CT Findings of Acute Cholecystitis and Its Complications

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1 Gastrointestinal Imaging Pictorial Essay Shakespear et al. CT of cute Cholecystitis Gastrointestinal Imaging Pictorial Essay Downloaded from by on 01/20/18 from IP address Copyright RRS. For personal use only; all rights reserved Jonathan S. Shakespear 1 kram M. Shaaban Maryam Rezvani Shakespear JS, Shaaban M, Rezvani M Keywords: acute cholecystitis, CT, gallbladder, ultrasound DOI: /JR Received September 17, 2009; accepted after revision December 15, ll authors: Department of Radiology, University of Utah, 30 N 1900 East, #171, Salt Lake City, UT ddress correspondence to J. Shakespear (jonathan.shakespear@hsc.utah.edu). JR 2010; 194: X/10/ merican Roentgen Ray Society CT Findings of cute Cholecystitis and Its Complications OJECTIVE. The purpose of this article is to describe and illustrate the CT findings of acute cholecystitis and its complications. CONCLUSION. CT findings suggesting acute cholecystitis should be interpreted with caution and should probably serve as justification for further investigation with abdominal ultrasound. CT has a relatively high negative predictive value, and acute cholecystitis is unlikely in the setting of a negative CT. Complications of acute cholecystitis have a characteristic CT appearance and include necrosis, perforation, abscess formation, intraluminal hemorrhage, and wall emphysema. E valuating the gallbladder in the setting of acute right upper quadrant pain is a common endeavor in many radiology departments and justifiably so. recent meta-analysis showed that no clinical or laboratory finding is sufficient to rule in or rule out the diagnosis without an associated imaging examination. Thus, patients presenting with clinical features suggesting acute cholecystitis should undergo imaging to confirm the diagnosis [1]. bdominal ultrasound is the obvious study of choice to evaluate acute gallbladder disease. Multiple studies have shown its high sensitivity and specificity in acute cholecystitis and cholelithiasis. few articles published in the early days of MDCT also touted it as a sensitive and specific test for acute cholecystitis, but such hopes were not supported by later articles. In fact, in a recent retrospective study evaluating the utility of ultrasound versus CT in acute cholecystitis, ultrasound proved to have significantly higher sensitivity (83% vs 39%), positive predictive value (75% vs 50%), and negative predictive value (97% vs 89%) than CT, with both techniques showing similar specificity (95% vs 93%) [2]. lthough these numbers are similar to our experience with CT, to our knowledge, no large prospective study has been performed to evaluate CT in acute cholecystitis. ecause ultrasound is sensitive, specific, and also low in cost and free of ionizing radiation, there is little reason to expect that CT will be pursued as a primary imaging technique for acute gallbladder disease. lthough ultrasound is the clear initial examination of choice for a patient with right upper quadrant pain, fever, leukocytosis, and a positive Murphy sign, such a classic presentation may not be typical in daily practice [3]. CT is frequently performed in patients with a wider differential diagnosis, confusing signs and symptoms, and pain that extends beyond the right upper quadrant. CT may also be performed in those who present after hours when the general availability of CT scanners accounts for increasing utilization. CT also is often obtained to evaluate for complications of acute cholecystitis. These reasons as well as the increasing use of CT to triage patients in emergency departments necessitate familiarity with the findings of acute cholecystitis and its complications. Pathophysiology Most acute cholecystitis is associated with gallstones (90 95%). It is estimated that approximately 10 20% of people in Western societies have cholelithiasis and that one third of those with gallstones will develop cholecystitis [4]. The presumed mechanism is transient or persistent gallbladder outlet obstruction by a stone, which leads to cholestasis and subsequent mechanical, chemical, or infectious irritation of the gallbladder wall. ile breakdown products (lysolecithin), prostaglandins, bacterial infection (present in 40 70%), and mechanical erosion from stones are thought to be key factors in mucosal irritation. calculous cholecystitis JR:194, June

