GI Radiology

Imaging modalities in GI

• Plain X-rays (Supine, Erect, Decubitus)

• Barium studies (Ba Swallow, Meal, Follow through, Enteroclysis, Enema)

• Ultrasound Abdomen• CT Scan/MRI Abdomen• ERCP, Cholangiography.• Angiography and Nuclear Medicine

Plain Abdominal X-rays

• Erect Chest• Supine Abdomen• Erect / Decubitus Abdomen ( 10 min )• Radiation Dose ( 1 Abd = 75 CXR)• Contraindicated – pregnancy

Indications.

• “Acute Abdomen”• Abdominal Pain. • ?Obstruction.

• Not Indicated for:– Trauma.– Solid organ assessment.

Basic Principles

• Five radiographic densities:– Gas/Air – Fat. – Soft Tissue/Water – Bone/Calcium– Metals

• Interface/line only visible when two of these densities interface with each other.

Approach to a AXR

• Technical Assessment.• Projection.• Bowel/Gas Shadows.• Normal/Abnormal Calcifications.• Solid Organs.• Look at lung bases and at the skeleton.

Normal Vs Abnormal Gas shadows

• Stomach.• Colon.• Small Bowel.

• Within the Lumen:– Dilated bowel ?

Obstruction• Outside the Lumen:

– Free ?perforation– In a cavity ?abscess

Contrast Medium for GI

Water Soluble• Ionic (gastrografin) Can

lead to pulmonary edema if aspirated.

• Non- Ionic ( Low Osmolar) Relatively safer if aspirated.

• Gadolinium (MRI)

• Barium ( Non-water soluble)• Can cause sever peritonitis and

fibrosis in perforation or leakage.

Contrast Swallow

• Indications: • Dysphagia• Pain• Reflux• Anemia• Tracheo-esophageal fistula• Perforation

• Contraindications:• Aspiration

Barium Meal

• Indications:• Dyspepsia• Upper abdominal mass• Weight Loss• Gastrointestinal Hemorrhage.• Partial Obstruction• Assessment for perforation

• Contraindications• Complete large bowel obstruction

• Pateint preparation:• NPO ---6 hrs• No smoking– increases GI motility

Small Bowel Follow through/ Small bowel enema (Enteroclysis)

• Indications:• Pain• Diarrhoea • Anemia/GI bleed• Partial Obstruction • Malabsorption• Abdominal mass

• Contraindications• Complete obstruction

• Patient Preparation:• Low residue diet• Bowel Prep (Dulcolax -2-4 Tab)

Small Bowel follow through VS Small bowel enema

Barium Enema

• Indications:• Change in bowel habits• Pain• Mass• Melaena / Anemia

• Single contrast – Obstruction & Intussusception.

• Contraindications:• Rectal biopsy—5 days• Toxic megacolon• Pseudomembranous colitis

• Preparation: (Two days)• Low residue diet• Bowel prep (Dulcolax – 4 Tab)

Ultrasound Abdomen

• Advantage• Cost effective• Adequate visceral visualization • Best for GB• No radiation

• Indications: Acute Abdomen, Obstructive jaundice, abdominal masses, collections, Free fluid, follow up- tumors.

• Disadvantage• Operator dependent• Poor in Obesity• Bowel gasses• Bones / Calcifications

CT Scan Abdomen

• Advantages• Accurate & quick• Bowel/ gasses/ bones • Reformation and angio

• Indications: Acute abdomen, Abdominal mass, tumor staging/follow up, Appendicitis/abscesses, Post op complications

• Disadvantages:• Radiation (250 CXR)• Renal failure• Contrast reaction

MRI Abdomen

• Advantages• Multiplaner• Renal failure• MRCP• Liver specific contrasts

• Disadvantages• Bowel motion/ contrast• Calcifications• Metallic implant• Relatively long procedure time• Claustrophobia

Cholangiography

• Endoscopic Retrograde Cholangiopancreatography (ERCP)

• MR Cholangiopancreatography (MRCP)

• T-tube Cholangiography.• Percutaneous Transhepatic

Cholangiography (PTC).