High-pitch free-breathing triple rule-out CT angiography for acute chest pain: a prospective sequential two-cohort comparison of radiation dose and diagnostic image quality.

OBJECTIVES: To evaluate the feasibility of high-pitch free-breathing triple rule-out CT angiography (TRO-CTA) by comparing image quality and radiation dose with a standard breath-hold protocol in patients with acute chest pain. MATERIALS AND METHODS: This prospective study enrolled 104 patients with acute chest pain who underwent TRO-CTA on a third-generation dual-source CT scanner, sequentially allocated to high-pitch free-breathing TRO-CTA (pitch = 3.2; Group A, n = 52) or standard breath-hold TRO-CTA (standard pitch; Group B, n = 52). Objective image quality (attenuation, noise, signal-to-noise ratio [SNR], and contrast-to-noise ratio [CNR]) was assessed across the coronary, pulmonary, and aortic territories. Subjective image quality (3-point scale), effective dose (ED), acquisition time, and clinical diagnoses were compared between groups. RESULTS: Radiation dose (ED: 1.81 ± 1.33 vs 15.63 ± 6.71 mSv) and acquisition time (0.48 ± 0.05 vs 6.83 ± 1.87 s) were significantly lower in Group A than in Group B (all p < 0.001). Vascular attenuation was significantly higher in Group A in the coronary arteries, main pulmonary artery, and ascending aorta (p < 0.05), whereas CNR was higher in Group B (all p < 0.01). Subjective image quality scores, including coronary diagnostic segment rates (98.0% vs 97.5%), were comparable across all vascular territories (all p > 0.05). Clinical diagnoses were similarly distributed between groups (p = 0.455). CONCLUSION: High-pitch free-breathing TRO-CTA substantially reduces radiation dose while preserving comparable diagnostic image quality, offering a clinically feasible low-dose alternative to standard breath-hold protocols for emergency patients with acute chest pain, particularly those with well-controlled heart rates. KEY POINTS: Question: Conventional TRO-CTA involves high radiation exposure (8.93-17.5 mSv) and breath-holding, posing safety and feasibility challenges in emergency patients with acute chest pain. FINDINGS: The high-pitch free-breathing protocol reduced effective dose by 88% and acquisition time from 6.83 to 0.48 s while providing comparable diagnostic image quality. Critical relevance statement: High-pitch free-breathing TRO-CTA may offer a low-dose imaging option on dual-source CT, with the potential to support more time-efficient emergency evaluation of acute chest pain.