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Everything you need to know about Computed Tomography (CT) & CT Scanning


Current Clinical Concerns in CT: Results : Oral Contrast Administration

Contrast selection

1. Can you tell me the benefits of using water as an oral versus hypaque or barium (redicat). How will adding water as an oral contrast for CTA's help?

Answer: The key use of water for CTA's is the elimination of editing of opaque bowel and stomach. Also, we can better judge bowel wall enhancement with water in the lumen, and not positive contrast.

2. Do you have an opinion about Locust Bean Gum associated with mannitol as an oral, negative contrast? It seems to assure a better stomach, jejunum and ileum distention compared to water.

Answer: I do not use it.

3. I would like to perform dedicated small bowel CT using a neutral contrast agent. In order to obtain optimal distention, I was thinking of using either water with IV glucagon, versus methylcellulose. Any recommendations on the issue?

Answer: We use water. There is a new agent from EZM which certain people have found helpful.

4. It has been my experience during the past 4 years that ER patients are prepped with Gastro, rather than barium sulfate solutions, for abdominal/pelvis CT scans when ordered from the ER. Additionally, it is my understanding that gastro is used for several reasons, to include: faster transit time throughout the bowel enabling the ability to scan sooner, it is so water soluble and decreases the chance of peritonitis if the patient has a perforated viscus, and /or needs to have surgery (i.e. appy). Additionally, it is my understanding that a patient should not receive Barium if there is a suspicion of bowel obstruction. Is Barium OK to use for ER patients?

Answer: We use hypaque (3%) but the barium products are also pretty dilute, so should be of no problem in the ER patient or on a routine basis. I have not seen any reported complications related to barium based CT products.

5. Can I give the patient water instead of contrast for all abdominal exams?

Answer: I still use positive contrast if:
a. No IV contrast used
b. Search and destroy scan
c. Routine f/u as in colon cancer or lymphoma
d. Many ICU patients

6. We are currently using cheetah barium at our outpatient clinic. We are getting many complaints of cramping/dysentery within 1-2 hours of drinking. We have had several patient accidents while at our center, or on their way home. I know some of this goes with the territory, but in your experience, have you had better luck with some other brands? I have been looking on the internet hoping to find a study/comparison of brands, but have had no luck finding any.

Answer: We use barium from EZM and have had no problems.

References
Wold PB, Fletcher JG, Johnson CD and Sandborn WJ. Assessment of small bowel Crohn disease: Noninvasive peroral CT enterography compared with other imaging methods and endoscopy-Feasibility study. Radiology 229: 275-281, 2003.

  • Summary: In this study 23 patients were evaluated with CT, traditional fluoroscopy and endoscopy. All patients received oral metoclopramide 75 minutes before the CT scan and glucagon prior to the CT. One group received 450-mL water aliquots for a total of 1800 mL administered over 75 minutes. The second group had a nasojejunal tube inserted, through which 1800 mL of methylcellulose was infused at 60 mL/minute. Two acquisitions were performed, at 40 and 70 seconds following IV contrast infusion. The adequacy of luminal distention was not significantly different between the two groups. The arterial phase acquisition was deemed noncontributory in 22/23 patients.

Antoch G, Keuhl H, Kanja J et al. Dual-modality PET/CT scanning with negative oral contrast agent to avoid artifacts: Introduction and evaluation. Radiology 230: 879-885, 2004.

  • Summary: This study evaluated of the utility of locust bean gum combined with mannitol (mannitol-LGB) as an oral contrast agent at PET/CT. Sixty patients were randomly assigned into 3 groups of 20, and received either (1) 800 mL of barium (2) 2 L of tap water or (3) mannitol-LBG. Seven of the 20 patients who ingested water had a diuretic urge during the PET/CT, vs none of the mannitol-LBG or barium patients. Two of the mannitol-LBG patients reported watery diarrhea following the scan. Evaluation of the CT images demonstrated statistically significant improvement in stomach and small bowel diameters using mannitol-LBG vs. water or barium. Mannitol-LBG and water resulted in similar mean intraluminal attenuation.

 

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