Journal of Nippon Medical School: Vol.68 No.6 page.498

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ArticleTitle Assessment of Abdominal Aortic Aneurysms Using A Cone-beam CT System: An Experimental Phantom Study and an Initial Clinical Evaluation Before and After Stent-graft Treatment in Patients with an Abdominal Aortic Aneurysm

AuthorList Kazuo Ichikawa¹, Tatsuo Kumazaki¹, Hiromitsu Hayashi¹ and Masami Ochi²

Affiliation ¹Department of Radiology, Center for Advanced Medical Technology and ²Second Department of Surgery, Nippon Medical School

Language EN

Volume 68

Issue 6

Year 2001

Page 498-509

Received April 18, 2001

Accepted June 5, 2001

Keywords cone-beam CT, abdominal aortic aneurysm, stents and prostheses, interventional procedure

Abstract 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∼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.

Correspondence to Kazuo Ichikawa, Department for Advanced Medical Technology, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan
rudolf@nms.ac.jp

ArticleTitle	Assessment of Abdominal Aortic Aneurysms Using A Cone-beam CT System: An Experimental Phantom Study and an Initial Clinical Evaluation Before and After Stent-graft Treatment in Patients with an Abdominal Aortic Aneurysm
AuthorList	Kazuo Ichikawa¹, Tatsuo Kumazaki¹, Hiromitsu Hayashi¹ and Masami Ochi²
Affiliation	¹Department of Radiology, Center for Advanced Medical Technology and ²Second Department of Surgery, Nippon Medical School
Language	EN
Volume	68
Issue	6
Year	2001
Page	498-509
Received	April 18, 2001
Accepted	June 5, 2001
Keywords	cone-beam CT, abdominal aortic aneurysm, stents and prostheses, interventional procedure
Abstract	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∼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.
Correspondence to	Kazuo Ichikawa, Department for Advanced Medical Technology, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan rudolf@nms.ac.jp