Late-Gadolinium enhancement MRI acquisition
All patients underwent contrast enhanced MR imaging using a 1.5-T MR
system (Achiva, Philips Medical, Best, The Netherlands) equipped with a
5-channel cardiac coil one to three months before the AF ablation. This
scan technique has been established, and the acquired images were used
for the AF ablation
procedure.8,9First, contrast enhancement–magnetic resonance angiography (CE-MRA) of
the PV–LA anatomy was acquired with a breath-hold 3D fast field echo
(FFE) sequence in the coronal plane during the first pass of a contrast
agent (gadobutrol, Gadovist; Bayer Yakuhin, Osaka, Japan) injection at a
dose of 0.1 mmol/kg. The purpose of the scanning in the coronal plane
was to reduce the number of acquisition slices and shorten the breath
holding time. Then the LGE-MRI of the LA with the PVs was acquired using
a 3D inversion recovery, respiration navigated, electrocardiogram-gated,
T1-FFE sequence in the transverse plane 15 minutes after the contrast
injection, which has been previously reported. The typical parameters
were as follows: repetition time /echo time = 4.7 / 1.5 ms, voxel size =
1.43 × 1.43 × 2.40 mm (reconstructed to 0.63 × 0.63 × 1.20 mm), flip
angle = 15°, SENSE = 1.8, and 80 reference lines. The inversion time
(TI) was set at 280 – 320 ms, using a Look-Locker scan. In case of AF,
the data acquisition was performed with the shortest trigger delay of
cardiac synchronization. In case of sinus rhythm, the data acquisition
was performed during the mid-diastolic phase of the left ventricle. The
typical scan time for the LGE-MRI study was 7 to 12 minutes depending on
the patient’s heart rate and respiration pattern. The images of the
CE-MRA, and LGE-MRI were transferred to customized software (MRI LADE
Analysis; PixSpace Inc, Fukuoka, Japan) for a further image post
processing and image analysis.