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

IV Contrast

question1. Why do we use IV contrast material?
question2. Do you use serum creatinine levels or GFR in your practice for establishing risk prior to CT scanning?
questionBy tradition we have used Creatinine levels but long term we will move over to GFR. GFR tends to be more accurate especially in older patients. Both can be used in clinical practice. I recently surveyed several Radiology audiences at meetings and the split is 50-50 for judging renal function.

Who should get baseline serum creatinine levels before CT?

  • Age > 60
  • History of renal disease, including:
    • Dialysis
    • Kidney transplant
    • Single kidney
    • Renal cancer
    • Renal surgery
  • History of hypertension requiring medical therapy
  • History of diabetes mellitus
  • Metformin or metformin-containing drug combinations

"The major preventive action against CIN is to ensure adequate hydration. The ideal infusion rate and volume is unknown, but isotonic fluids are preferred (Lactated RingerÕs or 0.9% normal saline). One possible protocol would be 0.9% saline at 100 mL/hr, beginning 6 to 12 hours before and continuing 4 to 12 hours after intravascular iodinated contrast medium administration. Oral hydration has also been utilized, but with less demonstrated effectiveness."

ACR Manual on Contrast Media
Version 9 (2013)

question3. What is GFR and why is it a more accurate measure than simply getting a creatinine level?
question4. Why are GFR numbers different for Caucasians and African Americans?
question5. Are all CT scans with IV contrast done the same way?
question6. What type of IV contrast material do we use and why?
question7. At what temperature do we store IV contrast material?
question8. Why do you warm IV contrast?
question9. What is the advantage of Visipaque as written in the literature?
question10. When do you use Visipaque-320 and when Omnipaque-350?
question11. Does the concentration of contrast mean that higher concentrations are better (AKA-isn’t a higher number better)?
question12. What is the volume of IV contrast material we use?
question13. What patients are considered high risk patients for IV contrast for CIN?
question14. Do we have set cutoffs for creatinine levels and if so what are they?
question15. Can we pretreat patients who have borderline renal function? If yes then how?
question16. Should patients be NPO for CT scanning? If yes for how long?
question17. What are the common volumes of contrast used for IV injection?
question18. What kind of IV access is ideal for use for IV contrast injection?
question19. Has there been any new developments in technology that may help us high injection rates in patients who can not tolerate an 18g needle (or at times even a 20g)?
question20. Can any IV the patient has in place be used to inject the contrast material?
question21. Can we use a central line or a PICC line for injection?
question22. What about the new “purple PICC/central lines” I hear about?
question23. What are some of the common normal “side effects” of IV contrast agents?
question24. Is there a relationship between patients receiving chemotherapy and CIN?
question25. Is it ok for patients to have both an MR and a CT with contrast on the same day?
question26. Have you ever seen a patient develop diffuse erythema distal to the IV injection site in the absence of extravasation?
question27. Patients often report a metallic taste in their mouth following use of IV iodinated contrast. Is there an explanation?
question28. Are there any contrast volume limitations for the use of IV contrast?
question29. Can you tell me a bit more about GFR and what it really means?


© 1999-2020 Elliot K. Fishman, MD, FACR. All rights reserved.