Time to detect periictal hyperperfusion following short acute symptomatic seizures using 1.5-Tesla arterial spin labeling magnetic resonance perfusion imaging

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Background: We evaluated the usefulness of capturing periictal hyperperfusion for the pathophysiological diagnosis of acute symptomatic seizures (ASS) using 1.5-Tesla (T) arterial spin labeling (ASL) perfusion images and examined the relationship between the time from ASS cessation to ASL imaging and the visualization of periictal hyperperfusion.Patients & Methods: In four patients who presented short ASS, we retrospectively analyzed the performance status and findings of 1.5-T ASL with triple post-labeling delays (PLDs) of 1.5, 1.75 and 2.0 s, as well as routine electroencephalography (EEG).Results: In two patients where ASL imaging was performed 1 or 9 h after ASS, periictal ASL hyperperfusion was markedly visualized. In one patient where images were taken 11 h later, fairly good visualization was obtained. The increase in signal intensity peaked at a PLD of 1.5 s and gradually attenuated with PLDs of 1.75 and 2.0 s. However, the areas where the signal remained intense even at a PLD of 2.0 s had a strong anatomical relationship with the lesion. No clear periictal hyperperfusion was visualized on ASL images taken 13 h later. Although paroxysmal discharges were recorded in one patient where EEG was performed 40 min after ASS, no paroxysms were detected in the other three patients whose EEG was recorded 8 h to 2 days later.Conclusion: We consider it appropriate to first perform ASL within 11 h, and then verify the results with subsequent EEG to accurately diagnose the pathophysiology of ASS.