Cupola Sign
2
The Cupola Sign 1 Geoffrey B. Marshall, BSc, MD Appearance The cupola sign (1) is seen at supine radi- ography as an arcuate lucency overlying the lower thoracic spine and projecting caudad to the heart (Fig 1). The superior border is well defined and the inferior margin is poorly delineated. The term cu- pola is used to indicate the inverted cup- shaped configuration of the lucency. Explanation When the patient is in the supine posi- tion, air within the peritoneal cavity (pneumoperitoneum) will preferentially accumulate in the anterior portion of the cavity, beneath the central tendon of the diaphragm and within the median sub- phrenic space (2). The central tendon of the diaphragm is composed of three leaves: right, left, and central. The central leaf is located anterior (3) and thus the likely site for the accumulation of gas while the patient is in the supine position. The median subphrenic space is located anterior to the stomach and gastrohepatic ligament. Occasionally, the falciform liga- ment may appear within the lucency, con- tiguous with its superior border (1). Discussion Pneumoperitoneum occurs due to any of a wide variety of causes, which may be benign or life-threatening. The most com- mon cause is recent abdominal surgery, after which air is usually resorbed by the patient over the ensuing 3–7 days (4). The duration of resorbtion is dependent on the initial volume of air introduced and the patient body habitus; asthenic pa- tients tend to experience a prolonged postoperative pneumoperitoneum (5). Other iatrogenic causes include perito- neal dialysis and endoscopic procedures (6). Spontaneous pneumoperitoneum is usually the result of a perforated hollow viscus, especially a perforated duodenal or gastric ulcer. The former cause is seen in the case presented, with confirmation of pneumoperitoneum at computed to- A trainee (resident or fellow) wishing to submit a manuscript for Signs in Imaging should first write to the Editor for approval of the sign to be prepared, to avoid duplicate preparation of the same sign. Published online 10.1148/radiol.2412040700 Radiology 2006; 241:623– 624 1 From the Department of Diagnostic Imaging, Foothills Medical Centre, 1403 29th Ave NW, Calgary, AB, Canada T2N 2T9. Received April 21, 2004; revision requested June 29; revision received July 1; accepted July 28. Ad- dress correspondence to the author (e-mail: geoff [email protected]). Author stated no financial relationship to disclose. RSNA, 2006 Figure 1 Figure 1: Single anteroposte- rior supine radiograph of the chest depicts an arcuate collection of free intraperitoneal air within the median subphrenic space (cupola sign). The superior border is well defined (arrows) compared with the inferior extent of the collection. SIGNS IN IMAGING Radiology: Volume 241: Number 2—November 2006 623 Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights.
description
Radiology
Transcript of Cupola Sign
The Cupola Sign1
Geoffrey B. Marshall, BSc, MD Appearance
The cupola sign (1) is seen at supine radi-ography as an arcuate lucency overlyingthe lower thoracic spine and projectingcaudad to the heart (Fig 1). The superiorborder is well defined and the inferiormargin is poorly delineated. The term cu-pola is used to indicate the inverted cup-shaped configuration of the lucency.
Explanation
When the patient is in the supine posi-tion, air within the peritoneal cavity(pneumoperitoneum) will preferentiallyaccumulate in the anterior portion of thecavity, beneath the central tendon of thediaphragm and within the median sub-phrenic space (2). The central tendon ofthe diaphragm is composed of threeleaves: right, left, and central. The centralleaf is located anterior (3) and thus thelikely site for the accumulation of gaswhile the patient is in the supine position.The median subphrenic space is located
anterior to the stomach and gastrohepaticligament. Occasionally, the falciform liga-ment may appear within the lucency, con-tiguous with its superior border (1).
Discussion
Pneumoperitoneum occurs due to any ofa wide variety of causes, which may bebenign or life-threatening. The most com-mon cause is recent abdominal surgery,after which air is usually resorbed by thepatient over the ensuing 3–7 days (4).The duration of resorbtion is dependenton the initial volume of air introduced andthe patient body habitus; asthenic pa-tients tend to experience a prolongedpostoperative pneumoperitoneum (5).Other iatrogenic causes include perito-neal dialysis and endoscopic procedures(6). Spontaneous pneumoperitoneum isusually the result of a perforated hollowviscus, especially a perforated duodenalor gastric ulcer. The former cause is seenin the case presented, with confirmationof pneumoperitoneum at computed to-
A trainee (resident or fellow) wishing to submit a manuscript forSigns in Imaging should first write to the Editor for approval ofthe sign to be prepared, to avoid duplicate preparation of thesame sign.
Published online10.1148/radiol.2412040700
Radiology 2006; 241:623–624
1 From the Department of Diagnostic Imaging, FoothillsMedical Centre, 1403 29th Ave NW, Calgary, AB, CanadaT2N 2T9. Received April 21, 2004; revision requestedJune 29; revision received July 1; accepted July 28. Ad-dress correspondence to the author (e-mail: [email protected]).
Author stated no financial relationship to disclose.
� RSNA, 2006
Figure 1
Figure 1: Single anteroposte-rior supine radiograph of the chestdepicts an arcuate collection offree intraperitoneal air within themedian subphrenic space (cupolasign). The superior border is welldefined (arrows) compared withthe inferior extent of the collection.
