Alexandre Dugas MD, Presenter: Nothing to Disclose

Eric Therasse MD, Abstract Co-Author: Nothing to Disclose

Vincent Louis Oliva MD, Abstract Co-Author: Nothing to Disclose

Marie-France Giroux MD, Abstract Co-Author: Nothing to Disclose

Claude Kauffmann PhD, Abstract Co-Author: Nothing to Disclose

Gilles P. Soulez MD, Abstract Co-Author: Speaker, Bracco Group Speaker, Siemens AG Research grant, Siemens AG Research grant, Bracco Group Research grant, Cook Group Incorporated

Multidetector CT (MDCT) is frequently used to determine the maximal diameter (Dmax) of abdominal aortic aneurysm (AAA)or progression of Dmax between to consecutive exams. The objective of this study was to define the more reproducible method to measure Dmax.

Thirty four patients with an AAA (≥4cm Dmax) having 2 consecutive MDCT exams with a minimum interval of 6 months were enrolled in the study. Three independent observers measured AAA diameters on all 68 exams using 7 different methods. Four Dmax measurements were taken on axial images: (AP, lateral, maximum (largest in any axis) and short axis (perpendicular to maximum) diameters. 3 measurements were taken on MPR images: largest diameter (perpendicular to the long axis of the aorta) on coronal & sagittal MPRs and on double oblique MPR (perpendicular to the long axis of the aorta on sagittal and coronal planes). Inter and intra-observer reproducibility of the 7 different Dmax measurements at baseline & follow-up and Dmax progression between the 2 exams were estimated by calculation of the intraclass correlation coefficient (ICC).

The means of all Dmax measurements were respectively estimated at 51.5, 51.2 and 51.1 mm for observers 1, 2 and 3 (NS). For all observers, the mean Dmax progression between baseline and FU examinations was estimated at 4.0 mm (AP and lateral axial, double oblique MPR), 4.1 mm (maximal and short axis axial), 4.2 mm (sagittal MPR) and 4.4 mm (coronal MPR). Dmax measurement on double oblique MPR had the best interobserver reproducibility (0.978, CI 0.967-0.986) and was more reproducible than short axis axial (0.940, CI 912-.961) and coronal MPR (0.964, CI: 0.947-0.977) measurements (p<0.05). Discordance between observers of more than 5 mm in Dmax measurements were respectively observed in 2.9% (double oblique MPR), 5.9 % (maximal axial and sagittal MPR), 8.8% (lateral axial), 10.3% (anteroposterior axial and MPR coronal) and 14.7% (short axis axial) of exams.

Maximal diameter of AAA should be measured on double oblique MPR since it is more reproducible and closer to the reality

The results of this study will allow standardization of AAA maximum diameter measurement with MDCT.

Dugas, A, Therasse, E, Oliva, V, Giroux, M, Kauffmann, C, Soulez, G, Abdominal Aortic Aneurysm Follow-up with MDCT: Reproducibility of Maximal Diameter Measurement.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5009557.html