Obesity research widens dialogue

February 10, 2006

Last year, an obese women in New York City claimed that her doctor suggested she go to the Bronx Zoo for an MRI because of her girth. Zoo officials, according to the New York Post, later said they had no elephant-sized MR machines onsite.

Last year, an obese woman in New York City claimed that her doctor suggested she go to the Bronx Zoo for an MRI because of her girth. Zoo officials, according to the New York Post, later said they had no elephant-sized MR machines onsite.

Dr. Raul N. Uppot quantified the impact obesity has on diagnostic imaging.

The story highlights a convergence of three trends happening in the U.S.: an increasing number of obese patients, a rising number of diagnostic imaging services being performed, and the inability of conventional imaging equipment to handle morbidly obese subjects.

Anecdotal evidence might abound about obesity's impact on imaging, but concrete data are hard to come by. They were, that is, until an enterprising young fellow from Harvard University decided to gather them.

Dr. Raul N. Uppot and colleagues at Massachusetts General Hospital put together the first study to objectively define and quantify the problem of imaging obese subjects. The RSNA took notice of Uppot's work and awarded him the 2004 Research Fellow Trainee Prize.

Uppot's research led to a plenary session at the 2005 RSNA meeting dedicated to obesity's impact on radiology.

"In recent years, the incidence of obesity has increased, and so has the influx of obese people into radiology departments," said Uppot, an instructor of radiology at Harvard Medical School. "Gastric bypass has become a very popular surgery, and people who didn't have to come to the hospital unless they were ill are now coming to get the surgery done."

Researchers retrospectively reviewed MGH's radiology reports from 1989 to 2003 that included the key words "limited due to body habitus." The investigators classified results by modality, calculated and compared annual percentages between modalities, and gauged percentage fluctuations per individual modality across a five-year period. They also looked at technical and physiological factors that lessened an imaging modality's effectiveness.

The team found that obesity disrupted 0.15% of all studies, with a statistically significant increase rate of 0.01% per year in the number of studies affected by body habitus since 1989. Ultrasound came up as the imaging modality most affected by obesity, followed by chest x-ray.

Uppot found that the direct economic impact of each study limited by body fat could be small, but the cumulative impact was much larger due to the steady rise in the prevalence of obesity and the additional diagnostic tests and increased hospital stay required to make up for a limited study.

Fallout from Uppot's study has been nonstop. The government of Virginia requested his testimony as an expert witness before it approved the installation of an MR scanner especially designed to fit larger patients. Several hospitals have approached him for talks on obesity and its impact on radiology. He has consulted for Siemens Medical Solutions, which unveiled its Definition CT scanner for obese patients at the 2005 RSNA meeting. (Similarly, Toshiba unveiled its "obese" scanner, the Aquilion LB, in 2005.)

"We've essentially sparked a dialogue inside radiology departments and among the manufacturers to address the problem of obesity," Uppot said.

Uppot's own inner dialogue regarding obese patients has been shaped by witnessing the rage, embarrassment, and humiliation they undergo in the radiology suite.

"There have been several occasions when I had to turn patients down because they exceeded the weight limits for our CT tables. These are already emotionally compromised patients, so it is a devastating psychological blow to them," he said.

Although the $1000 prize money won't be enough to fund future research projects, it helped pay for study materials such as books and computer software. The research experience has helped in other ways, however. Uppot has since become part of MGH's permanent staff as an assistant radiologist in the division of abdominal imaging and intervention.

"The award gave legitimacy to the study. To me, it meant the RSNA recognized this as an important issue and not just within the confines of our hospital," he said.

Because of this work, the 34-year-old Uppot has become a myth-buster as well.

"I've called every zoo in the Boston area," he said. "All of them have the exact same size machines we do."

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