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).