Interictal Brain Perfusion Imaging

All MRI scans were acquired on a 3 T scanner (Discovery MR 750 or Signa Premier, GE Medical Systems, WI, USA), using an 8-channel coil^{34 (link),54 (link),55 (link)}. Anatomical and perfusion images (ASL) were acquired in all cases. Parameters for anatomical image acquisition have been provided in our previous work^{53 (link)}, while those for ASL acquisition were: pseudo-continuous ASL, echo time 10.5–11.2 ms, repetition time 4531–4742 ms, single post labelling delay of 1525 ms, flip angle 111°, averages 3, slice thickness 4 mm, spacing between slices 4 mm, and spiral readout. Quantitative perfusion maps were automatically generated by GE reconstruction software. Children underwent sedation if clinically indicated^{26 (link)}. Since no clinical seizures were noted during the MRI scan, the perfusion patterns shown by the scans were considered to mirror the brain perfusion during the interictal state.