Radiology of Digestive System Department of Radiology Zhongshan Hospital, Fudan university RAO Sheng-Xiang

Plain film radiograph Hepatic angle Spenic angle Renal shadow Psoas muscle Properitoneal fat strip

Normal CT anatomy 1.LHV, left hepatic vein 2.MHV, middle hepatic vein; 3.RHV, right hepatic vein; 4.IVC, inferior vena cava 5.Ao,aorta 6.Stomach 1 2 4 6 3 5

1.LPV, left portal vein 2.Stomach 3.Speen 4.IVC, inferior vena cava 5.Ao,aorta 1 2 4 5 3

1.Gallbladder 2.RPV, right portal vein 3.antrum 4.duodenal bulb 3 1 4

1.CA,celiac axis 2.Splenic artery 3.common hepatic artery 4.Duodenum 5.Kidney 6.Pancreas 7.Portal vein 8.Adrenal gland 2 6 7 3 1 4 5 5

SMA:superior mesenteric artery CBD,common bile duct Spenic vein Pancreas

SMV, superior mesenteric vein SMA, superior mesenteric artery Uncinate process

CTA SMA, superior mesenteric artery CA,celiac axis Splenic artery common hepatic artery

main portal trunk; right portal branch; splenic vein; inferior mesenteric vein; superior mesenteric vein

RHV, right hepatic vein; MHV, middle hepatic vein; LHV, left hepatic vein IVC, inferior vena cava

pancreatic duct

Upper abdominal calcification may be an important sign of disease Gallstones ,Porcelain gallbladder Urinary Calculi Calcified adrenal glands Pancreatic calcification Tumor calcification ……………

Gallstones 15% -20%of gallstones contain sufficient calcium to be identified on plain film right upper quadrant laminated appearance (a dense outer rim and more radiolucent center)

Porcelain gallbladder calcification in the wall of the gallbladder indicative of chronic obstruction of the cystic duct, chronic gallbladder inflammation, and an increased risk of gallbladder carcinoma

Discontinuous mural calcification diffuse

Kidney stones About 85% of urinary calculi are visible on plain film. Staghorn Calculus a large calculus occupying the collecting system of the left kidney and assuming its shape

Calcified adrenal glands associated with adrenal hemorrhage in the newborn, tuberculosis, and Addison disease either side of the first lumbar vertebra

Pancreatic Calcifications chronic alcohol-induced pancreatitis Coarse and punctate calcifications extend upward across the left upper quadrant

Intestinal Distention The small bowel is dilated when it exceeds 2.5 to 3.0 cm in diameter. The colon is dilated when it exceeds 5 cm in diameter The cecum is dilated when it exceeds 8 cm in diameter.

Normal Bowel Gas Pattern The normal distribution of gas in the stomach and duodenum The colon----- mottled pattern of stool The small bowel----a few gas collections

Mechanical bowel obstruction Small Bowel Dilated loops of small bowel (>3 cm) Air-fluid levels that exceed 2.5 cm in length Air-fluid levels at differing heights within the same loop (strong evidence of obstruction) Small bubbles of gas trapped between the valvulae conniventes

Causes of Small Bowel Obstruction

Erect radiograph of the abdomen Air-fluid levels at different heights The valvulae conniventes that extend across the entire diameter of the bowel lumen

Mechanical bowel obstruction Large Bowel Most colonic obstructions occur in the sigmoid colon Dilation of the colon from the cecum to the point of obstruction The colon distal to the obstruction is devoid of gas

Causes of Large Bowel Obstruction

Sigmoid volvulus A large gas-filled loop(inverted U shape or a coffee bean shape) without haustra or septa, Arising from the pelvis and extending high into the abdomen and often to the diaphragm Barium enema: a beaking sign at the point of the twist

Adynamic ileus(Functional ileus) Decreased or absent peristalsis Diffuse gaseous, distension of bowel(small bowel and colon,rectum)

Pneumoperitoneum Common causes:bowel perforation, trauma, recent surgery Free air beneath the domes of the diaphragm

