Category: Clinical Stones: SWL
Introduction & Objective :
Ultra-low dose CT (ULD-CT) offers superior resolution, with equivalent radiation exposure, to a 2-view KUB. We undertook a retrospective-study to assess the impact of imaging modality (ULD-CT versus KUB) on stone-free-rates (SFR), and subsequent emergency department (ED) utilization and unplanned lithotripsy procedures.
Methods : Medical charts of patients undergoing SWL between Jan-2015 and Jun-2016 were retrospectively reviewed (n=248). All patients underwent KUB/ULD-CT at 3-6 weeks and were followed for 3-6 months; patients lacking follow-up were excluded (n=35). Outcomes studied were: 1. ED-utilization and 2. unplanned lithotripsy procedure, defined as a procedure on the side of the SWL within 3-months following ‘negative’ postoperative imaging.
The patients were well matched on baseline/stone-related characteristics (Table). The SFR in KUB cohort was 78.3% (n=134) and in ULD-CT cohort was 64.2% (n=27 [p=0.057]). 2/27 patients (7.4%) deemed stone-free on ULD-CT returned to ED within 3-months, while 17/134 patients (12.7%) deemed stone-free on KUB returned to ED during the same time-period (p=0.437). 1/27 patient (3.7%) needed an unplanned surgery in the ULD-CT group, while 13/134 patients (9.7%) needed an unplanned surgery in the KUB group (p=0.311; Figure).
ULD-CT may offer a better estimate of true SFR, and may mitigate unwanted ED and return-to-operating-room visits. Prospective studies may be warranted to evaluate this question further.