Report from ARRS: Cardiac CT images reveal serious problems outside heart

Nearly half of all patients whose hearts are scanned with CT may get a shocking surprise: a diagnosis of a serious problem that has nothing to do with the heart, according to a study presented today at the American Roentgen Ray Society meeting.

Researchers from the University of Michigan found that 43 of 98 patients scanned for clogged arteries also had significant or potentially significant signs of problems with their lungs, blood vessels, or other organs.

These discoveries ranged from possible lung cancer in 16 patients to potentially dangerous blood clots and aneurysms in 10 patients.

Lead author Smita Patel, an assistant professor of radiology at U-M, said the data show just how important it is for trained radiologists to view cardiac CT scans, rather than having the scans read by heart specialists alone.

"Many of these patients are having their scans at cardiology centers that may or may not employ a physician who specializes in radiology and has been trained to spot problems of any kind on medical images," he said. "Our research suggests that may leave potentially serious problems undiagnosed. The trained eyes of radiologists are needed."

Traditionally, these patients would be taken to a cardiac catherization lab for an invasive procedure to diagnose coronary artery disease. If the disease is present, a cardiologist immediately treats the patient with angioplasty or stenting. But up to 50% of these patients will not have coronary disease and, therefore, do not need an invasive angiogram.

Cardiac CT angiography can assess the coronaries noninvasively. When the arteries are normal, the patient often does not need to undergo further cardiac testing.

But the scans also reveal the finest details of structures near the heart - including the lungs, aorta, liver, and pancreas and the structures and spaces that surround them. The level of detail is increasing as CT scanners become more powerful.

The study presented by Patel used 16-slice CT scanners. But the U-M Cardiovascular Center has recently purchased a 64-slice CT scanner, which can image the entire chest in a few seconds.

The simultaneous rapid increases in the precision and utilization of coronary CTA make it important to study the rate at which nonheart problems are found, said coauthor Dr. Ella Kazerooni, a professor of radiology and chief of thoracic radiology at U-M.

Kazerooni noted that a smaller study by Johns Hopkins researchers showed that 16% of 75 chest pain and heart disease patients had major noncardiac findings on their cardiac CTA scans. The U-M results are from a larger group of patients imaged for any reason.

Radiologists have long known that medical images taken for one reason may reveal entirely unrelated problems or suspicious areas. These "incidentalomas" can pose serious questions of whether to perform a biopsy or other tests. The rise in cardiac CTA use by nonradiologists has raised concern that untrained eyes may miss problems outside the heart.

Patel and Dr. Naama Bogot, who read all the scans, found some sort of noncardiac abnormality in 61% of the patients. Many of these were judged insignificant. But in the 43 patients who had significant or potentially significant findings, the range of severity was wide.

In 16 patients, lung nodules larger than 4 mm in diameter showed up - two were later found to be stage I lung cancer. Eleven patients were shown to have a potentially serious lung disease, either emphysema or another condition. Four had fluid buildup in the lungs. Twelve patients had enlarged lymph nodes in the chest, and three had masses in the upper anterior chest.

Twenty patients had fluid in the sac that surrounds the heart, most of them minor but one major. Eight patients had an aneurysm or dissection in the upper part of their aorta, and one patient had blood clots threatening to block arteries in his lungs.

Since the upper part of the abdomen is visible when imaging the lower part of the heart during CT scanning, the researchers were also able to see potential problems there. Seven patients had lesions on their livers and one had a mass in the pancreas.

In all, Patel said, the high rate of noncardiac findings drives home the importance of having a team-based approach to reading cardiac CTA scans. At U-M, cardiologists and thoracic radiologists routinely take this cooperative approach.

The American College of Radiology has just issued a Clinical Statement on Noninvasive Cardiac Imaging online that will be published in the June issue of Radiology. It calls for specialized training, education, and levels of experience for both radiologists who read coronary CTA images and the technologists who conduct the scans.

- Provided by the University of Michigan