iPad-assisted percutaneous nephrolithotomy (PCNL): a matched pair analysis compared to standard PCNL

Pre- and post-operative safety considerations for patients undergoing percutaneous nephrolithotomy

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is a widely used surgical procedure for treating large and complex kidney stones. Although effective, it carries risks of complications such as bleeding, infection, and injury to adjacent structures. Optimisation of procedural techniques and perioperative care can help minimize these risks.

AREAS COVERED

This review examines key pre- and post-operative safety considerations for PCNL patients. Topics include pre-operative imaging, patient positioning, puncture techniques, tract dilation, postoperative drainage, and complication management. The literature search involved analyzing recent studies and clinical guidelines to identify best practices. The search was conducted in several databases, including PubMed, Embase, the Cochrane Library and clinical guidelines. Training modalities for improving procedural skills are discussed.

EXPERT OPINION

Improving the safety of PCNL requires a combination of meticulous surgical technique, proper patient selection, and adherence to standardized protocols. Continuous skill development and technological advancements will further improve patient outcomes.

Initial experience with augmented reality in planning renal access for PCNL

Achieving renal access during percutaneous nephrolithotomy is challenging, with a complication rate of 10-20%. This study aims to assess a novel technique for planning access to the renal collecting system using augmented reality (AR). Using Digital Imaging and Communications in Medicine software (DICOM 2-print), we generated 3-dimensional (3D) models of patients with different types of kidney stones (staghorn, lower pole, and pelvic stones) who underwent PCNL between 2018 and 2022. After viewing the patient's CT scans, surgeons explored the anatomical models using an AR system with a stereoscopic 3D lens array display. Using questionnaires, we quantitatively estimated the model's contribution on a scale of "1" ("poor") to "5" ("excellent") to the surgeon's understanding of stone location, patient anatomy, and ease of access compared to 2D CT imaging. A total of 38 questionnaires were completed by 13 urologists. Estimating renal location, renal pelvis, and stone mass were better demonstrated by AR (5 vs. 4, p < 0.001). The orientation of adjacent organs was better understood using AR (5 vs. 4, p = 0.004). In 86.8% of cases, surgeons preferred using AR models both before and during surgery, with 69.2% suggesting that AR could enhance procedural safety. The time frames for testing the models differed between senior and junior practitioners (p = 0.016) and were significantly reduced with model experience (p < 0.001). When comparing CT to 3D imaging, AR models provide a better understating of stone location, patient anatomy, and route of access to the collecting system. Further research is required to implement this innovative technique preoperatively and intra-operatively.

Feasibility of robot-assisted system for navigated needle positioning in the PCNL procedure in vitro

PURPOSE

The objective of this study was to explore the feasibility of using the TianJi Robot system for navigated needle positioning in the PCNL procedure in vitro.

METHODS

A pig kidney with a segment of ureter was selected as the in vitro organ model. Iodine contrast agent was infused into the renal pelvis to dilate the renal pelvis and calyx to establish the in vitro hydronephrosis model. Fluoroscopic images were obtained using a 3D C-arm and transferred to the robotic workstation. Three-dimensional reconstructed images were generated and displayed on the monitor screen. The surgeon planned the optimal puncture trajectory on the workstation. After that, the robotic arm was instructed to move to the surgical field. The guiding cannula was placed onto the robotic arm and brought close to the skin. The needle was placed along the guiding cannula. An 18G needle was inserted manually. Finally, a second CBCT scan was performed to validate the needle's location.

RESULTS

Three hydronephrosis models were used in the study, and a total of seven target calyces were planned. six target calyces were successfully punctured in one attempt, with a single-puncture success rate of 87.5%.

CONCLUSIONS

A high single-puncture success rate is achieved using the TianJi Robot system for navigated needle positioning in the PCNL procedure in vitro, marking an innovative step forward in urological interventions.

Conventional ultrasonography enabled with augmented reality needle guidance for percutaneous kidney access: an innovative methodologies randomized controlled trial

IMPORTANCE

Successful needle puncture of the renal collecting system is a critical but difficult procedure in percutaneous nephrolithotomy (PCNL). Although fluoroscopy and ultrasound are the standard imaging techniques to guide puncture during PCNL, both have known limitations.

OBJECTIVE

To assess the feasibility and safety of a new navigation system for needle puncture in ultrasound-guided PCNL.

DESIGN

This study employed a single-center randomized controlled trial (RCT) design to assess the feasibility and safety of a new navigation system for needle puncture in ultrasound-guided PCNL. Conducted between May 2021 and November 2021, the trial utilized computer-generated random numbers for participant allocation to control for selection bias.

SETTING

The trial was executed at Department of Urology, Peking University First Hospital in Beijing, China, which serves as an academic medical center.

PARTICIPANTS

All patients who met the inclusion criteria were randomly divided into two groups, with 29 patients in each group. One group underwent PCNL procedures using the new navigation system, while the control group underwent standard ultrasound-guided PCNL procedures. Included patients had renal pelvis or caliceal calculi larger than 2.0 cm in diameter or had multiple or staghorn stones. The puncture procedure was performed with the support of real-time ultrasound imaging and visual guidance displayed on the screen.

