Report from ARRS: Protocols help protect older patients from CT-induced kidney damage

The right prevention strategies can allow older patients with mild to moderate kidney disease to safely undergo contrast-enhanced CT, according to a study presented Wednesday at the American Roentgen Ray Society meeting in Orlando.

Contrast-induced nephropathy, the acute deterioration of renal function after exposure to contrast media, is typically determined by serum creatinine levels measured in a blood test. In most cases, the levels return to normal, but the damage in some patients can result in the need for kidney dialysis or even death. Those with diabetes and severe chronic renal disease are most at risk.

Researchers at the University of Buffalo measured the effectiveness of hospital protocols at Roswell Park Cancer Institute for contrast administration in patients with kidney disease, focusing on men over 70 and women over 80 years of age. Since some studies have shown a benefit for iso-osmolar media in patients with heightened risk factors, Visipaque is administered in these cases. Staff adapted the hydration method and type of contrast agent according to the severity of the patient's renal dysfunction, per hospital protocols.

Patients with severe chronic renal insufficiency (CRI), measured as creatinine clearance (CrCl) less than 30 mL/min in diabetic patients and less than 20 mL/min in nondiabetic patients, are not given any contrast.

The researchers retrospectively analyzed effectiveness of protocols based on patient groupings that indicate progressively higher risk for CIN:

• Group 1: Diabetic patients (2.8% of group) with CrCl of 60 mL/min or greater and nondiabetic patients with CrCl of 50 mL/min or more were given intravenous contrast Omnipaque (300 or 500).

• Group 2 (mild CRI, mean CrCl of 40.1 mL/min): Patients were given oral hydration and IV Visipaque 320. Diabetic patients were 18.1% of group.

• Group 3 (moderate CRI, mean CrCl of 30.4 mL/min): Patients (diabetic, 42.5%) were given IV hydration with Lactated Ringer's and Visipaque 320.

Based on the definition of CIN as an increase in serum creatinine of at least 25% and an absolute increase of at least 3 mg/dL from two to five days after contrast administration, incidence for the 279 patients in the study was as follows:

• Group 1: 5.6% (two of 36 patients)

• Group 2: 4.4% (nine of 203)

• Group 3: 2.5% (one of 40)

These differences were not statistically significant. Of the 12 patients who experienced CIN, 11 returned to baseline and remained stable. None needed dialysis.

The results indicate that even though patients in the third group had the most risk factors, they did not incur a higher risk for CIN.

"While we can't definitively state what is the optimal technique for preventing CIN, we can conclude that as far as patient outcomes are concerned, our stratification procedure and delivery method for contrast are effectively keeping rates of CIN low. It is important for radiologists to realize that a patient with moderate chronic renal insufficiency can safely receive IV contrast," said presenter Dr. Michael Petroziello, a recent graduate of the University of Buffalo, in an e-mail to Diagnostic Imaging.

Researchers are investigating whether patients with even higher risk factors than those in Group 3 could receive IV contrast.