2 Shakespear et al. Downloaded from by on 01/20/18 from IP address Copyright RRS. For personal use only; all rights reserved accounts for 5 10% of all acute cholecystitis. Most patients are critically ill with multiple comorbidities that predispose to cholestasis and gallbladder wall ischemia. CT Findings in cute Cholecystitis Typical CT findings in acute cholecystitis include gallbladder distention, wall thickening, mucosal hyperenhancement, pericholecystic fat stranding or fluid, and gallstones with a sufficient attenuation difference from bile to be visualized (about 65 75%) (Figs. 1 7). significant fraction of mixed cholesterol or pigment stones are so similar in attenuation to bile that they are not reliably identified by standard CT kilovoltage settings [5 8]. Reactive hyperemia resulting in increased enhancement of the hepatic parenchyma of the gallbladder fossa may also be present (CT rim sign) (Fig. 8). In a retrospective review of preoperative CT findings in 29 patients with pathologyproven cholecystitis, 59% had wall thickening, 52% had pericholecystic stranding, 41% had distention, and 31% had pericholecystic fluid [6]. The gallbladder was considered distended if it measured greater than 5 cm in the short axis and greater than 8 cm in length. Wall thickening was defined at greater than 4 mm in a noncollapsed gallbladder (short axis greater than 2 cm) [6]. Diffuse gallbladder wall thickening is a nonspecific finding that is associated with a wide variety of disease states including hypoalbuminemia, ascites, chronic cholecystitis, hepatitis, and unrelated inflammatory processes elsewhere in the abdomen (such as pancreatitis) [9, 10]. For example, a recent study identified gallbladder wall thickening in 19 of 21 patients with acute pyelonephritis [11] (Figs. 9 and 10). s noted, abdominal ultrasound is superior to CT in establishing the diagnosis of acute cholecystitis. The highest positive predictive values for acute cholecystitis with ultrasound are based on the presence of gallstones in conjunction with a sonographic Murphy sign (92%) or gallbladder wall thickening (95%) [12]. It should come as no surprise then that CT, with its limited ability to show gallstones and inability to evaluate for focal tenderness, would prove to be inferior. dditionally, gallbladder wall thickening may occasionally be less optimally visualized at CT than at ultrasound. nd even when optimally visualized, it may be unrelated to primary gallbladder disease. lthough less than that of ultrasound, the negative predictive value of CT in one study was approximately 89% (compared with 97% for ultrasound) [2]. CT presumably is most often obtained in patients who present with abdominal pain that is not classic for acute cholecystitis. negative CT may therefore exclude or at least argue against acute cholecystitis. If clinical suspicion remains, follow-up ultrasound could be performed to more confidently exclude the diagnosis. Gangrenous Cholecystitis Untreated acute cholecystitis may resolve within 7 10 days. However, complications are common. The most common complication is the development of gallbladder gangrene (2 38% of cases) with subsequent perforation (up to 10% of cases) [13, 14]. Defects in the gallbladder mucosa or sloughed intraluminal membranes suggest gangrene. Focal transmural defects in the gallbladder wall may be apparent in the setting of perforation. Loculated or freely flowing intraperitoneal bile may also be present to further establish the diagnosis of perforation (Figs ). Emphysematous Cholecystitis Emphysematous cholecystitis is caused by secondary infection of the gallbladder wall with gas-forming organisms. ffected patients are more commonly diabetic (30 50%), male, and years old. Emphysematous cholecystitis presents as gas within the gallbladder wall that, although characteristic on CT and abdominal radiographs, may complicate ultrasound evaluation. It often heralds the development of gangrene, perforation, and abscess