed models compared to mp-MRI, urologists were 2.4x and 2.8x more accurate at identifying the lesion(s), 2.7x and 3.2x faster, 1.6x and 1.63x more confident, and reported it was 1.6x and 1.7x easier to interpret. 3D-CADs and 3D-printed models were reported significantly more useful for overall pre-operative planning, identifying lesion location(s), determining degree of nerve sparing, obtaining negative margins, and patient counseling. Sub-analysis showed 3D-printed models demonstrated significant improvements in ease-of-interpretation, speed, usefulness for obtaining negative margins, and patient counseling compared to 3D-CADs.

Conclusion: 3D-CADs and 3D-printed models are useful adjuncts to mp-MRI in providing urologists with more practical, accurate, and efficient pre-operative planning.
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http://dx.doi.org/10.1016/j.urology.2021.08.031DOI Listing
September 2021

How specific are patient-specific simulations? Analyzing the accuracy of 3D-printing and modeling to create patient-specific rehearsals for complex urological procedures.

World J Urol 2021 Aug 14. Epub 2021 Aug 14.

Simulation Innovation Lab, University of Rochester Medical Center (URMC), 601 Elmwood Ave, Rochester, NY, USA.

Purpose: In the field of urology, 3D printing and modeling are now regularly utilized to enhance pre-operative planning, surgical training, patient-specific rehearsals (PSR), and patient education and counseling. Widespread accessibility and affordability of such technologies necessitates development of quality control measures to confirm the anatomical accuracy of these tools. Herein, we present three methods utilized to evaluate the anatomical accuracy of hydrogel PSR, developed using 3D printing and molding for pre-operative surgical rehearsals, of robotic-assisted partial nephrectomy (RAPN) and percutaneous nephrolithotomy (PCNL).

Methods: Virtual computer-aided designs (CADs) of patient anatomy were created through segmentation of patient CT scan images. Ten patient-specific RAPN and PCNL hydrogel models were CT scanned and segmented to create a corresponding model CAD. The part compare tool (3-matic, Materialize), point-to-point measurements, and Dice similarity coefficient (DSC) analyzed surface geometry, alignment, and volumetric overlap of each model component.

Results: Geometries of the RAPN parenchyma, tumor, artery, vein, and pelvicalyceal system lay within an average deviation of 2.5 mm (DSC = 0.70) of the original patient geometry and 5 mm (DSC = 0.45) of the original patient alignment. Similarly, geometries of the PCNL pelvicalyceal system and stone lay within 2.5 mm (DSC = 0.6) and within 15 mm (16% deviation) in alignment. This process enabled the refinement of our modeling process to fabricate anatomically accurate RAPN and PCNL PSR.

Conclusion: As 3D printing and modeling continues to have a greater impact on patient care, confirming anatomical accuracy should be introduced as a quality control measure prior to use for patient care.
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http://dx.doi.org/10.1007/s00345-021-03797-0DOI Listing
August 2021

Design and Implementation of an Emergency Undocking Curriculum for Robotic Surgery.

Simul Healthc 2021 Aug 11. Epub 2021 Aug 11.

From the Simulation Innovation Lab (R.M., P.S., T.H., K.C., A.E.G.) and Department of Urology (P.M., P.R., G.W., J.C., H.R., J.V.J., A.E.G.), University of Rochester Medical Center (URMC), Rochester, NY.

Introduction: Current training for robotic surgery crisis management, specifically emergency robotic undocking protocol (ERUP), remains limited to anecdotal experience. A curriculum to impart the skills and knowledge necessary to recognize and complete a successful ERUP was developed using an education approach then evaluated.

Methods: Baseline knowledge and confidence regarding ERUP were established for 5 robotic teams before completing 2 full-immersion simulations separated by an online self-paced learning module. In each simulation, teams operated on a perfused hydrogel model and were tasked to dissect a retroperitoneal tumor abutting a major vessel. During vascular pedicle ligation, a major vascular bleed and nonrecoverable robotic fault were remotely induced, necessitating ERUP with open conversion. After the simulation, participants completed surgery task load index (cognitive load assessment) and realism surveys. Weighted checklists scored participants' actions during each simulation. Surgical metrics including estimated blood loss, time to control bleeding, and undocking time were recorded. Curriculum retention was assessed by repeating the exercise at 6 months.

