Objective:To evaluate the distribution of lymph nodes metastases(LNM) in upper and middle abdomen from primarybiliary tract carcinoma and the imaging features of metastatic lymph nodes on contrast spiral CT scanning.Methods:A retrospective study was performed

consisting of 41 cases of biliary tract carcinoma(24 cases of extrahepatic cholangiocarcinoma and 17 cases of gallbladder cancer)

with upper and middle abdominal LNM identified by surgically and pathological procedure.All patients underwent CT scanning with intravenous contrast-enhancement on single-slice or 16-slice spiral CT.According to the LN location

upper and middle abdominal LN was classified as eight sites in this study as follows:porta hepatis

hepatoduodenal ligament

gastrohepatic ligament

gastrocolic ligament

gastrosplenic ligament

celiac

superior mesenteric and paraaortic area.Anatomic distribution and CT appearances of metastatic LN were observed.Results:(1)The incidence of LNM in each site from biliary tract carcinoma was:19.5%(8/41)in porta hepatis

90.2%(37/41)in hepatoduodenal ligament

22%(9/41)in gastrohepatic ligament

63.4%(26/41)in celiac

39%(16/41)in superior mesenteric and 48.8%(20/41) in paraaortic area respectively.Hepatoduodenal ligament lymphonode was the most common site of LNM from primary biliary tract carcinoma.The patients with gallbladder carcinoma had more LN sites involved than extrahepatic cholangiocarcinoma.(2)The MSAD(Maximum Short Axis Diameter)of metastatic LN varied from 1.4 to 4.8 cm.The density of most of metastatic nodes was hypoattenuation or iso-attenuation

and necrosis of metastatic LN was found in 69% sites and occurred more frequently in metastatic LN with MSAD ≥2.5 cm.Necrosis of metastatic LN could be categorized as 3 types:no obvious necrosis was found(type 1

31%);the volume of necrosis region was less than 1/2 in metastatic LN(type 2

24.1%);the volume of necrosis region was more than 1/2 in metastatic LN(type 3

44.8%).Conclusion:Distribution of LNM is determined by the lymphatic drainage route of biliary tract.The patients with gallbladder carcinoma have more LN sites involved than extrahepatic cholangiocarcinoma.Hypoattenuation or iso-attenuation compared with crura of diaphragm

heterogeneous enhancement

incomplete patterns of necrosis

is the image feature of upper and middle abdominal metastatic lymph nodes from biliary tract carcinoma on spiral CT scanning with bolus intravenous contrast-enhancement.