Cardiac Imaging: The Big Picture
A PICTURE TAKEN AT THE MEDICAL CENTER'S NUCLEAR CARDIOLOGY lab isn't just worth a thousand words — it could be worth a life.
Medical center researchers have been at the forefront of developing and using cardiac imaging techniques that can give cardiologists a more accurate picture of a patient's condition and improve quality of care.
"Now we can look at the blood flow to the heart, the heart's function and metabolism, the function and pathology of heart valves, and the structural and functional changes in the blood vessel walls," says Lynne Johnson, M.D., professor of medicine and director of the nuclear cardiology laboratory.
"Columbia investigators in the Division of Cardiology have made major contributions in research and development in echocardiography and nuclear imaging."
Columbia has been a leader in cardiac imaging since the 1970s, when cardiologists first began to send patients for nuclear stress perfusion imaging.
This type of imaging — single photon emission computed tomography, or SPECT — helps physicians diagnose coronary atherosclerosis by using low doses of radioactive drugs and gamma cameras to look at blood flow distribution to the heart.
SPECT's effectiveness has been further enhanced at Columbia by a method that involves simultaneously imaging radioactivity emanating from the patient's heart and from another source placed in the chest, which produces an image similar to a low resolution CT scan.
While one camera takes a picture of the radioactivity emanating from the heart — the emission scan — the other camera takes a picture of the radiation emanating through the chest — the transmission scan. Since the emission scan alone can sometimes be clouded by soft tissue, such as breast tissue, the second transmission image "corrects" the emission image for soft tissue artifact.
Dr. Johnson spent years helping to develop this technology.
The medical center also will soon start using a combined SPECT/CT technique, consisting of both a 16-slice CT scanner (a slice is part of an image of an organ that represents one dimension) that uses X-rays and a rotating SPECT camera that records gamma rays.
This new technology permits better attenuation correction because the high resolution CT scan can be used for the transmission map and allows fusion of anatomy (CT) and function of organs or blood vessels derived from the SPECT scans.
Shunichi Homma, M.D., the Margaret Milliken Hatch Professor of Medicine, and echocardiography faculty have been involved in the development of 3-D ultrasound imaging of the heart, which visualizes the cardiac structures in real-time in three dimensions.
This modality has a significant advantage over the currently used two-dimensional imaging which only displays a slice of the heart.
They are working with biomedical engineering faculty to develop algorithms to improve 3-D images.
Dr. Homma and his colleagues have been pioneers in the use of echocardiographic technology to evaluate patients with strokes due to blood clots that break off from either the heart walls or vascular lining and travel to the brain.
Identifying sources for these clots can prevent strokes.
Columbia also has the only PET facility in New York that contains an onsite cyclotron, a machine that produces radiopharmaceuticals, many of which decay very rapidly and must be injected immediately for imaging.
Special PET tracers include radiotracers that determine the heart muscle metabolism. Studies help physicians decide whether to do angioplasty or surgery to restore blood flow to hearts with poor function and coronary artery blockages.
Dr. Johnson and colleagues are interested in extending the application of nuclear medicine to vascular imaging to try to identify patients at risk for heart attack or stroke.
The new technology of SPECT/CT or PET/CT provides pictures of the diseased vessels with overlay of radiotracer uptake that indicates an abnormal process in the blood vessel wall indicative of an active area of atherosclerosis.
Dr. Johnson points to cardiac MRI as among the most promising new cardiac imaging methods being developed.
"It has the potential of doing many of the things that echocardiography and nuclear imaging can do," she says.
An MRI can produce high-resolution images to evaluate heart function, valve function, and blood flow to the heart muscle.
It also can identify heart muscle scarred after a heart attack.
"About 20 minutes after the contrast has passed through the heart, the MRI can reveal the areas of the heart damaged during a heart attack," Dr. Johnson says.
"No other imaging technology has the resolution of the MRI, which shows strong potential for identifying blood flow and localizing heart attacks in a single test."
Cardiac MRI is now available at CUMC under the auspices of Steve Wolf, M.D., a new recruit who will soon join P&S as assistant professor of clinical radiology in medicine.
The nuclear cardiology laboratory, the echocardiography laboratory, and the Center for Interventional Vascular Therapy are working together on projects to further the field of cardiac imaging through clinical correlation of imaging modalities that will enable better diagnosis of disease and treatment planning.
Their collaboration on several research projects also continues to improve the accuracy of testing methods.
CIVT: Adding Value to Columbia's Cardiology Legacy
THE SUCCESS A RENOWNED TEAM OF INTERVENTIONAL cardiologists has experienced since joining Columbia in August 2004 is as much a credit to the reputation of Columbia as it is to the team.
The Center for Interventional Vascular Therapy — CIVT — is recording growing numbers of procedures and patients.
Jeffrey Moses, M.D., professor of clinical medicine and director of the center, treats about 200 patients per month, and the number of patients cared for by other center physicians, including associate director Martin Leon, M.D., is increasing monthly.
"Our diagnostic activity has doubled from this time last year, and our intervention activity has quadrupled.
