Carlo Augusto Mallio MD, Presenter: Nothing to Disclose

Ruben Schmidt, Abstract Co-Author: Nothing to Disclose

Fabrizio Vernieri, Abstract Co-Author: Nothing to Disclose

Bruno Beomonte Zobel MD, Abstract Co-Author: Nothing to Disclose

Carlo Cosimo Quattrocchi MD, PhD, Abstract Co-Author: Nothing to Disclose

Martijn P. Van den Heuvel, Abstract Co-Author: Nothing to Disclose

To test whether structural connectivity impairment is centered on enthorinal cortex and hippocampus in Patients with diagnosis of alzheimer’s disease (AD) and amnestic mild cognitive impairment (aMCI).

Fifteen healthy controls (HC), 14 amnestic mild cognitive impairment (aMCI), 13 mild, and 15 moderate AD patients, participated in this study. Images were acquired using a 1.5 Tesla MRI system (Avanto B13, Siemens, Erlangen, Germany), including a T1 weighted MPRAGE (Magnetization Prepared Rapid Acquisition with Gradient Echo) and DTI obtained using b values of 0 and 1000 mm2/s and gradients applied in 12 different directions. White matter pathways were reconstructed for each subject, using the Fiber Assignment by Continuous Tracking (FACT) algorithm. We a priori selected the enthorinal cortex and the hippocampus as disease epicenter and calculate the percentage of affected connections directly linking to the epicenter (first ring) and to nodes with topological distance = 2 from the epicenter (second ring). Connections with a lower average strength (t-test, p < 0.05, uncorrected) in the patient group compared to the HC group were labeled as affected. For each of the three patient groups, the analysis was repeated for 10,000 random permutations of group assignments (i.e., HC or patient) to test for significance of the findings.

The analysis of number of streamlines yielded 5.2% of affected connections in the first ring (p = 0.1013) and 2.9% in the second ring (p = 0.1739) for aMCI; 20% of affected connections in the first ring (p = 0.0001) and 10.6% in the second ring (p = 0.0001) for mild AD; 37.9% of affected connections in the first ring (p < 0.0001) and 17.5% in the second ring (p < 0.0001) for moderate AD.

The results of this study show epicentral disruption of structural connectivity in aMCI and AD. Enthorinal cortex and hippocampus together form a good target to be considered as epicenter of structural connectivity impairment in aMCI and AD.

The pathways linking to nodes with lowest topological distance from the epicenter are prone to the most structural damage also reflecting disease progression from aMCI to moderate AD.

Mallio, C, Schmidt, R, Vernieri, F, Beomonte Zobel, B, Quattrocchi, C, Van den Heuvel, M, Epicentral Disruption of Structural Connectivity in Alzheimer’s Disease.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017123.html