Abstract 19530: Functional Assessment of Coronary Artery Disease Using Low-dose Dynamic Computed Tomography Perfusion

Abstract

Introduction: Computed tomographic angiography (CTA) is, despite its limitations, a powerful modality for noninvasive assessment of coronary artery disease (CAD). Current dynamic CT perfusion (CTP) techniques aim to improve CAD assessment, but deliver high radiation doses, limiting their clinical feasibility. Therefore, we propose a low-dose, dynamic CTP technique that allows for vessel-specific, functional assessment of CAD. Methods: A coronary angioplasty balloon was advanced into the proximal left anterior descending (LAD) coronary artery of seven swine (35-45 kg) to induce several levels of stenosis at maximal hyperemia (IC adenosine, 240 μg/min). Reference fluorescence microspheres and IV contrast (370 mg/mL iodine, 25 mL, 7 mL/s) were injected and prospective, ECG-gated dynamic CTP was performed using a 320-slice CT scanner at 100 kVp and 200 mA. Twenty volume scans were acquired per stenosis level for dose comparison to current techniques, but only two volume scans, denoted as V 1 and V 5 , were used for CTP measurement. V 1 was the first volume scan after the aortic input function exceeded a triggering threshold of 180 HU, and V 5 was the fifth volume scan post aortic triggering. All CTP measurements were compared to reference microsphere perfusion measurements using linear regression. Results: The result of dynamic CTP measurement was in good agreement with reference microsphere perfusion measurement (P CTP = 0.91 P MICRO + 0.37, R 2 = 0.85), as shown in the figure. Additionally, the effective dose of the proposed technique using a two-volume scan acquisition protocol was 2.6 mSv; much lower than the ~10 mSv effective dose of current dynamic CTP techniques. Conclusions: The results indicate the potential for substantial dose reduction in dynamic CTP while maintaining measurement accuracy. By reducing the number of volume scans necessary for accurate perfusion measurement, vessel-specific functional assessment of CAD by dynamic CTP is clinically feasible.