The aim of this study is to conduct a quantitative analysis of cone-beam CT (CBCT) images using a phantom, and then to evaluate the clinical usefulness of CBCT in the assessment of
abdominal aortic aneurysms (AAA) before and after
stent-grafting, both qualitatively as well as quantitatively. The phantom used in this study was a rectangular plate made of an
acrylic resin, which contained eight through-holes to mimic blood vessels. Each columnar cavity was filled with
contrast media and the diameter of each was then measured using a cone-beam multiplanar reformation/curved planar reformation (CB-MPR/
CPR) technique, and the results were compared with the corresponding results obtained by actual measurement. In the clinical assessment, nine patients with AAA (consisting only of males with an average age of 68 years old: 56 approximately 80) were enrolled. The clinical qualitative analysis of CBCT consisted of: 1) for the pre-operative state, the shape of the
aortic aneurysm, the relationship between the
aneurysm and the aortic branches, and 2) for the post-operative state, the shape of the
stent and any endoleakage present. The clinical quantitative analysis of CBCT included, for the
aneurysm, its inflection angle, its maximum diameter, the diameter of the proximal and distal necks, and the distance of these two necks from specific reference points. The quantitative analysis using the phantom showed no significant differences between the results based on CB-MPR/
CPR and those obtained by actual measurement. In the clinical qualitative analysis three-dimensional CBCT (3D-CBCT) depicted the anatomical relationship between the
aneurysm and the aortic branches well, an accomplishment that was not possible by conventional angiography. Cone-beam maximum intensity projection (CB-MIP) was as good in tracing the migration and deformation of the
stent following endovascular intervention as plain radiograms and conventional angiograms. CB-MPR/
CPR enabled us to obtain any cross-sectional image of the aorta desired, including a curved, longitudinal cross-section of the aorta. Thus, with the CB-MPR/
CPR technique it is easy to determine the distance of the proximal and distal necks of the
aneurysm, and the inflection angle, and those results were not significantly different from those obtained by angiography. The diameter of the
aneurysm, and the diameter of the proximal and distal necks as measured by CB-MPR/
CPR images were significantly different from those obtained by conventional contrast enhanced-CT (p<0.05). This suggests that CB-MPR/
CPR yields a cross-sectional view that is more perpendicular to the longitudinal direction of the aorta than that given by conventional contrast enhanced-CT, and thus provides a more accurate cross-sectional image of the
aneurysm than the latter. We conclude that, in the experimental phantom study CBCT had a high quantitative reliability, and that, in the clinical study CBCT provided useful information for both qualitatively and quantitatively evaluating AAA before and after
stent-grafting.