The role of isotropic diffusion MRI in children under 2 years of age

Our objective was to determine the contribution of diffusion MR imaging to standard MR imaging in the neuroradiological evaluation of children less th an 2 years of age. Echo-planar diffusion MR imaging was added to standard M R exams in 75 consecutive patients under the age of 2 years. Single-shot ec ho-planar spin-echo T2 weighted images (EPSE-T2) were acquired. Isotropic d iffusion-weighted images (DWT), attenuation coefficient maps (ACM), and app arent diffusion coefficient (ADC) maps were caIculated offline from images obtained with diffusion gradients (b = 1000 s/mm') in three orthogonal dire ctions. Two neuroradiologists determined if EPSE-T2, DWI, or ACM contribute d new information to spin-echo proton density (SE PD) and T2 studies, In 15 of IS abnormalities detected in 8 patients with symptoms less than 1 week in duration, DWI and/or ACM added information to SE PD and T2. Diffusion se quences detected five new lesions, showed six lesions with greater conspicu ity, and identified four lesions with different diffusion character. In pat ients with symptoms of more than 7 days duration, diffusion studies added n o information. Isotropic diffusion MR contributed to lesion detection and c haracterization in infants when symptoms were less than 1 week in duration. Diffusion MR is useful in patients with leukodystrophies, metabolic disord ers, and patients with acute ischemic lesions.