A new imaging technique will be available soon for use by cardiologists and surgeons that serves to improve outcomes for patients requiring pacemakers, bypass surgery or angioplasties. The new imaging tool has been developed as the result of the research conducted by Dr. James White and his colleagues at The University of Western Ontario. This technique provides a single, 3D high-resolution image of the heart viewing both its vasculature and the presence of scar tissue within the muscle. This novel imaging was designed 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, such as heart attacks or viral inflammation, usually lead to permanent damage or scarring of the myocardium. Dr. White explained: "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," he continued: "This is the first time we have been able to visualize myocardial scar and the heart's blood vessels at the same time. 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. 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 imaging tool provides 3D model of the heart.
This innovative 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 revealing 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 second image, acquired 20 minutes later, shows the heart's scar, also in 3D. As the two images are taken in a similar way using the exact same MRI pulse sequence, they are already perfectly suited to be fused to one another. The result is a fused, 3D model of the heart that demonstrates both the heart's vessels and scar tissue.
Evaluating heart condition before treatment.
The imaging technique was used 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 showed that this novel imaging technique might be useful for the planning of these vascular-based cardiac interventions. Dr White noted that in bypass or angioplasty procedures surgeons have to determine whether or not to open up blocked blood vessels, but if a scar exists in that region, no benefit will be expected. In addition, CRT pacemaker impulses conducted to scar tissue may eliminate any benefit from this device.