MAIN OUTCOMES AND MEASURES

The primary outcome was system feasibility and puncture success rate. Secondary outcomes included puncture time, total surgical time, number of attempts, postprocedure complications, and 1-year and 3-year stone recurrence rates. Stone clearance was defined by postoperative CT. Descriptive statistics summarized patient demographics, stone size, and location. Independent samples t -tests analyzed puncture time and total surgical time. χ2 or Fisher's exact tests compared stone clearance, complications, socioeconomic status, renal hydronephrosis, stone location, race, and medical history. Linear regression examined the correlation between BMI and puncture time. Significance was set at P <0.05.

RESULTS

For all 58 patients undergoing PCNL, needle punctures of the renal collecting system were completed with a success rate of 100%. The average time from planning the puncture protocol to successful puncture was significantly shorter in the AcuSee guidance system group (3.12 min, range 0.2-6.88 min) compared to the standard ultrasound-guided group (7.58 min, range 5.41-10.68 min), representing a reduction of ~59%. The total surgical time was also shorter in the AcuSee group for patients with no and mild hydronephrosis ( P <0.05). Complication rates were lower in the AcuSee group, with no major complications observed. However, three patients in the standard ultrasound-guided group have adverse effects after the PCNL procedure. The 1-year stone recurrence rate was significantly lower in the AcuSee group (3.4%) compared to the standard group (24.1%), and the 3-year recurrence rate was also lower (6.9% vs. 41.4%). Patient-specific factors such as BMI, renal morphology, and prior surgical history did not significantly affect the performance of the AcuSee system.

CONCLUSIONS AND RELEVANCE

The authors report the first clinical application of a new navigation system for needle puncture in ultrasound-guided PCNL. It has been demonstrated that it is feasible and safe compared to the standard ultrasound-guided group in percutaneous renal puncture. This technology provides intuitive and easy-to-use visual guidance, which may facilitate safe, accurate, and fast needle puncture of the kidney.

The relationship between map scores and complications after standard percutaneous nephrolithotomy

PURPOSE

Upper urinary tract stones are a common condition in urology clinics. Percutaneous nephrolithotomy (PCNL) is an effective procedure frequently used for the treatment of stones larger than 2 cm. MAP scoring is used to predict oncological outcomes and intraoperative complications after partial nephrectomy by using the thickness and adhesion of perinephric adipose tissue. We examined the relationship between MAP score and clinical and demographic findings of the patients, especially postoperative Hgb drop and postoperative complications.

MATERIAL-METHOD

Patients were divided into 2 groups: Those with MAP score < 3 and ≥ 3. The impact of the MAP score on the demographic, clinical, and surgical parameters of the groups was assessed and analyzed. The relationship between MAP score and complications based on Clavien Dindo classification was also examined. The study investigated factors affecting the development of complications, the amount of bleeding, and the influence of MAP scores on these outcomes.

RESULTS

The Hgb drop was 2.56 ± 1.00 in the group with a MAP score ≥ 3 which was statistically significantly higher than the group with a MAP score < 3 (1.43 ± 1.21) (p < 0.001). The stone-free rate was 81.7% in the group with a MAP score < 3, which was statistically significantly higher than the group with a MAP score ≥ 3 (59.6%) (p = 0.012).

CONCLUSION

As the MAP score of patients scheduled for standard PNL operation increased, there was a corresponding rise in Hgb drop, a decline in stone-free rates and an uptick in postoperative urinary complications of postoperative urinary infections.

Integrating 3D technology with the Sampaio classification for enhanced percutaneous nephrolithotomy in complex renal calculi treatment

Background

To investigate the safety and efficacy of percutaneous nephrolithotomy (PCNL) in the treatment of complicated renal calculi by integrating three-dimensional (3D) computed tomography (CT) reconstruction with the Sampaio classification of the renal collecting system.

Methods

Sixty-four consecutive patients with complex kidney calculi who underwent PCNL between January 2019 and October 2023 were retrospectively analyzed and divided into experimental group (3D printing) and control group (CT imaging) according to their willingness to pay for 3D imaging. Both groups underwent preoperative CT urography. The Digital Imaging and Communications (DICOM) in Medicine data of the experimental group from CT imaging were used for 3D reconstruction and model printing. Then, the Sampaio classification system was used to design the puncture channel and develop a surgical strategy.

Results

The 3D-printed models of the experimental group successfully displayed the Sampaio classification system. There was no significant difference in the baseline parameters between the groups. Compared with the control group, the experimental group exhibited significant improvements in the puncture time, number of puncture needles, number of puncture channels, target calyx consistency, number of first puncture channels, and stone clearance. There were no significant differences in the total operative time, decrease in the hemoglobin level, length of hospital stay, and postoperative complications between the groups.

Conclusions

Integration of 3D technology with the Sampaio classification of the renal collecting system can enhance the preoperative evaluation and planning of percutaneous renal access. This approach allows a more precise method of PCNL for treating complex renal calculi.

