Background:
Mechanical properties of coronary arteries (CA) hold clues to vascular health and viability. Traditionally assessed with intracoronary imaging, we present an angiography-based system to assess CA vasomotion using automatic vessel segmentation and spatio-temporal tracking. Elastic moduli computed from dynamic CA calibers are compared between non-KD patients (CTL), KD patients with no CA aneurysms (KDAN-), and those with aneurysms (KDAN+).
Methods:
Proximal CA angiograms are automatically segmented and tracked over a cardiac cycle. CA centerline is extracted and the mean caliber is computed from diameters along its length. The resulting caliber variation reflects the CA vasomotion (Figure 1a). We then calculated the Vasomotion Standard Deviation (VSD) and CA recoil with the mean constriction velocity (MCV). Finally, Elastic Pressure moduli were computed using trans-myocardium pressure gradients.
Results:
We analyzed 51 left CA segments from 23 patients (5 CTL, 5 KDAN-, 13 KDAN+). Data are mean ± SD normalized pixels (npx). VSD was significantly reduced (
p
<0.01) in KDAN+ (0.25±0.05) and KDAN- (0.27±0.04) vs CTL (0.38±0.07 npx). Coronary recoil was significantly reduced (p<0.05) in KDAN+ vs CTL, with MCV 3.50±0.67 vs 4.59±1.94 npx/sec. Pressure-dependent stiffness characteristics were equally atypical (Figure 1b).
Conclusion:
The proposed angiography-based stiffness assessment system shows abnormal CA vascular physiology in our cohort of KD patients. These results concur with previous invasive studies. The potential usability of this system for vascular health assessment could be applied to previously recorded CA angiograms for risk stratification.
Continuous, Full-scope, Spatio-temporal Tracking Metric based on KL-divergence
