Faster, safer scans just as accurate

JOHNS HOPKINS (US) — A new combination of CT scans is just as good at detecting and measuring the progress of coronary artery disease as older tests that are less safe, more complex, and more time-consuming.

“Our findings should reassure cardiologists and patients that the newer, state-of-the-art CT scans are just as good as established older technologies in diagnosing the presence and severity of coronary artery disease,” says Richard George, director of the CT Perfusion Laboratory at the Johns Hopkins University School of Medicine.

“In addition, the newer CT scans have the added advantages of being easier on the patient, taking less time to perform, using less radiation, and providing physicians with all the information they need in one test.”

The findings, presented this month at the American Heart Association’s Scientific Sessions in Chicago, came from a direct comparison study in 50 men and women with suspected arterial blockages who underwent the new combination CT scans along with traditional SPECT nuclear imaging tests and other diagnostic procedures.

The combination test consists of a high-tech CT angiogram, or CTA, to map any plaque buildup in the heart’s arteries and a so-called CT perfusion imaging test, or CTP, to gauge any slowdown in arterial blood flow.

Investigators used a 320 CT scanner, which can produce 3-D images of blood vessels no bigger than the average width of a toothpick (1.5 millimeters),

The test completes within a half-hour, giving physicians a clear picture of how much plaque has built up inside any particular small artery and whether such narrowing and subsequent hardening have compromised the heart’s blood supply. SPECT testing requires at least two hours to allow a chemical tracer of blood flow to be absorbed and then imaged.

Each year, nearly 800,000 American men and women with coronary artery disease suffer a heart attack, resulting in more than 150,000 deaths.

“This combo test really simplifies the diagnosis of coronary artery disease, providing the first comprehensive evaluation of atherosclerosis in the blood vessels and whether any such detected disease puts a patient at greater overall risk of heart attack in the near or long term,” says João Lima, professor medicine and radiology and senior study investigator.

“If older people are feeling symptoms of heart disease, but not showing reduced blood flow in the heart, then they and their physicians can breathe a sigh of relief because we know that aggressive or invasive therapies are not required.”

In addition to the CT scans, study participants underwent traditional SPECT testing, long considered the gold standard imaging test for coronary disease.

Nineteen patients with suspected narrowing of their coronary arteries also underwent a direct inspection of the blood vessels with a catheter that injects a contrast dye as seen by X-ray pictures, called an invasive coronary angiogram (ICA).

Lima says that as many as one-fifth of the 1.3 million invasive cardiac catheterizations performed each year nationwide to fix suspected blockages actually show that no such blockage exists, a problem that needs to be solved with better diagnostic tests.

Study funding was provided in part by Toshiba America Medical Systems, the maker of the adenosine used in CT imaging, Astellas Pharma U.S., and Bracco Diagnostics.

The study is being expanded, with a multi-center international trial already under way in hospitals in the United States, Asia, Europe, and South America.

In addition to receiving research funding from Toshiba, Astellas and Bracco, George serves as an unpaid advisor to Astellas, and Lima has served as a consultant to Bracco, the terms of which are being managed by The Johns Hopkins University in accordance with its conflict of interest policies.

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