Abstract 16028: Contrast Enhancement Dynamics of Radiofrequency Ablation Lesions

Abstract

Introduction: Late gadolinium enhanced MRI (LGE-MRI) done acutely after ablation shows a central area of no-reflow that enhances slowly. The dynamics and predictive value of this region to chronic lesion volume is unknown. Methods: RF lesions were created in a canine ventricle model using a 4 mm irrigated tip catheter. 3D LGE-MRI images were acquired in a 3T (Verio, Siemens) MR scanner (1.25 x 1.25 x 2.5 mm 3 ) at weeks 0, 1, 2, and 4 post ablation at multiple time points after contrast injection (Multihance, 0.15 mmol/Kg). The central no-flow volumes in MRI were normalized to the histological volumes and this ratio was compared across multiple post-contrast injection times. Results: The number of lesions analyzed was 33, 27, 11 and 20 at week 0, 1, 2 and 4, respectively in four animals. Histological volumes had a mean of 99±52 mm 3 (range 32-220 mm 3 ). The initial MRI done within five mins of contrast injection had average no reflow volumes of 330±170 mm 3 for week 0, 270±170 mm 3 at week 1, 120±100 mm 3 at week 2, and 50±46 mm 3 at week 4. The normalized no reflow volumes (normalized to chronic histological volume) for the initial MRI was 4.28±1.44 at week 0, 3.40±1.15 at week 1, 1.94±0.68 at week 2, and 0.65±0.42 at week 4. Based on a logarithmic fit to the decay in volume, the no reflow volume equaled the final histological volume 26.6 mins after contrast injection on day 0, 30.9 mins on week 1, 8.2 mins on week 2 and 0.3 mins after week 4. By one month after ablation, the no-reflow was negligible and the final lesion completely enhanced immediately after contrast injection. Conclusions: The no-reflow volume declines exponentially acutely after ablation and results in an accurate assessment of final lesion volume 26 to 30 minutes after contrast injection up to one week post - ablation. With tissue remodeling, the no reflow area enhances faster such that one month after ablation, lesions enhance completely immediately following contrast injection.