Application value of surgical navigation system based on deep learning and mixed reality for guiding puncture in percutaneous nephrolithotomy: a retrospective study

BACKGROUND

This study was conducted to investigate the clinical value of a navigation system based on deep learning and mixed reality for the treatment of kidney stones with percutaneous nephrolithotomy (PNL), and to improve its theoretical basis for the treatment of kidney stones.

METHODS

The data of 136 patients with kidney stones from October 2021 to December 2023 were retrospectively analyzed. All patients underwent PNL, and were categorized into a control group (Group 1) and a surgical navigation group (Group 2) according to puncture positioning method. Preoperative computed tomography (CT) was performed in both groups. In group 1, procedures were performed under standard ultrasound guidance. PNL was performed with navigation system fused with ultrasound to guide percutaneous puncture in group 2. The baseline information and procedural characteristics of both groups were compared.

RESULTS

PNL was successfully performed in both groups. No significant difference was found in the baseline date between the two groups. In group 2, real-time ultrasound images could be accurately matched with CT images with the aid of navigation system. The success rate of single puncture, puncture time, and decrease in hemoglobin were significantly improved in group 2 compared to group 1. (p < 0.05).

CONCLUSIONS

The application of navigation system based on deep learning and mixed reality in PNL for kidney stones allows for real-time intraoperative navigation, with acceptable accuracy and safety. Most importantly, this technique is easily mastered, particularly by novice surgeons in the field of PNL.

Predicting and Avoiding Complications in Percutaneous Nephrolithotomy in the Era of Personalized Medicine: A Scoping Review

BACKGROUND

Percutaneous nephrolithotomy (PCNL) is associated with a wide range of complications. This review aims to explore how recent technological advancements and personalized medicine can help prevent or predict these complications.

METHODS

A scoping review was conducted according to the PRISMA-SCR guidelines and registered on the Open Science Framework in April 2024. A literature search was performed on PUBMED, Web of Science, and Scopus databases. This review focused on predictive AI models, 3D surgical models, intrasurgical image guidance, and biomarkers. Articles meeting the following criteria were included: publication between 2019 and 2024, written in English, involving human participants, and discussing technological advancements or personalized medicine in the context of complications in PCNL.

RESULTS

Of the 11,098 articles searched, 35 new studies were included. We identified a few articles on predictive AI models. Several studies demonstrated that 3D presurgical models and virtual models could enhance surgical planning and reduce complications. New intrasurgical image and guidance systems showed the potential in reducing bleeding and radiation exposure. Finally, several biomarkers were identified as predictors of sepsis and other complications.

CONCLUSION

This scoping review highlights the potential of emerging technologies in reducing and predicting PCNL complications. However, larger prospective studies are required for validation.

Feasibility of stereotactic optical navigation for needle positioning in percutaneous nephrolithotomy

BACKGROUND

This study assessed the feasibility of acquiring single-attempt access to the pelvicalyceal system during percutaneous nephrolithotomy (PCNL) using stereotactic optical navigation combined with cone-beam CT (CBCT) imaging.

METHODS

Patients with a PCNL indication were prospectively included in this IRB approved study. After sterile preparation, fiducial markers were attached to patients' skin. An initial intraprocedural CBCT scan was acquired, on which the urologist planned the needle trajectory using the navigation software. After verifying that no critical structures were crossed, the needle guide was aligned with the plan. A needle was manually inserted through the needle guide to the indicated depth and a second CBCT scan was performed for needle position confirmation. Both, scanning and needle insertion, were performed under apnea. The study evaluated technical success, accuracy, procedure time, complication rate, and radiation dose.

RESULTS

Between June 2022 and April 2023, seven patients were included. In all patients, the navigation system allowed safe puncture. However, the technical success rate was only 29%. In 42% of the cases, pelvicalyceal access was achieved by a small manual adjustment. In the remaining 29%, the needle was retracted and positioned per clinical standard. The average deviation between the needle and target was 5.9 ± 2.3 mm. The average total procedure time was 211 ± 44 min. The average radiation exposure was 6.4 mSv, with CBCT scanning contributing to 82% of this exposure.

CONCLUSIONS

The optical navigation system facilitated safe needle insertion but did not consistently ensure accurate one-attempt needle positioning for PCNL. Real-time visualization and trajectory correction may improve the technical success rate.

Navigation systems and 3D imaging in percutaneous nephrolithotripsy: improving outcomes and safety

PURPOSE OF REVIEW

Percutaneous nephrolithotripsy (PCNL) is the first-line management option for large kidney stones (>2 cm). It remains, however, a demanding procedure with considerable morbidity. The present narrative review summarizes recent knowledge from original research studies investigating navigation systems/three-dimensional (3D) imaging in PCNL, particularly on publications during the past 12-18 months.

RECENT FINDINGS

Navigation systems and 3D imaging are primarily used for preoperative planning, with few intra-operative applications. Patient management and residents' training could benefit from their use.

