| Background:Metastatic lymphadenopathy is one of the most important prognosis factors for carcinoma of alimentary system. Correct preoperative staging of lymph nodes (LN) involvement is crucial in therapeutic decision-making. Many surgical documents concerned of it. Spiral CT can provide detail information about malignancies of alimentary system including the status of regional lymph nodes, but radiologic documents of spiral CT focusing on metastatic lymphadnopathy is still inadequate. Purpose:1. To evaluate the distribution of lymph nodes metastases (LNM) in upper and middle abdomen from common alimentary malignancies, such as primary hepatocellular cell carcinoma (HCC), biliary cancer, pancreatic carcinoma and gastric cancer on spiral CT scanning.2. To summarize the imaging features of metastatic LN on spiral CT scanning with intravenous contrast enhancement.3. To compare the CT features of metastatic LN in upper and middle abdomen from hepatocellular cell carcinoma, biliary cancer, pancreatic carcinoma and gastric cancer.Materials and methods:A retrospective study consisting of 271 cases of HCC, 41 cases of biliary cancer(24 extrahepatic cholangiocarcinoma and 17 gallbladder cancer), 48 cases of pancreatic carcinoma and 62 cases of gastric cancer, with upper and middle abdominal LNM identified by surgically procedure or CT imaging criteria (maximum short axis diameter MSAD of LN ï¿¡ 1.0cm ), was performed. All patients underwent CT scanning with intravenous contrast-enhancement on single-slice, 4-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 was observed. Results: 1. Anatomic distribution of upper and middle abdominal metastatic LN(1) The incidence of LNM in each site from HCC was: 55.2% (64/116) in porta hepatis, 60.3% (70/116) in hepatoduodenal ligament, 19.0% (22/116) in gastrohepatic ligament, 47.4% (55/116) in celiac, 14.7% (17/116) in superior mesenteric and 37.1% (43/116) in paraaortic area respectively. The patients with carcinoma, which involved two or more lobes of the liver, had more LN sites involved than carcinoma located in just one lobe.(2) The incidence of LNM in each site from biliary cancer was: 19.5% (8/41) in porta hepatis, 90.2% (37/41) in hepatoduodenal ligament, 22.0% (9/41) in gastrohepatic ligament, 63.4% (26/41) in celiac, 39.0% (16/41) in superior mesenteric and 48.8% (20/41) in paraaortic area respectively. Hepatoduodenal ligament was the most frequently involved area of LNMfrom perihilar cholangiocarcinoma (100%) and gallbladder cancer (100%), LNM from distal extrahepatic cholangiocarcinoma frequently located in the area around the head of pancreas. More LN sites were involved in carcinoma of gallbladder than in extrahepatic cholangiocarcinoma (3.6 vs 2.3 sites per case).(3) The incidence of LNM in each site from pancreatic carcinoma was: 8.3% (4/48) in porta hepatis, 29.2% (14/48) in hepatoduodenal ligament, 10.4% (5/48) in gastrohepatic ligament, 8.3% (4/48) in gastrocolic ligament, 10.4% (5/48) in gastrosplenic ligament, 50.0% (24/48) in celiac, 50.0% (24/48) in superior mesenteric and 35.4% (17/48) in paraaortic area respectively.(4) The incidence of LNM in each site from gastric cancer was: 6.5% (4/62) in porta hepatis, 19.4% (12/62) in hepatoduodenal ligament, 79.0% (49/62) in gastrohepatic ligament, 30.6% (19/62) in gastrocolic ligament, 6.5% (4/62) in gastrosplenic ligament, 58.1% (36/62) in celiac, 24.2% (15/62) in superior mesenteric and 33.9% (21/62) in paraaortic area respectively. Perigastric area (especially the gastrohepatic ligament and gastrocolic ligament) was the most common site that LNM occurred.2. Imaging features of upper and middle abdominal metastatic LN(1) Size: The MSAD of metastatic LN varied from 1.0 to 5.7 cm. There were 316 sites (49.1%) that the MSAD of metastatic LN was less than 2.5cm and 328 sites (50.9%) the MSAD of metastatic LN was more than or equal to 2.5 cm. Most (85.3%-89.4%) of ratio of MSAD/MLAD (maximum long axis diameter) was larger than 0.7.(2) Density: The density of most of metastatic nodes washypoattenuation or iso-attenuation, only 9.5% to 18.6% (depending on the type of primary carcinoma) was higher than the density of crura of diaphragm on contrast-enhanced CT scanning. Heterogeneous enhancement was common finding after intravenous contrast administration, with an incidence of 60.2% (388/644 sites). Homogeneous enhancement was found in 39.8% (256/644 sites) metastatic nodes. Depending on the type of primary carcinoma, peripheral enhancement was revealed in 12.5% to 23.1% LNM sites.(3) Margin: Depending on the type of primary carcinoma, blurring of the margin was revealed in 69.7% to 80.6% sites of metastatic LN. It was found that metastatic lymph nodes could conglomerate, with an incidence of 24% to 37.1%.(4) Ratio of necrosis: Necrosis of metastatic LN was found in 60.2% sites and occurred more frequently in metastatic LN with larger MSAD than with smaller MSAD. The necrosis odds of metastatic LN from different primary carcinoma was various, when 1.0cmgastric cancer (53.0%)>pancreatic carcinoma (48.3%)>HCC (37.9%), when MSADs2.5cm, the necrosis odds of metastatic LN from gastric cancer (84.8%)>biliary carcinoma (82.2%)>HCC (65.0%)>pancreatic carcinoma (64.7%).(5) Patterns of necrosis: Necrosis of metastatic LN could be categorized as 3 types: no obvious necrosis was found (type 1), the volume of necrosis region was less than 1/2 in metastatic LN (type 2) and the volume of necrosis region was more than or equal to 1/2 in metastatic LN (type 3). Most necrosis pattern of metastatic LN from HCC belonged type 1 (49.8%) and type 2(38.0%), type 3 only in 12.2% sites. Type 3 was found more frequently in biliary carcinoma (44.8%), pancreatic carcinoma (38.1%) and gastric cancer (41.3%). Conclusion1. Distribution of LNM was determined by the lymphatic drainage route of primary malignancies. Regional lymph nodes of the organ that primary carcinoma originated, celiac, mesenteric and paraaortic lymph nodes were the most common sites involved by malignancies of alimentary system.2. Hypoattenuation or iso-attenuation compared with crura of diaphragm, heterogeneous enhancement, obscure margin, necrosis and the ratio of MSAD/MLAD >0.7, were the image features of upper and middle abdominal metastatic lymph nodes from alimentary malignancies on spiral CT scanning with bolus intravenous contrast-enhancement.3. The odds and patterns of necrosis of metastatic lymph nodes were various in different primary malignancies of alimentary system.
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