Objectives Coronary CT angiography (CCTA) using retrospective helical scanning allows for cardiac function but requires high radiation exposure. This study aimed to investigate the optimal timing and feasibility of low-dose cine CT during the recirculation phase of the contrast agent. Materials and methods We conducted a retrospective analysis of MR perfusion examinations in 38 patients to determine the recirculation timing of the contrast agent, and, based on the findings of the MR perfusion study, a feasibility study of a low-dose cine CT during the recirculation phase was performed for 51 patients with suspected or known coronary artery disease. Results The MR perfusion study identified approximately 20 s after the contrast peak in the left ventricle (19.5 ± 4.3 HU) as the optimal recirculation time of contrast agent, with no significant correlation between left ventricular function and the timing. In cine CT images, CT values within the left (290.2 ± 42.1 HU) and right (264.1 ± 36.9 HU) ventricles were almost identical during the recirculation phase, with better contrast (p < 0.001) in the right atrium and ventricle compared to first-pass CCTA images. Cine CT showed high inter-rater reliability for left and right ventricular function assessment and better diagnostic performance than echocardiography for myocardial infarction assessment. The combined dose for CCTA (2.0 mSv) and cine CT (0.9 mSv) was 2.9 mSv. Conclusion A brief cine CT acquisition added to CCTA, timed to contrast recirculation, provides global and regional left ventricular function at a small incremental radiation dose (approximately 1 mSv). This single-visit protocol is a valuable alternative when echocardiography or MRI access is restricted or multiple examinations are not feasible. Key Points <Emphasis Type="BoldItalic">Question</Emphasis> This study aimed to investigate the optimal timing and feasibility of low-dose cine CT during the recirculation phase of the contrast agent. <Emphasis Type="BoldItalic">Findings</Emphasis> A 20-s recirculation time enabled low-dose cine CT (0.9 mSv) that allowed for effective cardiac function assessment. <Emphasis Type="BoldItalic">Clinical relevance</Emphasis> When coronary CT is already indicated, a short cine acquisition can provide complementary functional information and may reduce additional testing in selected patients. Graphical Abstract

Single-visit cardiac functional assessment by cine CT added to CCTA: segment-level validation of low-dose recirculation timing protocol

期刊论文
发表日期：

2025年11月20日

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Naoki Nagasawa,
Satoshi Nakamura,
Naoki Hashimoto,
Akio Yamazaki,
Yoshitaka Goto,
Suguru Araki,
Shintaro Yamaguchi,
Hajime Sakuma,
Kakuya Kitagawa

摘要

Objectives

Coronary CT angiography (CCTA) using retrospective helical scanning allows for cardiac function but requires high radiation exposure. This study aimed to investigate the optimal timing and feasibility of low-dose cine CT during the recirculation phase of the contrast agent.

Materials and methods

We conducted a retrospective analysis of MR perfusion examinations in 38 patients to determine the recirculation timing of the contrast agent, and, based on the findings of the MR perfusion study, a feasibility study of a low-dose cine CT during the recirculation phase was performed for 51 patients with suspected or known coronary artery disease.

Results

The MR perfusion study identified approximately 20 s after the contrast peak in the left ventricle (19.5 ± 4.3 HU) as the optimal recirculation time of contrast agent, with no significant correlation between left ventricular function and the timing. In cine CT images, CT values within the left (290.2 ± 42.1 HU) and right (264.1 ± 36.9 HU) ventricles were almost identical during the recirculation phase, with better contrast (p < 0.001) in the right atrium and ventricle compared to first-pass CCTA images. Cine CT showed high inter-rater reliability for left and right ventricular function assessment and better diagnostic performance than echocardiography for myocardial infarction assessment. The combined dose for CCTA (2.0 mSv) and cine CT (0.9 mSv) was 2.9 mSv.

Conclusion

A brief cine CT acquisition added to CCTA, timed to contrast recirculation, provides global and regional left ventricular function at a small incremental radiation dose (approximately 1 mSv). This single-visit protocol is a valuable alternative when echocardiography or MRI access is restricted or multiple examinations are not feasible.

Key Points

Question This study aimed to investigate the optimal timing and feasibility of low-dose cine CT during the recirculation phase of the contrast agent.

Findings A 20-s recirculation time enabled low-dose cine CT (0.9 mSv) that allowed for effective cardiac function assessment.

Clinical relevance When coronary CT is already indicated, a short cine acquisition can provide complementary functional information and may reduce additional testing in selected patients.

Graphical Abstract