Brain MRI
Brain MRI was performed within 2 days after the procedure using a 1.5
Tesla (T) scanner (Achieva 1.5T Nova Dual; Philips Healthcare, Best, The
Netherlands) with an 8-channel brain coil, or a 3 T scanner (Ingenia 3T;
Philips) with a dS head coil, or a Vantage Titan 3T (Canon Medical
Systems Corporation, Otawara, Japan) with a 16- or a 32-channel coil to
defect SCEs. In each patient, axial diffusion-weighted imaging was
performed using single-shot, spin-echo, echo planar imaging with twob values of 0 and 1000 sec/mm2 and three
diffusion directions. Other scan parameters were as follows: repetition
time/echo time 3600-5100/83-98 msec, 112-176×128-256 matrix,
288-512×288-512 reconstruction matrix, 220×220 mm field of view, slice
thickness 5.0mm, slice gap 1.0 mm, and 1-4 excitations. The apparent
diffusion coefficient map (ADC-map) was obtained to prevent the
over-detection of T2 shine-through effects on diffusion-weighted
imaging.
The definition for diagnosing SCE was based on the detection of new
hyperintense lesions of the diffusion-weighted MRI with hypointense
findings of the ADC-map according to a neuroimaging expert’s
recommendation.11 MRI images were independently
evaluated by certified radiologists in a blinded manner. A neurological
examination was performed on hospital admission and after the ablation
procedure by certified neurologists or certified physicians blinded to
the MRI findings. The neurological dysfunction was evaluated using the
National Institutes of Health Stroke Scale (NIHSS) and the modified
Rankin Scale (mRS).