Selecting contrast media for pediatric fluoroscopy: A primer
What type of gastroenteric contrast media should be used for pediatric fluoroscopy? Pediatric radiologists at Boston Children’s Hospital have prepared a comprehensive review of the enteric contrast media they routinely use, which is intended to serve as a resource for radiology trainees or adult radiologists who occasionally image children. Their article, published in Pediatric Radiology, supplements the primarily adult-based guidelines from the American College of Radiology’s Manual on Contrast Media v10.2, and provides suggestions for the proper use of these media in children.
The authors begin with a discussion of the characteristics, technical considerations, and uses of barium sulfate and iodinated water-soluble contrast media. Barium sulfate is an extremely versatile gastroenteric contrast media, is well tolerated orally by most children, and is considerably less expensive than most iodinated non-ionic contrast media. It is not absorbed or metabolized in the gastrointestinal tract and is excreted unchanged. Because of its favorable safety profile and versatility, barium sulfate is the most commonly used oral enteric media for fluoroscopy in children. However, it is generally not used when there is a potential risl for a perforated viscus.
Although only one iodine-based low-osmolar contrast medium - iohexol (Omnipaque, GE Healthcare) - has been cleared by the U.S. Food and Drug Administration (FDA) for pediatric enteric use, the authors state that virtually any low-osmolar contrast media (LOCM) can be safely used as enteric contrast media off label. LOCM offers the advantages of being water soluble, of binding with organic compounds, and of having relatively low levels of toxicity.
Lead author Michael J. Callahan, MD, and colleagues describe six common types of fluoroscopy procedures, explaining the indications for the studies and the types of contrast media used and how they are administered. They offer several recommendations and cautions. Highlights include:
Contrast esophagram, upper gastrointestinal examinations and contrast examination of the small bowel
These are the most commonly requested pediatric fluoroscopic gastrointestinal imaging studies, and barium sulfate suspension is used for most of these procedures performed at Boston Children’s. Water-soluble LOCM is used when a luminal leak or perforation is suspected. As such, either barium sulfate solution or low iosmolar contrast media (LOCM) such as iohexol 180 should be considered when administering enteric contrast media to premature neonates. It is the authors’ opinion that diatrizoate meglumine and diatrizoate sodium solution in whater should never be administered orally to a pediatric patient because of the extreme hyperosmolarity of these media and associated risks of aspiration pneumonitis and severe fluid shifts.
Enteric and ostomy catheter evaluations
This procedure is recommended for localization of gastrostomy, jejunostomy, gastrojejunostromy, nasojejunostomy and ceostomy catheters. The authors perform a catheter injection of either LOCM or barium sulfate via a syringe. LOCM is recommended in cases if an ostomy catheter may be extraluminal or recently placed.
Modified barium swallow
At Boston Children’s both a radiologist and a speech pathologist work together to determine the optimal way to administer barium sulfate powder mixed with liquids, semi-solid and solid food, and to tailor the eneteric media used for these exams to each individual patient.
Diagnostic contrast enema
The majority of contrast enemas are performed in newborns to evaluate clinical and radiographic signs of low intestinal obstruction. However, this exam is also performed for intractable constipation, post-surgical evaluation of the colon and/or lower small intestine, and evaluation of stricture in the setting of necrotizing enterocolitis.
The authors recommend the use of iothalamate megulumine for virtually all contrast enemas. They note that although it has a lower iodine content than other iodinated water-soluble contrast media, adequate visuallization is attained as a result of the large volume of contrast used. The authors do not recommend that full-strength, undiluted diatrizoate meglumine and diatrizoate sodium solution should ever be administered rectally to children of any age. Notably the authors rarely adminster barium sulfate for contrast enemas at their institution.
Stomagrams
The authors use a Foley catheter advanced into the ostomy with the balloon inflated outside the patient’s stoma. Iothalmate meglumine is administered via gravity for these studies..
Therapeutic contrast enema
For infants, the authors use equal volumes of diatrizoate meglumine and diatrizoate sodium solution in water. They caution that infants should be well hydrated prior to the enema. For older children and adolescents who have become obstructed due to viscous distal small bowel contents, the authors use diatrizoate meglumine and diatrizoate sodium solution diluted with iothalmate meglumine.
REFERENCE
- Callahan MJ, Talmadge JM, MacDougall RD, et al. Selecting appropriate gastroenteric contrast media for diagnostic fluoroscopic imaging in infants and children: a practical approach. Pediat Radiol. Published online October 10, 2016 DOI: 10.1007/s00247-016-3709-5.