An important challenge in the analysis of intravascular ultrasound images (IVUS) is the media-adventitia border detection. However

as a result of the inevitable artifact

plaque and imaging equipment effect

the target border always appears too fuzzy to be detected. In this paper

a new border detection method based on spatial-frequency domain image enhancement is proposed. The method uses enhancing processes in the spatial and xin the frequency domain during the detecting process. In the enhancing process

the directional filter band

neighborhood and histogram equalization are combined to overcome the defect of contrast reduction caused by directional filter and the defect of details vagueness caused by histogram equalization. Then in the detecting process

a heuristic graph-searching is applied to find the media-adventitia border by taking the enhanced image data matrix as the cost matrix. The experiment results show that the enhancing process not only strengthens the features of the media and adventitia greatly

but also improves the contrast and definition of the image. The graph-searching based on the enhanced results can detect the media-adventitia border accurately.The correct rate reached 92.76%.