Diffusion MRI: apparent diffusion coefficient (ADC) values in the normal brain and a classification of brain disorders based on ADC values

Diffusion-weighted imaging, dependent on motion of water molecules, provide s information regarding tissue integrity. Apparent diffusion coefficient (A DC) values in the normal brain parenchyma, and those in a variety of lesion s were studied by echo-planar diffusion MRI in 310 cases. Brain disorders w ere classified based on their ADC values, taking the ADC values of the norm al brain white matter as the principal category. In the normal white matter ADC ranges were 0.60-1.05 x 10(-3) mm(2)/s, and the mean ADC value was 0.8 4 +/- 0.11 x 10(-3) mm(2)/s. It was possible to distribute brain disorders, as well as artefacts on diffusion MRI to five major categories: category 1 , ADC similar to normal white matter; category 2, ADC lower than normal whi te matter; category 3, ADC higher than normal white matter; category 4, ADC similar to CSF; and category 5, markedly low or high ADC. Further studies can provide addition of different lesions as well as refinements of these c ategories. (C) 2001 Elsevier Science Ltd. All rights reserved.