Early changes in the apparent diffusion coefficient (ADC) in a mouse model of Sandhoff's disease occur prior to disease symptoms and behavioral deficits.

Sandhoff's disease is a lysosomal storage disease in which the ganglioside GM2 accumulates in lysosomes. It has been reported that MRI cannot detect abnormalities in spin echo images in clinically presymptomatic Sandhoff's disease patients. Because one of the results of GM2 accumulation is cell swelling and lysosomal distension, our goal was to determine if changes in the diffusion of water is perturbed. We utilized the MRI imaging modality diffusion-weighted imaging to measure the apparent diffusion coefficient in a mouse models of Sandhoff's disease, the hexb-/- mouse, and determined if diffusion-weighted imaging could be utilized to detect early changes prior to behavioral or overt disease symptom onset. Here we report for the first time a comprehensive behavioral characterization of the hexb-/- mouse in conjunction with the apparent diffusion coefficient measurement. Our data indicate that the apparent diffusion coefficient decreases in the hexb-/- mouse in many but not all brain regions prior to disease symptoms (<3.5 to 4 months of age) and behavioral deficits (3 months of age). The magnitude of the decrease ranged from 4-18%.