US artifacts.

Image artifacts are commonly encountered in clinical ultrasonography (US) and may be a source of confusion for the interpreting physician. Some artifacts may be avoidable and arise secondary to improper scanning technique. Other artifacts are generated by the physical limitations of the modality. US artifacts can be understood with a basic appreciation of the physical properties of the ultrasound beam, the propagation of sound in matter, and the assumptions of image processing. US artifacts arise secondary to errors inherent to the ultrasound beam characteristics, the presence of multiple echo paths, velocity errors, and attenuation errors. The beam width, side lobe, reverberation, comet tail, ring-down, mirror image, speed displacement, refraction, attenuation, shadowing, and increased through-transmission artifacts are encountered routinely in clinical practice. Recognition of these artifacts is important because they may be clues to tissue composition and aid in diagnosis. The ability to recognize and remedy potentially correctable US artifacts is important for image quality improvement and optimal patient care. Copyright RSNA, 2009