INTRODUCTION: The traditional injection method of contrast media (CM) has limitations in terms of volume and imaging quality. Choosing the optimal CM injection method is crucial for ensuring high-quality images and accurate diagnosis in triple-rule-out computed tomography angiography (TRO-CTA). This study aims to investigate the application value of combining region of interest (ROI) with CM injection method alterations in TRO-CTA. METHODS: A total of 596 patients with chest pain, chest tightness, and dyspnea as the primary clinical symptoms, underwent TRO-CTA examinations based on their clinical symptoms and test indicators. These patients were randomly assigned to one of three groups: the traditional group, the modified group, and the high-pitch helical scan (FLASH) group. Key parameters, including computed tomography (CT) values, vascular filling contrast numbers, image noise, signal-to-noise ratio, contrast noise ratio, image scores, CM volume, CM injection rate, radiation dose of the aorta, pulmonary artery, and coronary artery, were systematically compared across the three groups. RESULTS: The CM volume and radiation doses were significantly higher in the traditional group compared to the other groups (P <
0.05). CT values for the aorta and coronary artery in the traditional group were higher than those in the modified and FLASH group, while CT values for the pulmonary artery were lower in the traditional group compared to the modified and FLASH groups (ALL P-value for traditional group versus FLASH group, P-value for modified group versus traditional group <
0.05, P-value for modified group versus FLASH group >
0.05). CONCLUSION: The combination of the modified CM injection method and FLASH scanning mode reduces the required CM volume by nearly 30 mL and significantly decreases radiation dose exposure during the examination. This approach shows valuable potential for improving both the safety and effectiveness of TRO-CTA, with significant implications for clinical practice.