Imaging Guidelines

Introduction to Contrast-Enhanced Imaging

The decision to use contrast should be based on the urgency and importance of the diagnostic information, as recommended by the American College of Radiology 1, 2
The lowest possible diagnostic dose of contrast media should be used, and high osmolar contrast agents should be avoided in patients with impaired renal function, as recommended by the American College of Radiology 2
Absolute contraindication for contrast media administration is a GFR < 15 mL/min/1.73m², and caution is advised when GFR < 30 mL/min/1.73m², with macrocyclic chelate preparations recommended if necessary, as recommended by the American College of Radiology 2

Patients should be stratified into risk categories based on their eGFR, with the following risk categories:
eGFR (mL/min/1.73m²) Risk Category
> 45 Low risk
30-45 Intermediate risk
< 30 High risk
eGFR should be calculated using appropriate formulas, as serum creatinine alone can be normal despite significantly reduced GFR, especially in elderly patients or those with low muscle mass, as recommended by the Kidney International society 5

Hydration protocols, including intravenous isotonic saline before, during, and after the procedure, should be implemented, with a typical regimen of 1 mL/kg/hr for 6 hours before and 6-12 hours after contrast administration, as recommended by the American College of Radiology 2, 6
Aggressive hydration protocols, including oral and IV hydration, should be implemented to minimize the risk of contrast-induced nephropathy, as recommended by the American College of Radiology and the European Society of Radiology 7, 6
Nephrotoxic medications, such as NSAIDs and aminoglycosides, should be temporarily discontinued, and mannitol and diuretics should be avoided, as recommended by the American College of Cardiology 6
Metformin should be withheld for 48 hours after contrast administration and reinstituted only after confirming normal renal function, as recommended by the American College of Radiology 3

Patients with pre-existing renal insufficiency, diabetes mellitus, and cardiovascular disease are at higher risk of contrast-induced nephropathy, as recommended by the American College of Radiology and the American College of Cardiology 6, 8
For patients already on dialysis, gadolinium-based contrast can be administered without altering the dialysis schedule, as recommended by the American College of Radiology 1
In pediatric patients with eGFR < 30 mL/min/1.73m², the same precautions apply, and macrocyclic or newer linear gadolinium-containing contrast agents should be used in weight-adapted doses, as recommended by the American College of Radiology 9
Ultrasound is a preferred screening examination for certain conditions in patients with decreased renal function, as recommended by the American College of Radiology 4, 8

Macrocyclic gadolinium-based contrast agents (Group II) have a lower nephrotoxicity risk compared to iodinated contrast and are preferred for patients with renal impairment, as recommended by the American College of Radiology 8
For patients with eGFR < 30 mL/min/1.73m², macrocyclic gadolinium agents (Group II) can be used if contrast is absolutely necessary, with individual risk-benefit assessment mandatory, as recommended by the American College of Radiology 1, 8

Patients should be monitored for signs of contrast-induced nephropathy (typically develops within 48-72 hours) and considering follow-up renal function testing within 48-72 hours for high-risk patients, as recommended by the European Society of Radiology and the American College of Cardiology 10, 6, 11

Non-contrast CT can provide valuable information about hydronephrosis, renal size/volume, urinary tract calculi, and basic anatomical information, as recommended by the American College of Radiology 8
Alternative imaging modalities without contrast should be considered for patients with eGFR <30 mL/min/1.73m², as recommended by the American Journal of Kidney Diseases 2, 1