Right Atrial Scar Detection after Catheter Ablation: Comparison of 2D and High Spatial Resolution 3D-late Enhancement Magnetic Resonance Imaging

Rationale and Objectives: To prospectively compare the diagnostic performance of two-dimensional (2D) and high spatial resolution three-dimensional (3D) late enhancement magnetic resonance imaging (MRI) for the detection of scar tissue caused by catheter ablation of the right atrium in patients with atrial flutter. Materials and Methods: Forty-seven patients were enrolled. In 16 patients, imaging of the cavotricuspid isthmus was performed before and after catheter ablation, 16 subjects were imaged before, and 15 after catheter ablation, resulting in a total of 63 examinations. MRI included a standard 2D breathhold and a high-resolution navigator-gated 3D T1-weighted gradient-echo inversion-recovery sequence in right and left anterior oblique views. Two readers assessed the subjective image quality on a 4-point scale (1 = excellent) and the presence of late enhancement (blinded/ in consensus). Results: The average image quality was 1.6 for both imaging approaches. In consensus reading, the sensitivity was 83% versus 100%, specificity 97% versus 89%, accuracy 90% versus 94%, positive predictive value 96% versus 89%, negative predictive value 86% versus 100% for 20 and 3D, respectively. The interobserver agreement was 0.86 for 2D and 0.78 for 3D imaging. Conclusions: For the noninvasive identification of scars in the cavotricuspid isthmus after right atrial flutter, ablation 2D imaging was more consistent, whereas 3D sequences showed superior sensitivity for the depiction of late enhancement.