Results: Participants experienced high levels of cognitive demand and agreed that the simulation's realism and stress mimicked live surgery. Longitudinal analysis showed significant knowledge (+37.5 points, p = 0.004) and confidence (+15.3 points, p < 0.001) improvements from baseline to completion. Between simulations, checklist errors, undocking time, and estimated blood loss decreased (38→17, -40 seconds, and -500 mL, respectively), whereas action scores increased significantly (+27 points, p = 0.008). At 6 months, insignificant changes from curriculum completion were seen in knowledge (-4.8 points, p = 0.36) and confidence (+3.7 points, p = 0.1).

Conclusions: This simulation-based curriculum successfully improves operative team's confidence, knowledge, and skills required to manage robotic crisis events.
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http://dx.doi.org/10.1097/SIH.0000000000000596DOI Listing
August 2021

Validity of a patient-specific percutaneous nephrolithotomy (PCNL) simulated surgical rehearsal platform: impact on patient and surgical outcomes.

World J Urol 2021 Jun 24. Epub 2021 Jun 24.

Department of Urology, Simulation Innovation Lab, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY, 14642, USA.

Introduction: Simulators provide a safe method for improving surgical skills without the associated patient risks. Advances in rapid prototyping technology have permitted the reconstruction of patient imaging into patient-specific surgical simulations that require advanced expertise, potentially continuing the learning curve.

Objectives: To evaluate the impact of preoperative high-fidelity patient-specific percutaneous nephrolithotomy hydrogel simulations on surgical and patient outcomes.

Materials And Methods: Between 2016 and 2017, a fellowship-trained endourologist performed 20 consecutive percutaneous nephrolithotomy procedures at an academic referral center. For the first ten patients, only standard review of patient imaging was completed. For the next ten patients, patient imaging was utilized to fabricate patient-specific models including pelvicalyceal system, kidney, stone, and relevant adjacent structures from hydrogel. The models were tested to confirm anatomic accuracy and material properties similar to live tissue. Full procedural rehearsals were completed 24-48 h before the real case. Surgical metrics and patient outcomes from both groups (rehearsal vs. standard) were compared.

Results: Significant improvements in mean fluoroscopy time, percutaneous needle access attempts, complications, and additional procedures were significantly lower in the rehearsal group (184.8 vs. 365.7 s, p < 0.001; 1.9 vs. 3.6 attempts, p < 0.001; 1 vs. 5, p < 0.001; and 1 vs. 5, p < 0.001, respectively). There were no differences in stone free rates, mean patient age, body mass index, or stone size between the two groups.

Conclusion: This study demonstrates that patient-specific procedural rehearsal is effective reducing the experience curve for a complex endourological procedure, resulting in improved surgical performance and patient outcomes.
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http://dx.doi.org/10.1007/s00345-021-03766-7DOI Listing
June 2021

Application of IRIS Three-Dimensional Anatomical Models As Preoperative Surgical Planning Tools in the Management of Localized Renal Masses.

J Endourol 2021 03 23;35(3):383-389. Epub 2021 Feb 23.

Department of Urology, University of Rochester Medical Center, Rochester, New York, USA.

