Intraoperative Cone-beam CT for Percutaneous Nephrolithotomy

Percutaneous nephrolithotomy (PCNL) is a first-line treatment for kidney stones >2cm. Frequently, patients require multiple procedures to address their stone burden. The decision to proceed with a second-look procedure is based on follow-up CT imaging, which is obtained postoperatively. In this study, we propose the use of a portable CT scan technology to obtain follow-up imaging while the patient is still under anesthesia for the initial procedure. The goal of this study is to determine whether this allows the surgeon to identify residual fragments and render the patient stone-free within a single anesthetic event.

Percutaneous nephrolithotomy (PCNL) is considered a first-line management option for kidney stones larger than two centimeters. Unfortunately, because of the large stone burden, up to 70% of these patients are left with residual stone fragments after their initial PCNL. Additionally, an estimated 20% to 60% of such patients ultimately require further interventions due to residual stone fragments. The need for a subsequent procedure is determined by postoperative abdominal computed tomography (CT) imaging, which is routinely performed on the first postoperative day at this institution. The decision to proceed with a second procedure is based on findings from this postoperative CT scan. Cone-beam CT (CBCT) is a novel portable imaging technique that can allow cross-sectional imaging to be obtained intraoperatively, rather than post-operatively. Incorporating this modality would allow the surgeon to determine whether the procedure should be continued, in the event of residual fragments, or if it can be safely concluded. This would obviate the need for dedicated postoperative CT scans and, more importantly, reduce the need for subsequent procedures and consequently decrease the patient's length of stay.

This arm will receive cone beam CT to perform an abdomen-pelvis CT scan immediately following initial percutaneous nephrolithotomy, before the patient emerges from general anesthesia, to allow the surgeon to determine whether additional work is needed or whether the procedure can be concluded without requiring further imaging or future interventions.

This arm will contain a retrospective cohort of patients who underwent surgery prior to the enrollment of the intervention arm. These patients received the standard of care, namely helical CT postoperative day one.

The percentage of patients experiencing Clavien-Dindo Grade III-V complications related to the patients' surgery

The percentage of patients who are rendered without residual kidney stone burden after their surgery based on CT scan

Inclusion Criteria: Patients >18 years old Scheduled for percutaneous nephrolithotomy with stone fragmentation (laser/ultrasonic/mechanical) For the prospective intervention arm, willingness to consent to participate in the study Exclusion Criteria: Patients whose habitus does not allow for the use of the cone beam CT machine Patients whose stones only reside within the mid or distal ureter(s) and thus would not be easily imaged with cone beam CT Patients who have had lithotripsy on their renal unit within the prior 90 days Pregnant patients

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