Radiologic studies of the GI Tract Flashcards
Abdominal Radiographs (x-ray) positions and what they show
- Supine- Foreign bodies; Feeding tube placement; Calcifications, stones, masses
- Upright- Air fluid levels; Free air; Bowel obstruction
- Decubitus, Cross-table lateral- Free air
Which x-ray position in a normal acute abdominal series is most sensitive for detecting intra-abdominal free air?
Upright chest x-ray
Acute abdominal series (3-way)
Upright PA CXR, supine & upright abdomen
Valvulae conniventes
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)
Haustral folds are intrrupted by:
taenia coli
Biphasic Esophagram
Indications: dysphagia, odynophagia, heartburn
Evaluates: oropharynx, hypopharynx, esophagus, gastroesophageal (GE) junction
Pathology: reflux (common), hiatal hernia (very common), aspiration, neoplasm, esophagitis
Small Bowel Follow Through (SBFT)
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
Upper GI
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
Enteroclysis
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
Barium Enema (BE)
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
Barium Swallow
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
Ultrasound advantages and disadvantages
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
Common Indications for ultrasound
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)
Computed Tomography (CT): types and what they each show
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
Risks with CT
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)
Magnetic Resonance Imaging (MRI)
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)
Nuclear Medicine
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
Angiography/Interventional Radiology
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
Types of nuclear medicine scans and what they show
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
How to know what image to order?
ACR guidelines by symptoms