The use of volume-rendered images is gaining popularity in the surgical planning for complex procedures. IRIS™ is an interactive software that delivers three-dimensional (3D) virtual anatomical models. We aimed to evaluate the preoperative clinical utility of IRIS for patients with ≤T2 localized renal tumors who underwent either partial nephrectomy (PN) or radical nephrectomy (RN). Six urologists (four faculty and two trainees) reviewed CT scans of 40 cases over 2 study phases, using conventional two-dimensional (2D) CT alone (Phase-I), followed by the CT + IRIS 3D model (Phase-II). After each review, surgeons reported their decision on performing a PN or an RN and rated (Likert scale) their confidence in completing the procedure as well as how the imaging modality influenced specific procedural decisions. Modifications to the choice of procedure and confidence in decisions between both phases were compared for the same surgeon. Concordance between surgeons was also evaluated. A total of 462 reviews were included in the analysis (231 in each phase). In 64% (95% CI: 58-70%) of reviews, surgeons reported that IRIS achieved a better spatial orientation, understanding of the anatomy, and offered additional information compared with 2D CT alone. IRIS impacted the planned procedure in 20% of the reviews (3.5% changed decision from PN to RN and 16.5% changed from RN to PN). In the remaining 80% of reviews, surgeons' confidence increased from 78% (95% CI: 72-84%) with 2D CT, to 87% (95% CI: 82-92%) with IRIS ( = 0.02); this confidence change was more pronounced in cases with a high RENAL score ( = 0.009). In 99% of the reviews, surgeons rated that the IRIS accurately represented the anatomical details of all kidney components. Application of IRIS 3D models could influence the surgical decision-making process and improve surgeons' confidence, especially for robot-assisted management of complex renal tumors.
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http://dx.doi.org/10.1089/end.2020.0405DOI Listing
March 2021

Implementation of an E-Learning Academic Elective for Hands-On Basic Surgical Skills to Supplement Medical School Surgical Education.

J Surg Educ 2021 Jul-Aug;78(4):1164-1174. Epub 2020 Dec 10.

Department of Urology, Simulation Innovation Lab, University of Rochester Medical Center, Rochester, New York. Electronic address:

Objective: To examine the feasibility and utility of a completely online surgical skills elective for undergraduate medical students.

Design: The fully asynchronous, one-week, online learning elective addressed surgical instrument identification, knot tying, and suturing. Tools for knowledge acquisition and self-practice were outlined and individualized performance feedback on technical skills performance was incorporated from peers and experts through video conference.

Setting: University of Rochester School of Medicine & Dentistry, Rochester, NY.

Participants: A total of 86 third- and fourth-year medical students enrolled and successfully completed the elective.

Results: At elective completion, nearly all students met their course objectives and significantly increased their confidence in surgical instrument identification, knot tying, and suturing. Objective measures of student knowledge and technical skills acquisition were overwhelmingly positive, and faculty and students were very satisfied with providing and receiving performance feedback. Students reported that expert feedback was more useful than peer feedback, and more students than faculty reported that the online modality was equivalent to an in-person session for performance review.

Conclusions: This innovative online surgical skills elective improved undergraduate medical student confidence, knowledge, and skillset with surgical instrument identification, knot tying, and suturing while also facilitating effective expert feedback on individual performance.
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http://dx.doi.org/10.1016/j.jsurg.2020.11.014DOI Listing
June 2021

Utilizing 3D Printing and Hydrogel Casting for the Development of Patient-Specific Rehearsal Platforms for Robotic Assisted Partial Nephrectomies.

Urology 2021 Jan 28;147:317. Epub 2020 Oct 28.

University of Rochester Medical Center, Division Department of Urology, 601 Elmwood Ave, Rochester, NY.

Background: Three-dimensional (3D) printing technology has been utilized to create patient-specific (PS) replicas as visual aids for surgical planning. However, they cannot recreate the operative experience due to a lack of realistic tissue characteristics.

Objectives: Develop anatomically accurate, realistic, PS partial nephrectomy platforms suitable for pre-operative surgical rehearsals using 3D-printing and hydrogel casting.

Material: Patient CT scans were segmented into a computer-aided design (CAD) file and used to create injection casts. Kidney and tumor casts along with hollow vascular and urinary structures were 3D-printed. The hilar structures and tumor were registered into the kidney cast, injected with poly-vinyl alcohol (PVA) hydrogel, and processed to create the kidney phantom. Mechanical and functional testing protocols were completed to confirm that the properties of PVA matched the live tissue. Anatomical accuracy was confirmed by CT scanning the phantom and creating another CAD, which was compared to the original patient CAD. Full-procedural PS rehearsals were completed 24-48 hours prior to their respective live surgeries. Clinically relevant metrics (warm ischemia time, estimated blood loss, and positive surgical margins) from each rehearsal and live case were compared using a Wilcoxon-rank sum test.

