Ultra-low Dose Intraoperative CT During Endoscopic Stone Surgery: A Quality Improvement Study.

OBJECTIVES
To improve care in patients with large kidney stones using advanced intraoperative imaging techniques to reduce perioperative radiation exposure, improve stone-free rates (SFR), and reduce the number of surgical interventions in a quality improvement (QI) study.


PATIENTS AND METHODS
Patients with kidney stones appropriate for percutaneous nephrolithotomy (PCNL) treatment were scheduled into a hybrid operating room for endoscopic surgery (PCNL and/or ureteroscopy (URS)) with intent to perform intraoperative CT (ICT). Imaging was performed using an Artis Zeego Care+Clear™ (Siemens) robotic-armed multi-planar fluoroscopy system (RMPFS) with collimation to the level of the affected kidney(s). After the initial case, the proprietary CARE™ (Combined Applications to Reduce Exposure) protocol was used. When the hybrid room was unavailable, a mobile CT scanner (O-Arm, Medtronics) was used in the traditional room (n=2).


RESULTS
31 ICTs were performed in 23 consecutive patients during endoscopic stone procedures with a median effective radiation dose (ERD) of 1.39 mSv per scan, significantly less than the pre-operative non-contrast CT (12.02 mSv) in the same patients (p<0.001). Longitudinal radiation exposure associated with stone treatment significantly decreased by 83% (15.80 to 2.68 mSv, p<0.001) compared to a similar historical PCNL cohort. Clinically significant residual stones (≥3 mm) were identified at initial ICT in eight patients (35%) and further treated in six patients. One patient had missed residual stones diagnosed 34 days afterwards, which was apparent after reviewing ICT. Thus, final verified SFR was 87% for all stages. Mean number of procedures improved from 1.77 to 1.30 (p=0.05) and rate of post-operative CT scans improved from 82% to 26% (p<0.001).


CONCLUSION
Ultra-low-dose (ULD) ICT was demonstrated to simultaneously improve SFR and number of staged treatments, and greatly reduce the perioperative radiation dose for our patients. The findings support the continued use of this modality to benefit all patients with large stones.