K Sakai1, K Yamada, Y Nagakane, S Mori, M Nakagawa, T Nishimura. 1. Center for Promotion of Excellence in Higher Education, Kyoto University, Yoshidanihonmatsu-cho, Sakyo-ku, Kyoto City, Kyoto 606-8501, Japan. sakai@mbox.kudpc.kyoto-u.ac.jp
Abstract
BACKGROUND AND AIMS: The apparent diffusion coefficient (ADC) and anisotropy (eg, fractional anisotropy (FA)) of ischaemic tissue evolve over time. A reduction in diffusivity (ie, lambda(2) and lambda(3)) is an important marker for characterising hyperacute-stage infarction, as these parameters may reflect axonal membrane status. The study examines whether transverse diffusivity could be useful in assessing white matter infarcts of various ages. METHODS: Diffusion tensor imaging data from 44 adult patients (34 men, 10 women, aged 46 to 89 years, mean = 70.3) with acute white matter infarction (1-168 h) of the internal capsule were analysed. Relative eigenvalues were calculated as: (lambda(ipsi)-lambda(contra))/lambda(contra). Lesions were classified based on theoretically expected evolution of diffusivity over time as follows: stage I, FA higher than the contralesional region of interest (ROI); stage II, diffusivity lower than the contralesional side for all eigenvalues; stage III, one of two transverse eigenvalues (lambda(2) or lambda(3)) higher than the contralesional ROI. RESULTS: Stage I infarcts (n = 5) were found primarily within 24 h of the onset of symptoms, with one case found on the third day. Stage II infarcts were found most commonly within 24 h (n = 18), and fewer after 24 h. After the first day, the ratio of stage III infarcts increased significantly. Thus, diffusivity-based classification of white matter infarcts seems to show a chronological trend. CONCLUSIONS: Diffusion anisotropy may be useful for defining the biological tissue clock of white matter infarctions.
BACKGROUND AND AIMS: The apparent diffusion coefficient (ADC) and anisotropy (eg, fractional anisotropy (FA)) of ischaemic tissue evolve over time. A reduction in diffusivity (ie, lambda(2) and lambda(3)) is an important marker for characterising hyperacute-stage infarction, as these parameters may reflect axonal membrane status. The study examines whether transverse diffusivity could be useful in assessing white matter infarcts of various ages. METHODS: Diffusion tensor imaging data from 44 adult patients (34 men, 10 women, aged 46 to 89 years, mean = 70.3) with acute white matter infarction (1-168 h) of the internal capsule were analysed. Relative eigenvalues were calculated as: (lambda(ipsi)-lambda(contra))/lambda(contra). Lesions were classified based on theoretically expected evolution of diffusivity over time as follows: stage I, FA higher than the contralesional region of interest (ROI); stage II, diffusivity lower than the contralesional side for all eigenvalues; stage III, one of two transverse eigenvalues (lambda(2) or lambda(3)) higher than the contralesional ROI. RESULTS: Stage I infarcts (n = 5) were found primarily within 24 h of the onset of symptoms, with one case found on the third day. Stage II infarcts were found most commonly within 24 h (n = 18), and fewer after 24 h. After the first day, the ratio of stage III infarcts increased significantly. Thus, diffusivity-based classification of white matter infarcts seems to show a chronological trend. CONCLUSIONS: Diffusion anisotropy may be useful for defining the biological tissue clock of white matter infarctions.
Authors: Ahmed Shereen; Niza Nemkul; Dianer Yang; Faisal Adhami; R Scott Dunn; Missy L Hazen; Masato Nakafuku; Gang Ning; Diana M Lindquist; Chia-Yi Kuan Journal: J Cereb Blood Flow Metab Date: 2010-12-08 Impact factor: 6.200
Authors: Benjamin N Groisser; William A Copen; Aneesh B Singhal; Kelsi K Hirai; Judith D Schaechter Journal: Neurorehabil Neural Repair Date: 2014-02-11 Impact factor: 3.919