formation [15] (Fig. 14). Pericholecystic bscess cute cholecystitis is complicated with pericholecystic abscess formation in a reported 3 19% of cases [16]. bscesses will present as intramural and pericholecystic rim-enhancing fluid collections. dherent, thickened omentum will often be present. Extension of the pericholecystic abscess into the adjacent hepatic parenchyma will appear as a complex cystic mass with surrounding parenchymal edema (Figs. 13 and 14). The abscess can be unilocular or have septations and an irregular contour. Rim enhancement is typical, although not always present. Intralesional gas is uncommon. The cluster sign, or multiple adjacent small abscesses, can be helpful in distinguishing an abscess from other hepatic masses. Vascular Complications Inflammatory vessel wall destruction associated with acute cholecystitis results in gallbladder hemorrhage, which will manifest as high-attenuation material within the gallbladder lumen (Fig. 7). Vicarious excretion of recently administered iodinated contrast material in the bile is a potential mimic and an appropriate history should be obtained to avoid this pitfall (Fig. 8). Portal vein thrombosis and cystic artery pseudoaneurysm are also occasionally seen as sequelae of local vascular inflammation from acute or chronic cholecystitis [17, 18] (Figs ). Conclusion bdominal ultrasound should serve as the initial study in patients with suspected acute gallbladder disease. CT is best reserved for patients with a wider differential diagnosis, confusing signs and symptoms, and pain that extends beyond the right upper quadrant. CT findings suggesting acute cholecystitis include gallbladder distention, wall thickening, mucosal hyperenhancement, pericholecystic fat stranding, gallstones (approximately 65 75% of which are detectable by CT), and reactive hyperemia resulting in hyperenhancement of the hepatic parenchyma of the gallbladder fossa. It is important to keep in mind that CT does not reliably show gallstones, may underestimate gallbladder wall thickening, and lacks the ability to detect a Murphy sign. Nonspecific gallbladder wall thickening and adjacent fat stranding also may be present in a wide variety of systemic and intraabdominal disease processes that do not arise from the gallbladder. ecause of the low positive predictive value, CT findings suggestive of acute cholecystitis should be interpreted with caution and should probably serve as justification for further investigation with abdominal ultrasound. CT has a relatively high negative predictive value (89%), and acute cholecystitis is unlikely in the setting of a negative CT. However, follow-up may be warranted in a patient with high clinical suspicion for acute cholecystitis. Complications of acute cholecystitis have a characteristic CT appearance and include necrosis, perforation, abscess formation, intraluminal hemorrhage, and wall emphysema. When complications are suspected, the gallbladder wall should be carefully examined for gas, sloughed membranes, focal defects, pericholecystic fluid collections, and intramural abscess or hemorrhage JR:194, June 2010

3 CT of cute Cholecystitis Downloaded from by on 01/20/18 from IP address Copyright RRS. For personal use only; all rights reserved References 1. Trowbridge RL, Rutkowski NK, Shojania KG. Does this patient have acute cholecystitis? JM 2003; 289: Harvey RT, Miller WT Jr. cute biliary disease: initial CT and follow-up US versus initial US and follow-up CT. Radiology 1999; 213: merican College of Radiology (CR) Website. CR appropriateness criteria 2008: right upper quadrant pain. ccessed March 3, Laing FC. The gallbladder and bile ducts. In: Rumack CM, Wilson SR, Charboneau JW, eds. Diagnostic ultrasound, 2nd ed., vol. 1. St Louis, MO: Mosby Year ook, 1998: Paulson EK. cute cholecystitis: CT findings. Semin Ultrasound CT MR 2000; 21: Fidler J, Paulson EK, Layfield L. CT evaluation of acute cholecystitis: findings and usefulness in diagnosis. JR 1996; 166: arakos J, Ralls PW, Lapin S, et al. Cholelithiasis: evaluation with CT. Radiology 1987; 162: Chan WC, Joe N, Coakley FV, et al. Gallstone detection at CT in vitro: effect of peak voltage setting. Radiology 2006; 241: Cooperberg PL, Gibney