SUMMARY

Navigation systems and 3D imaging technology have emerged as a potential game-changer in PCNL. Even though available evidence is currently scarce/inconclusive, the safety/efficacy of navigation systems and 3D dimensional imaging use in PCNL appears promising. This advanced technology offers precise anatomical mapping, improved visualization, and surgical accuracy. Enabling a comprehensive preoperative evaluation and improving guidance, navigation systems, and 3D imaging technology may improve the safety and efficacy of PCNL. With continuous technological evolution, it is expected that improvements/innovations will offer further aid in such demanding procedures. Familiarization and cost reduction are necessary for widespread application, while larger-scale prospective studies and well designed randomized controlled trials are still needed.

Simplified biplanar (0-90°) versus monoplanar renal puncture technique in flank free modified supine percutaneous nephrolithotomy regarding outcomes and learning curve: Randomized clinical trial

Objective

To evaluate the learning curve and the success rate of the biplanar (0-90°) puncture technique in the flank-free modified supine position in comparison to the monoplanar puncture technique.

Methods

Randomized controlled study included 68 patients more than 18 years with renal stones more than 2 cm from August 2021 to August 2022 were randomly classified by closed envelope method into group A (34 patients) scheduled for monoplanar renal puncture technique in flank-free modified supine PCN. Meanwhile, group B (34 patients) was scheduled for the 0-90° simplified fluoroscopic puncture technique. Morbid obese patients and patients with contraindications for PNL were omitted from the study.

Results

There was no significant difference between both groups regarding stone distribution and patients' demographic data. There was a significant difference between both groups regarding puncture attempts. In 88.2% of patients in group B (Biplanar group), the success of renal puncture occurred from the 1st puncture attempt while in 11.2% of patients in group A (monoplanar group). There was a statistically significant difference between both groups in fluoroscopy time and total operation time (p-value <0.001 & p-value: 0.001), respectively. The stone-free rate was 85.2% vs. 88.2% in both groups, respectively, without significant difference. In this study puncture, attempt trials and puncture time were used as indicators for the easiness and rapid educability of the biplanar (0-90°) fluoroscopic guided renal puncture technique. In the biplanar (0-90°) group after 24 cases, the learning curve had reached the plateau.

Conclusion

Biplanar (0-90°) puncture technique in flank-free modified supine position allows an easy puncture technique with an easy learning curve without affecting the success rate or complication rate.

Mobile and eHealth technologies in the management and prevention of nephrolithiasis: A systematic review

INTRODUCTION

Kidney stone disease (KSD) is a common urological condition that often requires long-term care. Mobile health (mHealth) and eHealth technologies have the potential to enhance chronic disease management and behavioral change. To assess opportunities to apply these tools to improve KSD treatment and prevention, we aimed to assess current evidence on the use, benefits, and limitations of mHealth and eHealth in KSD.

METHODS

We performed a systematic review of primary research studies of mHealth and eHealth in the evaluation and management of KSD. Two independent researchers screened citations by title and abstract for relevance, then full-text review was performed for descriptive summary of the studies.

RESULTS

A total of 37 articles were included for analysis. Primary domains of evidence included: 1) "smart" water bottles and mobile-device apps for tracking fluid consumption, which showed increased intake in most studies; 2) ureteral stent tracking platforms, which improved the rate of long-term retained stents; 3) virtual stone clinics, which have been suggested to increase access, lower costs, and have satisfactory outcomes; 4) smartphone-based endoscopy platforms, which offered cost-effective image quality in resource-limited settings; 5) patient information about KSD online, which was typically characterized as poor quality and/or accuracy, particularly on YouTube. Most studies were proof-of-concept or single-arm intervention designs, with limited assessment of effectiveness or long-term clinical outcomes.

CONCLUSIONS

Mobile and eHealth technologies have significant real-world applications to KSD prevention, intervention, and patient education. A lack of rigorous effectiveness studies currently limits evidence-based conclusions and incorporation in clinical guidelines.

Clinical Value of Mixed Reality-Assisted Puncture Navigation for Percutaneous Nephrolithotripsy

OBJECTIVE

To evaluate the clinical value of mixed reality-assisted puncture navigation (MRAPN) in percutaneous nephrolithotripsy (PCNL).

METHODS

Two hundred patients undergoing PCN were enrolled, all of whom had kidney stones to be subjected to lithotripsy by PCNL and grouped according to surgical procedure into the MRAPN (n = 100) and non-mixed reality-assisted puncture (non-MRAPN) (n = 100) groups. CT data in DICOM format for all patients in the MRAPN group were imported into 3D reconstruction and mixed reality (MR) post-processing workstations, and holographic 3D visualization modelling. Comparing parameters such as the operative time (OT), puncture time (PT), number of attempts, and estimated blood loss (EBL), a Likert scale was used to assess the clinical value of MRAPN. The Cohen κ coefficient (k) was employed to evaluate consistency among assessors; safety was assessed.

RESULTS

There were no significant differences in patient demographic indicators or preoperative general information between the MRAPN and non-MRAPN groups (P > .05). The clinical value of MRAPN was higher for subjective scores regarding surgical planning, intraoperative navigation, didactic guidance and physician-patient communication (all P < .001). The PT was significantly shorter in the MRAPN group (P < .001), with a shorter overall OT and lower EBL (P < .001). There were no significant differences in the overall comparison, length of hospital stay, or preoperative or postoperative creatinine (all P > .05).