Results: The 7%-3freeze/thaw PVA best recreated the mechanical and functional properties of porcine kidneys, while anatomical verification showed ≤1 mm deviation of the kidney and tumor from the patient anatomy and ≤3 mm for the hilar structures. PS rehearsal platforms were fabricated using these methods for 8 patients (average tumor size 5.92 cm and nephrometry score 9.8). A positive correlation was found for warm ischemia time and estimated blood loss between rehearsals and live surgeries.

Conclusion: This reproducible method shows high anatomical accuracy, realistic tissue properties, and translational effects between rehearsals and live surgery. To determine the effects on patient outcomes, future studies will compare the impact of completing a pre-operative rehearsal vs standard surgical preparation.
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http://dx.doi.org/10.1016/j.urology.2020.10.023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7785697PMC
January 2021

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

J Endourol 2021 03 11;35(3):362-368. Epub 2020 Nov 11.

Department of Urology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.

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. 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. 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). 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.
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http://dx.doi.org/10.1089/end.2020.0363DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7987368PMC
March 2021

See Like an Expert: Gaze-Augmented Training Enhances Skill Acquisition in a Virtual Reality Robotic Suturing Task.

J Endourol 2021 03 21;35(3):376-382. Epub 2021 Jan 21.

Simulation Innovation Laboratory, Department of Urology, University of Rochester Medical Center, Rochester, New York, USA.

The da Vinci Skills Simulator (DVSS) is an effective platform for robotic skills training. Novel training methods using expert gaze patterns to guide trainees have demonstrated superiority to traditional instruction. Portable head-mounted eye-trackers (HMET) offer the opportunity for eye tracking technology to enhance surgical robotic simulation training. To evaluate if training guided by expert gaze patterns can improve trainee performance over standard movement training techniques during robotic simulation. Medical students were recruited and randomized into gaze training (GT,  = 9) and movement training (MT,  = 8) groups. First, the participants reviewed an instructional video, with the GT group emulating expert gaze patterns and the MT group ( = 8) standard movement-based instruction. Training consisted of 10 repetitions of "Suture Sponge 3" on the DVSS while wearing HMET; the first three repetitions were followed by group-appropriate video coaching (gaze movement feedback), while the remaining repetitions were without feedback. Finally, two multitasking repetitions with a secondary bell-counting task were completed. Primary outcomes included DVSS scores during training and multitasking. Secondary outcomes included metrics collected from the HMET (gaze patterns and gaze entropy). Total score, efficiency, and penalties improved significantly over the training in both groups; the GT group achieved higher scores on every attempt. Total scores in the GT group were higher than the MT group postvideo review (20.3 ± 21.8 3.0 ± 6.2,  = 0.047), after coaching repetitions (61.8 ± 18.8 30.1 ± 26.2,  = 0.01), and at the last training attempt (73.0 ± 16.5 63.1 ± 17.4,  = 0.247). During multitasking, the GT group maintained higher total scores (75 ± 10.1 63.3 ± 15.3,  = 0.01), efficiency (86.3 ± 7.4 77.4 ± 11.2,  = 0.009), and superior secondary task performance (error: 6.3% ± 0.06 10.7% ± 0.11,  = 0.20). Gaze entropy (cognitive-load indicator) and gaze pattern analysis showed similar trends. Gaze-augmented training leads to more efficient movements through adoption of expert gaze patterns that withstand additional stressors.
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http://dx.doi.org/10.1089/end.2020.0445DOI Listing
March 2021

The Future of Penile Prosthetic Surgical Training Is Here: Design of a Hydrogel Model for Inflatable Penile Prosthetic Placement Using Modern Education Theory.

J Sex Med 2020 11 15;17(11):2299-2306. Epub 2020 Sep 15.

Department of Urology, University of Rochester Medical Center, Rochester, NY, USA; Simulation Innovation Laboratory, Department of Urology, University of Rochester, Rochester, NY, USA. Electronic address:

Background: There is a significant need for a non-biohazardous, educational platform to equip and maintain the surgical skills required by urology trainees and low-volume implanters for inflatable penile prosthetic (IPP) placement.

