Deep Learning based Carotid Media-Adventitia and Lumen-intima Boundary Segmentation from Three-dimensional Ultrasound Images.

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Abstract

Quantification of carotid plaques has been shown to be important for assessing as well as monitoring the progression and regression of carotid atherosclerosis. Various metrics have been proposed and methods of measurements ranging from manual tracing to automated segmentations have also been investigated. Of those metrics, quantification of carotid plaques by measuring vessel-wall-volume (VWV) using the segmented media-adventitia (MAB) and lumen-intima (LIB) boundaries has been shown to be sensitive to temporal changes of carotid plaque burden. Thus, semi-automatic MAB and LIB segmentation methods are required to help generate VWV measurements with high accuracy and less user-interaction.
In this paper we propose a semi-automatic segmentation method based on deep learning to segment the MAB and LIB from carotid three-dimensional ultrasound (3DUS) images. For the MAB segmentation, we convert the segmentation problem to a pixel-by-pixel classification problem. A dynamic convolutional neural network (Dynamic CNN) is proposed to classify the patches generated by sliding a window along the norm line of the initial contour where the CNN model is fine-tuned dynamically in each test task. The LIB is segmented by applying a region-of-interest of carotid images to a U-Net model, which allows the network to be trained end-to-end for pixel-wise classification.
A total of 144 3DUS images were used in this development, and a 3-fold cross-validation technique was used for evaluation of the proposed algorithm. The proposed algorithm-generated accuracy was significantly higher than the previous methods but with less user-interactions. Comparing the algorithm segmentation results to manual segmentations by an expert showed that the average Dice similarity coefficients (DSC) were 96.46 ± 2.22% and 92.84 ± 4.46% for the MAB and LIB respectively, while only an average of 34s (vs. 1.13 min, 2.8 min and 4.4 min in previous methods) was required to segment a 3DUS image. The inter-observer experiment indicated that the DSC was 96.14±1.87% between algorithm-generated MAB contours of two observers’ initialization.
Our results showed that the proposed carotid plaque segmentation method obtains high accuracy and repeatability with less user-interactions, suggesting that the method could be used in clinical practice to measure VWV and monitor the progression and regression of carotid plaques. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.