Utilization of three-dimensional renal tumor target vessel reconstruction and localization technology for Zero-Ischemia Laparoscopic Partial Nephrectomy: A Clinical Perspective

doi:10.21203/rs.3.rs-4881344/v1

Objectives: To evaluate the safety and efficacy of utilizing three-dimensional renal tumor target vessel reconstruction to guide zero-ischemia laparoscopic partial nephrectomy.

Methods: We conducted a retrospective review of data from 80 patients who were treated between January 2016 and September 2022. The patients were categorized into two groups based on the mode of operation. We compared the operation time, intraoperative blood loss, and postoperative hospital stay between the two groups.

Results: In comparison to the traditional operation group, the zero ischemia group exhibited a longer operation time [(92.5±9.8) min vs. (71.6±9.9) min, P<0.001] and a higher volume of intraoperative blood loss[(152 ±22) ml vs. (80 ±19) mL, P<0.001], although there was no significant difference in postoperative hospital stay. Patients with renal hilar tumors experienced longer operation times [(109.3±10.2) min vs. (87.3±9.5) min, P<0.001] compared to those with tumors in other areas. There was no significant difference in intraoperative blood loss or hospital stay duration. Throughout the follow-up period, both groups did not experience complications such as bleeding, urine leakage, or tumor recurrence and metastasis. Three months post-operation, patients in the zero ischemia group demonstrated a faster recovery of glomerular filtration rate (GFR) compared to those in the traditional operation group, although there was no significant difference in serum creatinine level (P>0.05).

Conclusion: In certain cases of early renal cell carcinoma, the utilization of three-dimensional renal tumor target vessel reconstruction and localization technology can significantly enhance the feasibility of laparoscopic zero ischemia nephron sparing surgery.

Renal tumor target vessel localization

zero ischemia

laparoscopy

partial nephrectomy

Renal tumors represent one of the most prevalent malignancies affecting the urinary system. With the advancement and widespread use of imaging examinations, the incidence of renal cell carcinoma has notably increased, particularly in cases of early-stage renal cell carcinoma.^[1] Currently, partial nephrectomy is considered the optimal treatment for T1 stage renal tumors (<7cm), as it offers superior oncological and functional outcomes compared to radical nephrectomy.^[2] In traditional partial nephrectomy procedures, it is often necessary to occlude the renal artery to ensure a clear surgical field, followed by restoration of renal blood flow after tumor resection and repair, leading to preserved renal ischemia-reperfusion injury.^{[3, 4]}

The application of three-dimensional renal tumor target vessel reconstruction and localization technology involves the use of two-dimensional images, such as CT scans, to generate three-dimensional models using specialized computer software. These models enable the precise identification and labeling of tumors, blood vessels, and other tissues with distinct colors and transparency, providing surgeons with a comprehensive understanding of the anatomical structures surrounding the tumor.^{[5, 6]}

In recent years, numerous researchers have documented the utilization of three-dimensional reconstruction technology in the context of conventional partial nephrectomy. This technology has demonstrated the ability to effectively visualize the spatial relationship between the tumor and the kidney, accurately identify the preoperative tumor location, and enhance operative planning and preoperative communication.^[7] Despite its potential, the full extent of its application in partial nephrectomy remains to be fully investigated within the current literature. In this study we conduct a retrospective analysis of clinical data from 80 patients who underwent laparoscopic partial nephrectomy. The purpose of this study is to investigate the utility of three-dimensional renal tumor target vessel reconstruction and localization technology in zero-ischemic laparoscopic partial nephrectomy.

2.1 Clinical Information

A retrospective analysis was conducted on the data of 80 patients diagnosed with early renal cell carcinoma, who underwent treatment at the department of urology of Renji Hospital and Gongli Hospital between January 2016 and September 2022. The patients were categorized into two groups based on the surgical approach. Specifically, 30 patients underwent zero-ischemia retroperitoneal laparoscopic partial nephrectomy, while 50 patients received conventional retroperitoneal laparoscopic partial nephrectomy under renal artery occlusion, representing the traditional operation group.

In this study, we conducted a comprehensive data collection of patient information, encompassing gender, age, tumor diameter, and location for subsequent statistical analysis. We employed advanced three-dimensional renal tumor target vessel reconstruction and localization technology to assess the vascular condition of renal tumors prior to surgical intervention. Additionally, we meticulously recorded operative outcomes, including operation time, intraoperative blood loss, and postoperative hospital stay. Functional outcomes were assessed by monitoring creatinine levels pre-operatively, as well as at 3 and 12 months post-operation. Furthermore, we collected GFR of the affected kidneys at the same time points.

