Abstract 17376: Novel Non-contrast MRI Technique for Visualization of Ablation Lesions
Introduction: Late gadolinium enhanced MRI (LGE-MRI) is widely used to assess RF ablation lesions. However, this technique requires contrast injection and lesion visibility changes with time after injection. Non-contrast T1-weighted (T1w) MRI is only applicable to reliably visualize acute (< 7 days) RF lesions.
Hypothesis: T2*-weighted MRI can be used to visualize ablation lesions.
Methods: Novel non-contrast MRI technique for sub-acute (> 7 days) lesion visualization has been developed. This T2*-weighted technique exploits the difference in susceptibility between normal and ablated myocardium. Transformation of hemoglobin from blood vessels damaged during ablation into hemosiderin reduces T2* of ablated tissues. To validate the proposed technique RF ablations were performed in 3 canines using ThermoCool catheter (Biosense Webster) at 30 Watts for 30 seconds. Imaging studies were performed on a 3T MRI scanner (Verio, Siemens) at 0, 1, 4, and 8 weeks post-ablation. Scan protocol included T1w, T2*, and LGE scans with resolution of 1.25x1.25x2.5 mm.
Results: Representative T1w, T2*, and LGE images are shown in Figure 1. All RF lesions (n=13) were readily detectable on non-contrast T1w images acquired acutely (Fig. 1a). Lesion visibility in T1w was drastically reduced 1 week post-ablation (Fig. 1b). Visibility of the lesions in T2* images improves with time after ablation (Fig. 1c-e). Lesions have hypointense boundaries in T2* images acquired 1 and 4 weeks post-ablation. Whole lesions are hypointense in T2* images acquired 8 weeks post-ablation. Strong correlation (R2=0.9747) between lesions volumes estimated from LGE and T2* acquired 8 weeks post-ablation was found (Fig. 2).
Conclusions: Non-contrast T2* technique for visualization of RF ablations has been developed and validated. The technique can be used to detect RF lesions as early as a week post-ablation. T2* contrast of the lesions improves with time after ablation as amount of hemosiderin increases.
Author Disclosures: E.G. Kholmovski: Research Grant; Significant; Marrek Inc.. Ownership Interest; Modest; Marrek Inc.. Consultant/Advisory Board; Modest; Marrek Inc. R. Ranjan: Consultant/Advisory Board; Significant; Biosense Webster. N. Angel: None. N. Marrouche: Ownership Interest; Significant; Marrek Inc.. Consultant/Advisory Board; Significant; Biosense Webster.
- © 2015 by American Heart Association, Inc.