CT Scans Safe, Study Said

Computerized tomography imaging using iodine based material may not be harmful to kidneys

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) For decades, the use of iodine-based material to get images from inside the body has been linked to causing kidney damage. New research, however, questions the contrast material’s effect on the body.

Computerized tomography (CT) provides a 3-D view inside the body using multiple X-ray images. These images can help find health problems. They also involve exposing the body to radiation. Some researchers believe the radiation from too many CT scans could lead to cancer.

There are also health concerns about the material injected into patients that allows CT scanners to capture images. A new study has found that this material does not appear to increase the risk of kidney trouble.

"Ask a radiologist about side effects of CT scans."

Robert McDonald, MD, a radiology resident at the Mayo Clinic in Rochester, MN, led the research.

He and his team had noted a lack of evidence supporting claims that contrast-enhanced CT scans led to impaired kidney function. This condition is called contrast-induced nephropathy.

Researchers underscored that some past studies on contrast-induced nephropathy lacked control groups. Controls, in this case, are patients who did not receive contrast material during CT imaging.

From a review of studies that did have controls, scientists found that negative health outcomes related to contrast material were “extremely rare.”

Dr. McDonald and colleagues set out to get more comprehensive data on the subject. They looked at data on 21,346 patients. The patients received abdominal, pelvic and thoracic CT scans at the Mayo Clinic between 2000 and 2010.

About half of these patients had a contrast-enhanced CT exam. The other half received a similar scan without the contrast agent.

The study authors looked for negative health events in the two groups within 30 days of the CT exam.

When it came to acute kidney injury (AKI), there were no significant differences between the two groups. In the contrast group, 4.8 percent had AKI, while 5.1 percent in the non-contrast group did.

The rates of death were almost the same between the two groups. Also, the rates of emergency dialysis (a blood-cleansing procedure used to treat kidney failure) were similar.

Iodine-based contrast material is used in at least half of the 80 million or more CT scans performed each year in the US, Dr. McDonald noted in a press release.

The use of CT scans has steadily grown over the past 30 years. A paper in JAMA reported that CT use among US adults tripled between 1996 and 2010.

"For nearly 60 years, physicians have worried about contrast-induced nephropathy when using iodinated contrast material, particularly for patients with impaired kidney function," Dr. McDonald said. "Emerging evidence now suggests these concerns are likely vastly overestimated."

The study was published online Sept. 9 in the journal Radiology. One author received research grants from GE Healthcare.

Review Date: 
September 9, 2014
Last Updated:
September 9, 2014