Patrick McLaughlin FFRRCSI, Presenter: Nothing to Disclose

David Tso MD, Abstract Co-Author: Nothing to Disclose

Kevin Murphy MBBCh, MRCS, Abstract Co-Author: Nothing to Disclose

Joseph Coyle MBBCh, MRCPI, Abstract Co-Author: Nothing to Disclose

Edward Fitzgerald MBBCh, Abstract Co-Author: Nothing to Disclose

Kaspr De Johst, Abstract Co-Author: Nothing to Disclose

Luck Jan-Luck Louis MD, Abstract Co-Author: Nothing to Disclose

Michael M. Maher MD, FRCR, Abstract Co-Author: Nothing to Disclose

Savvas Nicolaou MD, Abstract Co-Author: Nothing to Disclose

The authors anecdotally observed a mild increase in attenuation value of bile within the gallbladder during CT of patients with malignant obstruction of the biliary tract. We therefore conducted a retrospective study to determine the incidence of this sign and to evaluate its sensitivity and specificity for predicting the cause of biliary obstruction.

6,157 biliary intervention procedures were performed between January 2007 and August 2012 at a single quaterny referral hepatobiliary centre. A subgroup of 630 patients who underwent abdominal CT prior to biliary intervention procedure were selected. CT images of these patients were reviewed by 2 abdominal radiologists and all patients with biliary dilation (n=357) were included. Patients who had a prior cholecystectomy or evidence of previous biliary intervention were excluded leaving 199 patients for analysis. Objective analysis of bile attenuation was performed within the gallbladder and common bile duct using 3cm2 and 0.5cm2 regions of interest. The presence or absence of pancreatic duct dilation, gallstones or discernable cause for biliary obstruction was recorded. Electronic medical and histopathological records were queried for all patients and definitive diagnoses were found in all but 1 case.

94 (47%) patients had biliary obstruction related to malignant diseases including primary pancreatic and biliary neoplasms aswell as secondary tumours and lymphoma. CT Courvoisier’s sign (gallbladder attenuation value of >15HU) was present in 65 (78%) of these patients of these patients. Bile attenuation values within the gallbladder were found to be significantly higher in cases of malignant vs benign obstruction of the biliary tract (24.55±22.7HU vs 10.88±10.1HU, p,0.001). In our cohort the sensitivity, specificity, PPV and NPV of the CT Courvoisier's sign for detection of malignant biliary obstruction was 69%, 83%, 78% and 75% respectively.

We define the CT Courvoisier sign as elevated attenuation (>15HU) of bile within the gallbladder which in our cohort of 199 patients with biliary obstruction was found to be a common and reliable CT indicator of malignant biliary obstruction.

The CT Courvoisier sign is found in approximately 40% of patients with biliary obstruction and has an 83% specificity for malignant obstruction.

McLaughlin, P, Tso, D, Murphy, K, Coyle, J, Fitzgerald, E, De Johst, K, Louis, L, Maher, M, Nicolaou, S, CT Courvoisier Sign: A Common and Comparatively Reliable CT Finding in Malignant Obstruction of the Biliary Tract.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13044459.html