Evaluation of the Consistency of Peri-ictal Hemodynamic Findings Revealed by Capturing More Than 3 Seizures Using 1.5-Tesla Pseudo-continuous Arterial Spin Labeling Magnetic Resonance Perfusion Imaging with Triple Post-labeling Delays: Report of 3 Cases

In the pathophysiological diagnosis of seizures in neuro-emergencies, the usefulness of arterial spin labeling perfusion imaging, which can be performed 24 hr a day, 7 days a week, in capturing peri-ictal hyperperfusion has been reported as a means of compensating for the limitations of electroencephalography, which is available only during regular hours. Herein, we retrospectively evaluated the consistency of arterial spin labeling findings in conjunction with electroencephalography findings in 3 patients with 3 or more seizures. Patients 1 and 2 both experienced 3 seizures and were transported outside of regular hours. On arterial spin labeling, consistent peri-ictal hyperperfusion was observed in the right posterior quadrant with a close anatomical relationship to the epileptogenic lesion in Patient 1 and in the right occipitotemporal lobe without an identifiable epileptogenic lesion in Patient 2. Subsequent electroencephalography failed to reveal any paroxysmal discharges. Patient 3 experienced 4 seizures. Electroencephalography performed immediately after the third seizure demonstrated ictal discharges in the right frontal region, while the other electroencephalography recordings showed paroxysmal discharges and rhythmic slow waves in the same region. In arterial spin labeling, hyperperfusion was observed in the right frontal lobe only during the second seizure, whereas hypoperfusion was observed in the same region during the other seizures. This pattern was likely attributable to an early transition from ictal hyperperfusion to postictal or interictal hypoperfusion, and was therefore considered a consistent arterial spin labeling finding. Although consistent peri-ictal hyperperfusion is commonly observed on arterial spin labeling, hypoperfusion may also be observed; as such, comprehensive evaluation, including electroencephalography findings, is required for accurate diagnosis.