HUP hopes to purchase faster, better heart scan
by Byron Kho
The Summer Pennsylvanian
July 22, 2004
Plans are underway at the Hospital of the University of Pennsylvania to purchase the next generation of multi-slice computerized tomography machines.
Available in fall of this year, the new 64-slice machines -- which will be able to scan internal structures in great detail through a series of midsections or slices -- are expected to make the prognosis of heart disease even faster and easier than it currently is. Today, the hospital utilizes two single-slice and three multi-slice detector machines in the Radiology department and the emergency room -- which features the most advanced 16-slice machine available to date.
The CT procedure involves sliding the body through an X-ray beam, which maps various internal structures through the use of a dye marker, or intravenous contrast. With the faster multi-slice detectors, only the time length of one breath is needed to capture thinner and more accurate "slices" for imaging and analysis.
The resulting three-dimensional images derived from these slices are useful for any number of medical procedures. Most often, they are used for cardiovascular applications, such as mapping the arteries for possible blockages caused by calcium or fatty deposits.
According to Dr. Harold Litt, the chief of cardiovascular imaging in the department of Radiology, "while every department uses the machine -- from oncology patients to brain studies for neurology -- the main advantage is for the heart and cardiovascular systems in general."
Litt cited emergency room statistics showing that only about 15 percent of patients complaining of chest pain actually do have heart attacks.
"The benefit of the multi-slice CT is that it's a fast exam. Two minutes -- that's all we need to show if they have coronary disease, and if we should get them treated immediately or not," he added.
This non-invasive test differs from previously used tests to screen for heart disease, including the often non-conclusive stress test and invasive angiograms. Multi-slice CT scans tend to be much more thorough by their use of 3-D graphics workstations and advanced X-ray tube technology, which is capable of viewing the captured structures at many different angles.
Litt cautions that there are still risks involved in using any CT scan.
"The multi-slice CT scan should not be used for general screening, like many places do. It should only be used for people at risk for heart disease, because it does involve exposure to radiation," he said.
The radiation exposure of the machine is equivalent to the background radiation that any resident of Philadelphia would be exposed to within a two to three year span. Another risk factor besides radiation is allergic reactions to the intravenous contrast, especially in those with kidney disease.
However, the advanced multi-slice CT machines tend to limit risk by lowering exposure to both radiation and intravenous contrast.
Ongoing research within the department seeks to ensure the validity of this testing procedure. One study attempts to assure efficiency: it analyzes CT usage and effectiveness among emergency room visitors complaining of chest pain, save for young people and those already with severe heart disease. Other studies hope to extend the usefulness of the procedure, through assessment of new medication efficacy and comparison models of coronary function in pigs.