CONCLUSION

MRAPN can safely and effectively improve the success of PCN, reduce complications, and decrease the PT, OT, and EBL.

Advances in percutaneous renal puncture: a comprehensive review of the literature

PURPOSE OF REVIEW

Percutaneous nephrolithotomy (PCNL) constitutes the gold standard procedure for patients suffering from more than 2 cm renal stones. The puncture is a very critical step of PCNL, affecting manoeuvrability of the nephroscope, possibility to remove stone fragments, risk of bleeding and radiation exposure. The aim of the current review was to discuss the advances in percutaneous renal puncture.

RECENT FINDINGS

Following technological evolution in medicine, there was a consistent development in the puncture techniques, aiming at the improvement of its efficacy and safety. The use of specific agents can improve ultrasonic guidance, making the challenging step of gaining access to the kidney easier for the experienced surgeon and more accessible for the resident urologist. Future developments in the electromagnetic and three-dimensional (3D) technology may establish a high level of accuracy with decreased rates of related complications, even in the hands of beginners.

SUMMARY

The advances in percutaneous puncture can lead to improved safety and accuracy of this procedure decreasing the radiation exposure and the complication rate.

The role of 'artificial intelligence, machine learning, virtual reality, and radiomics' in PCNL: a review of publication trends over the last 30 years

Introduction

We wanted to analyze the trend of publications in a period of 30 years from 1994 to 2023, on the application of 'artificial intelligence (AI), machine learning (ML), virtual reality (VR), and radiomics in percutaneous nephrolithotomy (PCNL)'. We conducted this study by looking at published papers associated with AI and PCNL procedures, including simulation training, with preoperative and intraoperative applications.

Materials and Methods

Although MeSH terms research on the PubMed database, we performed a comprehensive review of the literature from 1994 to 2023 for all published papers on 'AI, ML, VR, and radiomics' in 'PCNL', with papers in all languages included. Papers were divided into three 10-year periods: Period 1 (1994-2003), Period 2 (2004-2013), and Period 3 (2014-2023).

Results

Over a 30-year timeframe, 143 papers have been published on the subject with 116 (81%) published in the last decade, with a relative increase from Period 2 to Period 3 of +427% (p = 0.0027). There was a gradual increase in areas such as automated diagnosis of larger stones, automated intraoperative needle targeting, and VR simulators in surgical planning and training. This increase was most marked in Period 3 with automated targeting with 52 papers (45%), followed by the application of AI, ML, and radiomics in predicting operative outcomes (22%, n = 26) and VR for simulation (18%, n = 21). Papers on technological innovations in PCNL (n = 9), intelligent construction of personalized protocols (n = 6), and automated diagnosis (n = 2) accounted for 15% of publications. A rise in automated targeting for PCNL and PCNL training between Period 2 and Period 3 was +247% (p = 0.0055) and +200% (p = 0.0161), respectively.

Conclusion

An interest in the application of AI in PCNL procedures has increased in the last 30 years, and a steep rise has been witnessed in the last 10 years. As new technologies are developed, their application in devices for training and automated systems for precise renal puncture and outcome prediction seems to play a leading role in modern-day AI-based publication trends on PCNL.

Application of a novel computer-assisted surgery system in percutaneous nephrolithotomy: A controlled study

BACKGROUND

Most complex renal stones are managed primarily with percutaneous nephrolithotomy (PCNL). However, PCNL is still a great challenge for surgeons because of poor comprehension on complex adjacent structures. Novel techniques are required to assist in planning and navigation.

AIM

To apply and evaluate the Hisense computer-assisted surgery (CAS) system in PCNL.

METHODS

A total of 60 patients with complex renal stones were included. Thirty patients in the CAS group had three-dimensional (3D) virtual models constructed with the CAS system. The model assisted in planning and navigating in the CAS system. Thirty patients in the control group planned and navigated as standard PCNL, without the application of the CAS system. Success rate of one attempt, operation time, initial stone-free rate, decrease in hemoglobin, and complications were collected and analyzed.

RESULTS

There were no statistically significant differences in the baseline characteristics or planning characteristics. The success rate of one puncturing attempt (90% vs 67%, P = 0.028) and the initial stone-free rate (87% vs 63%, P = 0.037) were significantly higher in the CAS group. However, there were no statistically significant differences in the operation time (89.20 ± 29.60 min vs 92.33 ± 33.08 min, P = 0.859) or in the decrease in hemoglobin (11.07 ± 8.32 g/L vs 9.03 ± 11.72 g/L, P = 0.300) between the CAS group and the control group. No statistically significant differences in the incidence of complications (Clavien-Dindo grade ≥ 2) were found.

CONCLUSION

Compared with standard PCNL, CAS-assisted PCNL had advantages in terms of the puncturing success rate and stone-free rate. The Hisense CAS System was recommended to assist in preoperative planning and intraoperative navigation for an intuitive, precise and convenient PCNL.

