Dynamics of Water Diffusion Changes in Different Tissue Compartments From Acute to Chronic Stroke—A Serial Diffusion Tensor Imaging Study

Background and Purpose: The immediate decrease of the apparent diffusion coefficient (ADC) is the main characteristic change of water diffusion in acute ischemic stroke. There is only limited information on the time course of diffusion parameters in different tissue compartments of cerebral ischemia.Materials and Methods: In a longitudinal study, we examined 21 patients with acute ischemic stroke by diffusion tensor imaging within 5 h after symptom onset, 3 h later, 2 days, and 1 month after symptom onset. Acute diffusion lesion and the fluid-attenuated inversion recovery (FLAIR) after 2 days were used as volumes of interest to define persistent core, lesion growth, and reversible acute diffusion lesion. For all diffusion parameters ratios between the stroke lesion VOIs and the mirror VOIs were calculated for each time point. ADC ratio, fractional anisotropy ratios, and eigenvalues ratios were measured in these volumes of interest and in contralateral mirror regions at each time points.Results: In the persistent core, ADC ratio (0.772) and all eigenvalues ratios were reduced on admission up to 1 day after stroke and increased after 1 month (ADC ratio 1.067). Within the region of infarct growth time course of diffusion parameter changes was similar, but delayed. In the brain area with reversible diffusion lesion, a partial normalization of diffusion parameters over the time was observed, while after 1 month diffusion parameters did not show the signature of healthy brain tissue. There were significantly different trends for all parameters over time between the three tissue compartments.Conclusion: Diffusion tensor imaging displays characteristic changes of water diffusion in different tissue compartments over time in acute ischemic stroke. Even regions with reversible diffusion lesion show diffusion signatures of persisting tissue alterations

Subjective and objective knowledge and decisional role preferences in cerebrovascular patients compared to controls

Background: Risk knowledge and active role preferences are important for patient involvement in treatment decision-making and adherence. Although knowledge about stroke warning signs and risk factors has received considerable attention, objective knowledge on secondary prevention and further self-esteem subjective knowledge have rarely been studied. The aim of our study was to investigate knowledge and treatment decisional role preferences in cerebrovascular patients compared to controls. Methods: We performed a survey on subjective and objective stroke risk knowledge and autonomy preferences in cerebrovascular patients from our stroke outpatient clinic (n=262) and from pedestrians on the street taken as controls during a “World Stroke Day” (n=274). The questionnaire includes measures for knowledge and decisional role preferences from previously published questionnaires and newly developed measures, for example, subjective knowledge, revealed on a visual analog scale. Results: The overall stroke knowledge was low to moderate, with no differences between patients and controls. Knowledge about secondary prevention was particularly low. Only 10%–15% of participants correctly estimated the stroke absolute risk reduction potential of aspirin. The medical data interpretation competence was moderate in both groups. Age and basic mathematical and statistical understanding (numeracy) were the only independent predictors of objective stroke knowledge, whereas previous stroke had no impact on stroke knowledge. However, patients were thought to be better informed than controls. Approximately 60% of both patients and controls claimed to prefer a shared decision-making approach in treatment decisions. Conclusion: The level of stroke risk knowledge in patients with cerebrovascular diseases was as low as in randomly selected pedestrians, although patients felt better informed. Both groups preferred involvement in treatment decision-making. We conclude that educational concepts for increasing awareness of knowledge gaps as well as for stroke risk and for prevention strategies are needed

Comprehensive analysis of early fractional anisotropy changes in acute ischemic stroke

<div><p>Background and purpose</p><p>Cerebral ischemia leads to a rapid decrease of the apparent diffusion coefficient. For fractional anisotropy both increase and decrease have been reported in acute ischemic stroke. Aim of this study was to characterize early water diffusion changes in a homogenous group of acute stroke patients and to clarify the issue of early fractional anisotropy changes and their relation to time from symptom onset.</p><p>Methods</p><p>MRI data of patients with acute ischemic stroke examined by diffusion tensor imaging within 8h after symptom were analyzed. We calculated fractional anisotropy, eigenvalues and the isotropic and anisotropic components of the diffusion tensor. The values were calculated as ratios between the ischemic lesion and a mirror region in the unaffected side and correlated with clinical parameters.</p><p>Results</p><p>We included 63 patients: 49% female, mean age 69 ± 14 years, median NIHSS on admission 9 (IQR 4–14). For the whole sample, mean fractional anisotropy was increased (ratio: 1.083 ± 0.168), while all other diffusion parameters were decreased. Both the isotropic and anisotropic component of the diffusion tensor were decreased with a more pronounced decrease of the isotropic component (ratios: isotropic = 0.730 ± 0.106, anisotropic = 0.788 ± 0.127; p<0.001). There was no correlation of fractional anisotropy with time from symptom onset. Looking at individual patients, fractional anisotropy was increased in 70%. There were no differences in clinical characteristics between patients with increased and decreased fractional anisotropy.</p><p>Conclusion</p><p>Fractional anisotropy increase in acute stroke results from a more pronounced decrease of the isotropic diffusion component and is not related to time from symptom onset. Thus, fractional anisotropy is not helpful as a surrogate marker of lesion age in the very first hours of stroke.</p></div

Ratio of FA versus p and q.

<p>The ratio of FA is plotted against p and q, showing FA is increasing with increasing q.</p

Ratios of isotropic components (p) versus anisotropic components (q) of the diffusion tensor.

<p>The ratios of isotropic components (p) are plotted against the anisotropic components (q) of the diffusion tensor.</p

Mapping of the eigenvalues as ellipsoids, unaffected side and affected side.

<p>Mapping of the eigenvalues as ellipsoids divided into unaffected side (A) with FA = 0.292 and affected side (B) with FA = 0.313.</p

Values of FA, MD, eigenvalues (λ1, λ2 and λ3) and q divided into affected and unaffected side.

<p>Values of FA, MD, eigenvalues (λ1, λ2 and λ3) and q divided into affected and unaffected side.</p