Non-invasive Quantification of Atrial Fibrosis by MRI in Atrial Fibrillation

Three groups of patients will be considered: a control group (n = 10); a group of patients with paroxysmal or persistent AF with AF cryoablation procedure - within this group, MRI will replace CT-scan usually performed in routine before the procedure (n = 15); a group of patients with permanent AF (n = 15). MRI study will include pulmonary veins angiography with gadolinium injection (0.20 mmol/kg), 2D-cine imaging and late-enhancement imaging. A 3D gradient-echo sequence(Flash 3-D) will then be applied 20 minutes after the injection, with the following parameters : echo time 0.98 ms, repetition time 2.53 ms, angle 15°, resolution 2.0x1.3x1.0 mm. T1 map and two T2 sequences will be performed so as to determine LA relaxation times. Argus software will be used for post-treatment imaging. Quantitative data will be expressed in mean ± SD. A comparison of T1 and T2 values in LA will be performed between the three groups. Statistics will be performed with SPSS software in bilateral analysis and a value of p \< 0.05 will be considered as significant.