Visualization and Quantification of the Atrioventricular Conduction Axis Structure Using Rotating Frame Relaxation Maps in the Swine Heart

Motivation: Rotating frame relaxation mapping can detect fibrotic tissue and may offer contrast agent-free method for imaging the cardiac conduction system. Goal(s): To identify atrioventricular conduction axis (AVCA) structure from myocardium and central fibrous body (CFB) using TRAFF2 and T1ρ maps. Approach: TRAFF2, T1ρ, T1 and T2 maps, and MT imaging were performed on ex vivo swine hearts. AVCA structures were validated with Masson's trichrome histology sections. Results: Relaxation time differences between AVCA, myocardium and CFB were found in all imaging methods. TRAFF2 and T1ρ demonstrated higher contrast and stronger correlation with histology compared with other methods. Impact: AVCA structure can be visualized using RAFF2 and T1ρ relaxation time maps without contrast agents.