Can a Magnetic Resonance Cholangiopancreatography (MRCP) be done in a patient with impaired renal function, specifically a Glomerular Filtration Rate (GFR) of 24, or is a plain Magnetic Resonance Imaging (MRI) equally effective?

MRCP Safety in Patients with GFR of 24

In patients with a GFR of 24 mL/min/1.73m², MRCP can be safely performed using group II gadolinium-based contrast agents, as the risk of nephrogenic systemic fibrosis is very low and the potential benefits of accurate diagnosis outweigh the risks in most clinical situations.

Understanding the Risk Assessment

For patients with impaired renal function, the primary concern with gadolinium-based contrast media (GBCM) is the risk of nephrogenic systemic fibrosis (NSF). According to the American College of Radiology (ACR) and National Kidney Foundation (NKF) consensus statements, patients can be stratified into risk categories based on their GFR:

• Low risk: GFR > 45 mL/min/1.73m²
• Intermediate risk: GFR 30-45 mL/min/1.73m²
• High risk: GFR < 30 mL/min/1.73m² 1

With a GFR of 24, your patient falls into the high-risk category. However, this doesn't mean MRCP cannot be performed.

MRCP vs. Plain MRI for Biliary Imaging

MRCP with Contrast

• Provides superior visualization of biliary anatomy and pathology
• Can detect smaller lesions and better delineate strictures
• Allows assessment of both biliary anatomy and surrounding structures
• Better characterization of biliary abnormalities 2

Plain MRI without Contrast

• Can visualize larger biliary structures
• May miss smaller lesions or subtle abnormalities
• Less sensitive for detecting certain biliary pathologies
• According to ACR Appropriateness Criteria, MRI of the abdomen without contrast receives a lower rating (4 out of 9) compared to MRI with contrast (6 out of 9) for right upper quadrant pain evaluation 2

Safety Considerations for GFR of 24

The 2021 ACR-NKF consensus statement specifically addresses this situation, stating: "Since the risk of nephrogenic systemic fibrosis is so low with group II gadolinium-based contrast media (GBCM), the potential harms of delaying or withholding group II GBCM for an MRI in a patient with acute kidney injury or estimated glomerular filtration rate less than 30 mL/min per 1.73m² is likely to outweigh the risk in most clinical situations." 2

Recommendations for Your Patient

1. Use of Group II GBCM is appropriate: For patients with GFR < 30 mL/min/1.73m², macrocyclic agents (Group II) such as gadoterate meglumine, gadobutrol, or gadoteridol are recommended over linear agents 2, 3

2. Risk minimization strategies:

   • Use the lowest effective dose of contrast
   • Avoid repeat contrast administration within a short timeframe
   • Consider suspending nephrotoxic medications 24 hours before the procedure 1

3. Alternative approaches if contrast is absolutely contraindicated:

   • Non-contrast MRCP techniques using heavily T2-weighted sequences can still provide useful information about the biliary tree
   • In cases where detailed collecting system evaluation is needed, combining non-contrast MRI with retrograde pyelograms may be considered 2

Important Caveats

1. NSF risk is significantly lower with newer agents: The risk of NSF with group II agents is extremely low, even in high-risk patients 2, 4

2. Risk vs. benefit assessment: Delaying diagnosis of biliary pathology may pose greater risks than the small risk associated with contrast administration 2

3. No evidence for prophylactic hemodialysis: While some sources recommend hemodialysis after gadolinium administration in dialysis-dependent patients, there is no conclusive evidence that this prevents NSF 5, 6

Conclusion

For a patient with GFR of 24 requiring biliary imaging, MRCP with a group II gadolinium-based contrast agent is appropriate and likely to provide superior diagnostic information compared to plain MRI. The 2021 ACR-NKF consensus specifically supports this approach, emphasizing that the diagnostic benefits outweigh the very low risk of NSF with modern contrast agents.