Use of the Uro Dyna-CT in endourology - the new frontier

Intraoperative computed tomography for detection of residual stones in endourology procedures: systematic review and meta-analysis

BACKGROUND

Success rates in endourological procedures, notably percutaneous nephrolithotomy (PCNL) and ureteroscopy (URS), have demonstrated suboptimal outcomes, leading to more reinterventions and radiation exposure. Recently, the use of intraoperative computed tomography (ICT) scans has been hypothesized as a promising solution for improving outcomes in endourology procedures. With this considered, we conducted a comprehensive systematic review and meta-analysis encompassing all available studies that evaluate the impact of the use of intraoperative CT scans on surgical outcomes compared to conventional fluoroscopic-guided procedures.

METHODS

This systematic review was conducted in accordance with PRISMA guidelines. Multiple databases were systematically searched up to December of 2023. This study aimed to directly compare the use of an ICT scan with the standard non-ICT-guided procedure. The primary endpoint of interest was success rate, and the secondary endpoints were complications and reintervention rates, while radiation exposure was also evaluated. Data extraction and quality assessment were performed following Cochrane recommendations. Data was presented as an Odds ratio with 95%CI across trials and a random-effects model was selected for pooling of data.

RESULTS

A comprehensive search yielded 533 studies, resulting in the selection of 3 cohorts including 327 patients (103 ICT vs 224 in non-ICT). Primary outcome was significantly higher in the experimental group versus the control group (84.5% vs 41.4% respectively, 307 patients; 95% CI [3.61, 12.72]; p<0.00001; I2=0). Reintervention rates also decreased from 32.6% in the control to 12.6% in the ICT group (OR 0.34; 95%CI [0.12,0.94]; p =0.04; I2= 48%), whereas complication rates did not exhibit significant differences. Radiation exposure was also significantly reduced in two of the included studies.

CONCLUSION

This meta-analysis highlights a favorable outcome with intraoperative CT scan use in PCNL procedures, showing a considerable increase in SFR when compared to standard fluoroscopy and nephroscopy. Despite limited studies, our synthesis underscores the potential of ICT scans to significantly reduce residual stones and their consequences for endourology patients, as reinterventions and follow-up ionizing radiation studies.

Comparison of endoscopic versus CT assessment of stone-free status after percutaneous nephrolithotomy (PCNL)

This study is aimed to determine whether postoperative low dose computed tomography (LDCT) imaging is necessary after percutaneous nephrolithotomy (PCNL), or the surgeon's intraoperative assessment of residual fragments (RF) is sufficient and avoidance of postoperative imaging with reduction of radiation exposure can be achieved. Data of all 610 patients who underwent PCNL in prone position in our institution from February 2009 to September 2020 was collected. Parameters such as age, gender, BMI, ASA-Classification, stone related parameters and the surgeon's assessment of stone-free status were analyzed. The LDCT performed postoperatively was compared to the intraoperative assessment of the surgeon regarding RF. The mean age of patients was 52.82 years; the mean BMI was 28.18 kg/m2. In 418 cases, the surgeon made a clear statement about the presence of RF and postoperative LDCT was carried out. The discrepancy between the two methods (surgeon´s assessment vs. LDCT) was significant at p < 0.0001. The sensitivity, specificity, positive and negative predictive value of the surgeon when assessing RF were 24.05%, 99.45%, 98.28% and 50%. Stone free rate (SFR) after primary PCNL was 45.57%. The overall SFR at discharge was 96.23%. Although the surgeon´s assessment of RF was reliable, postoperative LDCT imaging should still be performed if endoscopic stone clearance is suspected due to the high false negative rate and the low negative predictive value. The optimal timing of postoperative imaging following PCNL remains unclear.

Using Intraoperative Portable CT Scan to Minimize Reintervention Rates in PCNL: A Prospective Trial

BACKGROUND AND PURPOSE

More than 40% of patients undergoing PCNL are left with residual stone fragments and often require secondary procedures. Portable CT (PCT) technology allows surgeons to obtain intraoperative cross-sectional imaging, identify and extract residual stones immediately, and thereby reduce the need for subsequent procedures. This prospective trial evaluates how incorporation of PCT during PCNL affects perioperative outcomes.

PATIENTS AND METHODS

We prospectively enrolled eligible patients undergoing initial PCNL for this trial (n=60), which entailed a single intraoperative CT-abdomen and ipsilateral antegrade ureteroscopy when the surgeon felt stone treatment was visually complete. If residual fragments were identified, the surgeon continued nephroscopy to find and remove them; if not, the procedure was concluded. These patients were compared to a retrospective cohort (n=174) who underwent initial PCNL with post-operative imaging performed the following day.

