Department of Medicine
Cardiovascular Imaging comprises three integrated components focusing on Computer Assisted Tomography (CT) applied to coronary angiography, Nuclear Cardiology including Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), and Echocardiography. These faculty have expertise in multiple imaging modalities. They work closely with clinical and basic scientists in the elucidation of pathophysiology of cardiovascular disease, improved diagnosis, and delineation of determinants of prognosis and responses to therapy.
Digital cardiac imaging technology combines with recent advances in computer capacity and speed in research involving a broad spectrum of activities utilizing all four imaging modalities. We work closely with the Department of Radiology in many of the activities in progress.
Our initial work with Computed Tomography employed a 40-slice CT scanner. Subsequently, we have been utilizing a 64-slice CT scanner in a program under the combined leadership of Drs. Matt Watkins and Curtis Green, both of whom have extensive experience in the field of computed CT and conventional angiography. Activities entail use of three state-of the-art SPECT cameras in inpatient and outpatient facilities and a PET scanner for assessment of myocardial viability and Rubidium myocardial perfusion studies. Work in this area focuses on assessment of prognosis and cardiovascular disease associated with diabetes mellitus.
Our Cardiac Magnetic Resonance Imaging activities are led by Dr. Tim Christian, who has extensive experience in studies in patients and experimental animals addressing myocardial perfusion and physiology.
Our Echocardiographic Laboratory is directed by Dr. Marc Tischler. Its focus is on valvular heart disease and restorative forces in congestive heart failure. Dr. Tischler interdigitates the echocardiographic laboratory research with investigations in magnetic resonance imaging. He has extensive experience with both modalities.
Research in the Echocardiography Laboratory and Cardiac Magnetic Resonance (CMR) Suite has focused on the natural history and pathophysiology of mitral regurgitation and the differential effects of mitral valve repair and replacement surgeries. We have also elucidated effects of alteration in ventricular geometry on exercise performance and ventricular filling in patients with congestive heart failure, and have been quantifying the extent of myocardial infarction, determinants of favorable responses to resynchronization therapy, and regional myocardial viability.
Echocardiography is a powerful, non-invasive diagnostic tool that can be applied at the bedside. Its effectiveness requires a thorough understanding of both the technology that enables image acquisition and the clinical implications of the images. Images are acquired by highly skilled sonographers and interpreted by cardiologists with specific subspecialty training in echocardiography. In addition to conventional 2-D and Doppler techniques, we have recently introduced live-time 3-D imaging to the laboratory including both trasthoraci and transesophageal approaches.
Current research endeavors include comparison of traditional stress echocardiography with newer 3-D acquisition sequences, assessment of atrial appendage morphology and function before and after percutaneous device closure, facilitation of biventricular pacing device implantation using 3-dimensional mapping of the left ventricle, and analysis of diastolic filling parameters in patients with diastolic dysfunction as a means of identifying those at risk for developing clinical diastolic heart failure. In addition, the laboratory has longstanding research collaborations with Dr. Philip Ades to characterize the effects of resistance training in elderly patients with coronary disease and with Dr. Martin LeWinter in elucidation of mechanisms of left ventricular restoring forces.
The cardiac MRI laboratory provides a strong research commitment to advancing the field of cardiac imaging. Cardiac imaging is performed with a Philips Integra 3 Tesla system and a GE 1.5 Tesla magnet. A 3 Tesla magnet and a 4.7 Tesla small bore facility dedicated to research enables us to improve our care of patients through investigation. The laboratory is situated on the campus of the University of Vermont and clinically operated through the Fletcher Allen Health Care system. All forms of cardiac imaging are performed including ventricular function analysis, myocardial viability determinations, myocardial perfusion imaging during vasodilator stress, structural and congenital heart disease, myocardial strain analysis, MR coronary angiography and diagnosis of infiltrative cardiomyopathies.
Cardiac MRI research has focused on technical protocol enhancements and validation of cardiac imaging at high field strength (3.0 Tesla). In particular, research efforts have focused on improving image quality, particularly through the use of multi-transit radiofrequency shimming (parallel transmission), to enable full spectrum cardiac imaging at 3.0 Tesla, including producing functional imaging better than or equal to 1.5 Tesla imaging. Research efforts have also focused on validation of clinical flow measurements with two dimensional velocity encoded sequences at high field strength.
Additionally, the research use of cardiac MRI assessment of myocardial viability and perfusion has been used as the gold standard for animal studies that require accurate assessment of these endpoints. Lastly, we have been participating in a multicenter trial examining the characterization of myocardium before and after stem cell infusion following myocardial infarction.
Last modified February 08 2012 03:44 PM