Most artifacts arise from violations of assumptions for creating the ultrasound image, including but not limited to (1) ultrasound travels at a constant speed in all tissues (1540 m/s) (2) ultrasound travels in a straight path (3) reflections occur from the initial ultrasound beam with one interaction at a perpendicular incidence for each boundary (4) attenuation of ultrasound echoes is uniform (5) all of the energy emitted by the ultrasound transducer exists in the main beam (6) the operator has transmit, receive gain, and other settings properly adjusted and (7) all of the elements in the transducer array, as well as the remainder of the imaging system, are operating optimally.Īrtifacts are caused by a variety of mechanisms that contradict the assumptions listed above. Understanding how artifacts are generated and how they can be recognized is crucial, which places high demands on the knowledge of the sonographer and the interpreting physician. 8.6 163-166.Ultrasound artifacts represent a false portrayal of image anatomy or image degradations related to false assumptions regarding the propagation and interaction of ultrasound with tissues, as well as malfunctioning or maladjusted equipment. More research is needed to know whether this finding is clinically relevant, but the prospects are looking bright. However, visualizing abdominal A-lines in every quadrant is concerning for bowel perforation in the cases presented. It is unclear what role the identification of abdominal A-lines can play in patient management, as this can be a normal finding when loops of gas-filled bowel are adherent to the abdominal peritoneum. However, explicit knowledge of sonographic artifacts such as the reverberation artifact can identify unexpected emergent diagnoses.
The sensitivity of ultrasound for these diagnoses will likely never be adequate to be used as a screening tool. Point-of-care ultrasound is not the test of choice to rule out necrotizing fasciitis, all foreign bodies, or bowel perforation. The patient is diagnosed with emphysemtaous cholecystitis and subsequently undergoes an uncomplicated cholecystectomy. A bedside ultrasound is completed as shown (Image 5). She appears well, without jaundice, but has a fever and a positive Murphy's sign.
Gallbladder with several reverberation artifacts originating within the gallbladder wall.Ī 48-year-old female presents for right upper quadrant abdominal pain. A diagnosis of necrotizing fasciitis is made, and the patient is taken to the operating room for debridement.
#COMET TAIL ARTIFACT MEANING FREE#
The radiograph confirms free air without retained foreign body. The ultrasound (Image 1) demonstrates an impressive reverberation, ring-down artifact, concerning for a retained metal foreign body versus free air. A bedside ultrasound is performed, followed by a plain radiograph. His right arm demonstrates evidence of significant cellulitis and possible abscess near the antecubital fossa. You suspect the patient is intoxicated from methamphetamines. 1Ī-lines are part of the normal sonographic thoracic exam, but reverberation artifacts in other anatomic regions can be pathologic and point toward life-threatening diagnoses.Ī 38-year-old male presents with worsening arm pain and swelling. Another example of reverberation artifact is known as ring-down artifact and typically originates from small metal objects or air bubbles. Comet tail artifacts are another type of reverberation artifact originating from the pleural surface. A-lines are the reverberated ultrasound waves that have bounced between the parietal and visceral pleura. A common example is the “A-lines” visualized on thoracic ultrasound. Reverberation artifacts occur when two interfaces with high acoustic impedance bounce the ultrasound waves between them. Reverberation artifact originating from the patient's upper extremity soft tissue.
0 kommentar(er)
