Impact of an institutional process change adopting end-systolic coronary CTA acquisition and automated dose selection on patient throughput and image quality

Abstract

Introduction

Guidelines recommend prospective ECG-triggered mid-diastolic coronary computed tomographic angiography (CCTA) acquisition after achieving optimal heart rate (HR) control in order to optimize scan image quality. With dual-source CCTA, prospective end-systolic acquisition has been shown to be less prone to motion artifacts at higher heart rates and may improve scan and CT laboratory efficiency by allowing CCTA without routine pre-scan beta-blocker (BB) administration.

Methods

We implemented an institutional process change in CCTA performance effective January 2023, comprising a transition from prospective ECG-triggered mid-diastolic acquisitions individually supervised by a physician at the scanner to an algorithmic approach predominately utilizing prospective end-systolic acquisition (200–400 ​ms after R peak), employing an automated dose selection algorithm, without BB administration. All scans were performed on a third-generation 192-slice dual-source scanner. We reviewed 300 consecutive CCTAs done pre- and post-process change in Jan 2022 (phase 0), Jan 2023 (phase 1), and in May 2023 (phase 2) after implementation of a process improvement involving more selective utilization of automated tube potential/current algorithms (CARE kV) to optimize image quality. Coronary segmental image quality was assessed by two experienced CCTA readers by consensus using an 18-segment SCCT model on a 5-point Likert scale (1 ​= ​non-interpretable; 2 ​= ​poor; 3 ​= ​acceptable; 4 ​= ​good; 5 ​= ​excellent). Measures of radiation dose, medication administration, and time required for patient scanning were compared. Logistic regression was used to determine factors associated with patient-level reduction in image quality (IQ) and with repeat scans.

Results

Post-process change, there was a significant reduction in the median overall patient appointment [phase 0: 95 (75–125) min vs. phase 1: 68 (52–88) min and phase 2: 72 (59–90) min; P ​< ​0.001] and scan times [phase 0: 13 (10–16) min vs. phase 1: 8 (6–13) min and phase 2: 9 (7–13) min; P ​< ​0.001]. Median IQ score in both post-process change phases was 4 (4–5) compared to a median score of 5 (4–5) pre-process change (P for comparison <0.001). The majority of segments post-process change had “good” IQ (Phase 1 segmental IQ scores: 5 ​= ​36.7 ​%, 4 ​= ​46.8 ​%, 3 ​= ​13 ​%, 2 ​= ​2.6 ​%, 1 ​= ​0.9 ​%; Phase 2 segmental IQ scores: 5 ​= ​26 ​%, 4 ​= ​49.7 ​%, 3 ​= ​16.3 ​%, 2 ​= ​6.1 ​%, 1 ​= ​1.9 ​%), whereas pre-process change, the majority of segments had “excellent” IQ (Phase 0 segmental IQ scores: 5 ​= ​56 ​%, 4 ​= ​34.3 ​%, 3 ​= ​7.5 ​%, 2 ​= ​1.8 ​%, 1 ​= ​0.4 ​%) There was no significant increase in non-interpretable scans at the patient level. The 22 ​% re-scan rate in phase 1 (vs. 6 ​% in phase 0, P ​= ​.002) improved to 15 ​% in phase 2. While patient related factors of body mass index [adjusted OR obese 2.64, 95 ​% CI 1.12–6.51, P ​= ​0.03; aOR morbidly obese 6.94, 95 ​% CI 2.21–23.52, P ​= ​0.001] and average HR [aOR (per 10 bpm increase) 1.51, 95 ​% CI 1.21–1.9, P ​< ​0.001] were associated with the scoring of any segment as ​≤ ​3 ​at the patient level in a fully adjusted model, the improved phase 2 of the process change was not [aOR 1.61, 95 ​% CI 0.78–3.32].

Conclusion

Implementation of an institutional process change utilizing prospective ECG-triggered dual-source end-systolic acquisition avoided the use of beta-blockers, significantly reduced patient appointment and scan times with acceptable diagnostic performance.