RG. Imaging of the gallbladder: Radiology 1987; 163: Shlaer WJ, Leopold GR, Scheible FW. Sonography of the thickened gallbladder wall: a nonspecific finding. JR 1981; 136: Zissin R, Osadchy, Gayer G, et al. Extrarenal manifestations of severe acute pyelonephritis: CT findings in 21 cases. Emerg Radiol 2006; 13: Ralls PW, Collette PM, Lapin S, et al. Real-time sonography in suspected acute cholecystitis: prospective evaluation of primary and secondary signs. Radiology 1985; 155: Jeffrey R, Laing FC, Wong W, Callen PW. Gangrenous cholecystitis: diagnosis by ultrasound. Fig. 1 Cholelithiasis in 62-year-old man with abdominal pain and abnormal hepatic enzymes., Longitudinal sonogram shows multiple echogenic, shadowing gallstones within gallbladder lumen., No stones are visible on contrast-enhanced axial CT image. Radiology 1983; 148: Reiss R, Nudelman I, Gutman C, et al. Changing trends in surgery for acute cholecystitis. World J Surg 1990; 14: Garcia-Sancho Tellez L, Rodrigues-Montes J, Fernandes LS, et al. cute emphysematous cholecystitis: report of twenty cases. Hepatogastroenterology 1999; 46: Takada T, Yasuda H, Uchiyama K, et al. Pericholecystic abscess: classification of US findings to determine the proper therapy. Radiology 1989; 172: Choi SH, Lee JM, Lee KH, et al. Relationship between various patterns of transient increased hepatic attenuation on CT and portal vein thrombosis related to acute cholecystitis. JR 2004; 183: katsu T, Tanabe M, Shimizu T, et al. Pseudoaneurysm of the cystic artery secondary to cholecystitis as a cause of hemobilia: report of a case. Surg Today 2007; 37: Fig. 2 cute cholecystitis in 84-year-old man with nausea, vomiting, and epigastric pain. xial contrast-enhanced CT image shows typical case of acute cholecystitis with calcified gallstones, wall thickening, mucosal hyperenhancement, and pericholecystic fat stranding. Fig. 3 cute cholecystitis in 67-year-old woman with Murphy sign and right upper quadrant and right flank pain. and, xial contrast-enhanced CT images show gallbladder wall thickening, distention (12.5-cm long axis), and pericholecystic fat stranding. Lamellated gallstone is impacted in gallbladder neck (arrow, ). JR:194, June

4 Shakespear et al. Fig. 4 cute cholecystitis in 86-year-old man with nausea, vomiting, and right upper quadrant pain., Coronal contrast-enhanced CT image through gallbladder neck shows impacted lamellated gallstone, wall thickening, and pericholecystic fluid., xial contrast-enhanced CT image shows layering and hyperdense sludge within gallbladder lumen. Downloaded from by on 01/20/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig. 5 cute cholecystitis in 57-year-old woman with abdominal pain that is not well visualized by CT., xial contrast-enhanced CT image through gallbladder shows mildly thickened gallbladder wall (? 5 mm), but pericholecystic fat is normal., Transverse sonogram shows obvious gallbladder wall thickening and echogenic sludge. Sonographic Murphy sign was also present. Fig. 7 cute cholecystitis and secondary colitis in 78-year-old man with diffuse abdominal pain., xial contrast-enhanced CT image through gallbladder fundus shows intraluminal stone, gallbladder wall thickening, and inflammation of pericholecystic fat. Hepatic flexure of right colon is also secondarily inflamed (arrow)., Coronal CT reformatted image shows secondary inflammation of hepatic flexure of right colon (arrow). Inspissated barium and extensive diverticular disease are noted. Fig. 6 calculous cholecystitis in 61-year-old woman with multiple comorbidities who exhibited fever and leukocytosis during extended hospital stay. xial contrast-enhanced CT image through pelvis shows marked distention of gallbladder that measures 7 cm in short axis. Small amount of gas is present within gallbladder lumen (arrow) JR:194, June 2010

