With New Laser Imaging Technology, Scientists Can Efficiently Determine Whether Donor Hearts Are Suitable For Transplantation

A new laser imaging technique will hopefully determine which donor hearts are suitable for transplantation and which ones will lead to poor outcomes, a group of French researchers found recently. Rarely, it does not require coronary angiography or the use of contrast agents that could damage the transplanted heart. Preliminary findings have been published in the April 2023 issue of the Journal of Biomedical Optics (JBO).
With New Laser Imaging Technology, Scientists Can Efficiently Determine Donor Heart Suitability for Transplant
Laser scatter imaging enables visualization of vascular details of beating donor transplant hearts for in vitro viability assessment (image credit: Plyer et al. researchers, JBO)
Based on previous experience, severe coronary artery disease (CAD) is a key determinant of whether primary graft failure and early death will occur after heart transplantation. And as the criteria for the donor population expands, the importance of cardiac screening before heart transplant allocation is becoming more prominent. With a long waiting list for heart transplantation, there is an urgent need to find ways to screen donor hearts (donor hearts) to determine their viability and potential complications.
However, invasive coronary angiography, currently considered the "gold standard" for donor heart evaluation, is actually performed in only about one-third of donor hearts. Ex vivo perfusion (ESHP) studies can be performed after the donor heart has been removed from the donor, and the contrast used in this method causes the heart to degenerate.
Because of this, researchers have been searching for a more optimal method to better preserve the heart.
The aforementioned French team recently investigated a non-contact laser scatter-based imaging technique that can assess the structure and function of the heart's blood vessels without the need for contrast. The researchers established the Laser Scattering Orthogonal Contrast Imaging (LSOCI) technique for the selective detection of multiple scattering of motile red blood cells. The laser is focused on the donor heart and the backscattered light from the moving particles can be observed with the camera, which produces a blurring effect that can be used as a contrast between the blood vessels and the surrounding tissue.
As a full-field optical technique, LSOCI enables the creation of high-resolution imaging of the entire cardiac peripheral vasculature with real-time imaging capabilities. Professor Elise Colin from the University of Paris Saclay, France, explained in a statement from the International Society for Optics and Photonics (SPIE), "The optical technique allows high-resolution imaging of the entire peripheral vascular system of the heart in real time."
To validate this approach, the researchers developed a clinical model to study the coronary circulation of the pre-transplant donor heart. They then mounted a laser and camera on an articulated arm fixed above a perfusion module (containing the donor heart) to generate and analyze a rapidly changing speckle pattern.
To overcome the challenges of tracking the vascular system due to the beating heart, the researchers further optimized a method called "multi-cycle enhanced signal-to-noise ratio" (MPE-SNR). Over time, they took a series of images and built a framework for depicting the vascular system at similar locations in the heart. Each image in the sequence was then optimized by using other images, reducing noise and enhancing detail.
The optimized images represent the vascular system at different points in time. It was using a series of such images that the researchers visualized vascular systems as small as 100 microns in a matter of seconds and accurately displayed blood circulation. In the future, this technique will hopefully be used to identify myocardial perfusion abnormalities, as well as characterize underlying heart disease (e.g., coronary artery disease).