meniscus sign

crescent sign

1. in radiography of the lung, a crescent of gas near the top of a mass lesion, signifying cavitation with a space above the debris; seen in aspergilloma, hydatidoma;

2. in computed tomography, a high attenuating layer of new blood in an aneurysm; indicates a ruptured abdominal aortic aneurysm;

3. in diagnostic ultrasound, a sonolucent crescentic layer in a tumor mass, typically necrosis in stromal tumors of the small bowel;

4. in diagnostic ultrasound, a hyperechoic crescent, representing the entering limb of an intussusception; also known as crescent-in-a-doughnut;

5. in osteoradiology, a subcortical lucent crescent in the femoral head, signifying osteonecrosis.

Synonym(s): meniscus sign

Colon A radiolucency typically seen in a barium enema of a child with intussusception, which consists of a rounded apex of the intussusceptum protruding into the column of contrast material
Lung Air meniscus sign

meniscus sign

Air crescent sign Radiology A semilunar radiolucency peripheral to a pulmonary mass described as typical of echinococcal infection/hydatid cyst disease; most common cause in the US for the MS is a fungus 'ball', usually due to Aspergillus fumigatus; it may be seen in lung abscesses, tumors, hematomas, granulomatous infections and Rasmussen's aneurysm.

cres·cent sign

(kres'ĕnt sīn)

1. radiography In the lung, a crescent of gas near the top of a mass lesion, signifying cavitation with a space above the debris; seen in aspergilloma, hydatidoma.

2. computed tomography A high attenuating layer of new blood in an aneurysm; indicates a ruptured abdominal aortic aneurysm

3. diagnostic ultrasound A sonolucent crescentic layer in a tumor mass, typically necrosis in stromal tumors of the small bowel.

4. diagnostic ultrasound A hyperechoic crescent, representing the entering limb of an intussusception; also known as crescent-in-a-doughnut.

5. osteoradiology A subcortical lucent crescent in the femoral head, signifying osteonecrosis
Synonym(s): meniscus sign.