Doctors now have better tool to assess individual kidney function

Doctors now have a much-improved tool to assess individual kidney function, thanks to the work of an international team led by University of Saskatchewan (U of S) medical imaging specialists Drs. Carl and Michal Wesolowski.

"The most popular method is probably not the best method, because the best method is hard to use," said Carl Wesolowski, explaining their new approach is much simpler and gives "best method" results. The team's work is described in a paper published in the March 2016 issue of the European Journal of Nuclear Medicine and Molecular Imaging.
How well each kidney is functioning—something called split renal function—is critical knowledge for anyone planning to donate a kidney or to guide doctors' decisions for surgery and other medical treatments.

"Most of the time kidneys are 50-50 in terms of their split function," explained Carl Wesolowski. "Sometimes having different sized kidneys is just an act of nature—you can be born that way—and you can have a small kidney that's normal and a big one that is normal as well. But sometimes, each kidney can function differently due to an illness such as high blood pressure, a cancerous tumor or a urine blockage. A kidney stone, for example, can prevent urine from draining properly, causing it to build up in the organ and eventually stopping it from working."

Determining how well each kidney is functioning individually involves injecting a radiopharmaceutical into the patient. A special camera is used to detect the radiopharmaceutical's progress through the kidneys and the resulting imaging is used to calculate how each kidney is working.

One of the things that the new imaging method does is allow a doctor to acquire images more tailored to the patient's diagnostic needs.

"We take the activity over a short period of time and then we plot the activity in each of the kidney against the activity in the liver," Michal Wesolowski said. "Using this number we can extrapolate kidney activity to a point at which there were zero counts in the liver. So the zero counts show the amount of kidney activity that is only from kidney drug extraction, that is, kidney function."

While that may sound complicated, Carl Wesolowski stressed it's simple enough that most technologists and physicians can understand the process without much translation, especially considering it is quite visual in that all of the information they need to know is quite neatly provided within the imaging area.

"Inside the region of interest we have a number of counts," Michal Wesolowski said. "So we plot the number of counts versus time, which shows you the activity from that (radiopharmaceutical) as a function of time which gives us graphs."