Diagnostic Radiology: Gastrointestinal System

Question 1

Barium swallow

Answer 1

Esophageal cancer:

• ***Stricture
• Shouldering appearance
• ***Irregular outline
• ***Proximal dilatation

Achalasia:

• ***Smooth tapered narrowing (Bird beak / Rat tail sign)
• Proximal dilatation

Question 2

Role of Imaging in Esophageal cancer / CRC

Answer 2

1. Staging
   - Histological confirmation
2. Treatment planning
3. Surgical planning
4. Follow-up / Assessment of treatment response

Question 3

Barium enema

Answer 3

Double contrast: Barium + Air

- Irregular stricturing —> ***Apple core appearance

Question 4

MRI role in CRC

Answer 4

• **Local staging

- relationship with surrounding fat / structures

Question 5

CT-colonography

Answer 5

Inflate colon with air —> CT

Question 6

Volvulus

Answer 6

Loop of intestine twist around itself and mesentery that supports it —> bowel obstruction

2 types:

1. Sigmoid
   - Elderly, institutionalised, learning difficulties
   - From Left lower abdomen to Right abdomen up to diaphragm (can only move upwards and goes to right upper quadrant) (打斜)
   - Dilated small + large bowel (∵ distal in colon)
   - ***Coffee bean sign
2. Caecal
   - Relatively young (30-50)
   - Left upper quadrant to right lower quadrant (打斜)
   - Dilated small bowel but not colon (∵ proximal)

Question 7

Small bowel obstruction

Answer 7

Signs:

• ***Dilated small bowel >3.5 cm
• ***Multiple fluid levels (>3)
• ***Paucity of large bowel gas (collapsed large bowel)

Causes:

• Adhesions (post-op)
• Hernia
• Malignancy (less common)
• Crohn’s (less common)

3-6-9 rule:

• Small bowel: <3 cm
• Large bowel: <6 cm
• Appendix: <6 cm
• Caecum: <9 cm

Question 8

Pneumoperitoneum

Answer 8

1. ***Free gas under diaphragm
2. ***Rigler sign
3. Air outlining falciform ligament, liver edge, gallbladder

Question 9

Appendicitis

Answer 9

1. Dilated appendix
2. Calcified calculus (Appendicolith) at entry
3. Perforation —> Pelvic collection of fluid

Question 10

Toxic megacolon

Answer 10

Complication of Ulcerative colitis (Mucosal ulceration, Continuous lesion)

• ***Grossly distended colon
• Featureless (***loss of haustra)
• Granular appearance ulceration (“Pseudopolyp” appearance)

Question 11

Crohn’s disease vs Ulcerative colitis

Answer 11

Crohn’s:

• Any part of GI tract
• Skip lesions
• Transmural inflammation
• Complications: **Fistulas, **Abscesses —> Strictures

UC:

• Colon only
• Uniform + Continuous
• Mucosal / Submucosal inflammation
• Rarely causes Fistulas, Abscesses, Strictures
• Complications: ***Toxic megacolon