Abstract
Morphologic evolution of recent small subcortical infarcts (RSSI) ranges from lesion disappearance to lacune formation and the reasons for this variability are still poorly understood. We hypothesized that diffusion tensor imaging (DTI) and blood-brain-barrier (BBB) abnormalities early on can predict tissue damage 1 year after an RSSI. We studied prospectively recruited patients with a symptomatic MRI-defined RSSI who underwent baseline and two pre-specified MRI examinations at 1–3-month and 1-year post-stroke. We defined the extent of long-term tissue destruction, termed cavitation index, as the ratio of the 1-year T1-weighted cavity volume to the baseline RSSI volume on FLAIR. We calculated fractional anisotropy and mean diffusivity (MD) of the RSSI and normal-appearing white matter, and BBB leakage in different tissues on dynamic contrast-enhanced MRI. Amongst 60 patients, at 1-year post-stroke, 44 patients showed some degree of RSSI cavitation on FLAIR, increasing to 50 on T2- and 56 on T1-weighted high-resolution scans, with a median cavitation index of 7% (range, 1–36%). Demographic, clinical, and cerebral small vessel disease features were not associated with the cavitation index. While lower baseline MD of the RSSI (rs = − 0.371; p = 0.004) and more contrast leakage into CSF (rs = 0.347; p = 0.007) were associated with the cavitation index in univariable analysis, only BBB leakage in CSF remained independently associated with cavitation (beta = 0.315, p = 0.046). Increased BBB leakage into CSF may indicate worse endothelial dysfunction and increased risk of tissue destruction post RSSI. Although cavitation was common, it only affected a small proportion of the original RSSI.
Highlights
Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Chancellor’s Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK 3 UK Dementia Research Institute, The University of Edinburgh, Edinburgh, UK 4 Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK 5 Academic Section of Geriatric Medicine, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UKRecent small subcortical infarcts (RSSIs) are the neuroimaging correlate of acute lacunar strokes, which make up to 25% of all ischemic strokes [1, 2]
dynamic contrastenhanced (DCE) MRI data were unavailable in one patient, 60 patients contributed to cavitation and diffusion tensor imaging (DTI), and 59 to blood-brain barrier (BBB) analysis
Most patients with a symptomatic RSSI had some degree of cavity formation on highresolution, isotropic T1 MRI sequences 1 year after the index stroke event
Summary
Isotropic, high-resolution T1 sequences increase the sensitivity of detecting small lacunar lesions following an RSSI, yielding some degree of cavitation in > 90% [3, 5]. A promising candidate is diffusion tensor imaging (DTI) by indicating the initial severity of ischemia and of microstructural (dis)integrity [9] Another candidate is dynamic contrastenhanced (DCE) MRI as increased general blood-brain barrier (BBB) leakage in subcortical tissues and into CSF has been seen in patients with more severe microvascular brain changes [10, 11], and could be associated with increased focal morphological damage following an RSSI. We hypothesized that (1) more severe DTI abnormalities of the RSSI at baseline and (2) greater BBB leakage 1–3-month post-stroke on DCE MRI would be associated with more severe focal tissue destruction 1 year after an RSSI. We used a high-resolution T1 sequence to increase the sensitivity for detecting cavity formation and quantified the amount of “total tissue destruction” as the ratio of the T1 cavity volume at year 1 and the FLAIR infarct volume at baseline, which we termed the cavitation index
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