Research On Image-based Gating Of Intracoronary Ultrasound Image Sequence

Intravascular ultrasound(IVUS) is one of interventional imaging modalities widely used for diagnosing vascular diseases in clinic, especially coronary arterval disease at present.Since coronary arteries attach to the heart's surface and moving regularly with the heart beat,intracoronary ultrasound(ICUS) image sequences will be impacted inevitably by motion artifact during imaging.The motion artifact will reduce image quality.The main work of this thesis is to restrain motion artifact in ICUS image sequence with digital image processing knowledge patterning electrocardiogram gating.Firstly,for ICUS image sequence got through retracing the ultrasound catheter continuously,difference matrix was structured by comparing the image-gray feature frame by frame.Then,after estimating patient's heart rate from difference matrix,the optimal path with the smallest cumulative difference value is sought from difference matrix adopting the dynamic programming algorithm in order to find each frame's matching frame in the adjacent cardiac cycle.Finally,in the difference matrix after an X-shaped inverted Gaussian kernal filtered,finding a frame along the optimal path sampled in the end-diastolic of an adjacent cardiac cycle to form a new sequence,which is the final gated sequence.The method is proposed to gat coronary artery ICUS image sequence without synchronous recording electrical signal,which could reduce the influence of motion artifact due to heart movement and enhance the visual effect of coronary artery ICUS image sequence longitudinal cut,which could provide more accurate image data for coronary artery vessel's quantitatively measurement (including the measure of configuration parameter and blood fluid dynamic parameter),the fusion with other coronary artery angiogram,the 3-D reconstruction of coronary arteries etc.