Access and Fluoroscopy Time Difference in Patients Undergoing Prone Percutaneous Nephrolithotomy (PCNL) With Ureteric Catheter Placement in Supine Versus Lithotomy Position

Objective: To compare the operative and fluoroscopy time in two different methods of ureteral stent insertion before prone percutaneous nephrolithotomy (PCNL).

Materials and method: Over 12 months, 124 patients with urolithiasis who went through prone PCNL were included in our study. All the patients had kidney stones and were divided into two groups based on the method of ureteral catheter insertion. This was done with the help of flexible or rigid cystoscopy in to group A and group B, respectively. Both groups had an equal number of patients, i.e., 62. The main outcome variables assessed were access time (from intubation to placement of access sheath) and fluoroscopy time during access.

Results: The categorical variables (age, gender, site of the stone) between the two groups were comparable. The access time in groups A and B were 48±4.30 and 77±10 minutes, respectively. The fluoroscopy times in groups A and B were 52±14.63 and 116±47.77 seconds, respectively. A statistically significant difference (p-value < 0.05) was observed for both the access and fluoroscopy time. None of the patients in either of the groups had a misplaced ureteral catheter requiring repositioning.

Conclusion: Flexible cystoscope-assisted insertion of ureteral catheter prior to PCNL significantly reduces operative time, fluoroscopy time, and consequently radiation exposure during PCNL.

Application of a three-dimensional visualization model in intraoperative guidance of percutaneous nephrolithotomy

OBJECTIVES

To establish a three-dimensional visualization model of percutaneous nephrolithotomy, apply it to guiding intraoperative puncture in a mixed reality environment, and evaluate its accuracy and clinical value.

METHODS

Patients with percutaneous nephrolithotomy indications were prospectively divided into three-dimensional group and control group with a ratio of 1:2. For patients in three-dimensional group, positioning markers were pasted on the skin and enhanced computed tomography scanning was performed in the prone position. Holographic three-dimensional models were made and puncture routes were planned before operation. During the operation, the three-dimensional model was displayed through HoloLens glass and visually registered with the patient's body. Puncture of the target renal calyx was performed under three-dimensional-image guiding and ultrasonic monitoring. Patients in the control group underwent routine percutaneous nephrolithotomy in the prone position under the monitoring of B-ultrasound. Deviation distance of the kidney, puncture time, puncture attempts, channel coincidence rate, stone clearance rate, and postoperative complications were assessed.

RESULTS

Twenty-one and 40 patients were enrolled in three-dimensional and control group, respectively. For three-dimensional group, the average deviation between virtual and real kidney was 3.1 ± 2.9 mm. All punctures were performed according to preoperative planning. Compared with the control group, the three-dimensional group had shorter puncture time (8.9 ± 3.3 vs 14.5 ± 6.1 min, P < 0.001), fewer puncture attempts (1.4 ± 0.6 vs 2.2 ± 1.5, P = 0.009), and might also have a better performance in stone clearance rate (90.5% vs 72.5%, P = 0.19) and postoperative complications (P = 0.074).

CONCLUSIONS

The percutaneous nephrolithotomy three-dimensional model manifested acceptable accuracy and good value for guiding puncture in a mixed reality environment.

Querying the significance of patient position during computerized tomography on the reliability of pre-percutaneous nephrolithotomy planning

BACKGROUND

Computerized tomography (CT) is considered indispensable in percutaneous nephrolithotomy (PCNL) planning. We aimed to define the reliability of pre-PCNL CT for planning renal access by assessing renal positional changes between supine and prone CTs.

SUBJECTS AND METHODS

CT urographies (CTU) of 30 consecutive patients were reviewed for distances upper pole (UP)-diaphragm, UP-diaphragm attachment, renal pelvis (RP)-lateral body wall, RP- posterior body wall, and lower pole (LP)- anterior-superior iliac spine (ASIS). The posterior and lateral renal axes angles were also calculated.

RESULTS

The most consistent overall movement in transition from prone to supine was backward rotation, as demonstrated by a decrease in distance UP-posterior body wall (p = 0.010) and increase in the posterior renal angle (p < 0.0001). This finding correlated with the patient's body mass index (BMI) (p = 0.029). The left kidney was more mobile than the right one, moving significantly for five of the measured parameters compared to the right kidney which moved significantly for only two parameters. The UP-diaphragm distance of the left kidney correlated with age (p = 0.014), the RP-lateral wall distance correlated with previous abdominal surgery (p = 0.006), and the RP-posterior wall distance with BMI (p = 0.017). On the right, the UP-diaphragm distance correlated with gender (p = 0.002) and the lateral renal rotation was smaller (p = 0.046).

CONCLUSIONS

Kidneys present significant mobility between supine and prone positions. CT assessment should be performed in the position expected during surgery and should be interpreted with caution, while a real-time imaging modality should be used in the operating room.

