Imaging agent may help gauge kidney health: study

CHICAGO - Researchers at Washington University School of Medicine in St. Louis have developed an imaging agent that could help refine assessments of kidney health, potentially salvaging some otherwise discarded kidneys.

To assess whether RadioCF, the imaging agent, can be used to estimate nephron number in living animals, the researchers injected healthy mice with the compound. For comparison, they also injected mice carrying a mutation that reduced their nephron density by about a third.

For both groups of mice, the PET signal correlated with the density calculated by counting nephrons under a microscope.

The researchers also evaluated the compound in a donated kidney from a deceased 75-year-old woman that had been rejected for transplantation. They injected the kidney with RadioCF and performed a PET scan. Then, they injected it again with cationic ferritin and ran an MRI for comparison. As expected, the MRI produced more detailed data. But the two methods were closely correlated, indicating that RadioCF accurately measured the number of nephrons, tiny filters that clean waste from the blood in the kidney.

"If we could measure nephron number in people with diabetes or hypertension or something else that puts them at risk of chronic kidney disease, or in people in the early stages of kidney disease, doctors could initiate treatment early to try to preserve kidney function and reduce the chance they will develop end-stage kidney disease and require a transplant," said senior author Kevin Bennett, an associate professor of radiology at the university's Mallinckrodt Institute of Radiology.

Nearly 100,000 people in the United States have kidney failure and are waiting for transplants. However, more than 3,000 donated kidneys are deemed poor quality and discarded every year in the United States, particularly those from people who are older, have metabolic or cardiovascular conditions, or have died.

The study, posted on the university's website on Friday, has been published online in the American Journal of Physiology.