CORRESPONDENCE: LETTER TO THE EDITOR
Use of Electrocardiographic Gating in Computed Tomography Angiography of the Ascending Thoracic Aorta
Benjamin Cheong, MD, MRCP (UK), FACC and
Scott D. Flamm, MD*
* Cardiovascular Imaging, Hb-6, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio 44195 (Email: flamms{at}ccf.org).
We congratulate Hendel et al. (1) on their detailed documentation of appropriateness criteria for cardiac computed tomography (CT) and cardiac magnetic resonance imaging, which they published in the October 3, 2006, issue of the Journal. We are, however, concerned regarding the apparent recommendation for use of non-electrocardiographic (ECG)-gated CT angiography in the evaluation of potential aortic dissection (Tables 8 and 10 in Hendel et al. [1]).
The aortic root and ascending thoracic aorta move in concert with the left ventricle and have the greatest motion during systole. It is well documented that motion artifacts from aortic wall motion can simulate the appearance of a dissection flap, particularly in the aortic root and ascending thoracic aorta, leading to an erroneous diagnosis of ascending aortic dissection (2–4). The prevalence of this finding is described as being as high as 57% in non–ECG-gated CT angiographic studies (5).
The use of ECG gating (either prospective or retrospective gating) has been shown to effectively "freeze" cardiac pulsation and aortic wall motion and to reduce motion artifacts when compared to results of non–ECG-gated studies (6,7). Furthermore, the application of ECG gating by adequately trained technologists has no impact on the workflow of the CT examination (7). In our own practice, we prefer the use of prospective ECG gating to minimize radiation exposure to our patients.
Therefore, we believe that ECG gating should be mandatory for thoracic aortic CT angiograms performed to detect potential aortic dissection. We hope that the investigators agree and will promptly make this critical and appropriate correction.
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References
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1. Hendel RC, Patel MR, Kramer CM, et al. ACCF/ACR/SCCT/SCMR/ASNC/NASCI/SCAI/SIR 2006 appropriateness criteria for cardiac computed tomography and cardiac magnetic resonance imaging: a report of the American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Group, American College of Radiology, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, American Society of Nuclear Cardiology, North American Society for Cardiac Imaging, Society for Cardiovascular Angiography and Interventions, and Society of Interventional Radiology J Am Coll Cardiol 2006;48:1475-1497.[Free Full Text]2. Burns MA, Molina PL, Gutierrez FR, Sagel SS. Motion artifact simulating aortic dissection on CT AJR Am J Roentgenol 1991;157:465-467.[Abstract/Free Full Text] 3. Qanadli SD, El Hajjam M, Mesurolle B, et al. Motion artifacts of the aorta simulating aortic dissection on spiral CT J Comput Assist Tomogr 1999;23:1-6.[CrossRef][Web of Science][Medline] 4. Duvernoy O, Coulden R, Ytterberg C. Aortic motion: a potential pitfall in CT imaging of dissection in the ascending aorta J Comput Assist Tomogr 1995;19:569-572.[Web of Science][Medline] 5. Ko SF, Hsieh MJ, Chen MC, et al. Effects of heart rate on motion artifacts of the aorta on non–ECG-assisted 0.5-sec thoracic MDCT AJR Am J Roentgenol 2005;184:1225-1230.[Abstract/Free Full Text] 6. Willmann JK, Kobza R, Roos JE, et al. ECG-gated multi-detector row CT for assessment of mitral valve disease: initial experience Eur Radiol 2002;12:2662-2669.[Web of Science][Medline] 7. Schertler T, Glucker T, Wildermuth S, Jungius KP, Marincek B, Boehm T. Comparison of retrospectively ECG-gated and nongated MDCT of the chest in an emergency setting regarding workflow, image quality, and diagnostic certainty Emerg Radiol 2005;12:19-29.[CrossRef][Medline]
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