Non-contrast-enhanced T₁-weighted MRI of myocardial radiofrequency ablation lesions (original) (raw)

2017, Magnetic Resonance in Medicine

Purpose-To demonstrate imaging of radiofrequency ablation lesions with non-contrastenhanced T 1-weighted (T1w) MRI. Methods-Fifteen swine underwent left ventricular ablation followed by MRI using different preparations: endocardial or epicardial ablation of naïve animal, or endocardial ablation of animal with myocardial infarction. Lesion imaging was performed using free-breathing, non-contrastenhanced, T1w sequence with long inversion time (TI). Also acquired were T 1 maps and delayed contrast-enhanced (DCE) imaging. Hearts were excised for ex vivo imaging, and sliced for gross pathology and histology. Results-All ablations were visibly enhanced in non-contrast-enhanced T1w imaging using TI =700 ms. T1w enhancement agreed with regions of necrosis in gross pathology and histology. Enhanced lesion cores were surrounded by dark bands containing contraction band necrosis, hematoma, and edema. In animals with myocardial infarction, chronic scar was hypointense in T1w, whereas acute ablations were enhanced, allowing discrimination between chronic scar and acute lesions, unlike DCE. Contrast was sufficient to create 3D volume renderings of lesions after minor postprocessing.