LAUSR

Transluminal attenuation gradient (TAG)-defined as the gradient of the contrast agent attenuation drop along the vessel-is an imaging biomarker that indicates stenosis in the coronary arteries. Coupling TAG (or contrast dispersion along the vessel) with fluid dynamics, TAFE (transluminal attenuation flow encoding) equation is a theoretical platform that quantifies blood flow in each coronary artery based on computed tomography angiography (CTA) imaging. However, this theoretical concept has never been validated experimentally. The aim of this proof-of-principle phantom study is to validate TAFE based on CTA imaging. Dynamic CTA images were acquired every 0.5 seconds. The average TAFE estimated flowrates were compared against four predefined pump values in a straight ( 20, 25, 30, 35 and 40 ml/min) and a tapered phantom (25, 35, 45 and 55 ml/min). Using TAFE formulation with no correction, the flowrates were underestimated by 33% and 81% in the straight and tapered phantoms, respectively. The TAFE formulation was corrected for imaging artifacts focusing on partial volume averaging and radial variation of contrast enhancement. After corrections, the flowrates estimated in the straight and tapered phantoms had an excellent Pearson correlation of r=0.99 and 0.87 (p<0.001), respectively with only a 0.6%?0.2 ml/min difference in estimation of the flowrate. In this proof-of-concept phantom study we corrected the TAFE formulation and showed a good agreement with the actual pump values. Future clinical validations are needed for feasibility of TAFE in clinical use.