Imaging the 3D Structure of Sinoatrial Node 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 sinoatrial node (SAN). Goal(s): To identify SAN from the surrounding myocardium using RAFF2 and T1ρ maps. Approach: RAFF2, T1ρ, T1 and T2 maps, and MT imaging were performed on ex vivo swine hearths at 7T and 3T. SAN location was validated with Masson’s trichrome histology sections. Results: Relaxation time differences between SAN and myocardium were found in all imaging methods. TRAFF2 and T1ρ demonstrated higher contrast than other methods. SAN can be distinguished as area with elevated relaxation times in TRAFF2 maps. Impact: Detection and visualization of 3D SAN structure can be done using RAFF2 and T1ρ relaxation time maps without contrast agents.