  Adolescent idiopathic scoliosis (AIS) is a lifetime disease that arises in
children. Accurate estimation of Cobb angles of the scoliosis is essential for
clinicians to make diagnosis and treatment decisions. The Cobb angles are
measured according to the vertebrae landmarks. Existing regression-based
methods for the vertebra landmark detection typically suffer from large dense
mapping parameters and inaccurate landmark localization. The segmentation-based
methods tend to predict connected or corrupted vertebra masks. In this paper,
we propose a novel vertebra-focused landmark detection method. Our model first
localizes the vertebra centers, based on which it then traces the four corner
landmarks of the vertebra through the learned corner offset. In this way, our
method is able to keep the order of the landmarks. The comparison results
demonstrate the merits of our method in both Cobb angle measurement and
landmark detection on low-contrast and ambiguous X-ray images. Code is
available at: \url{https://github.com/yijingru/Vertebra-Landmark-Detection}.
