Mercedes sign of gas-containing gallstones. Gallstone fissures may contain nitrogen gas yielding a triradiate lucent pattern. When present, aids in CT visualization of noncalcified gallstones. Not to be confused with emphysematous cholecystitis.

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Large parathyroid adenoma. Usually oval/bean-shaped, but larger adenomas can be multilobulated. “Polar vessel” sign = Enlarged feeding artery or draining vein terminating @ parathyroid adenoma. Watch📽️ to learn more: bit.ly/pt-adenoma
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Parathyroid adenoma. Tc-99m sestamibi: Radiotracer initially taken up by both thyroid & parathyroid tissue but washes out more rapidly from thyroid & persists in adenoma on delayed images. Watch📽️ to learn more: bit.ly/pt-adenoma

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Parathyroid adenoma. Most common cause of primary hyperPTH. Solid, homogeneous & very hypoechoic. Oval/bean-shaped, long axis craniocaudal. Hypervascular. Bright line separates from thyroid. Watch📽️ to learn more: bit.ly/pt-adenoma

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Giant cell tumor of proximal tibia. Eccentrically located at end of long bones (epiphysis + metaphyseal extension). Closed growth plates. Ages 20-40. +/- fluid-fluid levels, can co-exist with aneurysmal bone cyst. Rarely malignant but locally aggressive.
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Urothelial carcinoma (*) arising in a bladder (B) diverticulum (D). Bladder most common site for urothelial carcinoma (AKA transitional cell carcinoma), but only rarely seen in diverticula. Bladder diverticula can also be complicated with infection or calculi.

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Juvenile recurrent parotitis. Multiple nonuniform hypoechoic foci scattered throughout gland with central calcifications (arrows). Rare but 2nd most common cause of parotitis in childhood after mumps. Watch📽️ to learn more: bit.ly/rq-parotitis

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Pomegranate sign of acute parotitis. Uniform anechoic foci scattered throughout the gland. Similar to pseudonodular “giraffe” ultrasound pattern that can be seen in Hashimoto’s thyroiditis. Watch📽️ to learn more: bit.ly/rq-parotitis
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Acute left parotitis. 2 y.o. with enlarged, heterogeneous, hyperemic left parotid gland with adjacent lymphadenopathy (LN). Normal right gland. In children, most common cause viral (mumps). Watch📽️ to learn more: bit.ly/rq-parotitis

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Sublingual dermoid cyst. Rare, benign, squamous epithelial lining & contains skin appendages. Sublingual space bounded medially by genioglossus/geniohyoid muscles, inferolaterally by mylohyoid. Watch📽️ to learn more: bit.ly/subderm
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Calyceal diverticulum. Often asymptomatic. Can present with hematuria, stone formation or infection. Mimics cyst on conventional imaging, contains excreted contrast on excretory phase due to communication with collecting system.

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Interstitial ectopic pregnancy on T2W MRI. Pregnancy within proximal fallopian tube surrounded by uterine wall. Higher risk of rupture compared to the more common tubal ectopic pregnancy. Sac located eccentric to junctional zone with thin (<5 mm) overlying myometrium. #FOAMrad

Carpal tunnel anatomy. Median nerve (MN) deep to flexor retinaculum, anterior to flexor digitorum superficialis & profundus tendons (FD). Flexor carpi radialis tendon (FCR) anterior to scaphoid. Watch📽️ to learn more: bit.ly/rq-cts
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Join me for “Ultrasound of the Hand & Wrist: What the Surgeon Wants to Know,” a FREE webinar Wed,11/8/2023 at 1 PM EST hosted by the AIUM in conjunction w/ Samsung. Register here: bit.ly/wristwebinar, or go to aium.org. Boston Imaging AIUM Ultrasound #mskrad

Multifocal primary hepatic lymphoma. Rare. Often solitary unlike diffusely infiltrating secondary lymphoma. T1 dark, T2 bright (relative to liver), hypoenhancing w/ faint rim enhancement. Marked restricted diffusion due to hypercellularity. Path = High-grade B-cell.

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Ventral wrist ganglion cyst causing median nerve compression. MN identified by its fascicular, honeycomb configuration. Thickened nerve proximal to cyst, normal diameter distally = Notch sign. Watch📽️ to learn more: bit.ly/rq-ganglion
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Dorsal wrist ganglion cyst. May see pedicle connecting to joint. Dorsal wrist most common location. Unlike joint recess fluid & bursal collections, will not collapse with compression.
Watch📽️ to learn more: bit.ly/rq-ganglion
Boston Imaging Samsung Healthcare #FOAMrad

Porcelain gallbladder. Dense calcification outlining gallbladder wall (arrows). Most (90-95%) have associated gallstones (*). Originally thought to have a high association with GB adenocarcinoma, but more recent studies have shown a much weaker risk (<1% per year).

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Multiple splenic hemangiomas. Most common benign neoplasm of spleen. Centripetal enhancement from periphery inward, uniform fill-in on delayed images = Similar enhancement to hepatic hemangiomas, except characteristic peripheral nodular pattern often absent.

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Prepatellar bursitis. Fluid accumulation anterior to patella in prepatellar bursa (arrows). Typically caused by direct trauma or repetitive kneeling. Less commonly caused by gout, RA, or infection. May see calcifications if chronic.

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