Radiologic studies of the GI Tract

Question 1

Abdominal Radiographs (x-ray) positions and what they show

Answer 1

1. Supine- Foreign bodies; Feeding tube placement; Calcifications, stones, masses
2. Upright- Air fluid levels; Free air; Bowel obstruction
3. Decubitus, Cross-table lateral- Free air

Question 2

Which x-ray position in a normal acute abdominal series is most sensitive for detecting intra-abdominal free air?

Answer 2

Upright chest x-ray

Question 3

Acute abdominal series (3-way)

Answer 3

Upright PA CXR, supine & upright abdomen

Question 4

Valvulae conniventes

Answer 4

thin, circular, folds of mucosa, some of which are circumferential and are seen on an X-ray to pass across the full width of the lumen (these are the folds of small bowel that are similar to the haustra in the colon)

Question 5

Haustral folds are intrrupted by:

Answer 5

taenia coli

Question 6

Biphasic Esophagram

Answer 6

Indications: dysphagia, odynophagia, heartburn

Evaluates: oropharynx, hypopharynx, esophagus, gastroesophageal (GE) junction

Pathology: reflux (common), hiatal hernia (very common), aspiration, neoplasm, esophagitis

Question 7

Small Bowel Follow Through (SBFT)

Answer 7

Often done in conjunction with upper GI

Indications: inflammatory bowel disease (IBD), malabsorption, diarrhea, partial SBO, unexplained GI bleed

Evaluates: distal duodenum/duodenojejunal junction to ileocecal valve

Pathology: Crohn disease, lymphoma, tuberculosis (TB), sprue, adhesions, partial/intermittent obstruction

Question 8

Upper GI

Answer 8

Indication: epigastric pain, hematemesis, nausea, vomiting, guiac positive stools

Evaluates: esophagus, stomach, duodenum

Pathology: gastritis/duodenitis, gastric or duodenal ulcers, diverticula, benign or malignant tumors

Question 9

Enteroclysis

Answer 9

Not often done

Provides more anatomical detail than SBFT

Involves placing a tube in the jejunum and instilling methylcellulose or air after the barium

Can also be used with computed tomography (CT)

Evaluates: jejunum, ileum

Pathology: same as SBFT

Question 10

Barium Enema (BE)

Answer 10

Types and indications:

Double contrast: rectal bleeding, polyps, cancer, IBD

Single contrast: fistula or sinus tract, patient unable to tolerate or cooperate with double contrast study

Water soluble contrast (Gastrografin®): risk for intestinal perforation, therapeutic for disimpaction

Contraindications to any type:
Suspected acute perforation
Acute, fulminating colitis (toxic megacolon)
Immediately after biopsy

Evaluates: Colon and rectum

Pathology: Ulcerative colitis, polyps, colorectal carcinoma, ulceration/strictures

Question 11

Barium Swallow

Answer 11

General term for fluoroscopic-radiographic contrast exam of the oral, pharyngeal, and/or esophageal swallowing

Types:
Pharynx dynamic and static imaging
Modified barium swallow
Biphasic esophagram

Question 12

Ultrasound advantages and disadvantages

Answer 12

Advantages:
No ionizing radiation: Safe in pediatric population and pregnant women
Real time
Portable in critical care units

Disadvantages:
Operator dependent
Body habitus & intestinal gas can affect exam quality

Question 13

Common Indications for ultrasound

Answer 13

Evaluation of:
Gallbladder (cholecystitis) and biliary system

Solid organ lesions; can also help differentiate between solid vs. cystic

Appendicitis (esp. in children and pregnant women)

Vascular flow evaluation (Doppler)

Question 14

Computed Tomography (CT): types and what they each show

Answer 14

Without IV contrast:
Detection of renal stone or hemorrhage

With IV contrast:
Ischemic, infectious, or inflammatory disease, trauma, tumor
Arterial, venous, portal venous, delayed phases of IV contrast

Enteric contrast: oral or rectal route

CT cholangiopancreatography

Question 15

Risks with CT

Answer 15

Risks related to IV contrast:
Nephrotoxicity
Allergic reaction

Risks related to ionizing radiation:
Tissue injury
Carcinogenesis

Pregnancy:
Contraindication unless life threatening illness
Use other imaging test if possible, US and MRI
Pregnancy test (β-hCG) in females in productive age (refer to facility/hospital policies)

Question 16

Magnetic Resonance Imaging (MRI)

Answer 16

No ionizing radiation

Images are produced by alternating magnetic fields with radio-frequency signals and detecting the effect on body tissues

Must fill out screening form regarding heart valves, pacers, metallic objects in the body

Exams take longer than CT

Very low risk of allergic reaction to gadolinium

Risk of nephrogenic systemic fibrosis (NSF) in patients with severe renal dysfunction

MR cholangiopancreatography (MRCP)

Question 17

Nuclear Medicine

Answer 17

Provides functional information often not available with other modalities

Spatial resolution inferior to other imaging modalities

Improvements in endoscopy, US, CT, MRI have limited their applications to specific clinical problems

Question 18

Angiography/Interventional Radiology

Answer 18

Most used today for therapeutic rather than diagnostic indications including:
GI bleeding
Biliary obstruction
Image-guided biopsy
Abscess drainage
Feeding tubes
Portal hypertension
IR oncology

Question 19

Types of nuclear medicine scans and what they show

Answer 19

HIDA – cholecystitis, bile leak, biliary atresia
Gastric emptying – gastric motility
Tagged RBC scan – source of GI bleed
Sulfur colloid scan – evaluate liver, spleen
PET/CT scan – tumor imaging

Question 20

How to know what image to order?

Answer 20

ACR guidelines by symptoms