Abstract
Objective
Partial nephrectomy (PN) is the standard treatment for T1a renal masses, increasingly applied to T1b tumours due to advancements in robotic surgery and imaging. While CT urograms are standard, three-dimensional (3D) reconstruction is gaining traction for complex tumours to enhance preoperative planning. This study aimed to compare the impact of 3D reconstruction on operative time and ischaemic time during robot-assisted PN.
Methods
A prospective, non-randomised study was conducted on 112 patients who underwent robot-assisted PN between January 2020 and October 2022. Patients were divided into two groups: Group A (n=56) with the aid of 3D reconstruction for complex tumours and Group B (n=56) without 3D reconstruction. Operative time and ischaemic time were analysed, along with other outcomes such as margin positivity and postoperative complications.
Results
Despite higher tumour complexity in Group A, mean operative time (190.1 [standard deviation, SD 38.5] min vs. 189.3 [SD 42.6] min) and mean ischaemic time (20.4 [SD 5.6] min vs. 20.3 [SD 5.3] min) were comparable between Group A and Group B. Margin positivity and complications were also similar, suggesting that 3D reconstruction aids in efficient surgery even for complex cases.
Conclusion
3D reconstruction enhances understanding of complex renal tumours, maintaining operative efficiency comparable to less complex cases. Further randomized studies are needed to confirm these findings.
Keywords: Three-dimensional reconstruction, Robot-assisted partial nephrectomy, Nephron sparing surgery, Augmented reality, Robotic urological surgery, Minimally invasive surgery
1. Introduction
Partial nephrectomy (PN) is increasingly being performed for cT1 renal masses and is the standard of care for cT1a masses [1]. In the recent era with surgical advancements in robotics and advancements in imaging such as three-dimensional (3D) printing technology, there is an increasing number of patients with cT1b tumours being offered PN with good oncological and functional outcomes in terms of preservation of nephrons [2,3]. Though a CT urogram with contrast is the standard imaging performed across all centres prior to nephron-sparing surgery, there is a preference for the addition of 3D printing beyond the routine imaging [4]. This 3D reconstruction helps in preoperative planning and in understanding the anatomy better, which has also resulted in selective clamping in some cases of robot-assisted PN (RAPN) [5]. This prospective non-randomised study aimed to compare the intraoperative outcomes in RAPN performed with the aid of 3D reconstruction against RAPN performed for lesser complexity tumours without 3D reconstruction.
2. Patients and methods
2.1. Study design
This prospective non-randomised study was conducted to evaluate the impact of 3D reconstruction on operative time and ischaemic time. 3D reconstruction was performed in patients who presented with complex tumours for which the operating surgeon felt that adding 3D reconstruction would help better understanding the anatomy and the approach to the complex mass. Patients who underwent RAPN with the aid of 3D reconstruction were designated as Group A and those who underwent RAPN without 3D reconstruction were designated as Group B. Data were collected from a prospectively maintained database that was analysed retrospectively to assess the pathological outcomes. Informed consent was obtained from all patients, ensuring confidentiality in accordance with the Declaration of Helsinki. The study was also approved by the Institutional Review Board of Apollo Hospitals, Chennai, India (AMH CS 083/10–23).
2.2. Patient selection
The study included all patients (3D reconstruction [n=56] and standard imaging [n=56]) undergoing RAPN in our urology unit between January 2020 and October 2022. All consecutive patients who underwent RAPN were selected for the study.
2.3. Surgical procedure
All surgeries were performed by a single experienced surgeon (Ragavan N) proficient in RAPN who had a track record of more than 200 cases of RAPN and more than 1000 cases of robotic urological procedures prior to the beginning of the study. The preoperative workup included a CT scan with contrast and 3D reconstruction, which were performed by Innersight Laboratories in Germany for cases that were deemed complex based on R.E.N.A.L. scores. The data collection focussed on complexity scores based on a CT urogram, operative time, docking time, ischaemic time, blood loss, selective clamping of renal arteries, intraoperative complications, and pathological parameters including margin positivity. The surgical technique remained the same across both arms and the 3D reconstructed images were utilised intraoperatively both by the console surgeon and the bedside assistant as required during the procedure. The routine practice was to clamp only the artery, followed by tumour resection with the aid of intraoperative ultrasound and single-layered renorrhaphy.
