The Cerebrovascular Reactivity Adjusted Fractional Amplitude of Low-Frequency Fluctuations Abnormalities in Middle Cerebral Artery Stenosis and Occlusive Disease

This study investigated the variation characteristics of static fractional amplitude of low-frequency fluctuations (sfALFF) and dynamic fALFF (dfALFF) in Middle cerebral artery stenosis or occlusion(MCA-S) patients, and explored these two indicators alterations with cerebrovascular reactivity (CVR) correction. A total of 41 MCA-S patients and 50 matched controls underwent resting-state functional MRI and neuropsychological testing. Group differences in sfALFF/dfALFF were compared between the two groups, and the brain regions with differences in sfALFF/dfALFF with and without CVR correction were explored. Subsequently, partial correlation analysis was employed to evaluate the correlation between the abnormal brain regions and neuropsychological assessments. After CVR correction, MCA-S patients displayed increased sfALFF in Vermis_6, ipsilesional Cerebelum_8, Hippocampus, and other regions, alongside elevated dfALFF in Vermis_7, ipsilesional Hippocampus, and contralesional Cerebelum_8 (P < 0.001). No significant correlations were found between fALFF metrics and neuropsychological scores post-Bonferroni correction. Uncorrected analyses showed group differences in sfALFF/CVR within ipsilesional Occipital_Mid and Parietal_Inf, while CVR-adjusted results revealed changes in ipsilesional Cerebelum_8 and contralesional Caudate (P < 0.05). For dfALFF, uncorrected differences emerged in ipsilesional Postcentral, whereas CVR correction highlighted ipsilesional Temporal_Inf alterations. In summary, MCA-S patients exhibited abnormal neuronal activity associated with both sfALFF and dfALFF. With CVR correction, vascular confounding effects on the BOLD signal were partially mitigated, thereby enabling more accurate reflection of underlying neural activity alterations.