Diagnostic Imaging Pathways - Abdominal Aortic Aneurysm (Repair Follow-up)
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Population Covered By The Guidance
This pathway provides guidance for imaging follow-up of adult patients following endovascular abdominal aortic aneurysm repair (EVAR).
Date reviewed: May 2018
Date of next review: May 2021
Published: June 2018
Quick User Guide
Move the mouse cursor over the PINK text boxes inside the flow chart to bring up a pop up box with salient points.
Clicking on the PINK text box will bring up the full text.
The relative radiation level (RRL) of each imaging investigation is displayed in the pop up box.
| SYMBOL | RRL | EFFECTIVE DOSE RANGE |
 | None | 0 |
 | Minimal | < 1 millisieverts |
 | Low | 1-5 mSv |
 | Medium | 5-10 mSv |
 | High | >10 mSv |
Teaching Points
Teaching Points
- Endoleaks occur in 15-25% of patients within the first 30 days of EVAR and are often asymptomatic 1
- Type II endoleaks are the most common and often spontaneously occlude. 2 Type I and III endoleaks are associated with an increased risk of rupture 3 and are usually managed promptly 4
- An early one-month postoperative study is done to assess adequacy of AAA exclusion, baseline endograft positioning and AAA size. If no endoleak is detected, subsequent studies may be performed annually 5
- Delayed endoleaks may occur months or years after EVAR so lifetime surveillance is recommended. 5 The incidence of delayed complications requiring treatment is about 3% 6, 7
- Annual duplex ultrasound is most likely sufficient for routine surveillance in the absence of new endoleak or sac enlargement, and eliminates radiation exposure, reduces cost and avoids use of contrast 5
- CTA is used if sac is increasing or duplex suggests an endoleak 5
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Computed Tomography Angiography (CTA)
- The 2-dimensional and 3-dimensional contrast-enhanced computed tomography imaging currently serves as the gold standard for serial endovascular aneurysm repair (EVAR) assessment. 8-10 EVAR follow-up protocols usually include arterial and delayed phase contrast images as well as non-contrast images 4
- High spatial resolution allows precise measurement of anatomy, visualisation of endoleaks 4 and assessment of device kink, fracture and migration 11
- Disadvantages include significant cumulative radiation exposure with lifetime surveillance and the use of iodinated contrast
- To reduce radiation exposure, CTA is only recommended at one-month and one-year follow-up, and if there is an abnormality detected on ultrasound thereafter 5
- Non-contrast imaging of the whole aorta is recommended every five years 5 however CTA might be considered if there is no contraindication to contrast
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Duplex Ultrasonography
- High-quality duplex ultrasound can be used for the assessment of aneurysm size, endoleak, and graft patency after endovascular exclusion of AAA 12
- In one systematic review, the unenhanced colour duplex scanning had a sensitivity of 66%, a specificity of 93%, a positive predictive value of 76%, and a negative predictive value of 90% compared with CTA. The sensitivity increased to 81% with contrast material-enhanced colour duplex US compared with unenhanced colour duplex US 13
- A recent meta-analysis found non-contrast enhanced ultrasound to have a lower endoleak detection rate than CTA, but concluded that missed findings are likely to be of lesser clinical significance 14
- There are no studies comparing the outcomes of different surveillance intervals 14
- Colour duplex ultrasound is suggested for annual surveillance, if neither endoleak nor AAA enlargement is observed 1-year after EVAR; CT imaging may be used if ultrasound is not possible 5
- If a type II endoleak is associated with an aneurysm sac that is shrinking or stable in size, 6-monthly colour duplex ultrasound surveillance is suggested for 24 months, then annually thereafter 5
- The accuracy is limited by 8
- obesity
- intestinal gas
- artery or AAA wall calcification; they can block ultrasound transmission
- operator skill 4
References
References
Date of literature search: March 2018
References are graded from Level I to V according to the Oxford Centre for Evidence-Based Medicine, Levels of Evidence. Download the document
- Dias NV, Riva L, Ivancev K, Resch T, Sonesson B, Malina M. Is there a benefit of frequent CT follow-up after EVAR? Eur J Vasc Endovasc Surg. 2009;37(4):425-30. (Level III evidence). View the reference
- Liaw JV, Clark M, Gibbs R, Jenkins M, Cheshire N, Hamady M. Update: complications and management of infrarenal EVAR. Eur J Radiol. 2009;71(3):541-51. (Review article). View the reference
- Mehta M, Paty PS, Roddy SP, Taggert JB, Sternbach Y, Kreienberg PB, et al. Treatment options for delayed AAA rupture following endovascular repair. J Vasc Surg. 2011;53(1):14-20. (Level III evidence). View the reference
- Hallett RL, Ullery BW, Fleischmann D. Abdominal aortic aneurysms: pre- and post-procedural imaging. Abdominal radiology (New York). 2018 (Review). View the reference
- Chaikof EL, Dalman RL, Eskandari MK, Jackson BM, Lee WA, Mansour MA, et al. The society for vascular surgery practice guidelines on the care of patients with an abdominal aortic aneurysm. J Vasc Surg. 2018;67(1):2-77.e2. (Guideline). View the reference
- Hiramoto JS, Reilly LM, Schneider DB, Sivamurthy N, Rapp JH, Chuter TA. Long-term outcome and reintervention after endovascular abdominal aortic aneurysm repair using the Zenith stent graft. J Vasc Surg. 2007;45(3):461-5; discussion 5-6. (Level II evidence). View the reference
- Vallabhaneni SR, Harris PL. Lessons learnt from the EUROSTAR registry on endovascular repair of abdominal aortic aneurysm repair. Eur J Radiol. 2001;39(1):34-41. (Level II evidence). View the reference
- Back MR. Surveillance after endovascular abdominal aortic aneurysm repair. Perspect Vasc Surg Endovasc Ther. 2007;19(4):395-400; discussion 1-2. (Review article). View the reference
- Hiatt MD, Rubin GD. Surveillance for endoleaks: how to detect all of them. Semin Vasc Surg. 2004;17(4):268-78. (Review article). View the reference
- Chisci E, Setacci F, Iacoponi F, de Donato G, Cappelli A, Setacci C. Surveillance imaging modality does not affect detection rate of asymptomatic secondary interventions following EVAR. Eur J Vasc Endovasc Surg. 2012;43(3):276-81. (Level III evidence). View the reference
- Roos JE, Hellinger JC, Hallet R, Fleischmann D, Zarins CK, Rubin GD. Detection of endograft fractures with multidetector row computed tomography. J Vasc Surg. 2005;42(5):1002-6. (Level V evidence). View the reference
- Wolf YG, Johnson BL, Hill BB, Rubin GD, Fogarty TJ, Zarins CK. Duplex ultrasound scanning versus computed tomographic angiography for postoperative evaluation of endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2000;32(6):1142-8. (Level III evidence). View the reference
- Sun Z. Diagnostic value of color duplex ultrasonography in the follow-up of endovascular repair of abdominal aortic aneurysm. J Vasc Interv Radiol. 2006;17(5):759-64. (Review article). View the reference
- Zaiem F, Almasri J, Tello M, Prokop LJ, Chaikof EL, Murad MH. A systematic review of surveillance after endovascular aortic repair. J Vasc Surg. 2018;67(1):320-31.e37. (Review article). View the reference
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