Cardiovascular Imaging Research

A large number of BIRC investigators are focusing on various aspects of cardiovascular disease. Some of the goals of our researchers are to:

  1. Achieve earlier detection of the presence of coronary disease through novel perfusion imaging;
  2. Identify high-risk patients through measuring the amount of scar in the heart. Scar is the common end point of many cardiac disease processes, including heart attacks and inflammatory conditions. The presence and extent of scar plays a major role in how effective heart therapies will be, including: coronary artery bypass surgery, implantable defibrillators, and specialized pacemakers.
  3. Develop improved ways to image and track stem cells to improve heart function.
  4. Determine how blood flow to the heart is altered in patients with genetic heart diseases, such as Hypertrophic Cardiomyopathy;
  5. Develop preclinical imaging techniques for studying cardiovascular disease in murine models;
  6. Study cerebrovascular disease and the understanding of effects of carotid flow patterns on the likelihood of stroke events  

Preclinical Imaging Developments

Murine (mouse) models are very important in the development of new imaging techniques that can be used to monitor cardiac function in cardiac disease. For these projects, the team works with colleagues in basic biological science to develop imaging methods that will be suitable for investigating disease progression and regression in models of cardiac disease. Currently, histological stains used in conjunction with micro-CT are being explored as a non-destructive, 3-dimensional way of visualizing cardiac tissues and providing histology-like information. Most of this work is performed within the Robarts Pre-clinical Imaging facility using state-of-the-art micro-CT and micro-ultrasound scanners.

A micro-CT image of a mouse heart with volume-rendered coronary arteries visualized in colour. The staining and imaging protocol that produced this image was developed in Dr. Maria Drangova’s lab.

Additional information related to the guidance of cardiovascular therapy is provided in the Image-guided Intra-Cardiac Surgery section under Image-Guided Surgery and Therapy, Page 53.

Early Detection of Cardiovascular Disease

The linings of blood vessels and heart valves are vulnerable to the deposition of fat and cholesterol. In the arteries this deposition leads to a reduction in caliber and eventual blockage, while in the valves it leads to stiffening and stenosis. The cardiovascular team within BIRC is evaluating the role of high-resolution MRI to detect disease at an early stage when cholesterol reducing drugs may be able to halt or even reverse this process. They are also investigating the role of stress perfusion MRI and CT for the early detection of disease in patients with coronary artery disease.

BIRC imaging scientists are also using MRI methods to image myocardial injury related to coronary artery disease and assess methods to track stem cell delivery to these areas.  They have found a way to introduce a gene into stem cells that will augment the cells’ ability to take in surrounding iron. This will allow tracking of the location and functional activity of transplanted stem cells indefinitely using MRI.  The team has also developed a method to radioactively label stem cells to allow their tracking following injection using nuclear imaging techniques.

The BIRC imaging team was the first in the world to demonstrate the ability of MRI to highlight regions of muscle injury following myocardial infarction, and recently was the first to demonstrate the ability to perform this imaging in 3D with simultaneous visualization of the coronary arteries.

Identification of High Risk Patients 

Patients who have suffered heart attacks or who have genetic or inflammatory heart disease frequently have scarred heart muscle. This scarring is a barrier to improvement by medical therapy and promotes sudden cardiac death (SCD) due to arrhythmia. Scar imaging may allow for more optimal delivery of specialized pacemaker leads that are designed to both improve heart function and shock the heart out of life threatening heart rhythms. BIRC investigators are studying MRI scar imaging to identify patients likely to suffer SCD, using Gd-DTPA as a contrast agent to precisely delineate the anatomic extent and characteristics of this scar. This is applicable to a variety of cardiac diseases including myocardial infarction and a number of inflammatory conditions. This may play a major role in guiding clinicians to make management decisions to improve patient outcomes.

The Effect of Coronary Disease on Blood Flow to the Heart 

BIRC scientists have pioneered CT methods to measure blood flow to the heart muscle. This technique allows the concurrent evaluation of the coronary artery anatomy to determine if an obstruction is present, and simultaneously assess the effect of that obstruction on blood flow to the heart.

Industrial Partners: Dr. Ting-Yim Lee continues to work with GE Healthcare to develop methods for the accurate measurement of myocardial blood flow using contrast enhanced CT.

Clinical Trials:

1) IMAGE-HF is a CIHR-funded study to determine the impact of advanced cardiac imaging procedures on outcomes in patients with poor heart function,

2) Rb-ARMI: given the current shortage of radioactive Tc, this CIHR-funded work will determine if Rubidium PET imaging can be used as an alternative agent to monitor myocardial blood flow.

Energy-Subtraction Angiography

The vast majority of all patients in Canada diagnosed with vascular disease undergo x-ray angiography to determine the extent of the disease. The method of digital subtraction angiography (DSA) is widely used to suppress background anatomic structures (including ribs and lung fields) and provides clear high-quality images of the arteries. However, due to the combination of respiratory and cardiac motions and the need to acquire mask and iodinated images separated by many seconds, DSA fails when applied to cardiac imaging. Dr. Cunningham’s lab is developing a method of "energy-subtraction angiography" that uses images acquired at different x-ray energies, all within a small fraction of a second, to suppress background clutter and produce clear, unobstructed images of arteries in the beating heart.

Technologies for Radiofrequency Ablation

Radiofrequency ablation is an image-guided intervention for the treatment of atrial fibrillation, a dangerous condition that can lead to strokes. This procedure involves the insertion of catheters into the heart, via the patient's vasculature, and the application of radiofrequency energy directly to the heart wall. The use of image-guidance for the navigation of the catheter to therapy targets has been widely adopted, but there is no imaging support for the delivery of the radiofrequency dose. BIRC researchers are investigating the use of MRI-compatible robotics and advanced pre-operative and intra-operative imaging to give interventional cardiologists a more complete view of the ablation procedure and deliver patient-specific therapeutic dosing for radiofrequency ablation.

MRI-compatible robotic catheter manipulator developed by BIRC researchers allows radiofrequency ablation to be performed inside the MRI bore.

Investigators
Derek Boughner, MD, Cardiac Valves
Ian Cunningham, PhD, Energy Subtraction Angiography
Maria Drangova, PhD, Cardiac Imaging
Qingping Feng, MD, PhD, Cardiac Physiology
Donna Goldhawk, PhD, Molecular Imaging
Gerard Guiraudon, MD, Cardiac Surgery
Lorne Gula, MD, Cardiology
Rob Hegele, MD, Genetics of Cardiovascular Disease
Doug Jones, PhD, Cardiovascular Physiology
James Lacefield, PhD, High-frequency Ultrasound
Ting-Yim Lee, PhD, PET/CT Imaging
Terry Peters, PhD, Image-guided interventions
Geoff Pickering, MD, PhD, Cardiology
Tamie Poepping, Ph.D., Medical Physics
Frank Prato, PhD, Cardiac Imaging
Kem Rogers, PhD, Atherosclerosis
Allan Skanes, MD, Cardiology
Robert Stodilka, PhD, SPECT/CT Imaging
Terry Thompson, PhD, MR Spectroscopy
James A. White, MD, Cardiac MRI / Cardiology
Gerald Wisenberg, MD, Cardiac Imaging
Raymond Yee, MD, Cardiology