Artifacts in contrast-enhanced ultrasound: a pictorial essay

Abstract

Although contrast-enhanced ultrasound (CEUS) has become a widely utilized and accepted modality in much of the world, the associated contrast agents have only recently received approval in the United States. As with all radiological techniques, image artifacts are encountered in CEUS, some of which relate to commonly encountered ultrasound artifacts, while others are unique to this technique. Image artifacts must be recognized when performing and interpreting examinations to improve technique and diagnostic accuracy. In this article, we review artifacts that may be encountered in CEUS, and where possible discuss how to minimize them or mitigate their effect on image quality and interpretation.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

“…Examples of strongly echogenic lesions include calcifications, AMLs and hemangiomas, and air bubbles produced during thermal ablation. These are attributed to the ineffective subtraction of nonlinear harmonic signals of these echogenic lesions and the echogenic interface [208]. This artifact can be suppressed by adjusting power and gain settings to the proper level.…”

“…A slowly enhancing lesion can show this phenomenon due to unintended bubble destruction when the transducer remains in a stationary position for a long time and may lead to misdiagnosis. Lowering the frame rate, intermittent imaging, placing the focal zone beyond the area of interest, and sweeping through a lesion may help avoid this artifact [208].…”

General principles and overview of vascular contrast-enhanced ultrasonography

“…These artifacts may appear accentuated in CEUS images, since techniques such as spatial compounding and frame averaging are not activated in order to reduce microbubble disruption. In the second category, some artifacts are caused by the inadvertent disruption of microbubbles, such as signal loss due to continuous scanning in one image plane or the near-field signal loss caused by an inappropriately high MI [9,29]. In this section, we will focus on CEUS artifacts more closely related to vascular applications of CEUS.…”

How Much Should I Record During a CEUS Examination? Practical Aspects of the “Real-Time” Feature of a Contrast Ultrasound Study

“…The essence of this is twofold; it is unlikely that extending the "video-clip" beyond 60 seconds will capture any further relevant information, and recording of washout is a prolonged effort, not needing continuous image storage. More important is the potential for microbubble "destruction" with prolonged, intense scanning over one area, with near field lesions most vulnerable, resulting in "pseudo-washout" [12,13]. In short, continuous scanning for the first 60 seconds and then intermittent scanning after 60 seconds, taking an image on average every 30 -60 seconds for the duration of the remainder of the examination will probably suffice.…”

“…Das lässt einen zweifachen Schluss zu: Es ist unwahrscheinlich, dass die Verlängerung des "Videoclips" über 60 Sekunden hinaus weitere relevante Informationen erfasst, und die Aufzeichnung des Washouts ist eine zusätzliche Bemühung, die im Hinblick auf eine kontinuierliche Bildspeicherung nicht nötig ist. Wichtiger ist die potentielle Zerstörung von Microbubbles durch längeres, intensives Scannen auf einem Bereich, was zu einem "Pseudo-Washout" führt, wobei Nahfeldläsionen am anfälligsten sind [12,13]. Kurz gesagt, werden wahrscheinlich ein kontinuierliches Scannen für die ersten 60 Sekunden und dann ein intermittierendes Scannen nach 60 Sekunden, wobei ein Bild im Durchschnitt alle 15 Sekunden bis zum Ende der Untersuchung erstellt wird, ausreichen.…”