Abstract
Objectives: The endovascular management of abdominal aortic aneurysm
(AAA) relies on accurate preoperative imaging for proper patient
selection and operative planning. Three-dimensional (3-D) computed
tomography (CT) with reformatted images perpendicular to blood flow
has gained popularity as a method of AAA assessment and image-based
planning before endovascular aneurysm repair (EVAR). The current
study was undertaken to determine the interobserver agreement of
AAA measurements obtained with axial CT and reformatted 3-D CT and
to compare the consistency of the 2 methods in selecting patients
for EVAR. Methods: Eight observers assessed the axial CT and reformatted
3-D CT scans for 5 patients with AAAs to determine whether the patients
were candidates for EVAR. 3-D CT with multiplanar reformatted images
was performed by Medical Media Systems (AIMS). Each observer measured
the length and diameter of the proximal neck, maximal AAA, aortic
bifurcation, common iliac diameter, and aortic angulation. The proximal
neck and common iliac arteries were also assessed for thrombus, calcification,
and tortuosity. Agreement of the measurements on axial CT scans was
compared with those on AIMS CT scans by calculating the K statistic.
Complete agreement was defined as kappa = 1.0. The limits of agreement
between observers were also calculated. Results: The cumulative interobserver
agreement of MMS CT scans (kappa =.81) was greater than for axial
CT scans (kappa=59). The kappa value for each of the diameter measurements
was greater with the MMS CT scans. In 79% of cases the observers'
measurements were less than 2 mm, from the mean with MMS CT, compared
with 59% for axial CT. The kappa value for deciding whether a patient
was an endograft candidate on the basis of aortic neck was greater
with the MMS CT (0.92 vs 0.63). The limits of agreement between observers
were also better with the MMS CT. Conclusions. The interobserver
agreement in planning EVAR is significantly better with MMS CT compared
with traditional axial CT. The routine use of MMS CT appears justified
before EVAR to improve the accuracy and consistency of patient selection
Users
Please
log in to take part in the discussion (add own reviews or comments).