Aim: To design and develop an anatomic, hydrogel-based simulation platform for training and evaluate IPP placement using modern education theory.

Methods: The backward design concept was used as a framework in the design and development of an IPP simulation platform. Steps included delineating requirements from a physicians' perspective, translating requirements into engineering tasks (deliverables), developing a prototype, and pilot validation. Using a combination of 3-dimensional printing and hydrogel casting, a genitourinary tract model was constructed to replicate the appropriate steps of IPP placement guided by expert feedback. Full-immersion IPP simulations were performed through both infrapubic and penoscrotal approaches by 4 expert surgeons under operative conditions. Questionnaires evaluating the simulation's realism, value as a training tool, and further recommendations were completed.

Outcomes: Using backward design educational pedagogy, a high-fidelity, full-procedural IPP simulation was fabricated and verified as an adequate educational tool for training and assessment.

Results: An expert consensus on the anatomic landmarks, steps and substeps, instruments, and errors to be included in the model was reached using a hierarchical task analysis and was successfully translated into a prototype hydrogel model. Experts performed all appropriate steps of IPP surgery and rated the simulation highly in terms of its realism and value as a training tool. On average, experts agreed that the model could function as a training tool, assessment tool, prerequisite for IPP accreditation, and requirement before live surgery. Experts stated they would have their trainees ideally complete an average of 1.75 models before live surgical training. All experts believed an operative checklist would be an ideal assessment tool. Witthaus MW, Saba P, Melnyk R, et al. The Future of Penile Prosthetic Surgical Training Is Here: Design of a Hydrogel Model for Inflatable Penile Prosthetic Placement Using Modern Education Theory. J Sex Med 2020;17:2299-2306.
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http://dx.doi.org/10.1016/j.jsxm.2020.08.003DOI Listing
November 2020

Multi-institutional validation of a perfused robot-assisted partial nephrectomy procedural simulation platform utilizing clinically relevant objective metrics of simulators (CROMS).

BJU Int 2021 06 6;127(6):645-653. Epub 2020 Oct 6.

Department of Urology, University of Rochester, Rochester, NY, USA.

Objective: To conduct a multi-institutional validation of a high-fidelity, perfused, inanimate, simulation platform for robot-assisted partial nephrectomy (RAPN) using incorporated clinically relevant objective metrics of simulation (CROMS), applying modern validity standards.

Materials And Methods: Using a combination of three-dimensional (3D) printing and hydrogel casting, a RAPN model was developed from the computed tomography scan of a patient with a 4.2-cm, upper-pole renal tumour (RENAL nephrometry score 7×). 3D-printed casts designed from the patient's imaging were used to fabricate and register hydrogel (polyvinyl alcohol) components of the kidney, including the vascular and pelvicalyceal systems. After mechanical and anatomical verification of the kidney phantom, it was surrounded by other relevant hydrogel organs and placed in a laparoscopic trainer. Twenty-seven novice and 16 expert urologists, categorized according to caseload, from five academic institutions completed the simulation.

Results: Clinically relevant objective metrics of simulators, operative complications, and objective performance ratings (Global Evaluative Assessment of Robotic Skills [GEARS]) were compared between groups using Wilcoxon rank-sum (continuous variables) and parametric chi-squared (categorical variables) tests. Pearson and point-biserial correlation coefficients were used to correlate GEARS scores to each CROMS variable. Post-simulation questionnaires were used to obtain subjective supplementation of realism ratings and training effectiveness.

Results: Expert ratings demonstrated the model's superiority to other procedural simulations in replicating procedural steps, bleeding, tissue texture and appearance. A significant difference between groups was demonstrated in CROMS [console time (P < 0.001), warm ischaemia time (P < 0.001), estimated blood loss (P < 0.001)] and GEARS (P < 0.001). Six major intra-operative complications occurred only in novice simulations. GEARS scores highly correlated with the CROMS.

