Context
Use of three-dimensional (3D) guidance for nephron-sparing surgery (NSS) has increased in popularity, especially for laparoscopic and robotic approaches. Different 3D visualization modalities have been developed as promising new tools for surgical planning and intraoperative navigation.
Objectives
To summarize and evaluate the impact of 3D models on minimally invasive NSS in terms of perioperative, functional, and oncological outcomes.
Evidence acquisition
A systematic literature search was conducted in December 2021 using the Medline (PubMed), Embase (Ovid), Scopus, and Web of Science databases. The protocol was registered on PROSPERO (CRD42022300948). The search strategy used the PICOS (Population, Intervention, Comparison, Outcome, Study design) criteria and article selection was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The risk of bias and the quality of the articles included were assessed. A dedicated data extraction form was used to collect the data of interest. Meta-analysis was performed using the Mantel-Haenszel method for binary outcomes, with results summarized as the odds ratio (OR), and the inverse variance method for continuous data, with results reported as the mean difference (MD). All effect estimates are reported with the 95% confidence interval (CI) and p ≤ 0.05 was considered statistically significant. All analyses were performed using R software and the meta package.
Evidence synthesis
The initial electronic search identified 450 papers, of which 17 met the inclusion criteria and were included in the analysis. Use of 3D technology led to a significant reduction in the global ischemia rate (OR 0.22, 95% CI 0.07–0.76; p = 0.02) and facilitated more frequent enucleation (OR 2.54, 95% CI 1.36–4.74; p < 0.01) and less frequent opening of the collecting system (OR 0.36, 95% CI 0.15–0.89; p = 0.03) and was associated with less blood loss (MD 23.1 ml, 95% CI 31.8–14.4; p < 0.01). 3D guidance for NSS was associated with a significant reduction in the transfusion rate (OR 0.20, 95% CI 0.07–0.56; p < 0.01). There were no significant differences in rates of conversion to radical nephrectomy, minor and major complications, change in glomerular filtration rate, or surgical margins (all p > 0.05).
Conclusions
3D guidance for NSS is associated with lower rates of detriment and surgical injury to the kidney. Specifically, a lower amount of nontumor renal parenchyma is exposed to ischemia or sacrificed during resection, and opening of the collecting system is less frequent. However, use of 3D technology does not lead to significant improvements in oncological or functional outcomes.
Anyone among our readership will have noticed that the popularity of three-dimensional (3D) models has increased exponentially within the last years. This is particularly true in the field of minimally-invasive nephron-sparing surgical approaches. 3D virtual (or even printed) models represent the evolution of other technologies such as intraoperative ultrasound and intravascular fluorescent dyes use. These have been implemented in the routine of minimally-invasive nephron-sparing surgery (NSS) to aid the surgeon in the planning of a selective clamping and/or the resection of the renal mass itself. In more expert surgeons’ hands, these technologies have allowed to push through the limits of partial nephrectomy.
Unique to 3D models versus the mentioned technologies above, is the improved navigation of the anatomy of the kidney and the renal tumor. Indeed, 3D models allow to overcome the need for the “building-in-mind” process otherwise required when viewing the conventional two-dimensional cross-sectional imaging.
Although very fancy models can be obtained via the different 3D visualisation modalities, the impact of the adoption of 3D technologies on the outcomes of NSS is yet to be determined. A group of authors on behalf of the European Association of Urology (EAU) Young Academic Urologists and the EAU Section of Uro-Technology aimed to target this unmet need by a systematic review and meta-analysis of the literature [1].
As concerning the intraoperative parameters, compared to a “standard” minimally-invasive NSS (performed without the aid of 3D technologies), the authors observed a lower rate of global ischemia (main renal artery was clamped in the 74% vs. the 27% of the cases), a higher likelihood of enucleate the mass (19% vs. 31%), a less frequent violation of the collecting system (27% vs. 16%), and lower blood losses (110 ml vs. 130 ml), favouring 3D technology-aided NSS. No significant differences were found in terms of intraoperative complications, duration of ischemia and operative time. As concerning the postoperative parameters, lower transfusion rate (1% vs. 7%) favoured 3D technology-aided NSS, but no differences were found in terms of conversion to radical nephrectomy, minor / major complications rate, change in renal function measured by glomerular filtration rate (although no long-term functional data were reported), and positive surgical margins rate. Subgroup analyses by surgical approach (robot-assisted vs. pure laparoscopic) showed that only pure laparoscopic NSS benefited from a reduction in the operative time (by 10 minutes) derived from the use of 3D technology. No significant differences were observed for the other postoperative parameters.
The authors concluded that the use of 3D technology to guide NSS is associated with “lower rates of detriment and surgical injury to the kidney”. Actually, if according to the pooled analysis of the literature 1) selective clamping and 2) an enucleation resection strategy / techniques were more likely pursued when 3D technology aided NSS, one would have thought that a lower amount of healthy renal parenchyma was 1) exposed to ischemia and 2) sacrificed during resection… but instead, the outcome measurements typically included in the famed trifecta (margins, ischemia / renal function, and complications) were found comparable irrespective of the use of 3D technology [2].
In summary, there is still a long way to go before reaching the recommendation of integrating 3D technologies in the daily routine of NSS. Three main questions remain open to debate, namely:
1) What is the cost-benefit ratio? Adoption of 3D technologies is usually expensive and can be responsible of financial toxicity: most health systems are unlikely to be able to afford costs in the absence of clear benefits in terms of outcomes and thus omit 3D technologies in the typical pathway of renal cancer patients [3];
2) Who is the surgeon who can make the most of it? As was the case with the advent of robotics, the urological community has to investigate further about the impact of 3D technology in relation to the surgeon’s experience (maybe the performance of 3D technology is likely to be most impressive when evaluated on inexperienced surgeons);
3) Which technology is the best? Different 3D visualisation modalities have been developed to aid either pre-surgery planning or intraoperative navigation. For instance, in the setting of the herein commented review, analysis by technology type (augmented reality versus virtual reality versus 3D printed models) showed that only augmented reality led to a reduction in operating time by 25 minutes, but no differences were found for any other outcome…do we make it enough? Repeating what was published four years ago, it seems that the evidence of an impact on surgical outcomes are (still) yet to come [4].
References:
[1] Piramide F, Kowalewski KF, Cacciamani G, et al. Three-dimensional model-assisted minimally invasive partial nephrectomy: A systematic review with meta-analysis of comparative studies. Eur Urol Oncol. 2022 Dec;5(6):640-650. doi: 10.1016/j.euo.2022.09.003. Epub 2022 Oct 7. PMID: 36216739.
[2] Hung AJ, Cai J, Simmons MN, Gill IS. “Trifecta” in partial nephrectomy. J Urol. 2013 Jan;189(1):36-42. doi: 10.1016/j.juro.2012.09.042. Epub 2012 Nov 16. PMID: 23164381.
[3]Scott ER, Singh A, Quinn A, Boyd K, Lallas CD. How I do it: Cost-effective 3D printed models for renal masses. Can J Urol. 2021 Oct;28(5):10874-10877. PMID: 34657662.
[4] Bertolo R, Hung A, Porpiglia F, et al. Systematic review of augmented reality in urological interventions: the evidences of an impact on surgical outcomes are yet to come. World J Urol. 2020 Sep;38(9):2167-2176. doi: 10.1007/s00345-019-02711-z. Epub 2019 Mar 2. PMID: 30826888.