The study inclusion criteria were clinical T1N0M0 exophytic renal tumors diagnosed by CT or MRI, with R.E.N.A.L scores less than 12 and PADUA scores less than 14, and the tumor diameter was 2~7 cm, and without prior anti-tumor treatment or history of abdominal and low back surgery.

Exclusion criteria encompassed individuals with evident anatomical abnormalities, a history of surgery in the area of operation, or other significant systemic diseases, as well as those who were lost to follow-up or failed to undergo postoperative GFR assessment. Approval for the study was obtained from the Ethics Committee of Shanghai Pudong New Area Gongli Hospital and RenJi Hospital (Medical ethics approval number: GLYYls2023-010), and all patients provided informed consent after being informed about the risks associated with the operation before operation.

2.2 Surgical Interventions

The 64-slice spiral plain renal scan plus enhanced CT and renal artery CT angiography (CTA) were conducted on all patients in both groups (Fig.1 A). Subsequently, the DICOM data from the CTA were analyzed and processed using computer software to generate a three-dimensional image. A collaborative team comprising skilled imaging doctors, urologists, and software engineers worked together to rectify and reconstruct the 3D image in accordance with subsequent procedures (Fig.1 B). The 3D reconstruction images were utilized to illustrate the relationship between the tumor and the renal vascular system, as well as to identify the tumor's target vessels. It is important to note that all procedures were consistently performed by the same experienced urologist.

Following general anesthesia, t the patient was positioned laterally. Trocars of 10, 5, and 12mm were implanted above the iliac ridge in the midaxillary line, below the costal margin in the anterior axillary line, and below the 12th costal line in the posterior axillary line to reach the retroperitoneum. An auxiliary channel was added according to intraoperative conditions. Patients in both groups underwent "spherical coronal" partial nephrectomy.

In the traditional operation group, after blocking the renal artery, the renal capsule was incised sharply approximately 3mm from the boundary between the renal solid substance and the renal tumor. The renal parenchyma was incised wedge-shaped into the renal parenchyma to find the transitional zone between the renal parenchyma and the tumor pseudocapsule. A combination of sharp incision and blunt dissection ensured complete resection of the renal tumor, followed by suture closure of the wound.

In the zero ischemia group, utilizing three-dimensional reconstruction model of tumor and renal vessels, the appropriate surgical entry point was selected by the method of renal tumor target vessel localization. "Spherical coronal" resection of renal tumors was performed. The general orientation of the renal tumor target vessels was preliminarily determined based on the three-dimensional renal tumor target vessel reconstruction and localization. When the tumor target vessels were separated, the combination of scissors and suction device was applied to the blunt and sharp separation along the tumor envelope. When the tumor target vessels were completely exposed, the Baig forceps or Hem-o-lok clamp were applied to disassemble the vessels (Figure1C, D). Following complete tumor resection, the bleeding vessels and renal wound were sutured using barbed absorbable suture.

2.3 Statistical Methods

The study data underwent analysis utilizing statistical software SPSS 24.0 (IBM Co., Armonk, NY, USA). Counting data is presented as percentages, for instance. Inter-group comparisons were conducted using the χ² test. Measurement data were expressed as mean ± standard deviation (x̅±s), and inter-group comparisons were performed using independent sample t-tests. A significance level of P<0.05 denoted statistical significance in the observed differences.

3.1 General clinical data of patients

A total of 80 patients with early renal carcinoma were enrolled in the study, including 30 in the zero ischemia group and 50 in the traditional operation group. Both groups demonstrated comparability in terms of gender, age, tumor diameter, and pathological stage. (Table 1).

3.2 Comparison between zero ischemia group and traditional operation group

All the patients in the traditional operation group were successfully operated without transferring to open operation. Among the zero ischemia group, 4 patients conversion to laparoscopic partial nephrectomy subsequent to renal artery blockage, and the other 26 patients completed zero ischemia laparoscopic partial nephrectomy, without conversion to open or radical nephrectomy. The operation time [(92.5±9.8) min vs. (71.6±9.9) min, P<0.001] and intraoperative blood loss [(150±22) mL vs. (80±19) mL, P<0.001] were increased in the zero ischemia group compared with the traditional operation group. There was no significant difference in length of hospitalization [(7.2 ± 0.4) d vs. (7.1 ± 0.9) d, P>0.05, Table 2].

