Combined Microstructural Assessment of Progressive Apraxia of Speech by Diffusion Tensor Imaging-Based Tractography and Multi-Shell NODDI

Progressive apraxia of speech (PAOS) is a tauopathy characterized by difficulties with motor speech programming and planning. Grey and white matter (GM & WM) brain regions were interrogated by diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI). Twenty-three patients with PAOS and 22 matched controls underwent diffusion MRI. Global WM differences in PAOS were better attained by intracellular volume fraction (ICVF), whereas GM global differences were better attained by mean diffusivity (MD) and isotropic volume fraction (isoVF). DTI and NODDI represent unique aspects of brain tissue microstructure and can be used as PAOS biomarkers.