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Low Dose CT Benefits Lung Cancer Detection

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The National Cancer Institute (NCI) is today releasing initial results from a large-scale test of screening methods to reduce deaths from lung cancer by detecting cancers at relatively early stages. The report shows twenty percent fewer lung cancer deaths seen among those who were screened with low-dose spiral CT than with chest X-ray.

The National Lung Screening Trial (NLST), a randomized national trial involving more than 53,000 current and former heavy smokers ages 55 to 74, compared the effects of two screening procedures for lung cancer — low-dose helical computed tomography (CT) and standard chest X-ray — on lung cancer mortality and found 20 percent fewer lung cancer deaths among trial participants screened with low-dose helical CT. The NLST was sponsored by NCI, a part of the National Institutes of Health, and conducted by the American College of Radiology Imaging Network (ACRIN) and the Lung Screening Study group. A paper describing the design and protocol of the NLST, “The National Lung Screening Trial. [Read more…]

Researchers Advise Protecting Kidneys Before CT Scans

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Dyes containing iodine used to enhance CT scan quality can seriously harm kidneys; and a new study recommends that patients take an inexpensive pre-scan drug, called N-acetylcysteine which protects kidneys from damage. These ‘dyes’ or contrast agents put many older people and those with diabetes or heart failure at the most risk, and they have the most to gain from taking the drug.

The study is published in the Annals of Internal Medicine by researchers from the University of Michigan Health System, who were led by Aine Kelly, M.D., M.S., an assistant professor in the Department of Radiology at the U-M Medical School. The study is a meta-analysis of data from 41 randomized controlled studies that evaluated various drugs for their ability to protect kidneys: only N-acetylcysteine prevented contrast-induced nephropathy. Theophylline was not as effective, while furosemide actually raised kidney risk.

"Our goal is to improve the safety and quality of these common tests by studying drugs that reduce the risk of kidney failure," says senior author Ruth Carlos, M.D., associate professor of radiology.

Mild to moderate kidney damage occurs in one in four high-risk people who have CT scans, and in as many as one in ten people with normal kidney function. In some cases, it causes acute kidney failure. "Millions of people receive contrast agent each year, including most heart patients who have angioplasties and stents, as well as those having a CT scan. Contrast agent helps physicians see the things we need to see, but it also does pose a hazard to some people," says Kelly. "This drug, which is quick, convenient, inexpensive and widely available, with no major side effects, appears to be the best choice to protect those whose kidneys are most at risk."

In fact, Kelly says, patients who know they have weakened kidneys – also called impaired renal function – should speak up when their doctor orders a CT scan, angiogram or angioplasty, and make sure they get a tablet of N-acetylcysteine beforehand.

Source: Annals of Internal Medicine, 19 February 2008, Volume 148 Issue 4

CT Heart Scan Reliable for Detecting Blocked Arteries

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An international team of cardiac specialists, led by Johns Hopkins researchers, found that sophisticated computed tomography (CT) heart scans are almost as reliable as more invasive procedures.

The 64-slice CT scans, initially tested at Hopkins, will help cardiologists select patients who can avoid more invasive procedures. But the newer scans will not replace the cardiac catheterization, or coronary angiography, although perhaps 25% of the 1.3 million cardiac catheterizations performed annually in the U.S may be unnecessary.

In addition, the latest study showed that early detection with 64-CT would be a good forecaster of patients needing angioplasty or coronary bypass surgery.

Researchers chose 291 men and women over 40 years of age who already planned to have cardiac catheterization to check for blocked arteries. They were then checked to see who developed coronary artery disease, and who required subsequent bypass surgery. On average 91% of patients with blockages were detected by 64-CT scan, which also identified 83% without blockages. This accuracy, said researchers, enabled them to identify patients needing angioplasty or bypass surgery. More than 250,000 Americans undergo coronary bypass surgery annually.

"This study is the first step to realizing the full potential of CT imaging in predicting coronary artery disease, and these scans complement the arsenal of diagnostic tests available to physicians to prevent heart attacks," says cardiologist Julie Miller, M.D., who led the study at Hopkins.

"Use of 64-CT scans will dramatically improve our ability to detect and treat people with suspected coronary disease and chest pain much earlier in their disease," says cardiologist João Lima, M.D., senior investigator to the team whose findings will be presented at the American Heart Association’s (AHA) annual Scientific Sessions in Orlando, Florida. "Cardiac catheterization is still the gold standard for evaluating clogged arteries, but our results show that this test could easily be the best backup or alternative."

Source: Johns Hopkins Medicine

High Res Heart CT Scans Risk for Patients

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With more and more technologies becoming available, doctors are finding that they must increasingly weigh the side effects of testing procedures.

After gaining FDA approval in 2004, CT angiography, a high resolution scan of the heart for blocked arteries, has been much more widely used. However, there is a risk–especially to younger people, as these scans expose patients to 20 times the amount of radiation as a mammogram.

Researchers reported that a CT angiography should be used sparingly, especially on young women, who have a 1-in-143 chance of developing cancer after just one high resolution CT scan.
The study was published in the Journal of the American Medical Association.