Noninvasive assessment of tissue heating during cardiac radiofrequency ablation using MRI thermography.
BACKGROUND
Failure to achieve properly localized, permanent tissue destruction is a common cause of arrhythmia recurrence after cardiac ablation. Current methods of assessing lesion size and location during cardiac radiofrequency ablation are unreliable or not suited for repeated assessment during the procedure. MRI thermography could be used to delineate permanent ablation lesions because tissue heating above 50°C is the cause of permanent tissue destruction during radiofrequency ablation. However, image artifacts caused by cardiac motion, the ablation electrode, and radiofrequency ablation currently pose a challenge to MRI thermography in the heart. In the current study, we sought to demonstrate the feasibility of MRI thermography during cardiac ablation.


RESULTS
An MRI-compatible electrophysiology catheter and filtered radiofrequency ablation system was used to perform ablation in the left ventricle of 6 mongrel dogs in a 1.5-T MRI system. Fast gradient-echo imaging was performed before and during radiofrequency ablation, and thermography images were derived from the preheating and postheating images. Lesion extent by thermography was within 20% of the gross pathology lesion.


CONCLUSIONS
MR thermography appears to be a promising technique for monitoring lesion formation and may allow for more accurate placement and titration of ablation, possibly reducing arrhythmia recurrences.
Kolandaivelu
Aravindan
A
The Johns Hopkins University School of Medicine, Baltimore, MD, USA. akoland1@jhmi.edu
Zviman
Menekhem M
MM
Castro
Valeria
V
Lardo
Albert C
AC
Berger
Ronald D
RD
Halperin
Henry R
HR
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D001831:Body Temperature / Q000502:physiology*; D017115:Catheter Ablation; D003937:Diagnosis, Differential; D004195:Disease Models, Animal; D004285:Dogs; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011300:Preoperative Care; D011379:Prognosis; D055502:Secondary Prevention; D013817:Thermography / Q000379:methods*