A diffusion tensor MRI study of patients with MCI and AD with a two year clinical follow up

Elisa Scola (1) , Marco Bozzali (2) , Federica Agosta (1) , Giuseppe Magnani (1) , Massimo Franceschi (3) , Maria Pia Sormani (4) , Mara Cercignani (5) , Elisabetta Pagani (1) , Monica Falautano (1) , Massimo Filippi (1) , Andrea Falini (1)

1 Scientific Institute and University Ospedale San Raffaele, Milan
2 Santa Lucia Foundation, IRCSS, Rome
3 Multimedica-Santa Maria, Castellanza
4 UniGe - Università degli studi di Genova = University of Genoa
5 UCL - University College of London [London]

Objective. We assessed whether brain changes detected by DT-MRI can improve the understanding of structural damage in AD, and are associated with different risks of conversion to AD in amnestic MCI (aMCI). Methods. Twenty-one aMCI, 21 AD, and 20 controls underwent conventional and DT-MRI at baseline. All subjects were clinically followed up over two years; at the end of follow up, aMCI were grouped into converters to AD (aMCI-C) and nonconverters (aMCI-NC). Mean diffusivity (MD) and fractional anisotropy (FA) were obtained from total grey (GM) and white matter (WM), and from GM and WM regions of interest (ROIs). On T1-weighted images, normalised volumes of the whole brain (NBV), GM (NGMV) and WM were measured. Results. A significant “trend” of worsening with a trajectory “normal/aMCI/AD” was found for NBV and NGMV, total GM and WM MD, total WM FA, as well as for diffusivity abnormalities in several GM and WM ROIs, mainly located in posterior brain regions. aMCI-C had GM and WM changes similar to those seen in AD, whereas aMCI-NC showed a DT-MRI pattern similar to that of controls. DT-MRI metrics that better distinguished aMCI-C from aMCI-NC were MD of total GM and WM, hippocampi, anterior insulae, frontal and parietal WM, and occipital GM and WM, and FA of temporal WM. Volumetric variables were not able to distinguish the two aMCI subgroups. Conclusions. Subtle brain diffusivity changes occur from the prodromal stages of AD, mainly in posterior brain regions, and spread over the course of the disease to involve the frontal lobe. In aMCI, the severity of microstructural damage within and beyond the medial temporal lobe is associated with an increased short-term risk to develop AD.

Mots clés: ALZHEIMER'S DISEASE; DEMENTIA; MRI

Elisa Scola, Marco Bozzali, Federica Agosta, Giuseppe Magnani, Massimo Franceschi, et al.. A diffusion tensor MRI study of patients with MCI and AD with a two year clinical follow up. Journal of Neurology, Neurosurgery and Psychiatry, 2010, 81 (7), pp.798. ⟨10.1136/jnnp.2009.189639⟩. ⟨hal-00557412⟩