Implementation of Ultra-Low-Dose CT for Renal Stone Surveillance Was Associated With Reduced Ultrasound and...

Renal stone surveillance often relies on ultrasound and radiography of the kidney, ureter, and bladder (KUB) because of concerns about CT radiation and cost, despite CT's superior accuracy. Limited awareness and accessibility of ultra-low-dose (ULD) CT contributes to underuse. The aim of this study was to reduce ultrasound use for renal stone monitoring by 30%, with KUB tracked secondarily, without increasing Medicare-allowed amount through the implementation of a ULD CT protocol.

Using the Six Sigma define, measure, analyze, improve, and control framework, a multidisciplinary team analyzed baseline imaging patterns and identified key drivers of ultrasound and KUB overuse: radiation concerns and lack of awareness and accessibility. Interventions included incorporating a tin-filter ULD CT protocol and recommending CT for surveillance imaging. Imaging utilization and costs were monitored in three phases (baseline, implementation, and sustained adoption).

Implementation of the ULD CT protocol reduced mean radiation dose by 66% (from 5 to 1.7 mSv) compared with standard low-dose noncontrast CT. Compared with the baseline, in the sustained adoption phase, ultrasound utilization decreased from a median of 35 examinations per month (interquartile range [IQR], 30-36) to 10 examinations per month (IQR, 8.5-18), representing a 71.4% reduction (P = .002); KUB utilization decreased from a median of 15.0 examinations per month (IQR, 9-19) to 4.0 examinations per month (IQR, 3-5.5) (P = .005); and ULD CT increased from a median of 0 examinations per month (IQR, 0-0) to 43.5 examinations per month (IQR, 32.5-58.5) (P < .001). The Medicare global fee for combined ultrasound and KUB was $133.59 compared with $180.82 for ULD CT, an absolute difference of $47.23, not accounting for potential additional time and coordination associated with two radiology visits for ultrasound- and KUB-based surveillance.

Implementing ULD CT standardized renal stone surveillance reduced ultrasound and KUB use but had a modest increase in cost difference in Medicare-allowed amount. Findings support the broader adoption of ULD CT and aligning with updated national guidelines.