1. “Must Know” GI Radiology for Family medicine residents
Joanna R. Fair, M.D., Ph.D.
Vice Chair of Education
Department of Radiology
Some images courtesy of
Radiology Department Faculty and Residents
and
Petra Lewis, M.D.
Associate Professor of Radiology
Dartmouth Medical School

2. GI Imaging Objectives
Know the radiographic findings and imaging evaluation of suspected small bowel obstruction
Know radiographic findings for other significant bowel findings (large bowel obstruction, pneumoperitoneum)
Identify the appropriate imaging evaluation for focal abdominal pain conditions:
RLQ pain, suspect appendicitis
LLQ pain, suspect diverticulitis
RUQ pain, suspect acute cholecystitis
Suspect pancreatitis

3. Suspected bowel obstruction

4. Plain Films Appropriate utilization Assessment Bowel obstruction
Free air (pneumoperitoneum)
Assessment
Bowel gas pattern
Obstruction- small or large bowel
Ileus
Abnormal air
Pneumoperitoneum

5. Abdominal film - Normal

6. Abdominal film - Normal
Stomach
Liver
Right kidney
Spleen
Descending colon
Cecum
Small bowel

7. Normal abdominal series
Supine: bowel caliber
Upright: air-fluid levels

8. Based on the following image, what is the MOST likely diagnosis
Ileus
Small bowel obstruction
Large bowel obstruction
Perforated bowel
Normal
SBO

9. Based on the following image, what is the MOST likely diagnosis
Ileus
Small bowel obstruction
Large bowel obstruction
Perforated bowel
Normal
SBO

10. Algorithm for suspected SBO
Paulson EK, Thompson WM, Radiology 2015; 275:332–342

11. Small bowel obstruction vs Ileus
Dilated small bowel >3 cm
Stomach dilated
Not all small bowel dilated
Decompressed large bowel
Upright or decub film: Differential air fluid levels (different levels in same loop)
Gasless abdomen
Dilated small bowel > 3 cm
Large bowel dilated
Can have air-fluid levels

12. Small bowel obstruction
Paulson EK, Thompson WM, Radiology 2015; 275:332–342

13. Small bowel obstruction

14. PACS case 1

15. Based on this image the MOST likely diagnosis is:
Ileus
Small bowel obstruction
Large bowel obstruction
Sigmoid volvulus
Cecal vovulus
Distal large bowel obs, but could easily be ileus

16. Based on this image the MOST likely diagnosis is:
Ileus
Small bowel obstruction
Large bowel obstruction
Sigmoid volvulus
Cecal vovulus
Distal large bowel obs, but could easily be ileus
Could be distal large bowel obstruction

17. Ileus Difficult to distinguish from SBO Look for colon air
Illeus – can be difficult to distinguish from SBO. Look for colonic air, air fluid levels at same level
Difficult to distinguish from SBO
Look for colon air
colon and small bowel distended

18. Ileus

19. Distal large bowel obstruction
Difficult to distinguish from ileus
Dilated large bowel
Dilated small bowel if ileocecal valve incompetence

20. The most likely diagnosis based on this image is:
Small bowel obstruction
Cecal volvulus
Paralytic ileus
Sigmoid volvulus
Sigmoid volvulus

21. The most likely diagnosis based on this image is:
Small bowel obstruction
Cecal volvulus
Paralytic ileus
Sigmoid volvulus
Sigmoid volvulus

22. Sigmoid Volvulus Coffee bean shaped loop ‘pointing’ to LLQ
At risk individuals
Elderly, bed bound, chronic constipation,

23. What is your BEST interpretation of this image?
Small bowel obstruction
Bowel perforation
Large bowel obstruction
Paralytic ileus
Free intraperitoneal air

24. What is your BEST interpretation of this image?
Small bowel obstruction
Bowel perforation
Large bowel obstruction
Paralytic ileus
Free intraperitoneal air
Free intraperitoneal air

25. Pneumoperitoneum Upright PA CXR most sensitive film Abdominal film
Lucent crescent under diaphragm (also check lateral)
Abdominal film
Must have LL decub to see air against liver
Supine (need lots of free air)
Rigler (double wall) sign
CT most sensitive

26. Pneumoperitoneum Left lateral decubitis Massive free air over liver
Rigler (double wall) sign
Air on both sides of bowel wall

27. Pneumoperitoneum Falciform ligament sign Small free air
Football sign left
Small free air right
Falciform ligament sign
Small free air

28. Focal Abdominal Pain

29. Focal abdominal pain Sites How to select imaging? RLQ pain LLQ pain
RUQ pain
Upper abdomen, concern for pancreatitis
How to select imaging?
ACR Appropriateness Criteria!

30. ACR Appropriateness Criteria
From the American College of Radiology
Evidence-based
Guides appropriate imaging in wide variety of situations
Relative utility
Relative radiation exposure
Google “ACR Appropriateness”

31. RLQ pain – suspect appendicitis

33. US residents average annually: ☢☢☢ from background + ☢☢☢ from imaging
Relative Radiation Level - RRL
Examples
** Estimated added lifetime risk of fatal cancer:
Ultrasound; MRI
Zero ☢
Chest or Hand Radiographs
Minimal or Negligible
(1/1,000,000 – 1/100,000) ☢☢
Pelvis Radiographs; Mammography
Very Low
(1/100,000 – 1/10,000)
☢☢☢
Abdomen CT; Nuc Med Bone Scan
Low
(1/10,000 – 1/1000)
☢☢☢☢
Abdomen/pelvis CT with and without contrast; PET/CT
Moderate
(1/1000)
☢☢☢☢☢
CTA chest/abdomen/pelvis with contrast
(1/500)
US residents average annually:
☢☢☢ from background + ☢☢☢ from imaging

34. CT- Appendicitis
Right lower quadrant inflammation, abscess, and/or appendicolith
Normal appendix
Appendicolith with acute appendicitis

35. PACS Case 2

36. LLQ pain – suspect diverticulitis

38. Diverticulitis
Diverticulosis

39. PACS Case 3

40. RUQ pain – suspect acute cholecystitis

43. RUQ Ultrasound- Gallstones
Mobile, echogenic focus with posterior acoustical shadowing
liver Gb
gallstone
Gb- Gallbladder

44. PACS Case 4

45. Nuclear Medicine HIDA (Cholescintigraphy)
If US is equivocal
Small amount of radiotracer, IV
Targets a particular organ or physiology, in this case, liver + biliary tree

46. Normal HIDA Liver shows up immediately
Blood pool disappears in 5-10 min
Rapid progress into biliary tree
Goes into CBD, small bowel, GB

47. Case

48. Case Part 2 No GB @ 4 hours Acute cholecystitis No GB @ 30 min
Option 2: 2 mg MSO4, wait 30 min
Option 1: Wait 4 hours
No 4 hours
Acute cholecystitis
No 30 min
Acute cholecystitis

49. Upper abdominal pain – suspect pancreatitis

51. 2 echogenic stones in the distal CBD
US of the CBD
2 echogenic stones in the distal CBD

53. PACS Case 5

54. Summary Start with plain films for suspected bowel obstruction
CT often needed next
Use ACR Appropriateness Criteria to select advanced imaging for abdominal pain
CT for suspected appy, diverticulitis, complicated pancreatitis
US for suspected acute cholecystitis, uncomplicated pancreatitis
Nuclear Medicine HIDA for acute cholecystitis if ultrasound equivocal