Page 28 - Radiology Book

etravasation of contrast
Metformin
Although contrast media-induced renal failure is rare in patients
with normal renal function precautions need to be taken with certain patient populations. The US Food and Drug Administration state that Metformin should be temporarily withheld for radiological iodinated contrast media studies.
Category I
Patient with normal renal function with no know comorbid conditions – no need to discontinue metformin prior to iodinated contrast media study.
Category II
Patients with multiple comorbid conditions with normal renal function – Metformin should be held at the time of study with iodinated media for 48 hours. Repeat serum Cr is not necessary after study; clinical decision and communication between the radiologist and health care provider should be done to establish procedure for reassessing renal function and restarting Metformin.
Category III
Patients taking metformin who have known renal dysfunction – Metformin should be suspended at the time of contrast injection and cautious followup of renal function performed prior to reinstituting.
Nephrogenic Systemic Fibrosis (NSF)
Gadolinium-based contrast agent (GBCA) have been shown to cause NSF in patients with end-stage CKD, severe CKD and in patients with AKI (7).
The following patients are at risk for NSF:
• On dialysis
• Severe CKD (CKD 4 or 5, GFR < 30 mL/min/1.73 m2) without
dialysis
• GFR 30-40 mL/min/1.73 m2 • AKI
Identifying At-Risk Patients
The following patients should have GFR calculated prior to GBCA administration:
• Age > 60
• Kidney surgery
• History of known cancer involving the kidney • Kidney transplant
• Single kidney
• Diabetes mellitus
Once at risk patients are identi ed, alternative examinations that don’t employ a GBCA should be considered.
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