Real-time magnetic resonance-guided radiofrequency ablation and lesion evaluation in an magnetic resonance-compatible isolated beating pig heart platform

Figure 1. MR-compatible isolated beating pig heart platform setup. A: The PhysioHeart platform (LifeTec) was adapted to enable MR compatibility for detailed cardiac assessment. The explanted heart was perfused through a closed circuit, incorporating both preload and afterload to provide a physiologically realistic simulation. Venous blood (depicted in blue) was first heated and oxygenated outside the MR room, after which it was returned to the setup for perfusion (depicted in red). B: Photo of the MR-compatible isolated beating pig heart platform on the scanner table in the MR room. C: Photo of the isolated beating pig heart, resting on the posterior RF receive flex coil. D: Photo of the anterior RF receive flex coil placed on top of the isolated beating pig heart. Ao = aorta; CO2 = carbon dioxide; LA = left atrium; LV = left ventricle; PA = pulmonary artery; MR = magnetic resonance; MRI = magnetic resonance imaging; O2 = oxygen; PV = pulmonary vein; RF = radiofrequency; RV = right ventricle.

Figure 2. Real-time MR-guided ablation catheter navigation using 2D and 3D visualization. A: Real-time 2D active catheter imaging within the pig heart. The ablation catheter stands out owing to a clear susceptibility artifact, with microcoils near the catheter tip producing a pronounced “halo” effect. B: A combination of 2D active catheter imaging and 3D active catheter tracking displayed as an overlay within the NorthStar system. The rendered tip of the catheter displayed can be seen in the left ventricular cavity. C: Ablation targeting the lateral wall of the left ventricle. The catheter projection is visible within the 3D anatomic shell, showing precise positioning. D: Ablation details become visible when the mouse hovers over the ablation point, providing contextual information. E and F: Images of the interventionalist navigating the ablation catheter inside the left ventricle, guided by real-time MR imaging and the 3D anatomic shell. MR = magnetic resonance; 2D = 2-dimensional; 3D = 3-dimensional.

Figure 3. Ventricular radiofrequency ablation lesion characterization using T1 mapping. A, C, and E: Ventricular short-axis gray-scale T1 mapping acquisition data, showing the preablation baseline (A) and postablation images (C and E). Arrows highlight ablation lesions, which appear as a low signal-intensity core surrounded by a high signal-intensity border. B, D, and F: Ventricular short-axis parametric T1 maps, illustrating the preablation baseline (B) and postablation images (D and F). Regions of interest indicate T1 mapping values of the lesion cores used in quantification.

Figure 4. Histologic ablation lesion assessment and comparison with CMR mapping. A histologic representation of the ablation lesion, highlighting a distinct biphasic pattern comprising a lesion core and peripheral zone, as demonstrated by gross pathology and phosphotungstic acid-hematoxylin staining. This biphasic architecture is corroborated by corresponding T1 and T2 parametric maps, underscoring the integration of imaging and histologic findings. CMR = cardiovascular magnetic resonance.