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J Med Syst (2014) 38:10DOI 10.1007/s10916-014-0010-8
RESEARCH ARTICLE
Multiresolution Image Registration in Digital X-Ray Angiography with Intensity Variation Modeling
Mansour Nejati & Hossein Pourghassem
Received: 13 September 2013 /Accepted: 10 January 2014 /Published online: 28 January 2014 # Springer Science+Business Media New York 2014
Abstract Digital subtraction angiography (DSA) is a widely used technique for visualization of vessel anatomy in diagnosis and treatment. However, due to unavoidable patient motions, both externally and internally, the subtracted angiography images often suffer from motion artifacts that adversely affect the quality of the medical diagnosis. To cope with this problem and improve the quality of DSA images, registration algorithms are often employed before subtraction. In this paper, a novel elastic registration algorithm for registration of digital X-ray angiography images, particularly for the coronary location, is proposed. This algorithm includes a multiresolution search strategy in which a global transformation is calculated iteratively based on local search in coarse and fine sub-image blocks. The local searches are accomplished in a differential multiscale framework which allows us to capture both large and small scale transformations. The local registration transformation also explicitly accounts for local variations in the image intensities which incorporated into our model as a change of local contrast and brightness. These local transformations are then smoothly interpolated using thin-plate spline interpolation function to obtain the global model. Experimental results with several clinical datasets demonstrate the effectiveness of our algorithm in motion artifact reduction.
Keywords Digital subtraction angiography . elastic image registration . multiresolution . thin-plate spline
Introduction
Digital subtraction angiography (DSA) is a widely used X-ray technique for vascular imaging and treatment [1, 2]. In this technique, a sequence of X-ray projection images is acquired during the passage of the injected radiopaque contrast material through the vessels of interest. The first few images of the sequence are pre-contrast or mask images taken prior to the injection of the contrast material and therefore, blood vessels are not visible in them. Other images that are acquired during the passage of the contrast material are often referred to as live images.
By subtracting the mask image from each live image, interfering background structures in the live images are largely removed and the visualization of vessels is improved. However, the mask and the live...