GI Imaging Flashcards

1
Q

GI Imaging

Modalities

A
  • X-Ray/ Radiograph
  • Fluoroscopic procedures
    • Barium swallow
    • Upper GI study / Small bowel follow through
    • Contrast enema
  • Ultrasound (US)
  • Nuclear medicine/Meckel scan
  • Computed tomography (CT)
  • Magnetic resonance imaging (MR)
    • MR Enterography
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Abdominal XR

Overview

A
  • Use beams of energy that pass through body tissues onto a special film
  • Structures appear different based on XR absorption
    • Air containing structures ⇒ black
    • Bone and metal ⇒ white
  • Easily available test
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Abdominal XR

Views

A

Can be obtained w/ pt:

  • Supine view ⇒ lying flat w/ exposure from above
  • Erect/Upright view ⇒ standing up
    • Can see fluid levels
      • Stomach ⇒ always except if supine
      • Small bowel ⇒ 2-3 levels possible
      • Large bowel ⇒ none normally
  • Cross table lateral view ⇒ lying flat w/ exposure from the side
    • Left side down

≥ 2 views ⇒ obstruction series

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Abdominal XR

Indications

A

Baseline study for eval of:

  • GI sx such as vomiting, abdominal pain, distention, constipation, diarrhea, etc
  • Common GI disorders:
    • Intestinal obstruction
    • Constipation
    • Appendicitis
    • Colitis
    • Inflammatory bowel disease
    • Abdominal mass
    • Pneumatosis/Pneumoperitoneum
  • Foreign body ingestion
  • Feeding tube placement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Abdominal XR

Features

A
  • Bowel gas pattern
  • Free/Extra luminal air
  • Soft tissue masses
  • Calcifications
  • Lung bases
  • Osseous structures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Abdominal XR

Normal Anatomy

A
  • Solid organs ⇒ soft tissue density
  • Air containing structures (stomach and bowel) ⇒ black
  • Bone ⇒ white
  • Small bowel ⇒ central
    • Contains valvulae which extend across the lumen
  • Large bowel ⇒ peripheral
    • Has haustral markings
    • Contains stool
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Normal

Bowel Gas Pattern

A
  • Stomach bubble ⇒ LUQ
  • Small bowel
    • Contains air throughout
    • Normal caliber < 2.5 cm
  • Large bowel
    • Air in rectum or sigmoid normally
    • Air in the rectum mitigates against obstruction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Abnormal

Bowel Gas Patterns

A
  • Functional ileus
    • Localized ileus (Sentinel loops)
    • Generalized adynamic ileus
  • Mechanical obstruction
    • Small bowel obstruction (SBO)
    • Large bowel obstruction (LBO)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Localized Ileus

A
  • Seen as sentinel loops on XR
    • One or two persistently dilated loops of small or large bowel
    • Gas in rectum or sigmoid
  • Location of sentinel loop is indicative of the underlying abnormality:
    • RUQ ⇒ cholecystitis
    • RLQ ⇒ appendicitis
    • LUQ ⇒ pancreatitis or ulcer
    • LLQ ⇒ diverticulitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Generalized Ileus

A

Term describes diffusely dilated small and large bowel

  • Ileus = stasis of bowel contents
    • Paralytic or adynamic
  • See gas in dilated small and large bowel to the rectum
  • Common in the postop setting
  • Bowel sounds absent or hypoactive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Obstructive

Bowel Gas Pattern

A
  • Asymmetric caliber of bowel loops
    • Loops proximal to obstruction ⇒ dilated
      • See dilated loops of small bowel
    • Loops distal to obstruction ⇒ compressed or airless
      • Paucity of bowel gas distally
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Pneumoperitoneum

A

Free intraperitoneal air

  • XR findings:
    • Air beneath diaphragm
    • Air outlined against liver/flank
    • Multiple other signs possible
  • Causes
    • Rupture of hollow viscus
      • Not perforated appendicitis
    • Ulcer
    • Tumor
    • Trauma
    • Instrumentation
    • Post-op (expected up to 5-7 days)
    • Necrotizing enterocolitis (Neonatal setting)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

GI Fluoroscopy

Overview

A

Provides dynamic assessment of the GI tract

  • Upper GI Tract
    • Barium swallow/Esophagram
      • Upper GI tract coated w/ barium
      • See & assess anatomy and function of esophagus, stomach, and duodenum
      • Detect inflammation, hiatal hernias, scarring, blockages, intestinal malrotation and volvulus
    • Upper GI study w/ or w/o small bowel follow through
  • Lower GI Tract
    • Contrast Enema
      • Water-soluble contrast introduced from below via a tube
      • Helpful in evaluating colon for polyp, tumor, inflammatory bowel disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Barium Swallow

