Deep Learning Based Rib Centerline Extraction and Labeling

Automated extraction and labeling of rib centerlines is a typically needed prerequisite for more advanced assisted reading tools that help the radiologist to efficiently inspect all 24 ribs in a computed tomography (CT) volume. In this paper, we combine a deep learning-based rib detection with a dedicated centerline extraction algorithm applied to the detection result for the purpose of fast, robust and accurate rib centerline extraction and labeling from CT volumes. More specifically, we first apply a fully convolutional neural network to generate a probability map for detecting the first rib pair, the twelfth rib pair, and the collection of all intermediate ribs. In a second stage, a newly designed centerline extraction algorithm is applied to this multi-label probability map. Finally, the distinct detection of first and twelfth rib separately, allows to derive individual rib labels by simple sorting and counting the detected centerlines. We applied our method to CT volumes with an isotropic voxel spacing of 1.5 mm from 113 patients which included a variety of different challenges and achieved a mean centerline accuracy of 0.723 mm with respect to manual centerline annotations. The presented approach can be applied to similar tracing problems, such as detecting the spinal column centerline.