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.