radiology of digestive system

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

12

3 4 5 6

1.LPV, left portal vein

2.Stomach

3.Speen

4.IVC, inferior vena cava

5.Ao,aorta

5

2

3

1

4

1.Gallbladder

2.RPV, right portal vein

3.antrum

4.duodenal bulb

3

4

1

1

1.CA,celiac axis2.Splenic artery3.common hepatic artery4.Duodenum5.Kidney6.Pancreas7.Portal vein8.Adrenal gland

12

3

4

55

67

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 calcificationmay be an important sign of diseaseGallstones ,Porcelain gallbladderUrinary CalculiCalcified adrenal glandsPancreatic calcificationTumor 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

diffuse Discontinuous mural calcification

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 symptomatic14mm-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 carcinomaFour basic radiographic patternsAn 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 stomachThe pattern of spread : local extension , distant metastases drop metastases to the ovaries

• 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)

extragastric

(most cases)

Growth pattern)

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 enhancementbiliary dilatationAtrophy (liver)

Perihilar and extrahepatic cholangiocarcinomas

typically exhibit an infiltrating growth pattern focal, circumferential thickening of the bile

duct with proximal dilatationperihilar 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

A B

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