3.3 Comparison of postoperative follow-up

There was no significant difference in preoperative renal GFR and serum creatinine levels between zero ischemia group and traditional operation group (P>0.05). There was no significant difference in serum creatinine levels between the two groups at 3 and 12 months after surgery (P>0.05). However, we observed that the renal GFR recovered faster in the zero ischemia group, and there was a statistically significant difference in renal GFR 3 months after surgery between the two groups (P<0.001). But the difference became minimal 12 months after surgery (P>0.05, Table 3). After 1 month follow-up, no bleeding, urine leakage, infection and other related complications occurred in the two groups. After 12 months of follow-up, no tumor recurrence or metastasis was found in the two groups.

Partial nephrectomy, known for its comparable therapeutic efficacy to radical nephrectomy and its potential to lower the occurrence of postoperative chronic kidney disease, consequently reducing the risk of cardiovascular and cerebrovascular complications as well as mortality associated with chronic kidney disease, has been established as the standard surgical procedure for early-stage kidney cancer treatment in academic and clinical circles.^{[8, 9]}

In traditional partial nephrectomy, in order to create a relatively bloodless surgical field to ensure complete tumor resection and wound closure, it is often necessary to block the renal artery. However, this can result in renal warm ischemia-reperfusion injury and may affect the patient’s short-term and long-term renal function.^{[10, 11]} Previous studies have shown that each minute of warm ischemia time can impact long-term renal function.^[12] Therefore, many scholars have conducted research on reduction of warm ischemia-reperfusion injury, and have proposed various methods to shorten warm ischemia time. These methods include intraoperative hypothermia with ice water,^[13] microwave/radiofrequency-assisted partial nephrectomy,^[14] and highly selective renal artery occlusion.^[15] In 2011, Gill et al. first proposed the concept of "zero ischemia" partial nephrectomy, which means not blocking the renal artery before tumor resection, fundamentally avoiding the warm ischemia time and maximizing the protection of renal function.^[16] However, zero-ischemia partial nephrectomy requires high demands on preoperative preparation and the skills of the surgeon. Therefore, the precise identification of tumor-feeding vessels preoperatively and the accurate control of these vessels intraoperatively become crucial aspects of this surgery.

Currently, in clinical practice, the assessment of renal tumors and surrounding anatomical structures heavily relies on two-dimensional imaging information from CT or MRI scans. These images are displayed in black and white, and are limited in perspective, lacking three-dimensional depth perception. Three-dimensional reconstruction technology involves the process of creating a complete three-dimensional image by overlaying continuous two-dimensional images using computer-aided design software. This technology emerged in the 1980s and 1990s, initially finding application in the industrial sector before gaining widespread use in the medical field due to its distinct advantages.^[17-19] In a 3D reconstruction model different tissue structures are marked with various colors and transparencies, enabling clinicians to accurately understand the anatomy of the tumor and surrounding tissues. This technology allows for various degrees of zooming, rotation, and transparency adjustments, facilitating the precise identification of key information such as tumor size, location, depth of infiltration, relationship with the collecting system, vascular distribution, and adjacency to surrounding organs.^[20] The application of this technology in the field of renal tumors is still in its preliminary exploration stage. In 2014, SIBER-STEIN et al. from Duke University successfully utilized three-dimensional reconstruction technology to print the world's first renal tumor model. This model matches the size of the patient's affected kidney, including the major vascular structures, renal pelvis, and proximal ureter, with the tumor being differentiated by a distinct color from the renal parenchyma. It effectively displays the relationship between the tumor and the kidney, facilitating preoperative tumor localization, aiding in surgical planning, and enhancing preoperative communication.^[21]

