Invited commentary

Abstract

Kapetanios and colleagues have comprehensively reviewed the published literature on the use of contrast-enhanced ultrasound (CEUS) for detection of endoleaks after endovascular aneurysm repair (EVAR). Unfortunately, the methodology used may only amplify biases present in the reviewed publications. Thus, analyses in the current review do not provide substantial new insights. Skepticism about comparative studies is warranted as double-blind ultrasound examinations cannot be done. Unbiased data are not available. We cannot know the thoroughness of the conventional imaging, which might have been abbreviated if CEUS was already planned. Direct comparisons are not practical. Significantly, the authors observed that the sensitivity of both conventional ultrasound and CEUS improved over time. This would be the expected finding as imagining technology evolves and sonographer training and protocols improve. Our vascular laboratory at UC Davis never made CEUS a required part of post-EVAR imaging; but for several years, we used CEUS routinely. Although CEUS is now rarely performed, we do use contrast material occasionally. We have a very good vascular laboratory. The ultrasound systems are up to date. The technologists are all well trained and perform only vascular ultrasound studies. We have a detailed protocol for post-EVAR studies and allow up to 2 hours for the examination and documentation. The use of contrast material made the examinations substantially more complex. Examinations needed to be scheduled with a nurse available to establish intravenous access and to administer the contrast agent. We did not track the additional costs associated with the contrast material, required supplies, and personnel time. The primary reason that we stopped using contrast material, however, was neither inconvenience nor cost. We stopped doing CEUS because we never found endoleaks that were undetected with conventional ultrasound techniques. Furthermore, ultrasound routinely identified endoleaks found with computed tomography scanning. This paper should not be a call to arms for routine use of ultrasound contrast agents in post-EVAR examinations. There are other factors in post-EVAR surveillance that are recognized as important. Rather than encouraging routine use of contrast material, existing best practices should be emphasized: imaging in an accredited vascular laboratory; post-EVAR imaging using appropriate protocols, with sufficient time allocated for thorough studies; imaging by appropriately trained and credentialed vascular technologists (RVT or equivalent); and interpretation of the studies by knowledgeable and qualified physicians (RPVI credential or equivalent). CEUS is not the standard for post-EVAR imaging in most vascular laboratories. There is potential for harm if the authors' conclusions about the superiority of CEUS are accepted at face value. This paper might lead some to believe that CEUS is necessary for post-EVAR surveillance. If the cost and complexity disadvantages of CEUS were to dissuade surgeons from using ultrasound for routine surveillance, computed tomography scanning might be unnecessarily overused or compliance with surveillance schedules might decrease. Evidence supporting a recommendation for routine use of ultrasound contrast agents for post-EVAR examinations is weak. CEUS may have value in selected circumstances, but high-quality conventional color duplex ultrasound remains an excellent tool for post-EVAR surveillance, and its routine use is recommended in two recent Society for Vascular Surgery guidelines.1Zierler R.E. Jordan W.D. Lal B.K. Mussa F. Leers S. Fulton J. et al.The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures.J Vasc Surg. 2018; 68: 256-284Abstract Full Text Full Text PDF PubMed Scopus (67) Google Scholar, 2Chaikof E.L. Dalman R.L. Eskandari M.K. Jackson B.M. Lee W.A. Mansour M.A. et al.The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm.J Vasc Surg. 2018; 67: 2-77.e2Abstract Full Text Full Text PDF PubMed Scopus (1133) Google Scholar Meta-analysis of the accuracy of contrast-enhanced ultrasound for the detection of endoleak after endovascular aneurysm repairJournal of Vascular SurgeryVol. 69Issue 1PreviewThe purpose of this systematic review and meta-analysis was to investigate the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) for detection of endoleak after endovascular aneurysm repair (EVAR). Full-Text PDF Open Archive