Trial launched to assess 320-slice CT ability to detect CAD

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An international study on CT perfusion imaging at 15 medical centers in eight countries, led by researchers at Johns Hopkins University in Baltimore, have enrolled the first dozen patients to figure out how well various imaging tests can measure the degree of blockage or narrowing in any particular artery and their use in predicting patients who need catheterization or angioplasty, or bypass surgery.

In addition to having a standard SPECT imaging test, all study participants (400 men and women with high risk of coronary artery disease, or CAD) will undergo a CT angiogram (CTA), plus a CT perfusion (CTP) imaging test to gauge any changes in the volume of blood flow, said senior study investigator Joao A. Lima, MD, a professor of medicine and cardiologist at Johns Hopkins.

A 320-slice CT scanner will be used to perform both CTA and CTP which can produce 3D images of minute blockages forming in blood vessels (1.5 mm). Results from both 320-slice CT tests will be compared to those from SPECT and what is found by cardiac catheterization, according to Lima.

"Perfusion imaging is a simple and easy test for patients to undergo," said Lima, who adds that the whole procedure usually takes less than 20 minutes to set up and perform. Cardiac catheterization, which also checks for heart vessel blockages, takes longer, between 30 minutes and 45 minutes to perform, and requires several hours for recovery.

Lead study investigator Richard T. George, MD, a cardiologist and assistant professor of medicine at Johns Hopkins, said that the 320 CT is fast and exposes patients to far less radiation. “CTP involves an average radiation exposure of about 8 mSv--a SPECT test averages between 10 mSv and 26 mSv and cardiac catheterization ranges between 2 mSv and 10 mSv,” he said.

George cautioned that CT scans are not a substitute for catheterization, but are "an alternative diagnostic tool" physicians can use to "get a real picture" of the extent of coronary blockages and their effects on blood flow, especially when physicians need both sets of information to make treatment decisions.

The CT device being used in the study is an Aquilion One, 320-detector row CT scanner manufactured by Toshiba America Medical Systems which also provided funding support for the study.