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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?
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?
question

Our standard agent is Omnipaque-350 but for high risk patients we use an iso-osmolar agent which is Visipaque-320.

A list of increased risk patient follows but we also use Visipaque-320 for all PE studies, cardiac CTA studies, and all pediatric patients.


Patient-related Risk Factors for CIN

Established

– Pre-existing renal impairment with diabetes
– Pre-existing renal impairment without diabetes
– Dehydration
– Congestive heart failure
– Multiple myeloma
– Advanced age
– Administration of nephrotoxic drugs

Newly identified

– Hypertension
– Metabolic syndrome

CIN, contrast-induced nephropathy
Asif A et al. Am J Ther. 2003;10:137-147; Morcos SK et al. Eur Radiol. 1999;9:1602-1613.


"Intravenous contrast material application in high risk patients is unlikely to be associated with permanent adverse outcomes. SCr levels after contrast material administration are lower in iodixanol than iopromide groups."

Iso-osmolality versus Low Osmolality Iodinated Contrast Medium at Intravenous Contrast-enhanced CT: Effect on Kidney Function
Nguyen SA et al.
Radiology 2008; 248:97-105

"In patients with impaired renal function, SCr levels are less likely to increase when iso-osmolality iodixanol is used, as compared with low osmolality iopromide."

Iso-osmolality versus Low Osmolality Iodinated Contrast Medium at Intravenous Contrast-enhanced CT: Effect on Kidney Function
Nguyen SA et al.
Radiology 2008; 248:97-105


"Fewer patients in the iodixanol group (8.5%) than in the iopromide group (27.8%) had SCr increase 0.5 mg/dL or higher (≥25%, P=.012)."

Iso-osmolality versus Low Osmolality Iodinated Contrast Medium at Intravenous Contrast-enhanced CT: Effect on Kidney Function
Nguyen SA et al.
Radiology 2008; 248:97-105


nephrotoxicity

nephrotoxicity

Contrast induced nephropathy: CT of the kidney looks as if the contrast was just injected. Look at aorta and see that no injection of contrast occurred.

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?

 

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