Cupola Sign

An anterior free air collection in the midsubphrenic space underneath the middle leaf of the central tendon of the diaphragm can be detected on supine films by its characteristic location and configuration.5'16'28 The cupola sign, also known as visualization of the inferior border of the heart, appears as a radiolucency of varying size, sharply defined above but poorly delimited below, overlying and extending lateral to the spinejust caudad to the heart (Figs. 7-19 through 7-21). Its upper margin is straight or slightly concave downward. Within its lucent shadow may be seen the falciform ligament (Fig. 7-19). The appearance of this intraperitoneal collection is affected by the volume of air defining it and by the orientation of the diaphragm. A small linear free air deposit can be simulated by extraperitoneal air near the

Transverse Band Air Sign

A supine film reveals a thin transverse line of lucency (arrowheads) delineating the undersurface of the central tendon of the diaphragm beneath the pericardium, mimicking an extraperitoneal air collection. Note the smooth downward deflection of the superolateral border, characteristic for the cupola sign. (From Baker and Cho.6)

A supine film reveals a thin transverse line of lucency (arrowheads) delineating the undersurface of the central tendon of the diaphragm beneath the pericardium, mimicking an extraperitoneal air collection. Note the smooth downward deflection of the superolateral border, characteristic for the cupola sign. (From Baker and Cho.6)

diaphragm29 (Fig. 7-20). A gas-filled stomach or transverse colon situated high in this space should not be mistaken for free air.

The cupola sign, described by Mindelzun and Mc-Cort28 in 1986, is one of the most valuable manifestations of free air on plain films, but it has been under-emphasized. The middle leaf of the central tendon, ventrally positioned with respect to either the right or left leaf,30 is the preferred site for free air accumulation in the supine position. On portable chest radiographs, especially in immobile patients confined in the intensive care units, this upper abdomen should be carefully evaluated to diagnose pneumoperitoneum that may be clinically unsuspected. 6,17,31

Diaphragm Muscle Slip Sign, Leaping Dolphins Sign

The diaphragm muscle slip sign is a recently recognized, yet surprisingly common, right upper quadrant sign that refers to visualization of the costal muscle slips of the diaphragm outlined by a relatively large pneumoperi-toneum. It appears in the superior half of the right upper quadrant as sharply defined, long arcuate interfaces or curved bands of increased density14 (Figs. 7-4b, 7-21 through 7-23). Generally, two to four elongated, parallel curves can be seen, each gently arching convex upward, and all merge together superomedially. Resembling the

Cupola Sign Radiology

Fig. 7—21. Diaphragm muscle slip sign in a patient with in-farcted small intestine and pneumoperitoneum.

(a) Two long arcuate interfaces, paralleling each other (arrows), represent the costal muscle slips of the diaphragm indenting the parietal peritoneum, thus delineated by adjacent free air. Super-omedially, they converge into the central tendon of the diaphragm, outlined also by pneu-moperitoneum—the cupola sign (open arrows). The wall of the markedly gas-distended colon is indicated by the arrowheads.

(b) Corresponding CT image confirms the presence of two muscle slips anteromedially (arrows). The serosal surface of the transverse colon (T) and the falciform ligament (arrowheads) are well delineated by free air. (From Cho and Baker.14)

Cupola Sign Radiology

Fig. 7—22. Diaphragm muscle slip sign.

A massive pneumoperitoneum developed following endoscopic biopsy of a gastric ulcer.

(a) On a spine digital radiograph, three diaphragm muscle slips are depicted as distinct curved bands merging together superomedially.

(b) A CT image through the dome of the diaphragm reveals two discrete muscle slips (arrows) separating free air into three ovoid pockets. Muscle slips are also seen on the left (arrowheads).

(From Cho and Baker.14)

Fig. 7—22. Diaphragm muscle slip sign.

A massive pneumoperitoneum developed following endoscopic biopsy of a gastric ulcer.

(a) On a spine digital radiograph, three diaphragm muscle slips are depicted as distinct curved bands merging together superomedially.

(b) A CT image through the dome of the diaphragm reveals two discrete muscle slips (arrows) separating free air into three ovoid pockets. Muscle slips are also seen on the left (arrowheads).

(From Cho and Baker.14)

Diaphragm Cupola Sign

Fig. 7—23. Diaphragm muscle slip sign; leaping dolphins sign.

(a) Three diaphragm muscle slips (arrowheads) converging superomedially into the central tendon (arrow) are visualized by free air on a supine chest radiograph. (b) It has an appearance reminiscent of the graceful bending of dolphins leaping in unison. (From Baker and Cho.6)

Radiology Leaping Dolphin Sign

graceful dorsal curvature of the dolphins leaping in unison, the pattern is also named the leaping dolphins sign6 (Fig. 7-23).

The muscle slip sign for pneumoperitoneum should not be confused with the less distinct, more numerous curvilinear shadows that are depicted as a result of extraperitoneal air infiltrating the diaphragmatic muscle itself32 (Fig. 7-24). In chronic obstructive pulmonary disease, the supporting edge of the costal muscle slips may occasionally be visualized by overinflated lung that may even indent the underlying hepatic surface. In general,

Fig. 7-24. Visible muscle of the diaphragm due to extraperitoneal air.

A supine film reveals diaphragmatic muscle fibers depicted by infiltrating extraperitoneal air as several gently curved, vertical lines (short arrows). They are indistinct, short, and accompanied by crescentic deposits of retroperitoneal air under the diaphragm (arrowheads) as well as in the flank (long arrow).

(From Cho and Baker.14)

Diaphragm Cupola Sign

Fig. 7-25. Ligamentum teres fissure sign from antral ulcer perforation. (a) The open arrow points to free air trapped in the peritoneal recess within the fissure for the ligamentum teres, and the arrowhead highlights the anterior superior bubble sign. The asterisk indicates air in the duodenal bulb. (b) Corresponding CT image reveals a tiny amount of air trapped within the fissure (open arrow) and a small anterior superior bubble over the liver (arrowhead). (From Cho and Baker.4)

Fig. 7-25. Ligamentum teres fissure sign from antral ulcer perforation. (a) The open arrow points to free air trapped in the peritoneal recess within the fissure for the ligamentum teres, and the arrowhead highlights the anterior superior bubble sign. The asterisk indicates air in the duodenal bulb. (b) Corresponding CT image reveals a tiny amount of air trapped within the fissure (open arrow) and a small anterior superior bubble over the liver (arrowhead). (From Cho and Baker.4)

such superior protrusions of muscle slips abutting pulmonary air are situated more superolaterally than the "leaping dolphin" lucencies indicative of intraperitoneal air.

Essentials of Human Physiology

Essentials of Human Physiology

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Responses

  • fredrick
    What is muscle slip of the lung?
    7 years ago

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