Conclusions: This perfused, procedural model offers an unprecedented realistic simulation platform, which incorporates objective, clinically relevant and procedure-specific performance metrics.
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http://dx.doi.org/10.1111/bju.15246DOI Listing
June 2021

Development of a high-fidelity coronary artery bypass graft training platform using 3-dimensional printing and hydrogel molding.

J Thorac Cardiovasc Surg 2021 04 24;161(4):e291-e293. Epub 2020 Jun 24.

Division of Cardiac Surgery, University of Rochester Medical Center, Rochester, NY.

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http://dx.doi.org/10.1016/j.jtcvs.2020.05.106DOI Listing
April 2021

Development of a High-Fidelity Robot-Assisted Kidney Transplant Simulation Platform Using Three-Dimensional Printing and Hydrogel Casting Technologies.

J Endourol 2020 10 28;34(10):1088-1094. Epub 2020 Aug 28.

Simulation Innovation Laboratory, Department of Urology, Transplant, University of Rochester Medical Center, Rochester, New York, USA.

Despite the adoption of robotic donor nephrectomy, the steep learning curve of robotic recipient transplantation has hindered the implementation of a complete robot-assisted kidney transplantation (RAKT). We sought to develop a high-fidelity perfused full immersion nonbiohazardous platform for RAKT simulation training. A three-dimensional (3D) computer-aided design (CAD) model consisting of a kidney, pelvicaliceal system, renal artery, and vein was created from a CT scan of a donor patient. 3D printed casts designed from the CAD model were injected with various polyvinyl alcohol hydrogel formulations to fabricate an anatomical kidney phantom and surrounding abdominal cavity. The process was repeated using a recipient's CT scan to create the recipient pelvic model containing a bony pelvis, pelvic musculature, iliac arteries and veins, and bladder. Donor and recipient models each contained structures to simulate the perfused vascular and ureterovesical anastomosis. A board-certified transplant surgeon completed a robotic training curriculum, including four RAKT simulation procedures, from procurement of the donor kidney to final retroperitonealization. Metrics from the simulations (e.g., arterial, venous, ureterovesical, and total anastomosis times) were recorded and compared with surgical times from published data. The average time for the nephrectomies was 67.33 (±31.58) minutes. The average total anastomosis time was 60.85 (±9.73) minutes with 20.37 (±3.87), 20.17 (±4) and 15.1 (±2.35) minutes for arterial, venous, and ureterovesical anastomosis, respectively. The recorded arterial and venous anastomosis times were within published times for competency (Δ = 2.47 and Δ = 2.87, respectively), whereas the uterovesical time was within the mastery range (Δ = 0.45). Using a combination of 3D printing and hydrogel casting technologies, a high fidelity perfused full-immersion nonbiohazardous simulation platform for RAKT was developed. The utilization of this platform has the potential to replace the early cases in a learning curve while decreasing the barriers to utilization for transitioning transplant surgeons.
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http://dx.doi.org/10.1089/end.2020.0441DOI Listing
October 2020

Correction to: Mechanical and functional validation of a perfused, robot-assisted partial nephrectomy simulation platform using a combination of 3D printing and hydrogel casting.

World J Urol 2020 Jul;38(7):1643

Department of Urology, Simulation Innovation Laboratory, Univeristy of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY, 14642, USA.

The Eqs. 1, 2 and 3 come under the section "Kidney cortex testing" as per the original manuscript, but they have been incorrectly moved and separated into different sections in the original publication of the article.
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http://dx.doi.org/10.1007/s00345-020-03089-zDOI Listing
July 2020

Mechanical and functional validation of a perfused, robot-assisted partial nephrectomy simulation platform using a combination of 3D printing and hydrogel casting.

World J Urol 2020 Jul 2;38(7):1631-1641. Epub 2019 Nov 2.

Department of Urology, Simulation Innovation Laboratory, Univeristy of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY, 14642, USA.

Introduction And Objectives: There is a scarcity of high-fidelity, life-like, standardized and anatomically correct polymer-based kidney models for robot-assisted partial nephrectomy (RAPN) simulation training. The purpose of this technical report is to present mechanical and functional testing data as evidence for utilizing a perfused hydrogel kidney model created utilizing 3D printed injection casts for RAPN simulation and training.

