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Abstract
Ureteroscopy is the standard of care for diagnosing and treating kidney stones and tumors. However, current ureteroscopes have a limited field of view, requiring significant experience to adequately navigate the renal collecting system. This is evidenced by the fact that inexperienced surgeons have higher rates of missed stones. %22 of patients with residual stones require re-operation within 20 months. In order to aid surgeons to fully explore the kidney, this study presents the Navigated Augmented Reality Visualization for Ureteroscopic Surgery (NAVIUS) system. NAVIUS assists surgeons by providing 3D maps of the target anatomy, real-time scope positions, and preoperative imaging overlays. To enable real-time navigation and visualization, we integrate an electromagnetic tracker-based navigation pipeline with augmented reality (AR) visualizations. NAVIUS connects to 3D Slicer and Unity with OpenIGTLink, and uses HoloLens 2 as a holographic interface. We evaluate NAVIUS through a user study where surgeons conducted ureteroscopy on kidney phantoms with and without visual guidance. We observed that surgeons explored more areas within the collecting system with NAVIUS (average 23.73% increase), and experienced lower task load, as measured by NASA-TLX (up to 27.27% reduction). NAVIUS is a step towards intraoperative AR guidance for better surgical outcomes and surgeons’ experience. The codebase for the system is available at: https://github.com/vu-maple-lab/NAVIUS.
Links to Paper and Supplementary Materials
Main Paper (Open Access Version): https://papers.miccai.org/miccai-2025/paper/4752_paper.pdf
SharedIt Link: Not yet available
SpringerLink (DOI): Not yet available
Supplementary Material: https://papers.miccai.org/miccai-2025/supp/4752_supp.zip
Link to the Code Repository
https://github.com/vu-maple-lab/NAVIUS
Link to the Dataset(s)
N/A
BibTex
@InProceedings{AcaAyb_NAVIUS_MICCAI2025,
author = { Acar, Ayberk and Atoum, Jumanh and Connor, Peter S. and Pierre, Clifford and Lynch, Carisa N. and Kavoussi, Nicholas L. and Wu, Jie Ying},
title = { { NAVIUS: Navigated Augmented Reality Visualization for Ureteroscopic Surgery } },
booktitle = {proceedings of Medical Image Computing and Computer Assisted Intervention -- MICCAI 2025},
year = {2025},
publisher = {Springer Nature Switzerland},
volume = {LNCS 15970},
month = {September},
}
Reviews
Review #1
- Please describe the contribution of the paper
The paper presents an augmented reality system that works in conjunction with an electromagnetically tracked ureteroscope to help guide kidney stone removal procedures. It provides users with an indication of the position of the tip of the ureteroscope relative to a preoperative CT scan. A user study is performed on two phantoms with six surgeons who are asked to navigate freely within the urethra and kidney. The outcome is evaluated based on standardized questionnaires filed by participants as well as measurement of the ratio between the path length of the ureteroscope and the bounding box of the volume covered. Contributions:
- A new AR system to help guide a tracked ureteroscope
- Demonstration of the usability of the system compared to the state of the art approach
- Please list the major strengths of the paper: you should highlight a novel formulation, an original way to use data, demonstration of clinical feasibility, a novel application, a particularly strong evaluation, or anything else that is a strong aspect of this work. Please provide details, for instance, if a method is novel, explain what aspect is novel and why this is interesting.
- The topic is well suited for presentation at MICCAI
- The objectives of the paper are clear
- The AR system presented is sound if it can be established that a rigid registration between the patient and preoperative scans is feasible and clinically sensible.
- Please list the major weaknesses of the paper. Please provide details: for instance, if you state that a formulation, way of using data, demonstration of clinical feasibility, or application is not novel, then you must provide specific references to prior work.
- The paper would need at least a clinically founded discussion on whether it makes it is realistic to assume a rigid transform between the scan and the real patient as they do in the paper.
- Results are very thin and average score differences are not analyzed statistically for significance. For example, for the SUS questionnaire result, authors write: “In our results, only two questions had >1 difference in average responses for the two scenarios while the other metrics show no significant differences”. Do they assume a score different >1 means the difference is significant? Be careful when using terms that have very specific meaning in statistics.
