Association between tumor contact surface area and parenchymal volume change in robot‐assisted laparoscopic partial nephrectomy carried out using the enucleation technique

A Novel Method to Compute the Contact Surface Area Between an Organ and Cancer Tissue

The contact surface area (CSA) quantifies the interface between a tumor and an organ and is a key predictor of perioperative outcomes in kidney cancer. However, existing CSA computation methods rely on shape assumptions and manual annotation. We propose a novel approach using 3D reconstructions from computed tomography (CT) scans to provide an accurate CSA estimate. Our method includes a segmentation protocol and an algorithm that processes reconstructed meshes. We also provide an open-source implementation with a graphical user interface. Tested on synthetic data, the algorithm showed minimal error and was evaluated on data from 82 patients. We computed the CSA using both our approach and Hsieh's method, which relies on subjective CT scan measurements, in a double-blind study with two radiologists of different experience levels. We assessed the correlation between our approach and the expert radiologist's measurements, as well as the deviation of both our method and the less experienced radiologist from the expert's values. While the mean and variance of the differences between the less experienced radiologist and the expert were lower, our method exhibited a slight deviation from the expert's, demonstrating its reliability and consistency. These findings are further supported by the results obtained from synthetic data testing.

Innovative 3D method predicts surgery outcomes by calculating real contact surface of renal tumor

OBJECTIVE

The Contact Surface Area (CSA) is a predictor for peri-operative parameters and represents the contact area between the tumor and the organ. A precise method for calculating CSA is yet to be found. We tested a new CSA calculation method as a predictor of intra-operative parameters in robot assisted partial nephrectomy (RAPN).

MATERIALS & METHODS

The study population consisted of all consecutive patients treated with RAPN at a single high-volume European institution (between 2020 to 2023; 82 patients). We proposed a new method to measure the real value of CSA using an algorithm that leverages the geometry of kidneys and tumors obtained from 3D reconstruction. These reconstructions were obtained using the certified software Materialized Mimics InPrint. The peri-operative parameters of patients were recorded in an anonymous database. We explored the correlation between real CSA (RCSA), CSA of Hsieh (HCSA), PADUA and R.E.N.A.L. scores with peri-operative parameters using Spearman's correlation. Furthermore, we examined which of RCSA, PADUA and R.E.N.A.L. score better describes the intra-operative parameters, Warm Ischemia Time (WIT), Operating Time (OT), and Estimated Blood Loss (EBL) using Receiver Operating Characteristic (ROC) curve analysis. Multivariable linear regression analyses were performed.

RESULTS

Seventy-eight patients were prospectively enrolled. We observed a significant correlation between RCSA and WIT (P < 0.001), OT (P < 0.001) and EBL (P < 0.001). Moreover, RCSA outperformed both the PADUA and R.E.N.A.L. score as demonstrated in the ROC curve analysis. In ROC analysis was chosen a threshold for each of the parameters: for WIT 20 minutes, for OT 180 minutes and for EBL 200 mL. At multivariable regression analysis, RCSA emerged as the only independent predictor for WIT (P = 0.002), OT (P = 0.01) and EBL (P < 0.001).

CONCLUSIONS

Our original 3D RCSA calculation method was associated to intra-operative surgical outcomes. As compared to PADUA and RENAL score, our calculated RCSA represented a more reliable predictor of intra-operative parameters.

Limited impact of warm ischemic threshold for partial nephrectomy in the robotic surgery era: A propensity score matching study

OBJECTIVES

To evaluate the association between extended (≥30 min) warm ischemic time and renal function in patients undergoing robot-assisted partial nephrectomy.

METHODS

This multi-institutional study retrospectively recruited 1131 patients who underwent robot-assisted partial nephrectomy. Patients were classified into shorter (<30 min; n = 1038) and longer (≥30 min; n = 92) groups based on the ischemic time required, and 1:2 propensity score matching was used to minimize selection bias. The perioperative outcomes, including acute kidney injury and trifecta attainment, and mid/long-term renal function were assessed before and after matching.

RESULTS

Patients in the longer group had tumors with a significantly larger diameter and RENAL nephrometry score. The decline in the nadir of the estimated glomerular filtration rate was significantly greater in the longer than the shorter group in the unmatched and matched cohorts (-16.2 vs -5.5%, P < 0.001; 15.5 vs -9.5%, P = 0.003, respectively). A higher incidence of acute kidney injury (9.8 vs 2.6%, P = 0.002) was observed in the longer group before matching, whereas the difference was comparable after matching. Before matching, the decline in estimated glomerular filtration rate at 6 months postoperatively was greater (-8.2 vs -5.1%, P = 0.005) and trifecta attainment was lower (50.0 vs 63.5%, P < 0.001) in the longer group. However, the differences were comparable for both the parameters between the groups in the matched cohort.

CONCLUSIONS

While extended warm ischemia during robot-assisted partial nephrectomy can be demanded in case of large and complex tumors, its impact on postoperative renal function is limited.

[Three dimensional nephrometry system for partial nephrectomy: Our initial exploration]

OBJECTIVE

To construct a preoperative evaluation system for partial nephrectomy using CT three-dimensional visualization technology and to explore its practical value.

METHODS

The clinical data of the patients who underwent partial nephrectomy for renal tumors in Department of Urology, Peking University First Hospital were collected retrospectively. At the same time, the homogenized standard data of patients who underwent partial nephrectomy for renal tumors were collected in 16 clinical centers in China. The CT three-dimensional visualization system was applied (IPS system, Yorktal) to evaluate tumor anatomy, blood supply, perirenal fat and other information. The parameters were summarized to build a three-dimensional nephrometry system, on the basis of which virtual surgery design and intraoperative navigation were completed.