2.4. Statistical analysis
Descriptive statistics were presented with frequency (percentage) and mean with standard deviation (SD) for the categorical and continuous variables, respectively. Median (interquartile range) was presented when the data were skewed. The Student’s t-test or Mann-Whitney U test was used to determine significant differences between groups with and without 3D reconstruction. The chi-square test or Fisher’s exact test was used to determine the association between two independent categorical variables. All statistical analyses were carried out using SPSS (IBM Corp., Version 28.0, Armonk, NY, USA).
3. Results
Both groups had comparable age, body mass index, sex distribution of patients, and similar tumour size (cT); however, based on the R.E.N.A.L. nephrometry score, it was noted that patients with complex tumours underwent 3D reconstruction (Table 1). The mean operative time (190.1 [SD 38.5] min vs. 189.3 [SD 42.6] min) and the mean ischaemic time (20.4 [SD 5.6] min vs. 20.3 [SD 5.3] min) were similar in Group A and Group B (Fig. 1).
Table 1.
Descriptive statistics.
| Variable | 3D reconstructiona |
Overalla (n=112) | p-Valueb | |
|---|---|---|---|---|
| Yes (Group A; n=56) | No (Group B; n=56) | |||
| Age, year | 51.5±12.5 | 53.1±11.9 | 52.3±12.2 | 0.5 |
| Gender | 0.089 | |||
| Male | 42 (75) | 44 (79) | 86 (77) | |
| Female | 14 (25) | 12 (21) | 26 (23) | |
| Comorbidity | 1 | |||
| No | 20 (36) | 20 (36) | 40 (36) | |
| Yes | 36 (64) | 36 (64) | 72 (64) | |
| Body mass index, kg/m2 | 26.4±4.4 | 26±4 | 26.1±4.2 | 0.5 |
| Tumour size (cT) | 0.3 | |||
| cT1a | 28 (50) | 31 (55) | 59 (53) | |
| cT1b | 21 (38) | 23 (41) | 44 (39) | |
| cT2a | 7 (12) | 2 (3.6) | 9 (8.0) | |
| Location | 0.8 | |||
| Upper pole | 16 (29) | 20 (36) | 36 (32) | |
| Lower pole | 18 (32) | 17 (30) | 35 (31) | |
| Mid pole | 20 (36) | 18 (32) | 38 (34) | |
| Tumour extending >1 pole | 2 (3.6) | 1 (1.8) | 3 (2.7) | |
| R.E.N.A.L. score | <0.001 | |||
| Low | 5 (8.9) | 21 (38) | 26 (23) | |
| Intermediate | 31 (55) | 35 (62) | 66 (59) | |
| High | 20 (36) | 0 (0) | 20 (18) | |
| Operative time, min | 190.1±38.5 | 189.3±42.6 | 189.7±40.5 | 0.9 |
| Ischaemic time, min | 20.4±5.6 | 20.3±5.3 | 20.4±5.4 | 0.9 |
| Post-op complication | 1 | |||
| No | 54 (96) | 54 (96) | 108 (96) | |
| Yes | 2 (3.6) | 2 (3.6) | 4 (3.6) | |
3D, three-dimensional; Post-op, postoperative.
Values are presented as mean±standard deviation or n (%).
The bold value means that the result is statistically significant.
Figure 1.
Comparison of operative time, docking time, and ischaemic time between the patients who underwent RAPN with the aid of 3D reconstruction (Group A) and those who underwent RAPN without 3D reconstruction (Group B). RAPN, robot-assisted partial nephrectomy; 3D, three-dimensional.
Operative complications or margin positivity did not show statistical significance between the two groups. Both groups proved to be of similar distribution in terms of pT findings and tumour subtypes (p>0.05). There were two (3.6%) patients who had positive margins in Group A (3D reconstruction) and one (1.8%) patient who had positive margins in Group B (no 3D reconstruction). There was one recurrence in each group (p=1) during the follow-up for 1 year. None of the patients who had positive margins developed recurrence.
4. Discussion
The use of 3D reconstructed images in urology has garnered increasing interest, with recent studies demonstrating how 3D imaging facilitates percutaneous nephrolithotomy by providing improved access to the kidneys through enhanced visualization of the calyceal anatomy [6]. Moreover, a number of studies have investigated the utility of 3D reconstruction in the management of renal tumours, aiding surgeons in adopting a more tailored surgical approach in complex cases. These studies report a reduced incidence of global renal ischemia, an increased rate of tumour enucleation, and greater preservation of nephrons [7,8]. In this study, conducted at a tertiary care centre in India, the additional cost involved was less than USD 100. This makes the technology accessible across developing countries, as the images can be outsourced if a surgeon believes that incorporating 3D reconstruction will add value to preoperative planning.
