in radiologic imaging , the term artifact describes any part of an image that does not accurately represent the anatomic structures of the subject being evaluated . in ultrasonography ( us ) , artifacts may result in the appearance of structures in an image that are not present anatomically . the majority of these can be interpreted as  by - products  of the physical process of ultrasound image generation . most of them can be explained at a basic level by an understanding of the form of the focused sound beam , the interaction of sound with tissue , and assumptions made about the spatial assignment of reflected echoes . 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 . if misinterpreted , ultrasound artifacts can lead to serious misdiagnosis . to avoid confusion , radiologists should be able to recognize artifacts when they occur . we describe a case of a 10-year - old boy with acute abdominal pain , an unremarkable physical examination , and normal blood test . abdominal sonography was performed using a 46 mhz curvilinear probe and a 711 mhz linear probe . us showed a hyperechoic well - defined ovoid nonocclusive intraluminal mass in the abdominal aorta between the origin of the superior mesenteric artery ( sma ) and the ostia of the renal arteries , closely related to the origin of the sma [ figure 1a ] . color doppler examination revealed a normal color flow pattern with no definite mass lesion or intimal dissection flap [ figure 1b ] . a computed tomography angiography ( cta ) effectively ruled out an aortic intraluminal filling defect [ figure 1c ] . due to mismatched findings of us versus cta , the appearance of an aortic mass eventually proved to be an artifact , probably due to acoustic reverberation , not a thrombus . ( a ) sagittal grayscale sonographic image of the aorta shows an echogenic intraluminal filling defect ( arrow ) at the origin of the superior mesenteric artery ( sma ) . ( b ) color doppler image shows the normal flow pattern in the sma with no definite mass lesion or intraluminal dissection flap . ( c ) sagittal ct angiography reformatted image shows normal abdominal aorta and sma ( arrow ) with no evidence of filling defect or dissection . ( d ) sagittal sonographic image of the abdominal aorta without the sma in the scan plane confirms no intraluminal or mural aortic abnormality . the former can be seen as a complication of intra - arterial catheter placement in a neonate and is occasionally seen in a young patient with structural aortic anomalies , cyanotic heart disease , or a prothrombotic state , or secondary to trauma , dehydration , or sepsis . abdominal sonography identified a hyperechoic nonocclusive intraluminal mass in the abdominal aorta between the origin of the sma and the ostia of the renal arteries , closely related to the origin of the sma , without color doppler abnormalities . reimaging the patient 's aorta in the supine position in multiple planes , without including the sma , the lesion was considered an sma - related reflection pseudomass ( or mirror - image artifact ) . this is a form of reverberation artifact that is related to the presence or absence of the sma between the aorta and transducer . such an artifact can occur from reverberations between a mass and an adjacent highly reflective surface in b - mode imaging . the insonating beam is partially mirrored on the posterior wall of the sma in the passage from low - impedance blood to high - impedance fat between the sma and the aorta . thus , the fat anterior to the sma is reflected into the aortic lumen , resulting in an intraluminal echogenic artifact . the artifact could be operator dependent and is generated when the transducer , sma , and aorta are in alignment . when scanning the aorta by the same radiologist or another independent operator outside this plane , no such artifact can be identified . in this report , we have presented the detection of a hyperechoic nonocclusive intraluminal mass in the abdominal aorta between the origin of the sma and the ostia of the renal arteries . to avoid erroneous conclusions and unnecessary tests and procedures , the aorta should be scanned in multiple planes , both with and without the sma , to confirm whether the lesion disappears and should be interpreted as a reverberation artifact from the sma . this report highlights the importance of considering the possibility of an artifact when the findings of radiologic imaging are improbable or inconsistent with the clinical findings . when diagnostic uncertainty persists , alternate noninvasive forms of vascular imaging , such as contrast - enhanced ct or magnetic resonance angiography , should be performed .
artifacts are encountered routinely in clinical ultrasonography practice . 
 the ability to recognize and eliminate potentially correctable ultrasound artifacts is of great importance to image quality improvement and optimal patient care . 
 we describe an example of a superior mesenteric artery - related pseudomass as a form of reverberation artifact that could lead to misinterpretation of sonographic findings . 
 we present the ultrasonographic and computed tomography angiography findings and give an explanation for the appearance of the artifact .