SIGNSIN
IMAGING
Radiology: Volume 241: Number 2—November 2006 623
Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights.
mography (CT) (Fig 2) (7). Other causesof spontaneous pneumoperitoneum havebeen described in the literature (4–7).
Upright chest and lateral decubitusabdominal radiography are still consid-ered to be the standard initial radiologicinvestigation in the diagnosis of pneu-moperitoneum. Miller and Nelson (8)showed that as little as 1–2 mL of free aircould be detected if a strict protocol ofpositioning the patient in the left lateraldecubitus position for 10–20 minutes andthen in the upright position for an addi-tional 10 minutes was followed. This pro-tocol is of limited use for patients withclinical symptoms that preclude a wait ofthis duration, and in those patients unableto cooperate by maintaining the optimalposition described.
There are many useful signs that maycontribute to a diagnosis of free air atsupine radiography. In a retrospectivestudy done by Menuck and Siemers (9), adiagnosis of free air was made for 56% ofpatients known to have pneumoperito-neum who underwent supine radiogra-phy. This study emphasized a detailedsearch for lucencies projecting over theright upper quadrant to identify collec-tions of air within the subhepatic spaceand anterior to the right lobe of the liver.A blinded, retrospective study by Levineet al (10) showed a 59% sensitivity of
supine radiography for displaying free air,with right upper quadrant gas being themost common indicator of pneumoperito-neum (44% of cases). In a review of 100patients with confirmed pneumoperito-neum, Mindelzun and McCort (1) foundsix patients with radiographs that dis-played the cupola sign. For three of thepatients, this was the only indicator offree air. For the remaining three patients,the cupola sign was seen in associationwith air beneath the right and left dia-phragmatic leaves. Potential mimics ofthe sign include air within the lesser sac,air within a high transverse colon, gaswithin the pericardium or mediastinum,or air within a horizontally oriented stom-ach (1). Confusion between signs is obvi-ated by identification of rugae or haustrain cases of intraluminal gastric or trans-verse colonic air or by identification of thefalciform ligament superimposed over thelucency, which confirms the anterior loca-tion of the air collection in the peritonealspace rather than in the lesser sac. Pneu-momediastinum or pneumopericardiumshould not demonstrate the well-definedsuperior margin of the cupola sign.
CT is widely considered to be the ref-erence standard for confirming pneumo-peritoneum. Stapakis and Thickmancompared the sensitivity of CT with thesensitivity of upright chest radiography
for the detection of free air in 13 traumapatients who had undergone diagnosticperitoneal lavage. All 13 (100%) patientsdemonstrated free air at CT, while onlyfive of 13 (38%) patients showed free airat upright chest radiography (11).
Supine radiography remains an in-valuable initial investigation in confirmingthe presence of pneumoperitoneum as apotential source of the patient’s symp-toms. The cupola sign denotes free intra-peritoneal air within the median sub-phrenic space which may prompt furtherinvestigation, particularly in patients inwhom the diagnosis is unsuspected.
Acknowledgment: I thank Colette Marshall,BSc, MD for her assistance.
References1. Mindelzun RE, McCort JJ. The cupola sign of
pneumoperitoneum in the supine patient. Gas-trointest Radiol 1986;11:283–285.
2. Cho KC, Baker SR. Supine film manifestationsof pneumoperitoneum. In: Myers M, ed. Dy-namic radiology of the abdomen. 5th ed. NewYork, NY: Springer-Verlag, 2000; 319–320.
3. Agur AM. Grant’s atlas of anatomy, 9th ed.Baltimore, Md: Williams & Wilkins, 1991;137.
4. Cho KC, Baker SR. Extraluminal air: diagnosisand significance. Radiol Clin North Am 1994;32(5):829–844.
5. Felson B, Wiot JF. Another look at pneumo-peritoneum. Semin Roentgenol 1973;8:437–443.
6. Winek TG, Mosely HS, Grout G, Luallin D.Pneumoperitoneum and its association withruptured abdominal viscus. Arch Surg 1988;123(6):709–712.
7. Rice RP, Thompson WM, Gedgaudas RK. Thediagnosis and significance of extraluminal gasin the abdomen. Radiol Clin North Am 1982;20(4):819–837.
8. Miller RE, Nelson SW. The roentgenologicaldemonstration of tiny amounts of free intra-peritoneal gas: experimental and clinical stud-ies. Am J Roentgenol Radium Ther Nucl Med1971;112:574–585.
9. Menuck L, Siemers PT. Pneumoperitoneum:importance of right upper quadrant features.AJR Am J Roentgenol 1976;127:753–756.
10. Levine MS, Scheiner JD, Rubesin SE, Laufer I,Herlinger H. Diagnosis of pneumoperitoneumon supine abdominal radiographs. AJR Am JRoentgenol 1991;156:731–735.
11. Stapakis JC, Thickman D. Diagnosis ofpneumoperitoneum: abdominal CT vs. uprightchest film. J Comput Assist Tomogr 1992;16:713–716.
Figure 2
Figure 2: Contrast material–enhanced transverse CT imageconfirms the presence of pneumo-peritoneum (�) in the same pa-tient.
SIGNS IN IMAGING: The Cupola Sign Marshall
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