Comparing brain structural and perfusion MRI changes across ALS-FTD continuum

Introduction Clinical, genetic, and pathological findings suggest a close relationship between amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). This study is aim to compare brain structural and perfusion MRI changes across the spectrum between ALS and ALS-FTD. Methods An age- and sex matched sample of 20 healthy controls (HC), 27 ALS patients without dementia and 11 ALS-FTD patients were included. All subjects underwent a brain MRI, including structural images, arterial spin labeling and diffusion tensor imaging. Whole-brain voxel-based analyses were conducted to study the patterns of cortical atrophy, cerebral blood flow (CBF) and microstructural white matter changes within the three groups. Results The comparison of grey matter, CBF, fractional anisotropy (FA) and mean diffusivity (MD) between ALS and HC revealed no differences. ALS-FTD patients showed widespread cortical atrophy, decreased CBF, reduced FA and increased MD compared to HC and ALS. The hypoperfusion region of ALS-FTD patients agreed with those of significant grey matter loss, including bilateral frontal lobe, temporal lobe, and precentral gyrus. White matter changes mainly located in bilateral corticospinal tract and corpus callosum. It is noteworthy that, in term of all four kinds of data, ALS-FTD with HC and ALS-FTD with ALS, revealed a similar pattern of significant alterations, and changes were more widespread in the former comparison. Conclusion Perfusion changes corresponded well with structural changes in motor and extramotor areas in patients with ALS-FTD. Both structural and perfusion MRI findings lend support to the concept of ALS-FTD disease continuum.