- Discussion of the results is confusing, jumping back and forth between results from TLX, SUS and total distance travelled. Authors seem to suggest that a better ratio of convex hull path volume to scope path length is a proxy for a more complete exploration of space. This metric needs to be better explained and justified. It would seem like taking time into account is also fundamental.
- The paper is organized in an unconventional way, which makes it difficult to follow. The phantom production process and tracking methods are not described in the Methods section, but rather in a Results section. As a result, the methods section is sometimes difficult to follow as important details seem to be missing. For example, the methods do not mention which anatomical structures are segmented from the CT scan. We sort of figure it out once we get to the phantom production section, but some ambiguity remains.
- The paper sometimes refers to existing software functionality rather than methods. For example, in the Ureteroscope Tracking section, we can read: using the “Fiducial Registration Wizard” within SlicerIGT module”. It would be more appropriate to rapidly explain what this module is doing mathematically.
- Please rate the clarity and organization of this paper
Poor
- Please comment on the reproducibility of the paper. Please be aware that providing code and data is a plus, but not a requirement for acceptance.
The submission has provided an anonymized link to the source code, dataset, or any other dependencies.
- Optional: If you have any additional comments to share with the authors, please provide them here. Please also refer to our Reviewer’s guide on what makes a good review and pay specific attention to the different assessment criteria for the different paper categories: https://conferences.miccai.org/2025/en/REVIEWER-GUIDELINES.html
Despite the availability of the source code, some methodological of the user study are still difficult to understand or lacking, which compromises reproducibility.
- Rate the paper on a scale of 1-6, 6 being the strongest (6-4: accept; 3-1: reject). Please use the entire range of the distribution. Spreading the score helps create a distribution for decision-making.
(3) Weak Reject — could be rejected, dependent on rebuttal
- Please justify your recommendation. What were the major factors that led you to your overall score for this paper?
- Lack of clinical realism
- Poor statistical analysis
- Difficult to read The paper feels like a first draft of an interesting concept, but not ready of publication. The introduction of SLAM to build the anatomical model in real-time as suggested by authors would greatly benefit the realism of the procedure.
- Reviewer confidence
Very confident (4)
- [Post rebuttal] After reading the authors’ rebuttal, please state your final opinion of the paper.
Accept
- [Post rebuttal] Please justify your final decision from above.
Considering the rebuttal, it has become clearer that despite the lack of clinical realism of the proposed experiment (in practice it would be difficult to register a kidney to the tracking system), the proposed research is valuable in terms of demonstrating a potential contribution of AR to the guidance of such procedures. There are a few weaknesses in the statistical analysis that would need to be fixed for the final version of the paper. Most importantly, the stddevs and p-values should be reported when relevant (ex. change in convex hull volume).
Review #2
- Please describe the contribution of the paper
The paper describes the design of an augmented reality navigation system for ueretoscopic surgery along with a user study (6 surgeons) of it’s performance on a phantom. The system shows significant promise (notably the increased volume covered - figure 5).
- Please list the major strengths of the paper: you should highlight a novel formulation, an original way to use data, demonstration of clinical feasibility, a novel application, a particularly strong evaluation, or anything else that is a strong aspect of this work. Please provide details, for instance, if a method is novel, explain what aspect is novel and why this is interesting.
The description of the system, the phantom construction, and study design is thorough and useful. The study results in terms of usability (TLX/SUS) and exploration volume are impressive and indicate the system would be useful clinically. Although not possible to judge at this stage the accompanying code should be useful for other researchers in AR for surgery.
- Please list the major weaknesses of the paper. Please provide details: for instance, if you state that a formulation, way of using data, demonstration of clinical feasibility, or application is not novel, then you must provide specific references to prior work.
It is clear that the system is some way from clinical use. At present I doubt the EM tracking system could be used clinically as the method of attachment would compromise sterility. Secondly there is no registration method to match a human model to the patient (the fiducials used for the phantom would not be appropriate). The authors allude to this in the discussion but at present it is a significant unsolved problem.
