2.2 MRI acquisition
Before the AF ablation, LGE-MRI was performed in all patients using a
1.5T MR system (Achieva; Philips Medical, Best, The Netherlands)
equipped with a 5-channel cardiac coil. This scan technique has been
previously reported.9 First, contrast-enhancement
magnetic resonance angiography (CE-MRA) of the pulmonary vein (PV) -
left atrial (LA) anatomy was obtained in the coronal plane using a
breath-hold three-dimensional (3D) fast field echo sequence after the
injection of 0.1 mmol/kg of a contrast agent (Gadobutrol, Gadovist,
Bayer Yakuhin, Osaka, Japan).10 The purpose of the
scanning in the coronal plane was to reduce the number of acquisition
slices and shorten the breath-hold time. Next, 15 minutes after the
contrast injection, LGE-MRI of the LA including the PVs was performed
using a lateral 3D inversion recovery, respiratory navigation, ECG
gating, and T1-fast field echo sequence.11 The CE-MRA
and LGE-MRI images were transferred to customized software (MRI LADE
Analysis; PixSpace Inc, Fukuoka, Japan) for image post-processing and an
image analysis.