Clinical study on the minimally invasive percutaneous nephrolithotomy treatment of upper urinary calculi

BACKGROUND

Upper urinary tract stones are very common in my country, with an incidence of 1% to 5% in the North and an even higher incidence of 5% to 10% in the south. The incidence rate in the south is higher than that in the north, mainly due to the water quality, climate and eating habits of the region. From the perspective of sex, incidence is more likely in males than females. In the high-incidence population, young adults are most prone to stones. Men in the age range of 25 to 40 years are more likely to have stones.

AIM

To observe the therapeutic effect of minimally invasive percutaneous nephrolithotomy (mPCNL) on upper urinary tract stones and its influence on the renal function of patients.

METHODS

Patients with upper urinary tract stones who were treated in our hospital from February 2017 to March 2018 were selected as research subjects and were divided into the PCNL group and the mPCNL group according to the random number table method. The general conditions of the two groups of patients were observed during the perioperative period, and the differences in stone clearance, pain, renal function indicators and complication rates were compared between the two groups to determine which were statistically significant (P < 0.05).

RESULTS

The operation time of the mPCNL group was longer than that of the PCNL group (t = -34.392, P < 0.001), and the intraoperative blood loss of the mPCNL group was more than that of the PCNL group (t = 34.090, P < 0.001). There was no difference in renal function indices between the two groups of patients before treatment, and there was no difference in the levels of serum creatinine, β2 microglobulin or retinol binding protein in the mPCNL group after treatment. The visual analog scale score of patients in the mPCNL group was lower than that of the PCNL group (t = 12.191, P < 0.001), and there was no significant difference in the stone clearance rate between the two groups (χ² value = 1.013, P = 0.314). There was no significant difference in the incidence of urine extravasation, dyspnea and peripheral organ damage between the two groups (χ² value = 1.053, P = 0.305). At 1 mo after treatment and 3 mo after treatment, the quality of life of the mPCNL group was lower than that of the PCNL group, and the Qmax level of the mPCNL group was higher than that of the PCNL group.

CONCLUSION

mPCNL has a good therapeutic effect on upper urinary tract stones, with a high stone clearance rate without causing kidney damage or increasing the incidence of complications, and thus has good application value.

Percutaneous Kidney Puncture with Three-dimensional Mixed-reality Hologram Guidance: From Preoperative Planning to Intraoperative Navigation

BACKGROUND

Despite technical and technological innovations, percutaneous puncture still represents the most challenging step when performing percutaneous nephrolithotomy. This maneuver is characterized by the steepest learning curve and a risk of injuring surrounding organs and kidney damage.

OBJECTIVE

To evaluate the feasibility of three-dimensional mixed reality (3D MR) holograms in establishing the access point and guiding the needle during percutaneous kidney puncture.

DESIGN, SETTING, AND PARTICIPANTS

This prospective study included ten patients who underwent 3D MR endoscopic combined intrarenal surgery (ECIRS) for kidney stones from July 2019 to January 2020. A retrospective series of patients who underwent a standard procedure were selected for matched pair analysis.

SURGICAL PROCEDURE

For patients who underwent 3D MR ECIRS, holograms were overlapped on the real anatomy to guide the surgeon during percutaneous puncture. In the standard group, the procedures were only guided by ultrasound and fluoroscopy.

MEASUREMENTS

Differences in preoperative and postoperative patient characteristics between the groups were tested using a χ² test and a Kruskal-Wallis test for categorical and continuous variables, respectively. Results are reported as the median and interquartile range for continuous variables and as the frequency and percentage for categorical variables.

RESULTS AND LIMITATIONS

Ten patients underwent 3D MR ECIRS. In all cases, the inferior calyx was punctured correctly, as planned using the overlapping hologram. The median puncture and radiation exposure times were 27 min and 120 s, respectively. No intraoperative or major postoperative complications occurred. Matched pair analysis with the standard ECIRS group revealed a significantly shorter radiation exposure time for the 3D MR group (p < 0.001) even though the puncture time was longer in comparison to the standard group (p < 0.001). Finally, use of 3D MR led to a higher success rate for renal puncture at the first attempt (100% vs 50%; p = 0.032). The main limitations of the study are the small sample size and manual overlapping of the rigid hologram models.

CONCLUSIONS

Our experience demonstrates that 3D MR guidance for renal puncture is feasible and safe. The procedure proved to be effective, with the inferior calyx correctly punctured in all cases, and was associated with a low intraoperative radiation exposure time because of the MR guidance.

PATIENT SUMMARY

Three-dimensional virtual models visualized as holograms and intraoperatively overlapped on the patient's real anatomy seem to be a valid new tool for guiding puncture of the kidney through the skin for minimally invasive treatment.

Percutaneous puncture during PCNL: new perspective for the future with virtual imaging guidance

CONTEXT

Large and complex renal stones are usually treated with percutaneous nephrolithotomy (PCNL). One of the crucial steps in this procedure is the access to the collecting system with the percutaneous puncture and this maneuver leads to a risk of vascular and neighboring organs' injury. In the last years, the application of virtual image-guided surgery has gained wide diffusion even in this specific field.

OBJECTIVES

To provide a short overview of the most recent evidence on current applications of virtual imaging guidance for PCNL.

