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.
Keywords: Cardiac computed tomography; Coronary CT angiography; Image quality; Process change; Radiation.
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