Patient-specific timing acquisition for coronary CT angiography: A retrospective patient validation study.

Purpose: To retrospectively validate a patient-specific post-trigger delay technique for coronary CT angiography (CCTA) and compare it with the conventional fixed-delay approach using true peak arterial enhancement as the reference standard. Methods: Thirty-seven patients (mean age 63 ± 9 years; 35% male) who underwent dynamic CT perfusion imaging were retrospectively analyzed. Serial volumetric acquisitions were obtained during and after intravenous administration of 40-50 mL iodinated contrast. Time-attenuation curves from the descending aorta and major coronary arteries (LAD, LCx, RCA) were modeled using a gamma variate function to determine true time-to-peak enhancement (TTP), peak attenuation, and contrast-to-noise ratio (CNR). Coronary enhancement was simulated using (1) a fixed 5-second post-trigger delay and (2) a patient-specific delay defined as half the injection duration plus a dispersion constant. True peak enhancement was used as the reference standard. Timing accuracy and enhancement differences were evaluated using paired statistical analyses. Results: The patient-specific delay predicted peak coronary enhancement with a mean deviation of -0.80 ± 0.85 s, maintaining enhancement and CNR within 10% of peak values. The fixed 5-second delay showed a larger deviation (-2.11 ± 0.82 s; p < 0.001) and reduced coronary enhancement (-37%) and CNR (-27%) relative to peak (p < 0.05). Improvements were consistent across all coronary arteries. Conclusion: Injection-duration-based patient-specific timing more accurately predicts peak coronary enhancement than a fixed-delay strategy and improves CCTA contrast enhancement and CNR without increasing radiation dose or workflow complexity.