1Validating Point-based MR/CT Registration Based on Semi-automatic Landmark Extraction

Manually extracting 3D anatomical point landmarks from images is generally time-consuming and usually lacks reproducibility. To improve on this, we developed a semi-automatic procedure for landmark extraction. In this paper, we report on the validation of our procedure for the case of point-based rigid registration of MR/CT head images. The results of our semi-automatic procedure are compared with those of a manual pro-cedure for landmark extraction. Five observers participated in the study. Five MR/CT image pairs were used from which 7{9 landmarks were extracted using both procedures. Our experiments show that (a) the elapsed time spent for landmark extraction can sig-ni cantly be reduced with the semi-automatic procedure, (b) the registration results of both procedures generally have similar quality, and (c) the inter-observer variability in the localized landmark positions is smaller with the semi-automatic procedure. 1