[A new method of eliminating motion artifacts in DSA].

In digital subtraction angiography (DSA), the contrast of the vessels is greatly improved with the injection of contrast medium. In addition, more clear vessels can be visualized by eliminating the images of non-vessel organs, and those images are called subtraction image or DSA. Therefore, DSA is of wide use for diagnosis of cardiovascular disease. Subtraction of images obtained before and after injection of contrast medium may create motion artifacts due to the aspiration of patients. In this regard, being motivated by the doctors' experience that the displacement of diaphragm can be used as the reference to measure the heart beat, we present a method to eliminate the motion artifacts. In our method, firstly, a set of DSA images are taken before injection of contrast medium, which are called "mask images"; and one image taken after injection of contrast is called "target image". Secondly, a "reference mask image" is assigned, which is one of "mask images"; "and the displacement of diaphragm from "reference mask image" to the other mask images and the target contrast image is measured. Thirdly, based on the measurement results, several candidate mask images in which the displacement is less than a threshold can be selected. At last, the optimization algorithm is applied on the selected images, and the corresponding mask image that has minimum motion artifact is retrieved.