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Sequential Helical-Axial-Helical Triple-Rule-Out CT Angiography: Technical Feasibility and Territory-Specific Image
Yeon-Jun Kim1, Gi-Yong An2, Sung-Jin Cha2
1Department of Human Health Convergence, Graduate School, Kangwon National University, Samcheok 25913, Republic of Korea.
Insights
A new sequential triple-rule-out CT angiography (TRO-CTA) protocol provides excellent enhancement for evaluating coronary, pulmonary, and aortic causes of chest pain. This physiology-based approach ensures diagnostic image quality in emergency settings.
Area of Science:
- Radiology
- Medical Imaging
- Cardiovascular Imaging
Background:
- Conventional triple-rule-out CT angiography (TRO-CTA) protocols face challenges in optimizing contrast enhancement across pulmonary, coronary, and aortic circulations due to conflicting timing requirements.
- Acute chest pain evaluation requires simultaneous assessment of multiple potential pathologies, necessitating efficient and accurate imaging techniques.
Purpose of the Study:
- To evaluate a physiology-based sequential helical-axial-helical acquisition strategy for TRO-CTA.
- To determine if this sequential protocol can achieve consistent tri-territory vascular enhancement in emergency department patients with acute chest pain.
Main Methods:
- Retrospective analysis of 71 emergency department patients undergoing TRO-CTA with a structured sequential protocol (pulmonary, coronary, aortic phases).
- Individualized test-bolus timing guided the sequential acquisition.
- Objective (vascular attenuation, SNR, CNR) and subjective image quality assessments were performed by two radiologists.
Main Results:
- Mean vascular attenuation exceeded diagnostic thresholds in all three territories (pulmonary, coronary, aortic).
- Diagnostic interpretability was achieved in all territories in every examination without repeat contrast imaging.
- Good to excellent interobserver agreement was noted for subjective image quality scores.
Conclusions:
- A sequential physiology-based TRO-CTA strategy is technically feasible and provides consistent enhancement across all three vascular territories in an emergency setting.
- Further prospective comparative and outcome-based studies are needed to confirm the clinical impact of this imaging strategy.
Abstract:
Background/Objectives: Triple-rule-out CT angiography (TRO-CTA) enables simultaneous evaluation of coronary, pulmonary, and aortic causes of acute chest pain, but conventional single-acquisition protocols may compromise vascular enhancement because of conflicting contrast timing requirements. This study evaluated whether a physiology-based sequential helical-axial-helical acquisition strategy could provide consistent tri-territory enhancement in emergency settings. Methods: In this retrospective single-center study, 71 consecutive evaluable emergency department patients (mean age, 66.6 ± 17.0 years; 33 women) with undifferentiated acute chest pain underwent TRO-CTA using a structured sequential protocol (pulmonary, coronary, and aortic phases) guided by individualized test-bolus timing. Objective image quality was assessed using vascular attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR); subjective image quality was independently graded by two radiologists. Results: Mean vascular attenuation exceeded predefined diagnostic thresholds in all territories (pulmonary 546.7 ± 237.8 HU [95% CI, 490.4-603.0]; coronary 438.8 ± 113.9 HU [95% CI, 411.9-465.8]; aortic 604.3 ± 190.9 HU [95% CI, 559.2-649.5]). Diagnostic interpretability was achieved in all three territories in every technically analyzable examination without repeat contrast-enhanced imaging. Median subjective image-quality scores were 5 (IQR, 4-5) for pulmonary, 4.5 (IQR, 4-5) for coronary, and 4 (IQR, 4-5) for aortic phases; interobserver agreement was good to excellent. Mean total DLP was 461.5 ± 122.5 mGy·cm. Conclusions: A sequential physiology-based TRO-CTA strategy is technically feasible in a tertiary emergency setting and provides consistent tri-territory enhancement. Because this was a single-arm technical validation study, prospective comparative and outcome-based studies are required to confirm its clinical impact.
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