Photogrammetric measurement and visualization of blood vessel branching casting: a tool for quantitative accuracy tests of MR, CT, and DS angiography
Nicola D'Apuzzo · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2000
Currently three different angiographic techniques are used to measure and visualize major blood vessels in the human body: magnetic resonance (MR), computer tomography (CT) and digital subtraction (DS) angiography. Although these imaging systems have been already qualitatively compared, a quantitative assessment is still missing. The goal of this work is to provide a tool enabling a quantitative comparison of the three imaging techniques to an unbiased reference. MR-, CT- and DS-angiographies are first performed on a corpse. Then, a casting of the abdominal aorta and its main branches is prepared, removed from the body and measured with photogrammetric methods. The elongated and thin cast is fixed in a 3D frame with 16 signalized small spheres used for calibration and orientation purposes. Three fixed CCD cameras acquire triplets of images of the casting, which is turned in 8 positions. In order to perform multi-image matching, an artificial random texture is projected onto the object. For each triplet of images, a semi-automated matching process based on least squares matching determines a dense set of corresponding points. Their 3D coordinates are then computed by forward intersection, with a mean standard deviation of about 0.2 mm. The result from the 8 positions are merged together into a 3D point cloud and an adequate filter is applied to remove the noise and the redundancy in the overlapping regions. The paper depicts the basic design of the system and the measurement methods. Furthermore some preliminary results are presented.