Current Clinical Concerns in CT: Results : IV Contrast Administration
Contraindications/Interactions
1. I have a patient with hematuria and suspected TCC on a retrograde pyelogram, who requires renal CTA. She also has a known (contralateral) pheochromocytoma. What do you recommend with respect to the use of IV contrast in Pheo patients? Should they be premedicated? With what? Or should we just keep antihypertensives on hand, (which one?) and observe the patient for 30 - 60 minutes post injection?
| Answer: With nonionic contrast, the chance of a reaction is indeed very low. But, we would still recommend premedicating these patients. |
2. Is there a contraindication to giving intravenous contrast in an outpatient CT facility? Specifically- with respect to asthmatics.
| Answer: There is no difference between our use of contrast at any of our locations. The same guidelines apply; although, we are all aware of the isolation of many clinics. In these cases, especially, the use of nurse is very helpful. |
3. Any complications with using IV contrast on a patient while IV heparin is being used? How about using any IV/oral medication with IV contrast?
| Answer: There is no issue with heparin except to be careful with IV placement and during the injection. The key meds that are problematic with IV contrast are glucophage (metaformin) and NSAID's. |
4. I was wondering what your protocol is regarding patients with possible pheochromocytoma. I've always understood one is not to inject IV contrast on know pheo patients. Is that correct?
| Answer: With nonionic contrast, the chance of a reaction is indeed very low. But, we would still recommend premedicating these patients. |
5. What do you recommend for patients with Sickle Cell Anemia and those with Sickle cell trait? Are they handled alike?
| Answer: For Sickle Cell Anemia, because of the frequency of crisis, are handled more carefully than Sickle Cell Trait. Although there has been some discussion about whether you can use contrast in patients with Sickle Cell Disease, as long as patients have baseline normal renal function, the use of contrast is typically not an issue. |
6. What is your policy regarding IV contrast and pregnancy (assuming the CT is medically necessary)? Do you give it or reduce the dose? Is it actually harmful to the fetus?
| Answer: In regards to pregnancy, there is no known long term effect to the fetus with IV contrast. We do of course limit the use of CT in the pregnant patient, but the key is that we give enough contrast to make a correct diagnosis. It is optimal to minimize contrast, but the key is to make the correct diagnosis. I am not sure if Omnipaque or Visipaque would be best in this situation, but we use Visipaque as it provides equal or better quality images in the typical applications used in the pregnant patient (i.e. PE) |
7. Do you have any issues with giving IV contrast in patients who have glaucoma? Is there a historical problem?
| Answer: There is no issue to my knowledge of IV contrast and glaucoma. |
8. What is your recommendation for IV injection of contrast media in diabetic outpatients taking Glucophage (metformin).
| Answer: Standard recommendation is to stop glucophage that day and wait 24- 48 hours until you begin retaking it. Per the drug manufacturer, they would suggest checking a creatinine level before the patient begins re-taking the drug. |
9. What is JH's policy on breastfeeding mom's and contrast injections?
| Answer: The ACR has stated that in reality, no delay is necessary, but to be conservative, a 24 hour delay is all that is needed after contrast. |
References
Michael A. Bettmann Frequently Asked Questions: Iodinated Contrast Agents
RadioGraphics 2004; 24: 3-10.
- Summary: Many of the questions presented here are addressed in this recently published Radiographics article, which serves as an excellent reference.
Mukherjee JJ. Peppercorn PD. Reznek RH. Patel V. Kaltsas G. Besser M. Grossman AB. Pheochromocytoma: effect of nonionic contrast medium in CT on circulating catecholamine levels. Radiology. 1997; 202(1):227-31.
- Summary: This was a small study, including 10 patients with pheochromocytomas and related tumors compared to six healthy volunteers. Twenty-four hours prior to the study, all patients were administered phenoxybenzamine hydrochloride. Iodinated contrast (iohexol) and control (saline) were infused on 2 different days, and plasma catecholamine levels were sampled 8 times up to 60 minutes following the infusion. Results showed no statistically significant rise in epinephrine or norepinephrine levels in patients or the control subjects. However, 2 patients did have an increase in norephinephrine levels (with peak increases from 17.6 to 19.1 nmol.L). The authors conclude that specific blockade may not be necessary if iohexol is administered. However, in light of the unpredictable catecholamine responses in these 2 patients, the authors state that the administration of oral blockade with alpha- and beta-adrenoceptor antagonists to patients with biochemically proven catecholamine-secreting tumors "may be prudent."