Registration of preoperative CTA and intraoperative fluoroscopic image sequence for assisting endovascular stent grafting

摘要

We have investigated a registration method between preoperative 3D CT angiography (3D-CTA) and intraoperative fluoroscopic image sequence (with/without contrast injection) during intervention. Most registration methods are developed for assisting neurosurgery or orthopedic surgery, but our method is developed for inter-ventional procedure such as endovascular stent grafting. In our method, DRR (Digitally Reconstructed Radiograph) are generated by voxel projection of 3D-CTA after extracting an aorta region. By increasing/decreasing CT value in the aorta region of CTA, DRR with/without contrast media injection are obtained. Subsequently we calculate distance (or similarity) measures between DRR and fluoroscopic image iteratively by changing imaging parameters. The most similar DRR to fluoroscopy is selected. We validated our algorithm by using simulated/clinical fluoroscopic images and DRR (with/without contrast media injection) of thorax and abdomen. Several distance (or similarity) measures were investigated in this experiment. Validation results show that M-estimator of residual is good as matching measure, and registration is well performed for almost all cases. However, accuracy is not enough for non-contrasted thoracic images, and calculation time should be reduced for all cases.