Obesity gets in the way of good images

Dec 1, 2004

CHICAGO - The obesity epidemic that continues to impact the U.S. can be felt in the radiology suite where the number of patients who can't be imaged because they are too large correlates with the overall bulging of Americans.

"Hospital radiology departments are increasingly unable to adequately image and assess obese patients because of the limitations in current radiology equipment," said Dr. Raul Uppot, a fellow in abdominal imaging and interventional radiology at Massachusetts General Hospital in Boston.

Uppot reviewed all radiological reports at MGH between 1989 and 2003, extracting information about patients for whom radiology reports were "limited by body habitus" -- a euphemism for the patients being too big to properly assess. He presented his findings at the RSNA meeting on Wednesday.

Obesity interferes with ultrasound assessment because the transponder signal is weakened and distorted by fat, Uppot said. MRI studies are limited to persons who can fit into the bore of the device, which has a 24-inch diameter, and who weigh less than 350 lb. For CT devices, patients have to fit into a 29-inch bore, and cannot weigh more than 425 lb.

In 1989, Uppot determined that 0.10% of patients at MGH could not be imaged because of obesity. By 2003, that rate had nearly doubled to 0.19%. Remarkably, in 1989 about 9% of the population of Massachusetts was considered obese; in 2003, about 16% fit the obesity definition. The correlation between the two trends was statistically significant, he said.

In a separate study, Uppot tracked 28 patients in the first six months of 2004 who could not be imaged. About one-third of the patients were taken to an open magnetic resonance imaging device. The other either received no further treatment, or even went to surgery without benefit of radiological guidance.

The study results also indicated that ultrasound is most frequently impacted by obesity. Uppot found that 1.5% of patients sent for an ultrasound examination were unable to have a satisfactory study performed because of "body habitus." Similarly, 0.8% of patients sent for chest x-rays were unable to have useful examinations performed.

Uppot said he became interested in how often imaging examinations were less than adequate because MGH has a number of patients who undergo gastric bypass procedures in an attempt to control morbid obesity. When these patients were sent to radiology to see how well the procedure was doing, several were turned away because they were too big. He wondered how often that occurred, and commenced his study, he said.

By Edward Susman
AuntMinnie.com contributing writer
December 2, 2004

Gastric bypass battles bulge, but patients pose imaging challenge, March 27, 2003