Cardiac imaging breakthrough developed
LONDON, Ont. – Cardiologists and
surgeons may soon have a new tool to improve outcomes for patients
requiring pacemakers, bypass surgery or angioplasties. Research led by
Dr. James White and his colleagues at The University of Western Ontario
has led to a new imaging technique, which provides a single, 3D
high-resolution image of the heart revealing both its vasculature and
the presence of scar tissue within the muscle.
This novel imaging was performed using a 3-Tesla MRI at Western’s
Robarts Research Institute. The findings are published on-line in the
Journal of the American College of Cardiology: Cardiovascular Imaging.
Injuries to the heart, including heart attacks or viral inflammation,
commonly result in permanent damage or scarring of its muscle. “We’ve
known for some time that myocardial (heart) scar tissue can be imaged
using MRI, but what we’ve now been able to do is to take this imaging to
another level,” explains Dr. White. “This is the first time we have been
able to visualize myocardial scar and the heart’s blood vessels at the
“We are able to construct a three dimensional model of a person’s heart
to immediately understand the relationship between the heart’s blood
vessels and related permanent injury,” he said. “This will help direct
surgeons and cardiologists to better target the blood vessels that lead
to muscle capable of responding to their therapy, rather than to muscle
that is irreversibly diseased.”
The technique works by first acquiring a 3D coronary image using a
continuous infusion of a contrast called gadolinium, which makes the
blood-pool light up brightly. The 3-T MRI takes images as this contrast
is infused into the blood stream, providing a high resolution, 3-D image
of the heart showing coronary blood vessels.
Scar tissue is slow to give up this contrast agent and its signal is
therefore retained despite a washing out of contrast from the blood
stream and normal tissues. A repeat image, performed 20 minutes later,
highlights the heart’s scar, also in 3D.
Because the two images are taken in an identical way using the exact
same MRI pulse sequence, they’re already perfectly suited to be fused to
one another. The result is a fused, 3D model of the heart that shows
both the heart’s vessels and scar tissue.
The imaging technique was performed on 55 patients referred for either
bypass surgery or a specialized pacemaker designed to improve heart
function called Cardiac Resynchronization Therapy (CRT), demonstrating
that the procedure was clinically feasible.
The study was able to demonstrate that this novel imaging technique may
be valuable in the planning of these vascular-based cardiac
interventions. Dr. White describes that in bypass or angioplasty
procedures, surgeons have to decide whether or not to open up blocked
blood vessels, but if they can see there is scar in that region, no
benefit will be expected.
Similarly, CRT pacemaker leads delivered to regions of scarred heart
muscle may prevent any benefit from this therapy.
This research was funded by the Heart and Stroke Foundation of Ontario
and the Canadian Foundation for Innovation.
Dr. White is a Cardiologist and a scientist with Robarts and the
Biomedical Imaging Research Centre (BIRC) at Western and Lawson Health
Research Institute. He is an assistant professor in the Department of
Medicine at the Schulich School of Medicine & Dentistry and practices
within the Division of Cardiology at the London Health Sciences Centre.
Posted September 23, 2010