Pitfalls, Artifacts, and Remedies in Multi– Detector Row CT Coronary Angiography

Abstract

Coronary angiography is increasingly performed with multi-detector row computed tomography (CT) in the clinical setting. Successful use of this method, however, depends on the radiologist's knowledge of its potential pitfalls and familiarity with methods for minimizing or avoiding them. To identify artifacts and other pitfalls that commonly degrade image quality and that could result in misinterpretation, contrast-enhanced coronary angiograms acquired with a multi-detector row CT scanner with four detector rows in 110 consecutive patients were analyzed. The problems identified were classified into four broad categories: (a) motion-related artifacts caused by cardiac, pulmonary, or other body motion; (b) beam-hardening effects caused by metallic implants, severe calcifications, or air bubbles in the pulmonary artery that obscured the underlying coronary vessel lumen; (c) structural artifacts produced by adjacent contrast material-filled structures and overlying vessels; and (d) artifacts that resulted from technical errors or limitations. The most frequently observed artifacts were those related to cardiac motion. The most effective methods for minimizing cardiac motion artifacts are (a) premedication with beta-blockers to maintain optimal heart rate during scanning and (b) optimal selection of the reconstruction window.

Image Post-Processing and Interpretation

“…Artifacts of coronary CT angiography were classified into three categories ( Table 2). The first is cardiac motion-related artifact (Choi et al, 2004). This is caused by many factors, including a heart rate greater than 70-75 beats per minute during imaging acquisition, variations in heart rate during breath holding (Fig 16), arrhythmia, and inappropriate selection of pitch or reconstruction window.…”

“…The second is voluntary motion that is generally preventable with careful instruction of the patient (Choi et al, 2004). Artifacts due to breathing (Fig 17) or body motion are distinctive because they affect the bones of the anterior or lateral chest wall in addition to the coronary arteries; these are less likely to be correctable by additional reconstructions.…”

“…Oxygen supplementation may help dyspneic patients hold their breaths for a longer period. The third is high-attenuating artifact (Choi et al, 2004). High-attenuating artifact includes, blooming artifacts, beam hardening artifacts and streaking artifacts.…”

Angiografia coronariana minimamente invasiva através de tomografia com múltiplos detectores

“…Of course, the presence of cardiac arrhythmias, especially tachyarrhythmias with a variable R-R interval, such as in the case of atrial fi brillation, often makes it impracticable to conduct the test. Ectopic beats, even isolated, could affect adequate visualization of the coronary segments 64 (fi g.7).…”

Letter to the Editor: re: Body physique and heart rate variability determine the occurrence of stair-step artefacts in 64-slice CT coronary angiography with prospective ECG-triggering

“…Respiratory motion causes stair-step artefact both in the chest wall and in the coronary arteries [2]. This type of artefact frequently cannot be corrected by postprocessing techniques such as multisegment reconstruction or ECGediting [3], which are both common strategies used to overcome the effects of cardiac motion.…”