A
  • Used to visualize the pharynx and esophagus
  • Pt swallows liquid barium while XR images are obtained
  • Can be used for:
    • Dx of food impaction and esophageal FB
    • Esophageal cancer
    • GERD / hiatal hernia

Hiatal hernia shown in image on left. Esophageal reflux shown on right.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Upper GI Study

A
  • XR used to visualize stomach and small bowel
  • Duodenal sweep is assessed
    • 1st, 2nd, 3rd and 4th components
  • Normal location of duodeno-jejunal junction is left of spine @ level of duodenal bulb

Normal anatomy of stomach and proximal small bowel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Small Bowel Follow Through

A
  • Images of abdomen & pelvis obtained after upper GI study
  • Useful fo suspected abnl of small bowel
    • Stricture
    • Ulcer
    • Neoplasm

Normal small bowel follow through

17
Q

Water Soluble Contrast Enema

A
  • Dynamic evaluation of the colon performed under fluoroscopy
  • Rectal infusion of contrast
  • Can demonstrate polyps, colon cancer, fistulas, ulcers, stenosis etc.
18
Q

Abdominal US

Overview

A
  • Utilizes sound waves
  • Real time assessment
  • Advantages of US
    • Safe
    • Widely available
    • No ionizing radiation
    • Cheaper compared to CT/MR
19
Q

Abdominal US

Indications

A
  • Pyloric stenosis
  • Acute appendicitis
  • Intussusception
  • Inguinal hernia
    • US helps in real time evaluation of bowel peristalsis
  • Screening examination for palpable abdominal mass

Ex. pyloric stenosis on US

20
Q

Meckel’s Diverticulum

A
  • Remnant of the omphalomesenteric duct
  • Can cause bleeding (when contains ectopic gastric mucosa), intussusception, bowel obstruction or perforation
  • Rule of 2’s:
    • Incidence 2% of general population
    • Within 2 feet of ileocecal valve
    • Most have clinical sx before age 2 years
    • Approximately 2 inches in length (inflammatory mass may be much larger)
21
Q

Meckel’s Scan

A
  • Technetium-99m (99mTc) pertechnetate scan ⇒ Nuclear Medicine test
  • Look for presence of ectopic gastric mucosa in the large bowel
  • Test of choice to dx Meckel’s diverticula in children
  • Scan detects gastric mucosa ⇒ ~ 50% of symptomatic Meckel’s diverticula have ectopic gastric or pancreatic cells contained within them
  • Classic appearance ⇒ focal accumulation in RLQ
    • Coincident w/ and as intense as gastric uptake
    • ↑ in visibility w/ time
  • In children, scan is highly accurate and noninvasive
    • 95% specificity and 85% sensitivity
22
Q

Abdominal CT

Overview

A
  • Major imaging modality to assess bowel disease
  • ± IV contrast
  • Oral contrast preferred if assessment of bowel disease is needed
  • Con is ionizing radiation

CT, IV contrast alone

23
Q

Abdominal CT

Indications

A
  • Abdominal pain
  • Intestinal obstruction
  • Acute appendicitis
  • Diverticulosis/Diverticulitis
  • Colitis
  • Inflammatory bowel disease
    • Oral contrast indicated
  • Abdominal mass

CT w/ oral contrast seen in intestines

24
Q

Abd CT

Acute Perforated Appendicitis

A
25
Q

Abdominal MRI / MRI Enterography

Indications

A
  • Assessment of bowel disease
  • Inflammatory bowel disease
    • Crohn’s disease
    • Ulcerative colitis
  • Acute appendicitis
  • Abdominal mass
26
Q

Crohn’s Disease

Abd MR

A

There are inflammatory changes involving the terminal ileum w/ proximal small bowel dilatation.

27
Q

Normal

Abdominal MR

A
28
Q

Abdominal MRI

Pros/Cons

A
  • Advantages
    • Superior contrast resolution
    • No ionizing radiation
      • Most important factor, esp. in pts w/ IBD who may require imaging during acute flares
  • Disadvantages
    • Expensive
    • Longer duration study
    • Younger pts or pts who cannot lie still may need sedation/general anesthesia
    • Not always readily available