In this prospective study, 3D reconstruction was selectively performed for patients whose tumour anatomy was deemed complex based on a preoperative CT urogram. Patients who underwent 3D reconstruction were counselled preoperatively using these images, which facilitated a clearer understanding of their condition and the potential complications of the procedure. Tang et al. [9] demonstrated that 3D reconstruction significantly alleviated the anxiety levels of patients undergoing PN. However, as our study primarily focused on operative factors, patient anxiety levels were not specifically evaluated.
It is important to note that groups A and B are not directly comparable, as the patients in Group A, who underwent 3D reconstruction, presented with more complex tumours. Despite this, both the operative time and ischaemic time for the complex renal masses in Group A were comparable to those in Group B, which consisted of patients with low-complexity tumours and lower R.E.N.A.L. scores. This suggests that 3D reconstruction may enhance the surgeon’s understanding of hilar anatomy, leading to more efficient hilar dissection, even in cases of complex tumours. Notably, the ischaemic time remained similar between the two groups, indicating that precise anatomical understanding and identification of feeding vessels allowed surgeons to maintain operative speed and accuracy, regardless of tumour complexity.
In a few cases (n=3), the 3D reconstruction accurately predicted the location of a feeding vessel at the tumour base, enabling the bedside assistant to selectively clip the vessel intraoperatively. This may have contributed to reduced blood loss and shortened renorrhaphy time by improving the haemostasis in the surgical field. Additionally, our experience suggests that 3D reconstruction improved coordination between the console surgeon and the bedside assistant, potentially leading to similar operative time across groups. This is particularly relevant in academic institutions, where new trainees are regularly involved in surgical procedures. The role of 3D reconstruction in enhancing both the learning curve and surgical outcomes has been emphasized in a study by Esperto et al. [10].
While the margin positivity was higher in Group A (3.6%) compared to Group B (1.8%), this difference was not statistically significant and was likely attributable to the increased complexity of tumours in Group A despite having the 3D reconstruction to aid the surgeon. None of the patients with positive margins experienced recurrence during a median follow-up period of 18 months.
This study has limitations. Although it is prospective, it is non-randomised, introducing selection bias in this context. Additionally, since the groups were not matched, it would be prudent to compare two groups of similar complexity to confirm the role of 3D reconstruction within comparable cohorts. Additionally, the 3D models were not integrated into the surgeon’s console vision cart and required reassessment via a separate screen within the operating room. A large-scale, randomized study comparing groups with similar tumour complexity would add significant value to the growing body of literature on the use of 3D reconstruction and augmented reality in urological surgery.
5. Conclusion
3D reconstructed imaging significantly improves the surgeon’s understanding of complex renal tumour anatomy, resulting in operative efficiency comparable to that seen in lower-complexity cases. The enhanced anatomical visualization also facilitates better coordination between the surgical team and supports a quicker learning curve for trainees. Future randomized studies with comparable patient groups are needed to further validate these findings.
Author contributions
Study concept and design: Deerush Kannan Sakthivel, Narasimhan Ragavan.
Data acquisition: Deerush Kannan Sakthivel, Sindhu Sankaran, Madhav Tiwari, Sandeep Bafna.
Data analysis: Deerush Kannan Sakthivel, Sindhu Sankaran, Madhav Tiwari, Sandeep Bafna, Narasimhan Ragavan.
Drafting of the manuscript: Deerush Kannan Sakthivel, Sindhu Sankaran, Madhav Tiwari, Sandeep Bafna, Narasimhan Ragavan.
Critical revision of the manuscript: Deerush Kannan Sakthivel, Sindhu Sankaran, Madhav Tiwari, Sandeep Bafna, Narasimhan Ragavan.
Conflicts of interest
The authors declare no conflict of interest.
Acknowledgments
The authors would like to thank Ms. Pavithra Sampathkumar for data collection and Mr. Logesh Balakrishnan for statistical analysis.
Footnotes
Peer review under responsibility of Tongji University.
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