In my hospital, I would estimate 10 to 15 percent of all images of obese patients are limited by body habitus.

— Walter Pories, M.D.

More than a year after Raul Uppot, M.D., presented a study at RSNA 2004 on how obesity affects the quality of medical imaging, the issue is still a hot topic.

“This is not only a clinical issue for radiologists, it is also a psychological issue for obese patients,” said Dr. Uppot, who is an assistant radiologist at Massachusetts General Hospital (MGH) and a radiology instructor at Harvard University Medical School. “On a greater scale, obesity is a growing public health and economic issue.”

He has received a lot of telephone calls in the past year regarding the issues associated with imaging obese patients. He has talked with frustrated obese patients and their families about difficulties in managing their medical problems. He has talked with weary technologists who have to deal with these issues on a daily basis and want solutions. He has talked with the manufacturers of MR, CT and ultrasound equipment who are developing technological and design changes. He has even talked with the media about obesity as a public health issue in medical imaging and with venture capitalists who see a growing market that is underserved.

Special Focus Session at RSNA 2005

During a special focus session at RSNA 2005, “Obesity: The Impact On Radiology,” experts in abdominal imaging and bariatric surgery discussed the impact of obesity on general radiologic imaging, the surgical options for obese patients, the anatomy and imaging of gastric bypass surgery, and how to recognize and treat surgical complications of bariatric surgery.

Peter Mueller, M.D., division head of abdominal imaging and interventional radiology at MGH and a professor of Radiology at Harvard Medical School, was the moderator of the session.

Participants included Dr. Uppot; Walter Pories, M.D., chief of the Metabolic Institute and professor of surgery, biochemistry and exercise and sport science at the Brody School of Medicine at East Carolina University; and Mary Turner, M.D., a diagnostic radiologist at the Medical College of Virginia.

Dr. Uppot said research from MGH supports the claims of radiologists and technicians about the problems they have imaging obese patients. Researchers conducted a 15-year retrospective study of radiologic exams at MGH. They found 0.15 percent of the five million radiology studies at MGH included the disclaimer, “limited by body habitus.” The results do not include patients whose exams were cancelled because they could not fit on the table.

“Our study shows objectively that radiologists are having difficulty imaging obese patients and reading those images. Clearly, this is not a problem just at our hospital,” Dr. Uppot said.

Dr. Pories agreed. He even went so far as to say he thinks the percentages at MGH may be too low.

“In my hospital, I would estimate 10 to 15 percent of all images of obese patients are limited by body habitus,” Dr. Pories said. “If I have a patient who weighs more than 500 pounds, I’m not going to bother to give him a CT scan. The equipment wouldn’t be able to safely hold his weight.”

That decision-making process means the patient is never even counted among patients trying to get an imaging study.

During the focus session, Dr. Pories provided an overview on obesity surgery and explained how doctors use radiologic images to find post-surgical complications, such as leaks.

Impact of Obesity on General Radiologic Imaging

The 15 years of data from MGH showed an increasing number of radiographic studies limited because of patient weight.

During the focus session, Dr. Uppot discussed how each modality (plain radiographs, ultrasound, CT, MR imaging, nuclear medicine and interventional radiology) is affected by obesity. “Each modality has its own difficulties with obesity and therefore possible solutions are unique for each modality, ” he said.

Obesity is also affecting areas outside of imaging. Dr. Uppot pointed to the need for the hospital to purchase larger wheelchairs, larger beds and even larger diagnostic imaging machines.

Safety has become an issue. “There are limits to the amount of weight a CT or MR unit can hold,” he explained. “At our hospital, a patient cannot weigh more than 425 pounds on a CT table or more than 325 pounds for the MR unit.”

Dr. Uppot said manufacturers are developing new equipment to accommodate the overweight population. For example, a new MR unit is being released with a larger body girth and the ability to hold a patient weighing up to 550 pounds, and new CT techniques are being developed to do a better job of imaging obese people while limiting the need for increasing the radiation dose.

Understanding the Surgical Options for Obese Patients

Increasingly, hospitals are seeing more obese patients because of the popularity of gastric bypass surgery. In the past, obese patients went to the hospital only when they were sick.

Today, “healthy” obese patients go to the hospital for gastric bypass surgery and physicians are seeing obese patients pre-operatively, post-operatively and when they suffer complications from bariatric procedures.

A series of reports in the October 19 issue of the Journal of the

One article, on the trends in bariatric surgical procedures, found a rising number of procedures performed each year. In 1998, the estimated number of bariatric surgical procedures was 13,365. In 2003, the totalwas 102,794 with gastric bypass procedures making up 80 percent of all the bariatric surgeries. The numbers also showed a rising trend among women ( 81 percent to 84 percent), privately insured patients (75 percent to 83 percent), patients from ZIP code areas with highest annual household income (32 percent to 60 percent) and patients aged 50 to 64 years (15 percent to 24 percent).

Another article revealed that the risk of early death from bariatric surgery is substantially higher than previously suggested. That risk increased for older patients and male patients and for those who have the surgery at centers doing fewer cases. The outcomes, however, were significantly better when patients are cared for in ASBS Centers of Excellence, designated by the American Society of Bariatric Surgery. In a survey of 106 such centers, the 90-day operative mortality for a series of 33.117 centers was only 0.3 percent or three per thousand.

What Radiologists Can Do

With no end in sight to the increasing rate of obesity in the United States, the focus session participants urged their healthcare colleagues to become more aware of the situation and factor in a person’s weight when making decisions.

They also made the audience more aware of various aspects of bariatric surgery, such as how it is performed, how a person loses weight after the surgery, expected metabolic changes and post-surgical changes in anatomy as seen on an upper GI study.

Drs. Pories and Mueller also discussed how to manage surgical complications with surgical and minimally invasive interventional techniques.

To view the abstract from the Special Focus Session at RSNA 2005, go to rsna2005.rsna.org/rsna2005/V2005/conference/event_display.cfm?id=66601&p_navID=272&em_id=4404459.

To view the abstracts from the October 19 issue of JAMA, go to jama.ama-assn.org/content/vol294/issue15/index.dtl.

Images using the new MAGNETOM Espree from Siemens, the first 1.5 Tesla MR imaging unit offering “scan equity” for obese patients. It is the first 70 cm bore in MR and has a 550-pound weight limit. Espree offers at least 10 cm more vertical space than low-field, vertical-field open MR systems.

Image of joint stress in a 320-pound patient.

Courtesy Turville Bay MRI and Radiation Oncology


Image of a 5'4" 450-pound patient with a lower back pain.
Courtesy United Medical Park / Allen Memorial Hospitals and Siemens.

Image of a 560-pound patient with acute paniculitis.

Courtesy Laurel Highlands Advanced Imaging