5 CT of cute Cholecystitis Downloaded from by on 01/20/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig. 9 Diffuse secondary gallbladder wall thickening in 27-year-old woman with left flank pain from acute pyelonephritis. xial contrast-enhanced CT image shows diffuse, circumferential thickening of gallbladder wall associated with striated nephrogram in contralateral kidney. Hyperdense bile is due to vicarious excretion of IV contrast material administered hours before this examination. Fig. 8 Hemorrhagic cholecystitis in 40-year-old man with right upper quadrant pain. and, High-attenuation material fills gallbladder in these contrast-enhanced axial () and coronal () CT images. Patient had not had any recent contrast-enhanced examinations. Hyperenhancement of gallbladder fossa indicates transient reactive hyperemia of hepatic parenchyma. This has been described as CT rim sign and is analogous to rim sign of hepatobiliary scintigraphy. C, Longitudinal sonogram shows echogenic blood products filling gallbladder. Shadowing gallstones are present in fundus and gallbladder neck. Gross pathologic specimen was filled with hemorrhage. Fig. 11 Gangrenous cholecystitis in 30-year-old woman with leukocytosis and right lower quadrant pain. and, xial () and coronal () contrast-enhanced images show gallbladder wall thickening, pericholecystic inflammation, and focal mucosal defects without frank perforation. Pathologic specimen exhibited friable mucosa with focal ulceration. pproximately 30 gallstones were also present that are not well visualized with this technique. Fig. 10 Diffuse secondary gallbladder wall thickening in 47-year-old woman with idiopathic dilated cardiomyopathy and pelvic pain., xial contrast-enhanced CT image shows diffuse, circumferential gallbladder wall thickening without pericholecystic inflammation., xial contrast-enhanced CT image through liver shows heterogeneous enhancement consistent with hepatic congestion due to patient s dilated cardiomyopathy. ssociated right pleural effusion is also present. C JR:194, June

6 Shakespear et al. Fig. 12 Gangrenous cholecystitis in 84-year-old man with abdominal pain and leukocytosis. and, xial contrast-enhanced CT images show gallbladder inflammation and hyperdense sloughed membranes dependently layering within gallbladder lumen, consistent with necrosis. Perforation was also reported at surgery, but is not yet evident on this examination. Downloaded from by on 01/20/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig. 14 Emphysematous cholecystitis and hepatic abscess in 57-year-old woman with leukocytosis and mild right upper quadrant pain., Coronal contrast-enhanced CT image shows gas within gallbladder wall and poor enhancement of adjacent hepatic parenchyma., xial contrast-enhanced CT image shows secondary hepatic abscess (arrow) with surrounding inflammation. C, Longitudinal sonogram shows large, shadowing gallstone (cursors) impacted in neck of gallbladder. Fig. 13 Gangrenous cholecystitis in 78-year-old man with malaise, hypotension, and right upper quadrant pain. and, xial contrast-enhanced CT images show sloughed intraluminal membranes and hepatic abscess (arrow, ) adjacent to gallbladder fossa. Cholecystostomy tube drainage expressed copious purulent material. C 1528 JR:194, June 2010

7 CT of cute Cholecystitis Downloaded from by on 01/20/18 from IP address Copyright RRS. For personal use only; all rights reserved Fig. 15 Hemorrhagic cholecystitis and intramural pseudoaneurysm in 59-year-old man with acute right upper quadrant pain., xial unenhanced CT image shows distention of gallbladder with hyperdense blood products. Gallbladder wall edema is also present. and C, xial contrast-enhanced CT images in arterial () and portal venous (C) phases show round focus within gallbladder wall that is isodense to aorta in both phases of contrast, typical of pseudoaneurysm. This pseudoaneurysm affected intramural branch of cystic artery. Fig. 16 Right portal vein thrombosis due to acute cholecystitis in 62-year-old man with abdominal pain and elevated hepatic enzymes., xial contrast-enhanced CT image shows distention of gallbladder and diffuse wall thickening. Opacification of peripheral right portal vein branches is absent., More superior axial contrast-enhanced CT image shows thrombosis of right portal vein. There is hyperenhancement of right lobe of liver indicating compensatory hepatic artery perfusion of this region. cute onset and absence of other comorbidities in this patient suggest acute cholecystitis with secondary portal vein thrombosis. C JR:194, June