Dysphagia: Esophagus The length of the esophagus is tubular, and its termination is saccular A ring: the tubulovestibular junction is formed by a symmetric muscular ring B ring : an asymmetric mucosal ring or notch that occurs at the junction of esophageal squamous epithelium with gastric columnar epithelium

The esophageal vestibule demarcated by the muscular A ring and the mucosal fold of the B ring B ring (mucosal ring) <14mm---always symptomatic 14mm-20mm--50% symptomatic >20mm---asymptomatic

Benign Stricture Resulting from Reflux Esophagitis usually confined to the distal esophagus may be tapered, smooth, and circumferential (the classic appearance)

Esophageal carcinoma Four basic radiographic patterns An annular constricting lesion, appearing as an irregular ulcerated stricture, is most common. The polypoid pattern causes an intraluminal filling defect The infiltrative variety grows predominantly in the submucosa and may simulate a benign stricture. The least common pattern is that of an ulcerated mass.

Malignant Stricture Abrupt narrowing with irregular mucosa The prominent shoulders are characteristic of tumor

Polypoid Squamous Cell Carcinoma

Esophageal achalasia usually at age 30 to 50 years Absence of peristalsis of body of esophagus Failure of the LES to relax with swallowing Smooth,tapered or beaklike appearance

Anatomy of the Upper GI Tract

Normal anatomy of stomach composed of the cardia, fundus, body, and antrum

A well-distended stomach has a wall thickness of approximately 5 mm

Benign Ulcer(1) Projection beyond the lumen of stomach soomth lucent line (collar ) at the neck of ulcer

Benign Ulcer(2) Hampton line :a thin, sharp, lucent line that traverses the orifice of the ulcer.

Benign Ulcer(3) Radiating folds extending into the crater

Malignant ulcer location within the lumen of the stomach nodular, rolled, irregular, or shouldered edges

Gastric adenocarcinoma The most common malignancy in the stomach The pattern of spread : local extension , distant metastases drop metastases to the ovaries

Polypoid Gastric Carcinoma Polypoid Gastric Carcinoma. a lobulated filling defect (arrows) in the antrum of the stomach.

CT: focal wall thickening diffuse wall thickening a lobular mass with or without ulceration destruction of the multilayered pattern or with transmural enhancement regional lymphadenopathy; metastases

CT: Focal wall thickening transmural enhancement

CT:diffuse wall thickening

Locally invasive gastric adenocarcinoma heterogeneous thickening of the gastric fundus. growing into the splenic hilum , left adrenal gland

A large heterogeneous mass in the body of the stomach round and contains an ulcer A large metastasis lies in the liver

Lymphatic spread

Gastrointestinal stromal tumors (GISTs) the most common mesenchymal tumors distinct from true smooth muscle and neural tumors The best defining feature :the expression of KIT (CD117) arise from the pacemaker cells of Cajal

extragastric (most cases) Growth pattern) extragastric (most cases)

polypoid in appearance (small GISTs)

Large, heterogeneous exophytic mass

Extensive ulceration of the mass

Diffuse Liver Disease  Fatty liver Cirrhosis

Fatty liver(Steatosis) In normal adults, the precontrast attenuation value of the liver is consistently higher than that of the spleen Milder degrees of diffuse steatosis :the attenuation value of the liver is less than that of the spleen Marked diffuse steatosis :the liver parenchyma is lower in attenuation than the hepatic blood vessels

The attenuation value of the liver parenchyma is markedly lower than that of the spleen The intrahepatic vessels stand out as hyperattenuating structures

Focal fatty infiltration The same imaging features as diffuse infiltration Vessels run their normal course through the area of involvement (lack of mass effect )

Cirrhosis hypertrophy of the caudate lobe and left lobe with shrinkage of the right lobe inhomogeneity of hepatic parenchyma, irregularity (nodularity) of the liver surface, Extrahepatic signs :evidence of portal hypertension, splenomegaly, and ascites

nodularity of the liver contour atrophy of the medial segment (M) and enlargement of the lateral segment prominent notch in the right posterior surface of the liver

