lLoyola University Medical Center, Maywood, Illinois. mColumbia University Medical Center, New York, New York. nUT Southwestern Medical Center, Dallas, Texas. oSpecialty Chair, UMass Memorial Medical Center, Worcester, Massachusetts. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org AAA Follow-up (Without Repair) Discussion of Procedures by Variant Variant 1: Asymptomatic abdominal aortic aneurysm surveillance (without repair). US Duplex Doppler Aorta Abdomen US is the most widely studied and utilized imaging tool for evaluating an AAA, both for screening and during surveillance. US has been verified as having consistent measurement accuracy, which can approximate the accuracy demonstrated by CT and MRI or MR angiography (MRA) [17,18,26,27]. Studies have reported that US may underestimate the maximum AAA diameter by 4 mm, on average, and the interobserver measurement difference can range from 2 to 10 mm with US compared with <2 mm using CT [27-31]. Evidence is still lacking as to whether these differences are clinically impactful. Variation in accuracy is believed to be related to measurement technique. For example, there is debate as to whether to place the measurement caliper on the outer or inner edge of the vessel, without clear consensus on an ideal methodology [31]. Finally, no significant difference between rate of growth measurements between US and CT has been found [18,32]. US is also less capable of identifying specific aneurysm features beyond diameter, such as intraluminal thrombus or adjacent inflammation, both of which are more easily identified on CT [21,33,34].
Abdominal Aortic Aneurysm Follow up Without Repair . lLoyola University Medical Center, Maywood, Illinois. mColumbia University Medical Center, New York, New York. nUT Southwestern Medical Center, Dallas, Texas. oSpecialty Chair, UMass Memorial Medical Center, Worcester, Massachusetts. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org AAA Follow-up (Without Repair) Discussion of Procedures by Variant Variant 1: Asymptomatic abdominal aortic aneurysm surveillance (without repair). US Duplex Doppler Aorta Abdomen US is the most widely studied and utilized imaging tool for evaluating an AAA, both for screening and during surveillance. US has been verified as having consistent measurement accuracy, which can approximate the accuracy demonstrated by CT and MRI or MR angiography (MRA) [17,18,26,27]. Studies have reported that US may underestimate the maximum AAA diameter by 4 mm, on average, and the interobserver measurement difference can range from 2 to 10 mm with US compared with <2 mm using CT [27-31]. Evidence is still lacking as to whether these differences are clinically impactful. Variation in accuracy is believed to be related to measurement technique. For example, there is debate as to whether to place the measurement caliper on the outer or inner edge of the vessel, without clear consensus on an ideal methodology [31]. Finally, no significant difference between rate of growth measurements between US and CT has been found [18,32]. US is also less capable of identifying specific aneurysm features beyond diameter, such as intraluminal thrombus or adjacent inflammation, both of which are more easily identified on CT [21,33,34].