Reliability of cerebral vein volume quantification based on susceptibility-weighted imaging.

INTRODUCTION: Susceptibility-weighted imaging (SWI) visualizes even small cerebral veins and might, therefore, be valuable in monitoring neurological diseases affecting cerebral veins. Since it is generally difficult to evaluate individual results of quantitative MRI measurements, an automatic approach would be highly appreciated to assist the diagnostic process. The aim of this study was to evaluate the rescan and reanalysis reliability using an automatic venous volumetric approach based on SWI in healthy controls. METHODS: SWI was performed in ten healthy controls undergoing MRI examinations using a 32-channel head coil at 3 T five times on five different days. To test for rescan and reanalysis variability, the deep cerebral vein volume was quantified using ANTs and SPM8. RESULTS: Total volumes of cerebral deep veins measured during five MRI scans in ten individuals (n = 50 scans) showed intra-individual volume changes ranging from 0.07 to 1.03 ml (mean variability = 10.2 %). Automatic reanalyses revealed exactly the same results in all scans. CONCLUSION: Automatic SWI-based cerebral vein volumetry shows acceptable rescan-and excellent reanalyses-reliability in healthy volunteers. Therefore, this approach might be beneficial in intra-individual follow-up studies of neurological diseases affecting the cerebral venous system.

Longitudinal Volume Quantification of Deep Medullary Veins in Patients with Cerebral Venous Sinus Thrombosis : Venous Volume Assessment in Cerebral Venous Sinus Thrombosis Using SWI.

PURPOSE: Susceptibility-weighted imaging (SWI) visualizes small cerebral veins with high sensitivity and could, thus, enable quantification of hemodynamics of deep medullary veins. We aimed to evaluate volume changes of deep medullary veins in patients with acute cerebral venous sinus thrombosis (CVST) over time in comparison to healthy controls. METHODS: All magnetic resonance imaging (MRI) experiments were executed at 3 T using a 32-channel head coil. Based on SWI and semiautomatic postprocessing (statistical parametric mapping [SPM8] and ANTs), the volume of deep medullary veins was quantified in 14 patients with acute CVST at baseline and the 6­month follow-up, as well as in 13 healthy controls undergoing repeated MRI examination with an interscan interval of at least 1 month. RESULTS: Deep medullary venous volume change over time was significantly different between healthy controls and patient groups (p < 0.001). Patients with superior sagittal sinus thrombosis (SSST) showed a significant decline from baseline to follow-up measurements (9.8 ± 4.9 ml versus 7.5 ± 4.2 ml; p = 0.02), whereas in patients with transverse sinus thrombosis (TST) and healthy controls no significant volume changes were observable. CONCLUSIONS: Venous volume quantification was feasible and reproducible both in healthy volunteers and in patients. The decrease of venous volume in patients over time represents improvement of venous drainage, reduction of congestion, and normalization of microcirculation due to treatment. Thus, quantification of venous microcirculation could be valuable for estimation of prognosis and guidance of CVST therapy in the future.

Facing the Time Window in Acute Ischemic Stroke: The Infarct Core.

BACKGROUND: Increasing numbers needed to treat within the first hours after ischemic stroke onset indicate a strong time dependency of the viability of brain tissue. However, this time dependency is not reflected in recent randomized controlled trials of endovascular stroke treatment. This study evaluates whether and to which extent a time dependency exists in patients with embolic carotid T or M1 occlusions within the first 6 h of stroke onset. METHODS: Patient data were retrieved from the Freiburg stroke data bank. Time from onset to acquisition of the diffusion weighted images (DWIs) varied between 49 and 357 min. Ischemic lesions were semiautomatically segmented on apparent diffusion coefficient maps with a threshold of 600 × 10 (- 6) mm(2)/s. Occlusion location and thrombus length were determined with magnetic resonance angiography, T2*, and more recently susceptibility weighted image (SWI) sequences. A hyperintense vessel sign in FLAIR images as a possible surrogate for collaterals was also identified. RESULTS: A total of 155 patients with occlusions of the carotid T (n = 26), proximal M1 segment (n = 44), and distal M1 segment (n = 85) of the middle cerebral artery between 2011 and 2015 were included. Infarct volumes varied from 0.3 to 180.2 mL. Infarct size did not correlate with stroke onset to DWI times. Infarct volumes also did not associate with different locations of vessel occlusion, thrombus length, presence of the hyperintense vessel sign and initial infarct growth. CONCLUSION: We found no significant time dependency of the viability of brain tissue with embolic carotid T or M1 occlusions between 1 and 6 h after stroke onset. The early infarction volume is thus probably determined in the hyperacute phase by the quality of leptomeningeal collaterals and comparatively stable in this time period.