Segmentation of arteriovenous malformations nidus and vessel in digital subtraction angiography images based on an iterative thresholding method

Digital subtraction angiography (DSA) plays an important role in the diagnosis and therapy of vascular diseases. Segmentation of nidus and vessel in DSA images is an essential step in the diagnosis of arteriovenous malformations (AVM). In this paper, a novel segmentation method based on the global and iterative local thresholding is proposed to segment the nidus and vessel in DSA images. Firstly, the original image is divided into proper subimages. For each subimage, Ostu's method is primarily used and pixels are classified into two groups by the threshold. Then, according to the variance of the subimage intensities, the mean or median values of two groups are calculated to sort the pixels into three classes. These three classes represent the dark AVM and vessel, the bright background and undetermined regions in the original DSA image. The first two classes are determined directly and will not be processed further. The undetermined regions are processed in the next iteration to segment tiny vessels until the thresholds between two iterations are less than a preset one. Finally, all classes are combined to create the segmentation result. We test this method on DSA images of the AVM. Experimental results show that the proposed method performs better than the other state-of-the-art methods in the segmentation of DSA images. The proposed method can identify fine and tiny vessel structures, as well as distinguish large AVM nidus in one framework.