In this study, we employed a three-dimensional renal tumor-targeted vascular reconstruction technique. Patients underwent preoperative comprehensive CTA examination, followed by three-dimensional reconstruction using software to localize the renal tumor-targeted blood vessels. This approach optimized the surgical treatment plan, guided intraoperative procedures, and facilitated precise handling of the tumor-targeted blood vessels. Ultimately, it enabled the achievement of zero-ischemia preservation of the renal unit during laparoscopic surgery. In the zero ischemia group, there were 4 cases of T1b renal cell carcinoma located in the lower pole of the kidney. Preoperative three-dimensional renal tumor vascular reconstruction evaluated the tumor vasculature as multi-targeted. The plan was to perform laparoscopic partial nephrectomy without renal artery clamping. However, significant bleeding occurred during the operation, leading to mid-procedure renal artery clamping and subsequent partial nephrectomy. The remaining 26 patients successfully underwent zero-ischemia laparoscopic partial nephrectomy, with no occurrences of urinary leakage or bleeding complications during the perioperative period. Postoperative follow-up results revealed no cases of positive surgical margins or local recurrence. Patients in the traditional surgery group all underwent successful laparoscopic partial nephrectomy without conversion to open surgery or radical nephrectomy. In the comparison of serum creatinine levels at 3 and 12 months postoperatively between two patient groups, no statistically significant differences were observed. However, a significant difference was noted in the comparison of GFR at 3 months postoperatively, indicating a faster recovery of renal function in patients undergoing partial nephrectomy under zero ischemia using renal tumor-targeted vascular localization. At the 12-month follow-up, no tumor recurrence or metastasis was observed in either group. While statistically significant variances were found in surgical time and intraoperative blood loss between the two groups, the length of hospital stay and the incidence of postoperative complications showed no statistically significant differences. These findings suggest that employing renal tumor-targeted vascular localization for zero ischemia partial nephrectomy under laparoscopy does not increase perioperative risks compared to laparoscopic surgery with complete renal artery occlusion and kidney unit preservation, thus demonstrating the safety and efficacy of this approach.

Based on previous clinical experience, most physicians consider the surgical removal of renal hilar tumors to be challenging and unsuitable for zero ischemia partial nephrectomy. Therefore, this study analyzed the target blood vessels of tumors in different locations within the zero ischemia group. In comparison to the tumor target vessels of renal pole tumors, those of renal hilar tumors are mostly single and relatively large, making it easier to locate and block them during surgery. Additionally, 4 cases in the zero ischemia group were converted to artery blocking laparoscopic partial nephrectomy due to heavy bleeding. Their tumors were located at the lower pole of the kidney and had a diameter greater than 4cm with multiple tumor target vessels. This suggests that the renal tumor target vessel localization method is particularly suitable for patients with single early-stage renal cancer in the renal hilar region.

In clinical practice, we believe that three-dimensional reconstruction offers several advantages in guiding zero-ischemia LPN. Firstly, as opposed to traditional methods where the operating physician obtains information from two-dimensional CTA images and relies on spatial imagination to understand the anatomical features of the kidney and tumor, three-dimensional reconstruction provides a more intuitive display of the anatomical structures and adjacent relationships of the kidney, tumor, and their surrounding vascular systems. This enhances the amount of information obtained by the operating physician during preoperative image review. By reviewing three-dimensional reconstruction models before the procedure, the surgeon can more accurately and quickly locate the tumor during surgery and precisely control the tumor's blood supply during excision. Secondly, three-dimensional reconstruction can be employed through data analysis and reconstruction processes to understand the situation of tumor-feeding blood vessels. In zero-ischemia LPN surgery, early control of tumor-feeding blood vessels can effectively reduce intraoperative bleeding and provide a better surgical field of view, thereby enhancing the success rate of zero-ischemia LPN. Thirdly, three-dimensional reconstruction visually displays the tumor morphology, aiding in precise tumor resection and reducing positive margin rates. Previous research results have shown that three-dimensional reconstruction models, due to their intuitive, clear, and visual advantages, can reduce positive margin rates of surgical specimens in robot-assisted radical prostatectomy and partial nephrectomy. As certain kidney tumors may exhibit irregular growth patterns or satellite foci, the use of three-dimensional reconstructed images allows the lead surgeon to assess tumor morphology and satellite foci preoperatively, thereby reducing positive margin rates. In addition, in actual clinical practice, we have found that three-dimensional reconstruction images not only aid in preoperative assessment and the formulation of surgical plans, but also, due to their intuitive and visual nature, can be used for preoperative patient education and discussions, facilitating a better understanding of the condition and surgical aspects for patients and their families, thereby enhancing their comprehension of the disease and their cooperation with treatment.