- Please rate the clarity and organization of this paper
Good
- Please comment on the reproducibility of the paper. Please be aware that providing code and data is a plus, but not a requirement for acceptance.
The submission has provided an anonymized link to the source code, dataset, or any other dependencies.
- Optional: If you have any additional comments to share with the authors, please provide them here. Please also refer to our Reviewer’s guide on what makes a good review and pay specific attention to the different assessment criteria for the different paper categories: https://conferences.miccai.org/2025/en/REVIEWER-GUIDELINES.html
It would be good to see some tests of statistical significance (p-values) on the results.
- Rate the paper on a scale of 1-6, 6 being the strongest (6-4: accept; 3-1: reject). Please use the entire range of the distribution. Spreading the score helps create a distribution for decision-making.
(4) Weak Accept — could be accepted, dependent on rebuttal
- Please justify your recommendation. What were the major factors that led you to your overall score for this paper?
It’s a promising system and informative analysis, but the unsolved challenges required before clinical use (tracking and registration) limit its impact at the moment.
- Reviewer confidence
Confident but not absolutely certain (3)
- [Post rebuttal] After reading the authors’ rebuttal, please state your final opinion of the paper.
Accept
- [Post rebuttal] Please justify your final decision from above.
The rebuttal hasn’t changed my opinion of the paper. It is a promising system, but requires significant work before clinical application.
Review #3
- Please describe the contribution of the paper
The paper introduces NAVIUS, a navigated AR system designed to improve ureteroscopic surgery by providing real-time 3D maps, scope tip localization, and preoperative CT overlays. By integrating electromagnetic (EM) tracking with a pipeline connecting 3D Slicer, Unity, and HoloLens 2 via OpenIGTLink, the system enables surgeons to visualize critical anatomical information during kidney stone procedures. The authors evaluate NAVIUS on kidney phantoms in a mock OR, showing increased exploration of the renal collecting system (approximately 23.73% more volume coverage) and improvements in NASA-TLX workload metrics.
- Please list the major strengths of the paper: you should highlight a novel formulation, an original way to use data, demonstration of clinical feasibility, a novel application, a particularly strong evaluation, or anything else that is a strong aspect of this work. Please provide details, for instance, if a method is novel, explain what aspect is novel and why this is interesting.
- NAVIUS effectively combines EM tracking, CT-based segmentation, and head-mounted AR visualization, offering a cohesive solution to overcome the limited field of view in ureteroscopy.
- The system provides surgeons with real-time feedback on scope tip position and exploration coverage, which could help reduce the rate of missed stones.
- Detailed methods for producing anatomically realistic kidney phantoms are provided, enhancing the reproducibility of the experimental setup.
- A well-designed user study evaluates both objective measures (e.g., volume coverage, scope trajectory) and subjective workload (NASA-TLX, SUS), demonstrating the system’s potential to improve surgeon performance and confidence.
- Please list the major weaknesses of the paper. Please provide details: for instance, if you state that a formulation, way of using data, demonstration of clinical feasibility, or application is not novel, then you must provide specific references to prior work.
- The system relies on EM tracking, which is susceptible to interference from other OR devices, potentially affecting tracking accuracy and overall reliability.
- The user study is conducted on phantoms with a small sample of surgeons. While promising, further clinical validation on real patients is necessary to establish generalizability and robustness.
- The accuracy of the registration between preoperative CT data and the intraoperative tracking coordinate system depends on precise calibration, which may be challenging to maintain consistently in a live surgical environment.
- Although the SUS scores indicate acceptable usability, user feedback highlights the need for additional calibration procedures and possibly alternative tracking methods (e.g., visual navigation) to improve system robustness in the OR.
- Please rate the clarity and organization of this paper
Good
- Please comment on the reproducibility of the paper. Please be aware that providing code and data is a plus, but not a requirement for acceptance.
The submission has provided an anonymized link to the source code, dataset, or any other dependencies.
- Optional: If you have any additional comments to share with the authors, please provide them here. Please also refer to our Reviewer’s guide on what makes a good review and pay specific attention to the different assessment criteria for the different paper categories: https://conferences.miccai.org/2025/en/REVIEWER-GUIDELINES.html
N/A
- Rate the paper on a scale of 1-6, 6 being the strongest (6-4: accept; 3-1: reject). Please use the entire range of the distribution. Spreading the score helps create a distribution for decision-making.