Methods: Anatomically correct, tumor-laden kidney models were created from 3D-printed casts designed from a patient's CT scan and injected with poly-vinyl alcohol (PVA). A variety of testing methods quantified Young's modulus in addition to comparing the functional effects of bleeding and suturing among fresh porcine kidneys and various formulations of PVA kidneys.

Results: 7% PVA at three freeze-thaw cycles (7%-3FT) was found to be the formula that best replicates the mechanical properties of fresh porcine kidney tissue, where mean(± SD) values of Young's modulus of porcine tissue vs 7%-3FT samples were calculated to be 85.97(± 35) kPa vs 80.97(± 9.05) kPa, 15.7(± 1.6) kPa vs 74.56(± 10) kPa and 87.46(± 2.97) kPa vs 83.4(± 0.7) kPa for unconfined compression, indentation and elastography testing, respectively. No significant difference was seen in mean suture tension during renorrhaphy necessary to achieve observable hemostasis and capsular violation during a simulated perfusion at 120 mmHg.

Conclusions: This is the first study to utilize extensive material testing analyses to determine the mechanical and functional properties of a perfused, inanimate simulation platform for RAPN, fabricated using a combination of image segmentation, 3D printing and PVA casting.
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http://dx.doi.org/10.1007/s00345-019-02989-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7730938PMC
July 2020

Incorporation and validation of clinically relevant performance metrics of simulation (CRPMS) into a novel full-immersion simulation platform for nerve-sparing robot-assisted radical prostatectomy (NS-RARP) utilizing three-dimensional printing and hydrogel casting technology.

BJU Int 2020 02 3;125(2):322-332. Epub 2019 Dec 3.

Department of Urology, University of Rochester Medical Center, Rochester, NY, USA.

Objectives: To incorporate and validate clinically relevant performance metrics of simulation (CRPMS) into a hydrogel model for nerve-sparing robot-assisted radical prostatectomy (NS-RARP).

Materials And Methods: Anatomically accurate models of the human pelvis, bladder, prostate, urethra, neurovascular bundle (NVB) and relevant adjacent structures were created from patient MRI by injecting polyvinyl alcohol (PVA) hydrogels into three-dimensionally printed injection molds. The following steps of NS-RARP were simulated: bladder neck dissection; seminal vesicle mobilization; NVB dissection; and urethrovesical anastomosis (UVA). Five experts (caseload >500) and nine novices (caseload <50) completed the simulation. Force applied to the NVB during the dissection was quantified by a novel tension wire sensor system fabricated into the NVB. Post-simulation margin status (assessed by induction of chemiluminescent reaction with fluorescent dye mixed into the prostate PVA) and UVA weathertightness (via a standard 180-mL leak test) were also assessed. Objective scoring, using Global Evaluative Assessment of Robotic Skills (GEARS) and Robotic Anastomosis Competency Evaluation (RACE), was performed by two blinded surgeons. GEARS scores were correlated with forces applied to the NVB, and RACE scores were correlated with UVA leak rates.

Results: The expert group achieved faster task-specific times for nerve-sparing (P = 0.007) and superior surgical margin results (P = 0.011). Nerve forces applied were significantly lower for the expert group with regard to maximum force (P = 0.011), average force (P = 0.011), peak frequency (P = 0.027) and total energy (P = 0.003). Higher force sensitivity (subcategory of GEARS score) and total GEARS score correlated with lower nerve forces (total energy in Joules) applied to NVB during the simulation with a correlation coefficient (r value) of -0.66 (P = 0.019) and -0.87 (P = 0.000), respectively. Both total and force sensitivity GEARS scores were significantly higher in the expert group compared to the novice group (P = 0.003). UVA leak rate highly correlated with total RACE score r value = -0.86 (P = 0.000). Mean RACE scores were also significantly different between novices and experts (P = 0.003).

