Gadolinium-enhanced MRI accurately evaluated radiofrequency ablation lesions, correlating well with pathological findings during the first three phases of enhancement (r = 0.86 to 0.88, p < 0.001).
Does gadolinium-enhanced MRI accurately evaluate radiofrequency ablation lesions compared to histopathology in a canine model?
Gadolinium-enhanced MRI accurately characterizes radiofrequency ablation lesions, demonstrating distinct wash-in and wash-out kinetics compared to myocardial infarction.
Effect estimate: r = 0.86 to 0.88
p-value: p=< 0.001
OBJECTIVES: This study was designed to evaluate the characteristics of gadolinium-enhanced imaging of radiofrequency ablations. BACKGROUND: Gadolinium-enhanced magnetic resonance imaging (MRI) has been used successfully to evaluate tissue necrosis after myocardial infarction. In electrophysiology, radiofrequency energy is used to create a targeted myocardial necrosis for the treatment of various arrhythmias. METHODS: Using a power-controlled, cooled-tip 7-F catheter system, radiofrequency lesions (10 to 40 W for 30 s) were created on the epicardium of the right ventricle in eight mongrel dogs. After injection of 0.225 mmol/kg gadolinium, T1-weighted fast gradient echo images were obtained during a follow-up of 10 h using an intrathoracic high-resolution coil. Radiofrequency ablations were analyzed on the MR images and compared with gross anatomy and histopathology. RESULTS: Four distinct phases of signal enhancement were observed. After gadolinium injection, radiofrequency lesions were delineated clearly as contrast-free areas of low signal intensity (contrast-to-noise ratio CNR = -21.1 +/- 19.8). Signal enhancement in the lesion periphery started 4.0 +/- 1.8 min after injection and progressively extended toward the lesion center at a rate of 0.02 mm/min. Full delayed enhancement was observed after 98 +/- 21 min (CNR = +17.8 +/- 9.0). During the follow-up period, CNR started to decrease, but the lesions were detectable for as long as 10 h of follow-up. During the first three phases of enhancement, MRI correlated well with the pathological findings (r = 0.88, r = 0.88, and r = 0.86 p < 0.001, respectively). CONCLUSIONS: Radiofrequency ablation can be evaluated accurately by using gadolinium-enhanced MRI, which may allow the noninvasive assessment of procedural success. The dissimilar wash-in and wash-out kinetics compared with myocardial infarction suggest a different pathophysiological process with complete loss of microvasculature.
Dickfeld et al. (2006) studied Radiofrequency ablation lesions (n=8). Gadolinium-enhanced cardiovascular magnetic resonance imaging vs. Gross anatomy and histopathology was evaluated on Correlation of MRI with pathological findings (r = 0.86 to 0.88, p=< 0.001). Gadolinium-enhanced MRI accurately evaluated radiofrequency ablation lesions, correlating well with pathological findings during the first three phases of enhancement (r = 0.86 to 0.88, p < 0.001).