Welcome to the WSC 2021 Interactive Program

Background and Aims

Thrombus perviousness and length are important thrombus imaging characteristics related to outcome in patients with anterior circulation ischemic stroke. We investigated the association of thrombus characteristics with reperfusion and functional outcome in patients with posterior circulation stroke (PCS) who underwent endovascular treatment (EVT).

Methods

Thrombus imaging characteristics (perviousness, density, and length) were measured in patients with PCS registered in the MR CLEAN Registry between 2014-2018. All characteristics were assessed on thin-slice (<2.5mm) non-contrast computed tomography and computed tomography angiography imaging acquired within 30 minutes from each other. We compared thrombus characteristics in patients with or without excellent reperfusion (expanded Treatment In Cerebral Ischemia (eTICI) score ≥2C) and with or without favorable functional outcome (modified Rankin Scale score (mRS) 0-3) using the Mann-Whitney U-test.

Results

Sixty-six patients were analyzed. Median thrombus perviousness was 7 (IQR -1-21) Hounsfield Units (HU). Median density was 54 (IQR 44-66) HU and median length was 24 (IQR 15-42) mm. No significant between-group differences were found in thrombus characteristics (Table 1).

Conclusions

In this study of patients with PCS treated with EVT, thrombus imaging characteristics were not associated with reperfusion or functional outcome.

Background and Aims

To validate the reliability and efficiency of clinical diagnoses in practice based on a well-established system for automatic segmentation of Cerebral Microbleed (CMB).

Methods

This is a retrospective study based on MRI-SWI data sets from 1615 patients. All patients had been diagnosed with cerebral small vessel disease (CSVD) with clear cerebral microbleeds (CMBs) on MRI-SWI. The patients were divided into training, and validation cohorts of 1,285 and 330 patients respectively. The model training data were labeled layer by layer according to the consensus from two neuroradiologists with 15 years of work experience. After that, a three-dimensional convolutional neural network (CNN) was applied to the MRI data from the training and validation cohorts to construct a deep learning system (DLS) tested with the 72 patients, independent above the MRI cohort. The DLS tool was used as a segmentation program for these 72 patients. These results were evaluated and revised by 5 neuroradiologists and given an output analysis divided into Miss labeling, and Wrong labeling. The inter-rater agreement kappas test was used for quality analysis.

Results

The DLS achieved a Dice coefficient of 0.72. In the independent data's clinical evaluations, the neuroradiologists reported that more than 95% of the lesion could be directly detected, less than 5% of lesions were wrong labeled or miss labeled by our DLS. The inter-neuroradiologist-DLS agreement kappa value reaches 0.79 on average.

Conclusions

Automatic detection and segmentation of CMBs are feasible. The proposed well-trained DLS system could be a trusted tool for the segmentation and detection of CMB lesions.

Background and Aims

The cortico-spinal tract (CST) and cortico-cerebellar tract (CCT) are known as biomarkers for upper extremity (UE) recovery after stroke. Understanding this relationship may help to predict UE recovery and give useful information for treatment strategies of stroke patients.

Methods

Forty-two first-ever ischemic stroke patients, who had diffusion tensor imaging at two weeks and motor function assessment using Fugl-Meyer Assessment scale at two weeks and three months after onset, were included. Individual data were preprocessed, and functional anisotropy (FA) maps were generated using the FSL. To obtain region-specific FA values, the posterior limb of the internal capsule (PLIC), cerebral peduncle (CP), and superior cerebellar peduncle (SCP) were extracted from the JHU ICBM-DTI-81 atlas. The FA value in combined PLIC and CP regions and the FA value in the SCP region were used as the CST and CCT integrity, respectively. The linear regression was used to identify the relationship and predictive accuracy.

Results

The CST integrity had predictive values (p=0.0015) of UE recovery, but the CCT integrity was not (p=0.3350). In the multivariate model, there were interaction effects between the CST and CCT integrity (p=0.0241). Predictive accuracy using an interaction term of the CST and CCT integrity was higher than using the CST integrity only (CST*CCT; R²=0.360, CST; R²=0.224).

Conclusions

In UE recovery of stroke patients, the significance of the CCT depended on the CST integrity. Considering both CST and CCT may improve prediction accuracy of UE recovery of stroke patients. This study was supported by NRF grants (NRF-2020R1A2C3010304, NRF-2020R1C1C1011688), Republic of Korea.

Background and Aims

Ultrahigh-field strength 7 Tesla (7T) MRI provides a high signal to noise ratio which allows higher spatial resolution imaging and consequently its availability, for the first time allows visualisation of the very small perforating (Lenticulostriate, LSA) arteries non-invasively in humans. Using Time-of-Flight MR angiography technique, 7T MRI can be used to obtain angiographic imaging of these small cerebral vessels. The aim of this study was to visualize LSA arising from the Middle Cerebral and Anterior Cerebral arteries using ToF MRA at 7T.

Methods

Pilot study of 5 healthy subjects (mean age 39.4±19.2 years) with no history of neurological disease or vascular pathology who underwent 3D ToF MRA technique on a whole-body human 7T MR system equipped with a 32-channel receive coil. Set protocols were modified in between subject scans to achieve the best possible resolution, with scan time of 10 minutes. LSAs were identified on axial and coronal maximum intensity projections of 15mm thickness.

Results

The images showed good contrast between the LSAs and the background. On average, 5.0±1.2 stems and 7.2±1.5 branches of LSAs were visualized on both left and right sides. Across all LSAs identified, mean length was 22.6±9.9 mm. 3D volume rendered images of the ToF MRA (image) was used to ensure landmarks and confirm LSA origin.

Conclusions

This pilot study shows our ability to visualise LSAs using 7T ToF MRA. This technique can be exploited in understanding the underlying arterial pathology in patients with lacunar infarcts caused by cerebral small vessel disease stroke.

Clinical Trail Registration: https://clinicaltrials.gov/ct2/show/NCT04330222