Doctors debate soaring emergency CT utilization

News that CT use in the emergency room is soaring gets cheers in some corners and jeers in others. Radiologists heard from both sides of the appropriateness debate at a Monday morning session at the RSNA meeting.

"CT has become the most important diagnostic imaging modality in the emergency department. Although it has great diagnostic utility, it also represents a lot of radiation exposure to patients and significant healthcare costs," said Dr. Joshua Broder, an assistant professor of emergency medicine at the University of North Carolina at Chapel Hill.

Researchers at Broder's institution examining CT utilization in the ER from 2000 to 2005 found dramatic growth for studies of a range of organs. Cervical spine CT use shot up more than 460%, albeit from a relatively low baseline. During the study period, the number of admissions rose by only 13%, and the severity of injury and illness changed little.

"Utilization outpaced growth in volume. There has been a rise in use of CT as well as increased availability of the study and desire for diagnostic certainty. It remains to be seen if outcomes improve," Broder said.

Data on the increased use of CT in the emergency department are available for the Medicare population and for some particular indications. But the exact extent of use has not been fully investigated by study type and patient age, he said.

In the North Carolina study, a total of about 200,000 patients were admitted in a five-year period. Over 46,000 CT studies were performed on 27,000 of these patients. Researchers divided studies into five categories and found the following dramatic increases:

• head CT, up by 51%

• cervical spine CT, 463%

• abdominal CT, 72%

• chest CT, 226%

• miscellaneous (e.g., extremities and face), 132%

The cervical spine results were particularly striking, even though the numbers were very small in the first year studied. One major national study indicates a prevalence of 2% for spinal fractures in the ER, and it is doubtful that the large proportional increase was matched by prevalence of injury, Broder said.

"It is fairly unlikely that that 463% increase resulted in finding lots of spinal injuries that would [otherwise] have been missed," he said.

Researchers also see a bundling effect in CT utilization. Doctors who ordered a head CT, for example, were sometimes inclined to order a cervical spine CT as a precautionary measure, even if the second study was not directly indicated.

"Utilization in one segment feeds off the others," Broder said.

Attention has increased to the need for monitoring utilization in pediatrics to minimize risks of radiation exposure, but the same concern for younger adults, who are also at risk, has been lacking. The mean age group for the patients in the North Carolina study ranged from mid-40s to early 50s, and utilization rose greatly regardless of age, he said.

An analysis of repeat scans of the same body part showed that 2% of those who had a chest CT underwent repeated chest CT scans on three or more subsequent visits. Of about 10,000 who had abdominal CT, 4% had repeat abdominal CT scans on three or more subsequent occasions.

One drawback of the study was the lack of analysis of effects on patient management and outcomes. Audience members at the RSNA session pointed out that negative CT scans can save unnecessary hospital stays and that underutilization of CT can be dangerous and counterproductive.

Another study in the ER session urged greater use of whole-body CT, based on improved outcomes. Guidelines indicate that use of whole-body CT is appropriate as a secondary tool after trauma resuscitation, but it has been suggested that it also has value as the first study. Researchers at University Hospital of Munich found that whole-body MSCT should be used as the first screening study in major trauma cases, including unstable patients.

Dr. Markus Koerner, a resident in clinical radiology at Munich University Hospital, presented results of a study of almost 5000 major trauma patients seen between 2002 and 2004. Researchers looked at injury severity and survival rates for patients who received single-organ versus whole-body CT.

Depending on the analysis model used, the whole-body CT helped reduce mortality rates 13% to 26%. Liberal use of whole-body CT as a primary screening study does increase the rate of false negatives, but the benefits of a significant reduction in mortality more than make up for this disadvantage, according to Koerner.