Diffusion anisotropy measurements in ischaemic stroke of the human brain.

Magnetic resonance diffusion imaging was performed on 12 patients presenting with symptoms of acute ischaemic stroke (1-6 days post-ictus). Apparent diffusion coefficient (ADC) and diffusion anisotropy measurements were obtained from ischaemic and contralateral normal regions. ADC measurements were decreased by around 40% in ischaemic regions, indicated by an average stroke to normal ratio of 0.56 +/- 0.04 (p < 0.0001). The measured anisotropy was shown to be significantly increased in ischaemic regions, using both standard deviation and volume ratio anisotropy indices, which gave stroke to normal ratios of 1.78 +/- 0.27 (p = 0.003) and 0.87 +/- 0.05 (p = 0.005) respectively. The effects of gradient interactions, image registration, noise contamination and rotational variance and their implications for the results obtained in this study are discussed.