Focal Liver diseases Cyst Hemangioma Hepatocellular carcinoma metastasis

Cyst:CT appearance a well-circumscribed, homogeneous mass of near-water-attenuation value (less than 20 HU) no enhancement after IV contrast medium administration

Two large well-circumscribed, homogeneous, near-water-density masses no discernible wall

Hemangioma the most common benign liver tumor fed by hepatic artery branches internal circulation is slow generally remain stable in size over time

well-defined, hypodense on unenhanced scans Enhancement pattern : nodular enhancement from the periphery of the lesion and proceeding toward the center gradually

Precontrast CT :an attenuation value similar to that of the blood in the inferior vena cava(IVC)

Arterial phase :multiple areas of globular, peripheral enhancement. Note that the enhanced portions of the mass have an attenuation value similar to that of the intrahepatic vessels.

Equilibrium phase : near-complete enhancement of the mass with an attenuation value equivalent to that of the blood in the inferior vena cava(IVC) and hepatic veins

T2WI:marked hyperintense

Hepatocellular carcinoma The most common primary malignancy of the liver Risk factors : cirrhosis, chronic hepatitis Growth patterns: solitary massive, multinodular, and diffuse infiltrative Serum α-fetoprotein(AFP) levels are often elevated

Hypervascular :contrast enhancement on arterial phase images, with diminishing enhancement on delayed phase images Tumor thrombus Tumor capsule: a sharply marginated rim

Necrosis: central low density The satellite lesions

T2WI T1WI AP PP DP

Portal Vein Thrombosis Multiple hypodense nodules ----HCC Filling defect with the vein

Metastases The most common malignant masses in the liver Most commonly originate from the GI tract, breast, and lung Necrosis, fibrosis, calcification, or hemorrhage within the mass The most common enhancement pattern :continuous ring-like enhancement

Multiple Hypoattenuating lesions with mild continuous rim enhancement

T2WI:a central area of hyperintensity rim enhancement

Normal MR Cholangiopancreatography (MRCP).

Biliary Dilatation Diameter of intrahepatic bile ducts larger than 40% of the diameter of the adjacent portal vein Dilation of the common duct greater than 6 mm Gallbladder diameter greater than 5 cm

Causes of Biliary Tract Obstruction

Choledocholithiasis approximately 20% of cases of obstructive jaundice in the adult CT:high-density calcification within the duct MRCP has shown good sensitivity (86% to 100%) and specificity (85% to 100%) for ductal stones

MRCP Filling defects

Cholangiocarcinoma arise from the epithelium of bile ducts and are usually adenocarcinomas Growth patterns include mass forming, periductal infiltrating, and intraductal polypoid

Mass forming periductal infiltrating Intraductal polypoid

Peripheral cholangiocarcinoma Delayed enhancement biliary dilatation Atrophy (liver)

Perihilar and extrahepatic cholangiocarcinomas typically exhibit an infiltrating growth pattern focal, circumferential thickening of the bile duct with proximal dilatation perihilar lesions may be similar in appearance to the intrahepatic, mass-forming type of cholangiocarcinoma, or may manifest as an intraluminal polypoid mass

Pancreatic carcinoma a highly lethal tumor CT is recommended for initial imaging assessment CT:a hypodense mass that distorts the contour of the gland obstruction of the common bile duct and pancreatic duct and atrophy of pancreatic tissue beyond the tumor

B A C D

Signs of unresectability tumor involvement of adjacent organs enlarged regional lymph nodes (>15 mm) encasement or obstruction of peripancreatic arteries or veins metastases in the liver peritoneal carcinomatosis

Pancreatic Carcinoma: Nonresectable encases and narrows the celiac axis and its branches partially envelopes the aorta

Plain film radiographs of the abdomen are important for the assessment of the acute abdomen CT, US, and MR provide comprehensive evaluation of the abdomen, including the peritoneal cavity, retroperitoneal compartments, abdominal and pelvic organs, blood vessels, and lymph nodes

Thank you ! Email:rao.shengxiang@zs-hospital.sh.cn