Nancy J. Benedetti MD, Presenter: Nothing to Disclose

Michael D. Hope MD, Abstract Co-Author: Nothing to Disclose

With the commencement of lung cancer screening in the United States, the discovery of incidental thoracic findings, such as ascending aortic dilation, will become more common. Current guidelines recommend yearly CT follow-up for ascending aortas measuring 4.0-5.0 cm. However, little is known about patient outcomes in this population. We conducted a study to determine the incidence of incidental ascending aortic dilation and to determine the rate of change in aortic diameter over time in 55-80 year olds (lung cancer screening population). The objective of this study is to inform guidelines on follow-up of incidental ascending aortic dilation.

We searched 88,171 chest CT scans done on 31,963 patients aged 55-80 years old at our institution over a 14 year period (2000-2013) and determined the incidence of incidental ascending aortic dilation (4.0-5.0 cm). Patients were excluded if they had a known/repaired aortic aneurysm or dissection, mycotic aneurysm or history of connective tissue disease. For patients with at least 2 CT scans ≥6 months apart, we determined the growth rate of the aorta. We also conducted a chart review to assess for complications or vascular surgery interventions.

In our study sample of 25,039 patients after exclusions, we found a 2.7% incidence (n=678) of incidental ascending aortic dilation. Of the 678 patients with aortic dilation, 333 patients had follow-up studies with 3.3 years average length of follow-up between chest CT examinations. In the population of patients with follow-up studies, only 2.7 % (n=9) demonstrated interval growth of 3 to 7 mm over a time period of 1.5 to 7.5 years (average growth of 1.1 mm/year). None of these patients had complications (e.g.- dissection, rupture) or surgical intervention.

Current guidelines recommend yearly follow-up of patients with incidental ascending aortic dilation in the 4.0-5.0 cm range. However, we found aortic growth in only 2.7% of patients, a slow growth rate of 1.1 mm/year and no complications.

Current guidelines could be revised to: 1.) Increase the interval between follow-up studies 2.) Incorporate risk stratification to determine which patients would benefit most from yearly follow-up and which could safely be followed at longer time intervals.

Benedetti, N, Hope, M, Prevalence and Significance of Incidentally Noted Dilation of the Thoracic Aorta on Screening Chest CT.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14002491.html