Identification of White Matter Lesions in Patients With Acute Ischemic Lesions Using U-net

Shuai Liu; Xiaomeng Wu; Shengji He; Xiaowei Song; Fei Shang; Xihai Zhao

doi:10.3389/fneur.2020.01008

Identification of White Matter Lesions in Patients With Acute Ischemic Lesions Using U-net

Front Neurol. 2020 Sep 30:11:1008. doi: 10.3389/fneur.2020.01008. eCollection 2020.

Authors

Shuai Liu¹, Xiaomeng Wu², Shengji He², Xiaowei Song³, Fei Shang², Xihai Zhao¹

Affiliations

¹ Department of Biomedical Engineering, Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing, China.
² Department of Biomedical Engineering, School of Life Science, Beijing Institute of Technology, Beijing, China.
³ Department of Neurology, School of Clinical Medicine, Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing, China.

Abstract

Background: White matter lesions (WML) have been proved to be significantly associated with many brain diseases. Precise evaluation of burden of WML at early stage could provide insights in the prognosis and assist in intervention. However, acute ischemic lesions (AIL) exhibit hyperintensities on FLAIR images either, and are detected by diffusion weighted imaging (DWI). It is challenging to identify and segment WML in the patients with WML and AIL. Convolutional neural network (CNN) based architecture has been validated as an efficient tool for automatic segmentation. This study aimed to evaluate the performance of U-net in evaluation of WML in the patients with WML and AIL. Methods: A total of 208 cases from Chinese Atherosclerosis Risk Evaluation (CARE II) study were recruited in the present study. All subjects underwent imaging of FLAIR and DWI on 3.0 Tesla scanners. The contours of WML delineated by the observer and its scores rated by the observer were considered as gold standard. Among all 208 cases, 108 were randomly selected as train set, and the remaining 100 cases were used as test set. The performance of lesion segmentation toolbox (LST) and three U-net models were evaluated on three levels: pixel, lesion, and subject levels. The performance of all methods in WML identification and segmentation was also evaluated among the cases with different lesion volumes and between the cases with and without AIL. Results: All U-net models outperformed LST on pixel, lesion, and subject levels, while no differences were found among three U-net models. All segmentation methods performed best in the cases with WML volume (WMLV) > 20 ml but worst in those with WMLV < 5 ml. In addition, all methods showed similar performance between the cases with and without AIL. The scores determined by U-net exhibited a strong correlation with the gold standard (all Spearman correlation coefficients >0.89, ICCs >0.88, p-values <0.001). Conclusion: U-net performs well on identification and segmentation of WML in the patients with WML and AIL. The performance of U-net is validated by a dataset of multicenter study. Our results indicate that U-net has an advantage in assessing the burden of WML in the patients suffered from both WML and AIL.

Keywords: DWI; FLAIR; U-net; acute ischemic lesions; lesion segmentation; white matter lesions.