EVIDENCE ACQUISITION

A non-systematic review of the literature was performed. Medline, PubMed, the Cochrane Database and Embase were screened for studies regarding the use virtual imaging guidance for PCNL.

EVIDENCE SYNTHESIS

3D virtual navigation technology for PCNL was first used in urology with the purpose of surgical training and surgical planning; subsequently, the field of surgical navigation with different modalities (from cognitive to augmented reality or mixed reality) had been explored. Finally, anecdotal preliminary experiences explored the potential application of artificial intelligence guidance for percutaneous puncture.

CONCLUSION

Nowadays, many experiences proved the potential benefit of virtual guidance for surgical simulation and training. Focusing on surgery, this tool revealed to be useful both for surgical planning, allowed to achieve a better surgical performance, and for surgical navigation by using augmented reality and mixed reality systems aimed to assist the surgeon in real time during the intervention.

A novel method for estimating the urine drainage time from the renal collecting system

PURPOSE

Partial obstruction of the upper urinary tract is a common urological pathology that leads to progressive atrophy and dysfunction of the kidney. Most methods for evaluating the urine drainage rate, to assess the severity of partial obstruction, involve injection of markers into the blood stream and therefore the filtration rate from the blood effects the drainage rate. This study presents a novel method for assessing the drainage rate from the upper urinary tract by analyzing sequential fluoroscopic images from a routine nephrostogram, in which contrast material is introduced directly into the renal collecting system.

METHODS

Fluoroscopic images from 36 nephrostograms, following percutaneous nephrolithotomy, were retrospectively evaluated, 19 with a dilated renal pelvis. A radiological model for calculating the radiopacity of the renal pelvis, which reflects the amount of contrast material in each sequential image, was developed. Using this model, an algorithm was designed for generating a drainage curve and calculating the "drainage time" t_1/2 in which half of the contrast material has drained from the renal pelvis.

RESULTS

Analysis of images of a step-wedge phantom made of an increasing number of contrast material layers showed that the calculated radiopacity of each step was proportional to the amount of contrast material, independent of the background attenuation. Analysis of the nephrostograms showed that the drainage curves highly fitted an exponential function (R = 0.961), with a significantly higher t_1/2 for dilated cases.

CONCLUSION

The developed method may be used for a quantitative and accurate estimation of the urine drainage rate.

Simplified biplanar (0-90°) fluoroscopic puncture technique for percutaneous nephrolithotomy: the learning curve

PURPOSE

To evaluate the learning curve of the simplified fluoroscopic biplanar (0-90º) puncture technique for percutaneous nephrolithotomy.

METHODS

We prospectively evaluated patients with renal stones treated with percutaneous nephrolithotomy by a single institution's fellows employing the simplified bi-planar (0-90º) fluoroscopic puncture technique for renal access. The learning curve was assessed with the fluoroscopic screening time and the percutaneous renal puncture time. Data obtained were compared to a subset of patients operated by a senior surgeon.

RESULTS

Eighty-nine patients were included in the study. Forty patients were operated by fellow-1, 39 by fellow-2, and 10 patients by the senior surgeon. Demographic data of all patients between groups were homogeneous, with no difference in gender (p = 0.432), age (p = 0.92), stone volume (p = 0.78), puncture laterality (p = 0.755), and body mass index (p = 0.365). The mean puncture time was 7.5, 4, and 3.1 min for fellow-1, fellow-2, and expert, respectively. The mean fluoroscopic screening time for the puncture was 10, 11, and 5.1 s for fellow-1, fellow-2, and the expert, respectively. Stone cases, both fellows needed to complete 10 procedures to match the senior surgeon in the mean puncture time (p = 0.046); meanwhile, the fluoroscopic screening time was equal even before to complete 10 procedures.

CONCLUSION

This study suggests that with the simplified biplanar (0-90º) puncture technique, the fluoroscopic screening time used in the learning process is brief. A novice fellow could require to complete ten cases to flatten the learning curve treating complex stone cases, and a flat learning curve is seen since the beginning when treating simple renal stones.

[Navigation systems for the percutaneous access to the kidney]

BACKGROUND

Percutaneous access to the renal pelvis still remains the most difficult step before nephrolitholapaxy (PCNL). New imaging techniques, such as 3D imaging and various navigation instruments such as electromagnetic, sonographic, CT-controlled and marker-based/iPAD try to simplify this step and reduce complications.

OBJECTIVES

In this review, various new techniques for puncturing the renal collecting system are presented and their advantages and disadvantages are evaluated.

MATERIALS AND METHODS

A systematic literature search was carried out in MEDLINE, whereby only puncture techniques that have already been evaluated in clinical studies were included.

RESULTS

Five different navigation methods for puncturing the renal pelvis before PCNL were found.

CONCLUSION

Intraoperative navigation can be useful when puncturing the collecting system. The combination of ultrasound and fluoroscopy currently remains the gold standard. However, there is still a need for further, primarily clinical, prospective studies to determine which new imaging technology and navigation systems will prevail and thus facilitate the access route to the kidney, especially in the case of special anatomical conditions.