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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).