1. A computer implemented method for guiding transcatheter aortic valve implantations, the method implemented by the computer comprising the steps of: receiving an interventional 3D image of an aortic root reconstructed from a sequence of 2D images acquired from a C-arm computed tomography (CT) system being rotated about a patient through a predetermined number of degrees; segmenting the aortic root and detecting aortic root landmarks in the 3D image, wherein said aortic root landmarks include three lowest points of aortic root cusps, two coronary artery ostia, and three commissures points where the cusps meet; cropping an area inside the segmented aortic root out of the 3D volume for volume rendering; centering the 3D image on an intersection of two orthogonal planes, each containing the two detected coronary ostia, that are orthogonal to a plane spanned by three lowest points of the aortic root cusps; and volume rendering the 3D cropped aortic root image together with the detected landmarks onto a 2D image.