Overweight and Out of Luck

It has long been known that overweight and obese people are at an increased risk of developing heart disease, diabetes, hypertension, and other ailments. Now, a team of radiologists from Massachusetts General Hospital in Boston has identified another weight-related peril: America’s ever-expanding waistline is making it harder for doctors to diagnose medical problems.

There are physical limitations to using crucial diagnostic tools like x-ray, ultrasound, computed tomography, or magnetic resonance on overweight patients. CT and MR scanners are basically large tubes that patients are slid into so detailed images of their inner bodies can be taken. Some severely overweight Americans are too large to fit into these modern imaging machines and some are even too heavy to be supported by exam tables. In extreme cases, overweight patients have had to endure the humiliation of being examined and imaged using veterinary equipment.

But, even when equipment can accommodate bulkier bodies, the resulting images are often rendered hazy by layers of fat. These low-quality images were the focus of the Boston radiologists’ study. They found that the incidence of unsatisfactory imaging had nearly doubled at their hospital over a period of 15 years. “Physicians and radiologists have had a suspicion that obesity was causing problems,” said the study’s lead author, radiologist Raul Uppot. “Our study is the first objective proof that obesity is causing a problem.”

The problem is that fat scatters x-rays, ultrasound waves, and magnetic waves on their way to target organs or tissues. This reduces the likelihood of detecting abnormalities, like tumors, blood clots, or inflammatory problems such as appendicitis, said Uppot.

Uppot and his colleagues combed a hospital database containing more than 5 million radiology reports from 1989 to 2003, and found that cases in which image quality was compromised by the size of the patient rose steadily during that time. According to Uppot, there were only about 300 cases of these poorer-quality images in 1989, but nearly 1,000 by 2003.

This rise closely parallels the increase in the prevalence of obesity in Massachusetts from 1991 to 2001, when the number of obese people increased from about nine percent to 16 percent of the state’s population. About 65 percent of adult Americans are overweight and about 31 percent are obese, according to the National Institutes of Health.

Abdominal ultrasound scans were the procedures most frequently affected by the body mass of the patient, said the study, which appears in the August edition of the journal Radiology. This is because fat disperses sound waves more than x-rays or magnetic pulses, Uppot said.

Uppot’s study quantifies what many doctors have already recognized as a growing problem. “There isn’t a radiologist who hasn’t had trouble imaging obese patients,” said Laurence Needleman, an associate professor of radiology at the Jefferson Medical College at Thomas Jefferson University in Philadelphia.

The solution to this problem, according to Uppot, is two-pronged. He said that the long-term resolution is to decrease the prevalence of obesity in America, but added that the makers of imaging equipment can help in the short-term.

While the medical community urges Americans to battle the bulge, some manufacturers have responded to the challenges of imaging overweight patients by designing more powerful scanning equipment that can also accommodate larger people. Leading manufacturers of MR and CT machines, like Philips, GM, and Siemens, have introduced equipment that can handle bigger patients.

For example, Siemens began selling the Magnetom Espree, an MR scanner that has a table weight limit of 550 pounds and has an opening that is more than 27 inches. These specifications offer increased access to overweight patients who may not have been able to fit into older scanners. “It opens up the sort of exams you can perform on obese patients,” said Anne Sheehan, marketing manager of the Magnetom Espree for Siemens Medical Solutions. “I call it scan equity.”

But upgrading to newer machines like the Magnetom Espree comes at a cost. Sheehan said that one of the machines costs about $200,000 more than its predecessor.

The cost of upgrading equipment, though, is dwarfed by the expense incurred when obese patients cannot be adequately imaged by existing equipment, Uppot said. “It is an increased cost of health care, but it is less expensive than the alternatives,” which include extra imaging, extended hospital stays, and even exploratory surgery, he explained.

Uppot said that it is crucial for the medical community to improve its ability to image overweight patients because of the danger to those who cannot be adequately diagnosed using current imaging techniques. “Obesity not only affects their health, but it also affects their ability to get a proper diagnosis,” he said. “Hospitals everywhere should consider upgrading to equipment that allows a larger weight limit.”