Certainly, not all cases of renal tumors are suitable for this technique. When implementing the renal tumor targeted vascular embolization technique for zero ischemia laparoscopic partial nephrectomy, the following points should be noted: ① For exophytic tumor patients, it is recommended that the exophytic portion of the tumor be greater than 50%, with an optimal tumor diameter between 2 to 5 cm; ② This method is recommended for solitary tumors and tumors located at the renal hilum; ③ In order to avoid excessive intraoperative bleeding that cannot be controlled, it is advisable to routinely pre-separate the renal artery as a backup during the procedure.

The present study also has certain limitations. Firstly, as the three-dimensional renal tumor target vessel reconstruction technology is based on preoperative CTA examination, it is not suitable for renal tumor patients who are allergic to contrast agents or have impaired renal function and therefore cannot undergo CTA. Secondly, this study included cases with an average maximum tumor diameter of 4.8cm, and it remains to be further verified whether patients with larger tumor diameters, such as cT1b stage tumors, can benefit from this technique. Thirdly, due to the current limitations of the technology, real-time synchronous reconstruction models with the surgical field have not yet been achieved, thus the role of this technology in real-time intraoperative localization and navigation is still lacking. Furthermore, this study only provides a single-center small sample retrospective experience, and the relevant conclusions still require further validation through advanced-level research.

In conclusion, for some early-stage renal cancer patients, the application of three-dimensional renal tumor target vessel reconstruction technology can better achieve ‘zero-ischemia’ laparoscopic partial nephrectomy, which is beneficial for the preservation of renal function in patients. The target vessels of the solitary early-stage renal cancer in the renal hilum are relatively easy to locate, making it more suitable for the implementation of three-dimensional renal tumor target vessel reconstruction technology for performing ‘zero-ischemia’ laparoscopic partial nephrectomy.

ACKNOWLEDGEMENTS

This study was sponsored by the Top-level Clinical Discipline Project of Shanghai Pudong(No.PWYgf 2021-06)；Pudong New Area Traditional Chinese and Western Medicine collaborative flagship Department (Urology) construction plan (YC-2023-0405).

CONFLICT OF INTEREST

All authors have not any conflicts of interest to declare.

AUTHOU CONTRIBUTIONS

SX and YJS performed the experiments and collected the data. SX and GY analyzed the data. SX and JC wrote the manuscript. CZK conceived the study and coordinated the research. All authors contributed to editorial changes in the manuscript. All authors read and approved the finial manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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Table1 Comparison of general clinical data between two groups of kidney cancer patients

Variables	study group（n=30）	control group（n=50）	t/χ²	P
Gender
male	17	29
female	13	21
Age, years	51.1±6.9	53.9±7.8
Maximal tumor diameter, mm	41.1±10.4	42.8±11.1
Pathological stage
T1a	23	36
T1b	7	14
Number of target vessels
Single target	25	39
Multiple targets	5	11

Table2 Comparison of perioperative data between two groups（x̄ ± s）

Variables	study group（n=26）	control group（n=50）	t	P
Mean operative time( min)	92.5±9.8	71.6±9.9	8.873	＜0.001
Median estimated blood loss(ml)	150±22	80±19	14.655	＜0.001
Length of stay（d）	7.2±0.4	7.1±0.9	0.540	0.591

Table3 Comparison of renal function between two groups（x̄ ± s）

Variables	study group（n=26）	control group（n=50）	t	P
Before surgery
Serum creatinine（μmol/l）	73±9	75±8	1.005	0.318
GFR of affected kidney（ml/min）	42.1±6.8	42.5±6.1	0.265	0.792
At 6 months after surgery
Serum creatinine（μmol/l）	75±8	79±9	1.928	0.058
GFR of affected kidney（ml/min）	40.1±5.6	35.2±5.1	3.899	＜0.001
At 12 months after surgery
Serum creatinine（μmol/l）	73±7	76±7	1.795	0.076
GFR of affected kidney（ml/min）	41.8±5.2	39.5±5.8	1.716	0.090

No competing interests reported.

Utilization of three-dimensional renal tumor target vessel reconstruction and localization technology for Zero-Ischemia Laparoscopic Partial Nephrectomy: A Clinical Perspective

Status:

Version 1

Abstract

Figures

1 Introduction

2 Methods

3 Results

4 Discussion

Declarations

References

Tables

Additional Declarations

Status:

Version 1