In Ontario alone, more than 1,000 people are waiting for a kidney transplant. Kidney failure is a growing problem in Canada and with few kidneys available for transplantation, many patients spend years waiting— and some never have an opportunity to receive one.

With this in mind, doctors have begun accepting kidneys from sicker donors. While some of them perform well, others are in poor condition before they’re transplanted and tend to fail quickly.

To help doctors make informed decisions about which kidneys to accept for transplantation and who should receive them, a research team at St. Michael’s Hospital is embarking on a first-of-its-kind study. In collaboration with Ryerson University through the Institute for Biomedical Engineering, Science and Technology (iBEST), the team is aiming to develop ultrasound-based techniques that measure damage in transplant kidneys.

“We currently have no way of reliably assessing the quality of a donor kidney,” said Dr. Darren Yuen, a nephrologist at St. Michael’s and a scientist in the Keenan Research Centre for Biomedical Science. “This was the impetus behind our project. Scarring is a major type of kidney damage that can occur in donor kidneys. If we could measure scarring in a kidney before it’s transplanted, we could make sure that somebody who’s been on a waitlist for a long time doesn’t get a kidney that’s only going to last a year or two.”

The study began back in 2017, after an informal conversation between Dr. Yuen and Dr. Michael Kolios, co-director of iBEST. Dr. Yuen mentioned his inability to assess donor kidneys and Dr. Kolios jumped at the opportunity to help.

A medical physicist, Dr. Kolios has spent much of his career studying ultrasound imaging in medicine. Recently, however, he’s been doing work with photoacoustic imaging—a form of laser-generated ultrasound that produces greater specificity than conventional ultrasound imaging.

Working with Ryerson graduate student Eno Hysi, Dr. Kolios developed an ultrasound machine that uses laser to scan kidneys. The laser moves through the kidneys and gets absorbed by different chromophores—the part of a molecule responsible for color. Each chromophore produces a different colour, depending on the substance in the kidney it belongs to.

“The collagen, which is the major component of scarring, has a unique spectrum compared to blood,” said Dr. Kolios. “So we can distinguish between the signal from the scarring and the signal from the blood. We’ve been able to get very good results in determining the amount of collagen, and therefore scarring, in the kidneys.”

The results have been so good, in fact, that Drs. Yuen and Kolios were recently awarded a prestigious Collaborative Health Research Project (CHRP) grant to continue their work. Later this year, the doctors hope to begin a clinical trial, taking their machine over to an operating room in the hospital to scan kidneys as they arrive for transplantation.

If successful, the clinical trial—the first in the world to use photoacoustic imaging and ultrasound to evaluate kidney damage—could help doctors around the world make better use of donor kidneys.

The end goal, said Dr. Yuen, is to have a machine that surgeons could travel with, to make immediate decisions about whether kidneys should be transplanted.

And he’s feeling pretty good about their chances, thanks to the extent of their collaborations. “This is only possible because of iBEST, our other collaborators, VisualSonics, and buy-in from St. Michael’s surgeons and anesthetists who are really on board to do this,” said Dr. Yuen. “I think it’s all going to pay off. I think this has the potential to revolutionize how we allocate kidneys for transplantation.”