(4) Weak Accept — could be accepted, dependent on rebuttal
- Please justify your recommendation. What were the major factors that led you to your overall score for this paper?
NAVIUS represents a promising step toward enhanced ureteroscopic navigation by integrating AR and EM tracking. The system demonstrates measurable improvements in exploration volume and workload, which could translate to better clinical outcomes. However, limitations including reliance on specific hardware, calibration sensitivity, and the need for further clinical validation temper the overall impact. Addressing these concerns in future work would strengthen the system’s clinical viability.
- Reviewer confidence
Confident but not absolutely certain (3)
- [Post rebuttal] After reading the authors’ rebuttal, please state your final opinion of the paper.
Reject
- [Post rebuttal] Please justify your final decision from above.
While I appreciate the authors’ enthusiastic response and recognize the potential of the proposed NAVIUS system, I continue to recommend rejection in its current form. The rebuttal acknowledges key limitations—such as the reliance on electromagnetic (EM) tracking, the rigid registration assumption, and the lack of in vivo validation—but frames them primarily as future work. Unfortunately, MICCAI submissions must stand on the strength of their present contributions, and this paper falls short in several critical areas.
First, the system’s dependency on EM tracking introduces significant concerns around robustness and clinical feasibility—especially in OR environments known for interference and sterility challenges. While the authors cite supporting literature, they stop short of demonstrating that their approach would be practically viable or reliable beyond the phantom setup. Second, the statistical analysis is underdeveloped. Reporting raw score differences without significance testing or effect size metrics weakens the evidence base, especially given the small sample size. Third, the organization of the manuscript is poor; core methodological elements are buried in the Results section, and critical definitions and assumptions are insufficiently explained.
Despite its conceptual merit, the work reads more like a proof-of-concept than a mature, rigorously validated contribution suitable for MICCAI. I strongly encourage the authors to revise the methodology, improve the statistical evaluation, clarify the structure, and present more robust evidence in a future submission.
Author Feedback
We thank the reviewers for their assessment that the “study results…are impressive and indicate the system would be useful clinically”, “the system shows significant promise” (R2), and has “potential to improve surgeon performance and confidence” (R3). Reviewers note that “the description of the system, the phantom construction, and study design is thorough and useful” (R2), and “detailed methods for producing…phantoms are provided, enhancing the reproducibility” (R3). With this reproducibility and potential impact, NAVIUS is a stepping stone for improved visualizations in operating rooms (OR) and AR/navigation integration. We believe this study is well suited for MICCAI as R1 suggested, and would play an important role in furthering CAI research.
In this rebuttal letter, we address the reviewers’ main concern about clinical applicability due to challenges in registration and EM tracking, as well as the statistical analysis, and manuscript organization.
We agree with the concerns about directly using the current calibration and registration methods (R1, R2, R3). However, methods in the literature show that in-vivo registration is feasible with the help of sensorized fiducials and driving the endoscope to known positions [1]. Fluoroscopy in clinical scenarios also enables well-studied X-ray/CT registration. In this study, we focus more on demonstrating the benefits of integrated localization and AR visualization, and the current experiments and results indicate the potential for clinical translation. This step is necessary to power future in vivo and clinical studies with more surgeons for improved statistical analysis.
We acknowledge the EM tracker challenges related to interference (R3) and sterility (R2). Nonetheless, as stated in the previously cited paper [2] and earlier studies in the literature [3], EM trackers are usable in OR despite the interference. Since the surgeons are still in the loop during the operation, we see the errors given in these papers as acceptable. With a consistent error, we will still acquire a valid trajectory representing the explored structure, even with imperfect alignment to the CT mesh. To solve sterilization issues, sensors can be placed in the working channel, and scopes can be customized.
