Coronary heart disease is a common cause of death for human being. To treat artery stenosis due to accumulation of atheromatous plaques, stents are implanted to support the narrowing vessel. The relative position between stent and vascular wall is a critical factor for evaluating the treatment. However, low signal to noise ratio (SNR) of fluoroscopy sequences make it difficult for doctors to observe the stents clearly. In order to improve the clarity of stent effectively, the paper describes a novel algorithm based on deep neural network for stent markers detection so as to realize the time domain stacking. In this step, the response map generation model with weighted loss was designed to concentrate on small objects detection, which has unbalanced annotation between background and targets. In addition, a focus conversion learning algorithm by deblurring network was proposed for edge sharpness and the spatial resolution improvement to decrease influences by focus size. It can locate the marker pair successfully in both phantom and clinical images with 84.04% correction rate in marker detection and decrease the mean square error in the focus conversion algorithm. After quantitative indexes comparison and observation, it reveals that the proposed algorithm can effectively enhance stents without manual annotation, which provides the assistance to evaluate the treatment exactly.
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