4.2 AWT on MRI images
Recently, computed tomography (CT) images have been used to estimate the AWT.14 Despite its high spatial resolution, CT is inherently low in soft-tissue contrast, making the detection of atrial borders very difficult. The use of iodine-based contrast agents can increase the contrast of the endocardial borders, however, identifying the epicardial borders remains challenging. Even if the fact that MRI is noninvasive and provides superior soft-tissue contrast compared to CT, few MRI-based studies have been reported to measure the AWT of the LA in AF patients. A previous study regarding the LA wall thickness measured by CT images demonstrated that the mean LA wall thickness in chronic AF and paroxysmal AF was 2.1± 0.2 mm and 2.4 ± 0.2 mm, respectively.14 In this study, the AWT measured by MRI was 2.22±0.25 mm in 15 persistent AF patients, in good agreement with the previous study.