RESULTS

The two cohorts had similar demographic properties and stone characteristics, and location of percutaneous access. In the prospective arm, 50% of intraoperative PCT scans identified residual fragments, prompting continuation of surgery to remove them. This cohort had significantly higher stone-free rate (82% vs. 36%, p<0.01), lower rate of planned reintervention (7% vs. 32%, p<0.01), lower rate of urgent presentation with ureteral obstruction (0% vs. 7%, p=0.04), lower total CT-based effective radiation dose (8.4 vs. 14.6 mSv, p<0.01), and shorter length of stay (2.3 vs. 3.5 days, p<0.01) when compared to the retrospective cohort that did not use intraoperative PCT.

CONCLUSIONS

Obtaining an intraoperative portable CT scan during PCNL can substantially improve perioperative outcomes. Further evaluation of this modality through a randomized-controlled trial is warranted.

Percutaneous Nephrolithotomy with Intraoperative Computed Tomography Scanning Improves Stone-Free Rates

Introduction: The use of fluoroscopy during percutaneous nephrolithotomy (PCNL) may lead to an overestimation of stone-free rates. The objective of this study is to demonstrate the feasibility of intraoperative CT-guided PCNL compared with standard of care (SoC) PCNL. Patients and Methods: A prospective feasibility study (20 patients undergoing PCNL with an intraoperative CT scan between June 2017 and February 2020) and a retrospective study of a historical cohort (20 consecutive patients undergoing SoC PCNL between September 2015 and September 2016) were conducted. All procedures were performed by an expert endourologist in a tertiary referral hospital. Follow-up was performed at 6 weeks postoperatively. The primary goal is to investigate the practicality and potential benefits and harms of intraoperative CT scanning during PCNL. Secondary outcomes are a stone-free rate after the 6-week follow-up, perioperative radiation exposure, the need for postoperative imaging, and peri- and postoperative complications. Statistical significance was considered at p < 0.05. Results: The initial stone-free rate in the CT scan group was 65% (n = 13). In 25% (n = 5) of patients, residual stone fragments were removed after the perioperative CT scan. In the SoC group, 85% (n = 17) of patients were thought to be stone free perioperatively. At the 6-week follow-up, 80% (n = 16) in the CT scan group vs 50% in the SoC group (n = 10) were found to be stone free. Radiation exposure, perioperatively, was higher in the CT scan group. Complications were comparable between groups. Limitations of the study are the nonrandomized design of the study and nonstandardized follow-up imaging. Conclusions: Intraoperative CT scanning during PCNL is feasible and gives a better estimate of any remaining stone fragments compared with fluoroscopy only.

Percutaneous kidney stone surgery and radiation exposure: A review

During the past 3 decades, radiation exposure (RE) has increased drastically among patients undergoing percutaneous nephrolithotomy (PCNL), thus potentially causing new cases of cancer each year. The effective dose received by patients comes from pre- and post-operative computed tomography (CT) and intraoperative fluoroscopy (FL). We reviewed literature to find novel techniques and approaches that help to decrease RE of patients and personnel. We performed PubMed search using keywords percutaneous nephrolithotomy, intraoperative fluoroscopy, radiation exposure, imaging, percutaneous access, ultrasound, computed tomography, endoscopy, reconstruction, innovations, and augmented reality. Forty-four relevant articles were included in this review. As much as 20% of patients with first diagnosed urolithiasis exceed background RE level almost 17-fold. For diagnosing purposes using low-dose and ultra-low-dose CT, as well as low-dose dual energy scan protocols can be efficient ways to decrease RE while maintaining decent accuracy. Patients with urinary stones can be effectively monitored with digital tomosynthesis, ultrasound alone or ultrasound combined with plain film of the abdomen. Percutaneous access (PCA) into the kidney can be performed with reduced or even no RE, using novel PCA methods. REs from conventional imaging techniques during diagnosis and treatment increase probability of non-stochastic radiation effects. Urologists should be aware of protocols that decrease RE from CT and FL in diagnosis and management of urinary stones. Consideration of recently developed imaging modalities and PCA techniques will also aid in adherence to the “as low as reasonably achievable” principle.

Urological technology: where will we be in 20 years' time?

Since prehistoric times, our understanding of urology has rapidly expanded. Whilst primitive urologists began by using urine as a therapeutic substance, modern urologists may find themselves removing a kidney remotely by driving a robotic arm, with seven degrees of movement, while using image overlay-augmented reality. This review provides an insight into the potential status of urological technology in 20 years' time, assessed through an analysis of developments in imaging, diagnostics, robotics and further technologies. A particular emphasis is given to the promising fields of minimally invasive techniques, nanotechnology and tissue engineering, which likely hold the key to a new era for urology.