RSNA: Got Milk? Get a CT

CHICAGO, Nov. 29 -- Milk does a bowel good -- or at least as good as a pricey commercial contrast agent that produces only marginally better results for abdominal CT scans.

A study comparing the barium-based agent, VoLumen, to whole milk found that VoLumen was slightly better at bowel distention, said Lisa Shah-Patel, M.D., of St. Luke's-Roosevelt Hospital in New York.

But "milk had fewer side-effects, patients were more willing to drink milk, and only cost about .39 versus for VoLumen," Dr. Shah-Patel reported today at the Radiological Society of North America meeting here.

The study recruited 179 patients who were referred for CT with oral and intravenous contrast agents for assessment of abdominal symptoms. Sixty-two patients were assigned to drink VoLumen and 102 were randomized to milk.

The VoLumen group received 1,200 mL of VoLumen, divided into two doses (900 mL 30 minutes before the scan and 300 mL immediately prior to it. The milk group consumed 600 to 1,000 mL of whole (4%) milk, divided into two doses (400 to 600 mL one hour before the scan and 200 to 400 mL 20 minutes prior it).

The scans were read by two radiologists who were blinded to the contrast agents used. There were no significant differences between the two groups "although there was a trend toward better distention with the barium agent," she said.

She said 40% of the patients in the VoLumen said they would have preferred milk, while 85% of the patients on milk said they would select milk again in another study.

She said the study is ongoing and will eventually enroll 130 patients in each arm.

Both VoLumen and milk are negative contrast agents, meaning that the bowels would show up as "gray on the scan, versus the white image produced by positive contrast agents."

Traditionally, radiologists have favored positive to negative contrast agents, but in recent years there has been a shift to negative agents for certain scans, commented Michael Brant-Zawadzki, MD, medical director of radiology at Hoag Memorial Hospital Presbyterian in Newport Beach, Calif.

For example "scans for inflammatory bowel disease and other diseases that involve the intestinal wall would favor negative oral contrast agents and then positive vascular agents so the vasculature can be well differentiated from the bowel wall," he said. Dr. Brant-Zawadzki was not involved in the study, but he moderated an RSNA press conference where the results were reported.

"About 30 million to 40 million CT scans are performed each year and about 30% of them are done for abdominal conditions," he said.

He predicted that substituting milk for VoLumen would be very cost effective and "something I think a lot of radiologists are going to be considering."

Dr. Shah-Patel agreed that patients with inflammatory bowel disease would be good candidates for milk-based CT-scans.

Dr. Shah-Patel said her study excluded patients who reported a history of lactose intolerance. She said it was unclear if soy or rice milk could be substituted for whole milk "because the fat content is likely to be lower in those products." It is the fat content that provides sufficient bowel distension to conduct the scan.

She said one advantage of milk is that many patients refuse to drink the traditional oral contrast agents, a problem that is especially difficult with children.

Dr. Brant-Zawadzki suggested that chocolate milk should be tried in pediatric studies.