Noninvasive Numerical Dissection And Display Of Anatomic Structure Using Computerized X-Ray Tomography

Three-dimensional reconstruction images of anatomic structure are obtained by compu-terized x-ray tomographic scanning of a three-dimensional volume containing the organ of interest. The three-dimensional image data are displayed using numerical projection (reprojection) images. Reprojection images of reconstructed volumes are generated numerically by summing the reconstructed volume element (voxel) x-ray density values along selected parallel paths the reconstruction. In this manner, two-dimensional reprojection images of a three-dimensional reconstruction at any desired angle of view are generated. Obscuring superposed structures can be selectively removed from the reconstruction prior to reprojection to enhance the visibility of structures of interest. Noninvasive numerical dissection is the term applied to the process whereby the voxels representing obscuring structure are ignored in the parallel path summation process such that only the desired portions of a reconstruction are reprojected at selected viewing angles. The term noninvasive numerical tissue dissolution is applied to the process whereby structures are selectively dimmed but not removed from the reconstruction before reprojection, achieving a see or ghosting effect. Under these conditions, specific anatomic structures can be observed while looking through superposed structures which serve as references for anatomic relationships.