Automated software supported versus manual aorto-iliac diameter measurements in CT angiography of patients with abdominal aortic aneurysms: assessment of inter- and intraobserver variation.
BACKGROUND
Open surgical or endovascular abdominal aortic aneurysm (AAA) relies on precise preprocedual imaging. Purpose of this study was to assess inter- and intraobserver variation of software-supported automated and manual multi row detector CT angiography (MDCTA) in aortoiliac diameter measurements before AAA repair.


METHODS
Thirty original MDCTA data sets (4 x 2mm collimation) of patients scheduled for endovascular AAA repair were studied on a dedicated software capable of creating two-dimensional reformatted planes orthogonal to the aortoiliac center-line. Measurements were performed twice with afour-week interval between readings. Data were analysed by two blinded readers at random order Two different measurement methods were performed: reader-assisted freehand wall-to-wall measurement and semi-automatic measurement.


RESULTS
Aortoiliac diameters were significantly underestimated by the semi-automatic method as compared to reader-assisted measurements (p < 0.0031). Intraobserver variability of AAA diameter calculation was not significant (p > 0. 15) for reader-assisted measurements except for the diameter of the left common iliac artery in reader 2 (p = 0.0045) and it was not significant (p > 0. 14) using the semi-automatic method. Interobserver variability was not significant for AAA diameter measurements using the reader-assisted method and for proximal neck analysis with the semiautomatic method (p > 0.27). Relevant interobserver variation was observed for semi-automatic measurement of maximum AAA (p = 0.0007) and iliac artery diameters (p = 0.024).


CONCLUSIONS
Dedicated MDCTA software provides a useful tool to minimize aortoiliac diameter measurement variation and to improve imaging precision before AAA repair. For reliable AAA diameter analysis the reader-assisted freehand measurement method is recommended to be applied to a set of reformatted CT data as provided by the software used in this study.
Diehm
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N
Swiss Cardiovascular Center, Divisions of Angiology, Inselspital, University Hospital, Bern, Switzerland. nicolas.diehm@insel.ch
Baumgartner
I
I
Silvestro
A
A
Herrmann
P
P
Triller
J
J
Schmidli
J
J
Do
D D
DD
Dinkel
H-P
HP
D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D019412:Anatomy, Cross-Sectional / Q000379:methods; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging* / Q000473:pathology*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000473:pathology*; D001185:Artificial Intelligence; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D012986:Software Validation