Application of amplitude of low-frequency fluctuation in non-lesional epilepsy: a blood oxygenation level dependent functional MRI study

Abstract

Objective To study the changes of amplitude of low-frequency fluctuation (ALFF) in blood oxygenation level dependent functional MRI (BOLD-fMPI) in non-lesional epilepsy (NLE),and discuss its underlying neurophysiological mechanism. Methods The BOLD-fMRI data of 16 patients with NLE and 15 normal volunteers were analyzed by ALFF. The amplitude of the blood oxygenation level dependent activation of the resting state brain was investigated. The brain structures showing increased and decreased ALFF in NLE patients were demonstrated by comparing to normal subjects with 2-sample t-test with threshold of P＜0.05. Results As compared with those in normal subjects,the regions showing increased ALFF in NLE patients were distributed in the right temporal lobe (Montreal Neurological Institute [MNI] coordinates:x=15,y=90,z=21),medial frontal lobe (MNI coordinates:0,24,-24),ventral anterior cingulated (MNI coordinates:-12,30,27) and right cerebellar hemisphere (MNI coordinates:-51,-57,-4); while the regions showing decreased ALFF covered the areas of the left cerebellar hemisphere (MNI coordinates:-48,-15,39),posterior cingulum gyrus (MNI coordinates:60,-21,33) and precuneus (MNI coordinates:-6,-54,66). Conclusion NLE patients show abnormal brain functional organization in resting state; the increased ALFF is considered to be the facilitation such as epileptic activity generation and propagation,while the decreased ALFF might be considered as the functional inhibition in these regions. Key words: Epilepsy; Functional magnetic resonance imaging; Amplitude of low-frequency fluctuation