We're seeing patients at a rate of about 3,000 per year — and that number is rising."
Cardiologists at the center perform about 250 coronary stenting procedures per month.
Columbia's reputation has helped the center grow beyond the New York metropolitan area, says Dr. Moses.
The center has treated patients from other states, such as Florida, and other countries, such as Turkey and Greece.
"We certainly have the broadest array of talent in the region in all phases of heart care," he says.
"And the Columbia reputation magnifies our impact."
That impact has been seen most powerfully in the center's catheterization lab, which Dr. Moses describes as "the busiest lab in the city for coronary angioplasty."
Thanks in part to a doubling in size of the catheterization lab upon the arrival of Dr. Moses' team, CIVT is now at the forefront of developing and using such minimally invasive procedures as angioplasty, atherectomy, stenting, and mitral valvularplasty, a state-of-the-art technique that uses a catheter to open fused heart valves.
While the lab works to perfect these procedures, Dr. Moses also views the center as a pioneer in the use of drug-coated stents and new techniques to open completely blocked arteries.
"CIVT is already on its way to becoming the best and most innovative interventional cardiology group in the country," says Allan Schwartz, M.D., chief of cardiology in the Department of Medicine.
Dr. Schwartz, who was instrumental in bringing Dr. Moses' practice from Lenox Hill Hospital to Columbia, adds, "This particular recruit allowed us to leapfrog into a preeminent position ripe for bench-to-bedside application."
Under the leadership of Gregg Stone, M.D., director of research and education for CIVT, the center also conducts research in many new areas, such as the nonsurgical repair and replacement of valves, angiogenesis, the use of drugs for heart attacks, new ultrasound and imaging techniques, and methods for identifying plaques that cause heart attacks.
According to Dr. Schwartz, CIVT currently conducts more than 25 clinical trials, which he anticipates will grow to about 50 in the next six to 12 months.
Another avenue for cardiovascular research comes via Dr. Leon, associate director of CIVT.
Through Dr. Leon, the center is affiliated with the Cardiovascular Research Foundation, which Dr.
Leon founded in 1990 to conduct cardiovascular clinical trials and sponsor continuing education and training forums.
Affiliations like the one with the CRF and close cooperation with basic science laboratories at Columbia generate the resources to make Columbia's heart program so extensive, says Dr. Schwartz.
"The CIVT group brings tremendous possibilities for synergy with existing basic science labs here," Dr. Schwartz says.
"Basic scientists at other institutions have inquired about wanting to come here because of our opportunities for translational research."
BECAUSE OF THEIR RARITY, MANY PEDIATRIC HEART CONDITIONS can be difficult to study. Even in academic medical centers as large as Columbia's, clinical trials may consist of just a handful of patients, limiting the significance of the study's outcome.
Now the pediatric cardiology division in the Department of Pediatrics is participating in a multicenter program that supports clinical investigations of pediatric cardiological conditions.
"The Pediatric Heart Network is a very innovative program because it represents a new way to carry out evidence-based medicine," says Welton M. Gersony, M.D., the Alexander S. Nadas Professor of Pediatric Cardiology and lead investigator of the program for Columbia.
The Pediatric Heart Network consists of seven major academic medical centers funded by a $23.5 million grant from the National Heart, Lung, and Blood Institute of the NIH.
Lead investigators from each medical center work as a group with an outside chairman to design studies; investigators must agree on everything from study protocols to pharmaceutical interventions and ethical considerations.
At Columbia, four physicians, two nurse coordinators, and one administrative assistant participate in the program.
The other participating medical centers are Boston Children's Hospital, Children's Hospital of Philadelphia, Duke University Medical Center, Medical University of South Carolina Children's Hospital, Primary Children's Hospital of Utah, and the Hospital for Sick Children in Toronto.
Four years into the five-year grant (renewable in 2006), the network has completed its first major study, one that concerned children who had undergone the Fontan procedure, a technique created to treat various forms of "single ventricle," a congenital condition resulting in only one pumping heart chamber.
The operation, devised in 1968 by Dr. Francis Fontan, is designed to direct the blood coming back from the body directly to the lungs, without being pumped to the lungs by the heart.
Investigators evaluated patients' quality of life, echocardiograms, cardiac MRI findings, and exercise performance, which will generate baseline data to design future intervention trials.
Four abstracts were presented at the annual scientific sessions of the American Heart Association last November.
"This study was a classic example of why this research model works," says Daphne Hsu, M.D., professor of clinical pediatrics and associate principal investigator.
"As a consortium, we were able to study more than 500 patients. As a single institution, we would have been limited to 40 or 50."
In addition to the Fontan study, the Pediatric Heart Network is conducting five other trials in the areas of medical therapy for heart failure, surgical intervention for hypoplastic left heart patients, and drug trials to improve heart function in children with complex congenital heart disease.
"This national effort reflects the multidisciplinary and multi-institutional approach that has been the basis for research by the division of pediatric cardiology over the years," says Dr. Gersony.
"Expansion to a nationwide program bodes well for the future of treatments firmly set on evidence-based principles."