There is disclosed an embodiment for extracting anatomical features from a 3-dimensional B-mode ultrasound liver image for image registration. A system extracts anatomical features from a 3-dimensional B-mode ultrasound liver image for image registration. An image forming unit forms a 3-dimensional ultrasound liver image based on ultrasound signals reflected from the liver. A diaphragm extracting unit extracts a diaphragm region from the 3-dimensional B-mode ultrasound liver image. A vessel extracting unit extracts vessel regions from the 3-dimensional ultrasound liver image. A diaphragm refining unit refines the extracted diaphragm region with the extracted vessel regions to remove clutters from the diaphragm region. A registration unit extracts sample points from the diaphragm region with the clutters removed and the vessel regions for image registration.