ARDMS AB-Abdomen Exam Questions

The image shows a small hepatic lesion located very close to the anterior liver capsule, as indicated by the arrow. When imaging very superficial or near-field structures like subcapsular hepatic lesions, using a standoff pad is the most effective technique for optimizing visualization.

A standoff pad (also known as an acoustic stand-off or gel pad) helps increase the distance between the transducer and the superficial target. This improves the focus and beam shape for near-field imaging and minimizes reverberation and ring-down artifacts. It allows better evaluation of superficial lesions by positioning them within the focal zone of the transducer, which is usually set a few millimeters below the probe surface.

Differentiation from other options:

A . Decrease depth: While reducing depth can help center deeper lesions in the field of view, it does not address issues with near-field resolution.

B . Scan in upright position: This may help in gallbladder or fluid positioning but is not optimal for improving visualization of superficial liver lesions.

C . Move the transducer focus: Adjusting focus deeper into the image won't enhance resolution of very superficial structures unless a standoff is used to bring the lesion into the focal zone.

Rumack CM, Wilson SR, Charboneau JW, Levine D. Diagnostic Ultrasound. 5th Edition. Elsevier, 2018. Chapter: Liver, pp. 80--84.

Kremkau FW. Sonography: Principles and Instruments. 9th Edition. Elsevier, 2015. Chapter: Image Formation and Optimization, pp. 114--117.

AIUM Practice Parameter for the Performance of an Ultrasound Examination of the Abdomen and/or Retroperitoneum, 2020.

The image demonstrates a characteristic 'central dot sign' --- a hallmark finding of Caroli disease. This is best appreciated on ultrasound as a cystic dilation of the intrahepatic bile ducts with a central echogenic dot or linear structure (which corresponds to the portal vein and fibrous tissue within the dilated duct). The arrow in the image points to one such dilated duct.

Caroli disease is a rare congenital disorder characterized by segmental, saccular dilation of intrahepatic bile ducts. It is often associated with congenital hepatic fibrosis and may predispose to cholangitis, stone formation, and even cholangiocarcinoma.

Key ultrasound features of Caroli disease:

Cystic or saccular dilations of the intrahepatic bile ducts

The 'central dot sign' --- echogenic focus in the center of the dilated ducts (representing portal vein radicle or fibrous tissue)

May show associated hepatosplenomegaly or signs of portal hypertension

Differentiation from other options:

A . Sclerosing cholangitis: Typically causes diffuse or segmental biliary ductal wall thickening and stricturing; does not present with cystic dilations.

B . Alagille syndrome: A multisystem disorder often characterized by a paucity of intrahepatic bile ducts, not dilation.

D . Biliary atresia: Presents in infancy with obliteration of extrahepatic bile ducts, echogenic 'triangular cord' sign, and absence of a visible gallbladder. It does not cause ductal dilation.

Rumack CM, Wilson SR, Charboneau JW, Levine D. Diagnostic Ultrasound. 5th Edition. Elsevier, 2018. Chapter: Biliary System, pp. 152--155.

Radiopaedia.org. Caroli disease. https://radiopaedia.org/articles/caroli-disease

American College of Radiology (ACR). ACR--SPR Practice Parameter for the Performance of Pediatric Abdominal Ultrasound, 2022.

The sonographic images depict an acute thrombotic process involving the portal venous system. The absence of cavernous transformation in the setting of portal vein thrombus indicates that the process is acute. In chronic portal vein thrombosis, collateral vessels form in the porta hepatis to bypass the obstruction, a process known as cavernous transformation.

Sonographic features suggesting acute portal vein thrombosis:

Echogenic thrombus within the portal vein lumen

Absence of flow on color Doppler

Enlarged portal vein diameter early in the process

No evidence of cavernous transformation (i.e., no serpiginous collateral vessels at porta hepatis)

Cavernous transformation is a hallmark of chronic portal vein thrombosis and takes weeks to months to develop. Therefore, its absence on ultrasound supports an acute diagnosis.

Differentiation from other options:

A . Free fluid: Non-specific and may or may not be present in hepatic vascular thrombosis.

B . Ductal dilatation: Related to biliary obstruction, not portal or hepatic venous thrombosis.

C . Hepatic vein thrombosis: Seen in Budd-Chiari syndrome, which affects hepatic outflow, not portal inflow.

Rumack CM, Wilson SR, Charboneau JW, Levine D. Diagnostic Ultrasound. 5th Edition. Elsevier, 2018. Chapter: Portal Venous System, pp. 105--108.

American Institute of Ultrasound in Medicine (AIUM) Practice Parameter for the Performance of Hepatic Doppler Ultrasound Examinations, 2020.

Radiopaedia.org. Cavernous transformation of the portal vein: https://radiopaedia.org/articles/cavernous-transformation-of-the-portal-vein

Alpha-fetoprotein (AFP) is commonly elevated in patients with hepatocellular carcinoma (hepatoma), particularly in those with underlying cirrhosis or chronic hepatitis B/C. AFP is not typically elevated in adenomas, cholangiocarcinoma, or FNH.

According to Rumack's Diagnostic Ultrasound:

''Serum AFP levels are elevated in 50--70% of patients with hepatocellular carcinoma.''

Rumack CM, Wilson SR, Charboneau JW, Levine D. Diagnostic Ultrasound. 5th ed. Elsevier, 2017.

AASLD Guidelines for HCC Surveillance, 2018.

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Most thyroid cancer recurrences are found in the ipsilateral neck---particularly in the central (level VI) or lateral (levels II-V) compartments on the same side as the original malignancy.

According to AIUM Practice Parameters:

''Post-thyroidectomy recurrence most frequently occurs ipsilateral to the original tumor, commonly involving regional lymph nodes.''

AIUM Practice Parameter for Thyroid and Neck Ultrasound, 2020.

American Thyroid Association (ATA) Guidelines for Thyroid Cancer Management, 2015.