Conclusion: We present a realistic, feedback-driven, full-immersion simulation platform for the development and evaluation of surgical skills pertinent to NS-RARP. The correlation of validated objective metrics (GEARS and RACE) with our CRPMS suggests their application as a novel method for real-time assessment and feedback during robotic surgery training. Further work is required to assess the ability to predict live surgical outcomes.
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http://dx.doi.org/10.1111/bju.14940DOI Listing
February 2020

Design and Validation of a Cervical Laminectomy Simulator using 3D Printing and Hydrogel Phantoms.

Oper Neurosurg (Hagerstown) 2020 02;18(2):202-208

Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York.

Background: The development of technical skills for a cervical laminectomy are traditionally acquired through intraoperative learning and cadaveric courses. These methods provide little objective assessment, involve financial and biohazard considerations, and may not incorporate desired pathology.

Objective: To develop an inexpensive cervical spine laminectomy simulator capable of measuring operative performance and to assess its face, content, and construct validity.

Methods: A virtual model was generated and 3D printed into negative molds. A multilayered surgical phantom was fabricating by filling molds with hydrogels, plaster, and fiberglass. A pressure transducer measured simulated spinal cord manipulation. Participants completed full-procedural laminectomy simulations. Post-simulation surveys assessed face and content validity. Construct validity was assessed by comparing expert and novice procedural metrics.

Results: Twelve surgeons participated. The simulator received median face and content validity ratings of 4/5. Differences between experts and novices were found in mean intrathecal pressure wave count (84 vs 153, P = .023), amplitude (4 vs 12% > 2SD above expert mean, P < .001), area under curve (4 vs 12% > 2SD above expert mean, P < .001), procedure time (35 vs 69 min P = .003), and complication rates (none vs 3 incorrect levels decompressed and 1 dural tear, P = .06). Insignificant differences were found in mean pressure wave slope and blood loss.

Conclusion: This inexpensive cervical laminectomy simulator received favorable face and content validity ratings, and distinguished novice from expert participants. Further studies are needed to determine this simulator's role in the training and assessment of novice surgeons.
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http://dx.doi.org/10.1093/ons/opz129DOI Listing
February 2020

Validation of a Full-Immersion Simulation Platform for Percutaneous Nephrolithotomy Using Three-Dimensional Printing Technology.

J Endourol 2017 12;31(12):1314-1320

1 Department of Urology, University of Rochester Medical Center , Rochester, New York.

Introduction And Objectives: The restriction of resident hours with an increasing focus on patient safety and a reduced caseload has impacted surgical training. A complex and complication prone procedure such as percutaneous nephrolithotomy (PCNL) with a steep learning curve may create an unsafe environment for hands-on resident training. In this study, we validate a high fidelity, inanimate PCNL model within a full-immersion simulation environment.

Methods: Anatomically correct models of the human pelvicaliceal system, kidney, and relevant adjacent structures were created using polyvinyl alcohol hydrogels and three-dimensional-printed injection molds. All steps of a PCNL were simulated including percutaneous renal access, nephroscopy, and lithotripsy. Five experts (>100 caseload) and 10 novices (<20 caseload) from both urology (full procedure) and interventional radiology (access only) departments completed the simulation. Face and content validity were calculated using model ratings for similarity to the real procedure and usefulness as a training tool. Differences in performance among groups with various levels of experience using clinically relevant procedural metrics were used to calculate construct validity.

Results: The model was determined to have an excellent face and content validity with an average score of 4.5/5.0 and 4.6/5.0, respectively. There were significant differences between novice and expert operative metrics including mean fluoroscopy time, the number of percutaneous access attempts, and number of times the needle was repositioned. Experts achieved better stone clearance with fewer procedural complications.

Conclusions: We demonstrated the face, content, and construct validity of an inanimate, full task trainer for PCNL. Construct validity between experts and novices was demonstrated using incorporated procedural metrics, which permitted the accurate assessment of performance. While hands-on training under supervision remains an integral part of any residency, this full-immersion simulation provides a comprehensive tool for surgical skills development and evaluation before hands-on exposure.
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http://dx.doi.org/10.1089/end.2017.0366DOI Listing
December 2017
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