Using photoacoustic imaging to visualize scarring in donor kidneys before transplant

Reviewed by Emily Henderson, B.Sc.Might 2 2020

When kidney transplants first got here into apply within the 1950s, sufferers with continual kidney illness (CKD) might lastly image freedom from the unrelenting routine of blood-cleansing dialysis therapies. Simply over a half-century later, demand has utterly outstripped provide. The critically ailing languish for years on ready lists, whereas docs have little selection however to just accept donations of broken kidneys in a determined try to avoid wasting lives.

Transplant outcomes are so onerous to foretell that nephrologist Dr. Darren Yuen, of St. Michael’s Hospital in Toronto, compares it to “spinning a roulette wheel”. However lately revealed findings in JCI Perception are laying the groundwork to probably revolutionize this dynamic – and empower physicians to finally reset the gold normal in transplantation protocol.

The analysis is an integration of Yuen’s medical insights on kidney illness with the medical physics experience of Ryerson College’s Dr. Michael Kolios and Ph.D. candidate Eno Hysi, and their respective groups. Each Yuen and Kolios have labs on the Institute for Biomedical Engineering, Science, and Know-how (iBEST), a novel collaboration between the hospital and college, bringing collectively consultants from various and historically siloed analysis fields.

The staff’s new technique is a world-first in making use of photoacoustic (PA) imaging to visualise scarring in kidneys, also referred to as fibrosis, a standard type of injury in donor kidneys. Their outcomes produced clear photos of kidney scarring simply hours earlier than surgical procedure. Throughout this window of alternative, an correct evaluation might imply the distinction between implanting an organ with decades-long sturdiness – or one which rapidly fails, sending a affected person proper again to dialysis and the years-long waitlist.

Correct, non-invasive kidney screening

Needle biopsy – a painful process fraught with bleeding threat – is at present the one technique to evaluate the quantity of kidney scarring in potential donors. However its reliability is hampered by probably inaccurate estimates based mostly on a tissue pattern dimension of just one% of the kidney.

The present analysis takes a faster, non-invasive and extra complete path to quantify kidney injury, utilizing PA imaging as a substitute. The novel expertise combines laser and ultrasound – a sequence that Hysi likens to lightning and thunder. “We shine gentle on kidney tissue, which creates a stress wave that may be heard utilizing an ultrasound probe.”

The sound knowledge is then run by means of a proprietary algorithm based mostly on a method known as spectral unmixing.

Every form of physique tissue absorbs coloured laser gentle in its personal distinctive approach. Collagen – one of many most important elements in kidney scarring – absorbs coloration in a way that’s distinct from different elements within the kidney. Spectral unmixing teases out the variations. Maps generated by the expertise present the quantity and distribution of collagen, blood or different tissue – thus permitting physicians to ‘see’ the standard of donated kidneys.

“It wasn’t in any respect apparent that it could work”

When Hysi first proposed utilizing spectral unmixing to hone in on collagen, nothing in prior medical physics data hinted that the applying was even potential.

Usually, for the approach to work, you should see giant peaks and valleys in how elements soak up gentle. However collagen is flat, so it wasn’t in any respect apparent that it could work.”

Dr. Michael Kolios, Ryerson College

Hysi continued with a counterintuitive method. With so many different organic substances exhibiting peaks and valleys as soon as spectral unmixing is utilized, collagen may stand out conspicuously by advantage of its personal flatness.

The issue grew to become so intriguing that Hysi determined to discover this risk in parallel together with his personal doctoral analysis on most cancers monitoring. Two years later, the findings validated his speculation, and the proprietary algorithms at the moment are being patented.

In lower than two minutes, the brand new approach can generate a 2D picture with sufficient element to quantify complete scarring in a kidney. Inside 15 minutes, 3D imaging permits visualization not solely of general scarring, but in addition its various distribution all through the kidney.

Potential for vital, widespread affect

Because the analysis strikes into medical trials at St. Michael’s Hospital, Hysi and Yuen will assess how intently their predictions on kidney high quality mirror precise outcomes in sufferers. If profitable, their scoring technique might have a major affect on transplantation apply, and grow to be the brand new gold normal in kidney evaluation.

Healthcare methods might save the whopping $100,000 in direct, annual, per-patient prices to handle dialysis sufferers. However the best affect is in giving every affected person the very best kidney, preserving them off dialysis and giving them a brand new, sturdy lease on life.

Yuen sums up the two-year whirlwind of analysis: “I’ve by no means seen something like this earlier than. Clinicians and researchers working collectively, and discovering such nice leads to so quick a time – it is simply superb.”