Diagnostic Imaging of the Gastrointestinal Tract

Plain Radiographs Contrast Studies Ultrasound

Plain Radiographs Demonstrate distribution of fluid and gas within the tract

Plain Radiographs In normal abdomen dependant on radiographic contrast

Plain Radiographs Ascites significantly impairs diagnostic utility

Loss of serosal detail due to hydroperitoneum

Plain Radiographs Cannot resolve soft tissue opacities as separate structures

Ultrasound Resolves soft tissue opacities

Tumour within wall of small intestine

Ultrasound can see the wall lesion within the fluid filled loop of bowel, plain radiographs cannot

Ultrasound Cannot image through gas

Plain Radiographs and Ultrasound are complementary

Contrast Radiography Allows visualization of the mucosal surface and indicates status of bowel lumen

Contrast Radiography Provides data regarding GI function

Esophagus

Megaesophagus Esophageal Foreign Body

Megaesophagus Retention of air or food material within the esophagus

Megaesophagus

Contrast study required only if do NOT see distended esophagus on plain radiographs

Megaesophagus Retention of barium within the esophagus

Normal Barium Swallow

Megaesophagus

Esophageal Foreign Body

Usually easy to identify Good contrast with aerated lung

Esophageal Foreign body

Aspiration pneumonia is a common complication

Esophageal foreign body with aspiration pneumonia

Stomach

Gastric Dilation with Volvulus GDV

Right lateral projection

Gastric Ileus

Gastric Ileus Normal Stomach

Normal Stomach

Foreign Bodies

Radiopaque Foreign Body

Semi radiopaque foreign body

Hair Ball

Hairball v Food Material?

Hairball has smooth margins and may not contact stomach wall Do not disappear following fasting

Food material has irregular margins usually in contact with stomach wall Disappears following fasting

Fibres e.g. carpet, socks are difficult to identify on plain radiographs and ultrasound and frequently require contrast radiography

Double Contrast Gastrogram

Naso-gastric intubation

1-2 mls/kg undiluted barium 20ml/kg room air

Left lateral Right lateral Ventrodorsal Dorsoventral

Normal Double Contrast Gastrogram

Carpet Foreign Body

Gastric Foreign Body

Gastric Tumours

Uncommon

Filling defect on contrast study

May identify on ultrasound

But easily missed if stomach is gas filled

Gastric Tumour

Pyloric Dysfunction

Obstruction of pyloric outflow

Congenital

Obstruction of pyloric outflow Congenital Acquired Neoplasia

Obstruction of pyloric outflow Congenital Acquired Neoplasia Fibrosis

Plain Radiographs Enlarged Pylorus

Contrast Study Hyperperistalsis

The hourglass appearance must be present on several radiographs

Narrowing of pyloric canal

String or bird’s beak appearance

Narrowing of pyloric canal

Small Intestine

Obstruction is commonest abnormality identified

Foreign Body Intussuception Tumour

Foreign body most common

Complete obstruction v Partial obstruction

Normal width of small intestine 2-3 X width of a rib Width of a vertebral body

Obstruction results in fluid or gas distension or a combination of both

Foreign body may be Radiopaque Semi-radiopaque Radiolucent

Radiopaque small intestinal foreign body

Semi radiopaque small intestinal foreign body

Radiolucent small intestinal foreign body

Occasionally early enteritis, especially parvo virus infection will present with intestinal distension

Parvo virus enteritis

Cases with clear plain radiographic evidence of obstruction require surgery

They do not require an upper gastrointestinal series

The decision to perform an upper gastrointestinal study or a laparotomy is influenced by experience in interpreting the plain radiographs

Clear evidence of rupture of the gastrointestinal tract is a contraindication to an upper gastrointestinal series

Long standing cases of obstruction will also have hydroperitoneum

Pneumoperitoneum secondary to intestinal rupture

Fibres e.g. carpet or socks have a characteristic appearance on contrast studies

Look for a linear or reticular fibre pattern

Sock foreign body

Linear Foreign Body

Contrast column has acute angles with contrast accumulation at the angles

Linear Foreign Body

Partial obstruction of the small intestine

More challenging on plain radiographs

Partial obstruction of small intestine

Small Intestinal Tumours

Ultrasound most useful imaging modality

Normal small intestine 5 layers

Mucosal surface – white Mucosa – black Submucosa – white Muscularis – black Serosa – white

Normal small intestine

Normal single wall thickness <5mm

Intestinal Tumour Focal lesion

Intestinal tumour

Diffuse Thickening of Small Intestine

Gastro Intestinal Lymphoma Inflammatory Bowel Disease

Gastro Intestinal Lymphoma

Tumours of colon Uncommon

Normal colon

Tumour of the colon

Intussuception Rarely diagnosed definitively on plain radiographs

Intussuception Presents as non specific obstruction of small intestine

Ultrasound Target appearance Or Too many layers

Intussuception Requires a contrast study or ultrasound evaluation for confirmation

Intussuception

Contrast Radiographs Coiled spring appearance

Intussuception

Mega Colon