Arvin Radfar Akhavan BA, Presenter: Nothing to Disclose

Audrey Sigmund, Abstract Co-Author: Nothing to Disclose

Matthew A. Stratton, Abstract Co-Author: Nothing to Disclose

Pegah Entezari MD, Abstract Co-Author: Nothing to Disclose

Jeremy Douglas Collins MD, Abstract Co-Author: Consultant, C. R. Bard, Inc

James Christopher Carr MD, Abstract Co-Author: Speaker, Lantheus Medical Imaging, Inc

Are ascending thoracic aortic aneurysm (TAA) volumetric measurements with a novel volumetric method strongly correlated to, more sensitive than, and more reproducible than conventional orthogonal measurements?

ECG-gated CT angiography of subjects between 18 and 89 years old who were diagnosed with TAA and who had undergone at least two ECG-gated CTAs of the thoracic aorta at Northwestern Memorial Hospital as a standard of care were used for this study. Exclusion criteria included a history of known aortic dissection, non-diagnostic imaging studies, or a history of cardiac surgery or surgery on the aorta or aortic valve between or before two serial scans. Orthogonal diameter measurements were taken from CTA image reports. Volumetric measurements were obtained from the same CTA scans using a semi-automated Vitrea software.

Volumetric and orthogonal measurements were successfully obtained from 108 CTA imaging studies. The Pearson product-moment correlation coefficient demonstrated a Pearson r of 0.823 and 0.856 between maximum orthogonal and volumetric measurements in both the aortic sinus and the ascending aorta, respectively. Based on the paired t-test, both orthogonal and volumetric measurements demonstrated significant changes in aneurysm size to a confidence level of at least 95%. The comparison of inter-observer and intra-observer agreement showed high intra- and inter-observer reliability over both volumetric and orthogonal measurements. Intra-observer correlation coefficients for volume measurements ranged from 0.98 to 0.99 for measurements taken at different levels of the aorta, compared to 0.97-0.98 for diameter measurements at the same levels. Inter-observer correlation coefficients ranged from 0.94-0.98 for volumes and 0.92-0.97 for diameters.

Volumetric analysis of ascending TAA is highly correlated to the conventional two-dimensional method, there seems to be no significant difference in sensitivity between the two methods, and both methods demonstrated strong measurement reproducibility. From this research, the time-intensive volumetric analysis does not add a significant benefit over orthogonal analysis.

The results of this study suggest that volumetric analysis does not provide a significant advantage over the less time intensive, conventional orthogonal method of ascending TAA measurement.

Akhavan, A, Sigmund, A, Stratton, M, Entezari, P, Collins, J, Carr, J, Comparing a Volumetric Post-processing Analysis Technique to Orthogonal Measurement of Ascending Thoracic Aortic Aneurysms Using ECG-gated CTA.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13024343.html