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Characterization of edema after cryo and radiofrequency ablations based on serial magnetic resonance imaging.

ABSTRACT: INTRODUCTION:Radiofrequency (RF) and cryoablation are routinely used to treat arrhythmias, but the extent and time course of edema associated with the two different modalities is unknown. Our goal was to follow the lesion maturation and edema formation after RF and cryoablation using serial magnetic resonance imaging (MRI). METHODS AND RESULTS:Ventricular ablation was performed in a canine model (n?=?11) using a cryo or an irrigated RF catheter. T2-weighted (T2w) edema imaging and late gadolinium enhancement (LGE)-MRI were done immediately (0?day: acute), 1 to 2 weeks (subacute), and 8 to 12 weeks (chronic) after ablation. After the final MRI, excised hearts underwent pathological evaluation. As a result, 45 ventricular lesions (cryo group: 20; RF group: 25) were evaluated. Acute LGE volume was not significantly different but acute edema volume in cryo group was significantly smaller (1225.0?±?263.5 vs 1855.2?±?520.5?mm3 ; P?=?0.01). One week after ablation, edema still existed in both group but was similar in size. Two weeks after ablation there was no edema in either of the groups. In the chronic phase, the lesion volume for cryo and RF in LGE-MRI (296.7?±?156.4 vs 281.6?±?140.8?mm3 ; P?=?0.73); and pathology (243.3?±?125.9 vs 214.5?±?148.6?mm3 ; P?=?0.49), as well as depth, was comparable. CONCLUSIONS:When comparing cryo and RF lesions of similar chronic size, acute edema is larger for RF lesions. Edema resolves in both cryo and RF lesions in 1 to 2 weeks.

SUBMITTER: Yamashita K

PROVIDER: S-EPMC6363882 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Characterization of edema after cryo and radiofrequency ablations based on serial magnetic resonance imaging.

Yamashita Kennosuke K Kholmovski Eugene E Ghafoori Elyar E Kamali Roya R Kwan Eugene E Lichter Justin J MacLeod Robert R Dosdall Derek J DJ Ranjan Ravi R

Journal of cardiovascular electrophysiology 20181121 2

<h4>Introduction</h4>Radiofrequency (RF) and cryoablation are routinely used to treat arrhythmias, but the extent and time course of edema associated with the two different modalities is unknown. Our goal was to follow the lesion maturation and edema formation after RF and cryoablation using serial magnetic resonance imaging (MRI).<h4>Methods and results</h4>Ventricular ablation was performed in a canine model (n = 11) using a cryo or an irrigated RF catheter. T2-weighted (T2w) edema imaging and ...[more]

PMID: 30375090

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Project description:BACKGROUND:Myocardial edema in acute myocardial infarction (AMI) is commonly imaged using dark-blood short tau inversion recovery turbo spin echo (STIR-TSE) cardiovascular magnetic resonance (CMR). The technique is sensitive to cardiac motion and coil sensitivity variation, leading to myocardial signal nonuniformity and impeding reliable depiction of edematous tissues. T2-prepared balanced steady state free precession (T2p-bSSFP) imaging has been proposed, but its contrast is low, and averaging is commonly needed. T2 mapping is useful but requires a long scan time and breathholding. We propose here a single-shot magnetization prepared sequence that increases the contrast between edema and normal myocardium and apply it to myocardial edema imaging. METHODS:A magnetization preparation module (T2STIR) is designed to exploit the simultaneous elevation of T1 and T2 in edema to improve the depiction of edematous myocardium. The module tips magnetization down to the -z axis after T2 preparation. Transverse magnetization is sampled at the fat null point using bSSFP readout and allows for single-shot myocardial edema imaging. The sequence (T2STIR-bSSFP) was studied for its contrast behavior using simulation and phantoms. It was then evaluated on 7 healthy subjects and 7 AMI patients by comparing it to T2p-bSSFP and T2 mapping using the contrast-to-noise ratio (CNR) and the contrast ratio as performance indices. RESULTS:In simulation and phantom studies, T2STIR-bSSFP had improved contrast between edema and normal myocardium compared with the other two edema imaging techniques. In patients, the CNR of T2STIR-bSSFP was higher than T2p-bSSFP (5.9?±?2.6 vs. 2.8?±?2.0, P?<?0.05) but had no significant difference compared with that of the T2 map (T2 map: 6.6?±?3.3 vs. 5.9?±?2.6, P?=?0.62). The contrast ratio of T2STIR-bSSFP (2.4?±?0.8) was higher than that of the T2 map (1.3?±?0.1, P?<?0.01) and T2p-bSSFP (1.4?±?0.5, P?<?0.05). CONCLUSION:T2STIR-bSSFP has improved contrast between edematous and normal myocardium compared with commonly used bSSFP-based edema imaging techniques. T2STIR-bSSFP also differentiates between fat that was robustly suppressed and fluids around the heart. The technique is useful for single-shot edema imaging in AMI patients.

Dataset Information

Characterization of edema after cryo and radiofrequency ablations based on serial magnetic resonance imaging.

Publications

Characterization of edema after cryo and radiofrequency ablations based on serial magnetic resonance imaging.

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