RESULTS

A three-dimensional visualization image was established based on the enhanced CT urography. The nephrometry system included the longest diameter and volume of the tumor, proportion volume of tumor invading the parenchyma, maximum depth of the tumor invading the parenchyma, contact surface area, flatness of the tumor surface, renal segment where the tumor was located, vascular variation, and perirenal fat. The average two-dimensional diameter of the tumor was (2.78±1.43) cm, the average three-dimensional maximum diameter was (3.09±1.35) cm, and the average postoperative pathological size was (3.01±1.38) cm. The maximum tumor diameter in the three-dimensional image was significantly related to the prolonged renal artery clamping time and intra-operative blood loss (r=0.502, P=0.020; r=0.403, P=0.046). The three-dimensional and pathological tumor volume were (25.7±48.4) cm³ and (33.0±36.4) cm³, respectively (P=0.229). The tumor volume was significantly related to the intraoperative blood loss (r=0.660, P < 0.001). The proportion volume of the tumor invading into renal parenchyma was significantly related to the prolongation of renal artery clamping and the occurrence of postoperative complications (r=0.410, P=0.041; r=0.587, P=0.005). The tumor contact surface area and the presence of vascular variation did not show correlation with the perioperative data and postoperative complications. While the preoperative evaluation was completed, the reconstructed three-dimensional image could be zoomed, rotated, combined display, color adjustment, transparency, and simulated cutting on the Touch Viewer system. The process generally consisted of showing or hiding the tissue, adjusting the transparency of the interested area, rotating and zooming the image to match the position of the surgical patient. Together, these functions met the requirements of preoperative virtual surgery plan and intraoperative auxiliary navigation.

CONCLUSION

Three-dimensional images can provide a more intuitive anatomical structure. The CT three-dimensional visua-lization system clearly displays tumor anatomical parameters, blood supply and perirenal fat. The three-dimensional nephrometry system for renal tumors can help predict the difficulty of partial nephrectomy and perioperative complications. Importing the reconstructed three-dimensional visualization image into the specified program or robot operating system can complete virtual surgery and intraoperative navigation, helping the surgeon to better grasp the surgical process. The indexes included in the nephrometry system and the score weights of each index need to be confirmed and perfected by multi-center study with large samples.

Greater Renal Function Benefit from Enucleation Technique for More Complex Renal Tumors in Robot-Assisted Partial Nephrectomy

Background: Tumor enucleation technique in robot-assisted partial nephrectomy (RAPN) reportedly contributes to renal function preservation. Which tumors and which part to utilize this technique have not been determined. Patients and Methods: This multi-institutional retrospective study included patients who underwent RAPN at tertiary surgery centers. Patients were first stratified into High, Intermediate, and Low categories based on renal nephrometry score. Patients were further classified into I/B-enucleation (I/B-E, I + B ≤ 1) and I/B-resection (I/B-R, I + B ≥ 2) groups based on surface-intermediate-base margin score. Perioperative outcomes, including percentile change in estimated glomerular filtration rate (eGFR), new-onset chronic kidney disease, complication rate, surgical margin, and trifecta achievement, were compared between the I/B-E and I/B-R groups in each category. Odds ratios (ORs) and β-coefficients were also compared. Results: Overall, 704 patients were included in this study. Relative decrease in eGFR was significantly lower for the I/B-E group in all three categories, with medians of 8.1%, 4.4%, and 3.2% in the High, Intermediate, and Low, respectively. In multivariate analyses, excision technique was independently associated with eGFR change in all three. β-coefficient was higher in the High (5.06) category than in the Low (3.17) or Intermediate (3.33). Across all three categories, significantly more patients attained trifecta with a difference of 34.0%, 18.3%, and 15.1% in the High, Intermediate, and Low categories, respectively (all, p < 0.05), with a higher OR in the High (5.91) category than in the Low (3.20) or Intermediate (2.48). No significant differences were found in operation time, amount of estimated blood loss, rate of positive surgical margin, or complications. Warm ischemic time was significantly longer for the I/B-E group in the Intermediate (18.0 minutes vs 16.0 minutes, p = 0.002) and Low categories (13.0 vs 11.0, p = 0.006), but not significant in High (p = 0.344). Conclusions: I/B-enucleation in RAPN contributes to renal function preservation, and the impact was more emphasized in complex tumors.

Feasibility and necessity of the fourth arm of the da Vinci Si surgical system for robot-assisted partial nephrectomy

BACKGROUND

To investigate the feasibility of the fourth arm of the da Vinci Si system for robot-assisted partial nephrectomy (RAPN).

METHODS

Fifty-eight consecutive patients underwent RAPN with the same port placements. After reviewing the surgical videos and records, 38 patients showing usefulness of the fourth arm were categorized into Group A and those not showing usefulness into Group B. The background data, tumor characteristics, and perioperative outcomes were compared between the groups.

RESULTS

Group B had a larger proportion of tumors located on the inner side of the kidney, and the console time was significantly longer. Multivariable logistic regression analysis showed that tumors located on the inner side of the kidney were associated with the non-use of the fourth arm of the da Vinci Si system during RAPN.

CONCLUSIONS

Our findings suggested that use of fourth arm in RAPN by da Vinci Si should be considered for each tumor location.