Since the current attachment and registration solutions suffice for our phantom studies, we left these modifications out of scope. Our experiments represent and evaluate the core idea of navigated AR visualizations and their technical feasibility. We find the suggestions, such as visual navigation (R3) or SLAM (R1), very relevant and plan to move on to vision-based localization and registration, which can solve the majority of the challenges. We see NAVIUS as a crucial step and proof of concept before the visual pipelines. If accepted, we will expand the discussion to address the valuable feedback regarding the clinical feasibility of current methods, challenges, solutions, and future work as mentioned above.
Regarding the assumption of significance (R1), we report two metrics since they have >1 difference while the others have ≤0.5. We chose not to include the time differences after consideration with our clinical contributors, since the time differences were on the order of seconds, while the operations take around an hour. We will separate the phantom production steps, which are currently included in the “Experimental Setup”, more clearly (R1). We will clarify the terms, assumptions, metric choices, and structure in the camera-ready version, and add the required information to the methods section.
References: 1-) Autonomous medical needle steering in vivo, 2023 2-) Electromagnetic tracking in surgical and interventional environments: usability study, 2015 3-) Interference during the use of an electromagnetic tracking system under OR conditions, 2002
Meta-Review
Meta-review #1
- Your recommendation
Invite for Rebuttal
- If your recommendation is “Provisional Reject”, then summarize the factors that went into this decision. In case you deviate from the reviewers’ recommendations, explain in detail the reasons why. You do not need to provide a justification for a recommendation of “Provisional Accept” or “Invite for Rebuttal”.
The paper proposes NAVIUS, an augmented reality (AR) system designed to aid ureteroscopic surgery by integrating electromagnetic (EM) tracking with preoperative CT imaging to improve intraoperative navigation. The system is tested on kidney phantoms in a simulated OR environment with six surgeons, with evaluation conducted using both quantitative measures (e.g., path length vs. coverage ratio) and subjective workload assessments (e.g., NASA-TLX, SUS).
All three reviewers find the idea of combining AR visualization with EM tracking and preoperative data compelling, and recognize the promise of the system in improving surgeon performance. R2 and R3 specifically highlight the technical integration and user study design as strong points, noting that the phantom experiments offer a good preliminary validation. R1, while acknowledging the soundness of the AR system if registration is feasible, is more critical of the statistical analysis and organization of the manuscript.
R1 raises several major concerns regarding the statistics, limited discussion on the assumptions of rigid registration, and a paper structure that makes important methodological details difficult to follow. Additionally, they note imprecise usage of software terminology and a lack of clarity in metric justification. R2 shares the concern that the system is not yet ready for clinical use due to current limitations in registration and sterility associated with EM tracking, but ultimately considers the contribution strong enough to merit a weak accept. They emphasize the usefulness of the open-source code and see the work as a promising starting point for future development. R3 offers the most favorable assessment, appreciating the integration of hardware and software and the detail provided in the phantom construction. However, they also caution that EM tracking limitations and the lack of clinical data temper the immediate impact of the contribution.
In summary, the reviewers are aligned in viewing the system as promising, though there is disagreement regarding its current maturity and the clarity of its presentation. Concerns around statistical analysis, registration feasibility, and manuscript organization should be addressed in rebuttal.
The authors are invited to submit a rebuttal tha addresses the reviewers’ comments.
- After you have reviewed the rebuttal and updated reviews, please provide your recommendation based on all reviews and the authors’ rebuttal.
Reject
- Please justify your recommendation. You may optionally write justifications for ‘accepts’, but are expected to write a justification for ‘rejects’
N/A
Meta-review #2
- After you have reviewed the rebuttal and updated reviews, please provide your recommendation based on all reviews and the authors’ rebuttal.
Accept
- Please justify your recommendation. You may optionally write justifications for ‘accepts’, but are expected to write a justification for ‘rejects’
N/A
Meta-review #3
- After you have reviewed the rebuttal and updated reviews, please provide your recommendation based on all reviews and the authors’ rebuttal.
Reject
- Please justify your recommendation. You may optionally write justifications for ‘accepts’, but are expected to write a justification for ‘rejects’
Two reviewers indicate that while the proposed system is promising, the unsolved challenges required before clinical use, e.g. electromagnetic tracking and registration limit its impact as currently written.