“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

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

Suspected bowel obstruction

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

Abdominal film - Normal

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

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

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

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

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

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

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

Small bowel obstruction

PACS case 1

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

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

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

Ileus

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

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

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

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

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

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

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

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

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

Focal Abdominal Pain

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!

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” http://www.acr.org/Quality-Safety/Appropriateness-Criteria

RLQ pain – suspect appendicitis

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

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

PACS Case 2

LLQ pain – suspect diverticulitis

Diverticulitis Diverticulosis

PACS Case 3

RUQ pain – suspect acute cholecystitis

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

PACS Case 4

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

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

Case

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 GB @ 4 hours Acute cholecystitis No GB @ 30 min Acute cholecystitis

Upper abdominal pain – suspect pancreatitis

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

PACS Case 5

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