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Too Obese for X-Rays?

The health risks that go along with obesity are well-known and documented; being overweight or obese raises your risk of diabetes, stroke, heart disease, joint pain among many other diseases. But as more and more people are becoming obese regardless of these warnings, doctors are slowly beginning to notice some other, less predictable problems that the extra pounds can bring.

Researchers from Massachusetts General Hospital have recently reviewed 15 years of medical records to discover that obesity is getting in the way of accurate X-rays, CT scans, MRI and ultrasounds.

“Obesity has a growing effect on image quality,” Dr. Raul Uppot and colleagues wrote in Radiology.

Radiologists use the term “habitus limited” to describe the situation when a patient’s screenings do not come out clear enough to effectively diagnose a disease.

Uppot and colleagues reviewed 15 years of radiology reports encompassing well over 5 million MRI, CT scans, ultrasounds, PET scans and standard X-rays. Overall, 7,778 of these records were habitus limited, but the amount of problematic images seemed to increase slightly over the years. As a comparison, the average weight of a patient with an unclear image was 292 pounds, while that of patients with a clear image was 162 pounds.

Abdominal ultrasounds were most likely to be habitus limited. This is because, in an obese person, fat around the stomach region can block the ultrasound from hitting the organs, blurring the image. Also likely to be affected are chest radiography, abdominal radiography, abdominal CT, chest CT and MRI.

“This can prevent an accurate diagnosis of lung tumors, abdominal tumors, appendicitis, diverticulitis, trauma—almost anything,” said Uppot.

One of the major benefits of imaging tools is their ability to help a doctor quickly and painlessly diagnose a patient with a potentially serious disease or disorder. In the past, when one type of imaging didn’t work for a particular patient, a radiologist would typically try another tool, but these aren’t always options. Uppot gave the example of an obese patient who could not get a clear X-ray. “A radiologist may then try an MRI, but if the patient weighs 500 pounds or more, the MRI table cannot support him.”

So, when patients cannot get a good image of the body, doctors have to turn to other ways of determining what is wrong inside a patient’s body, including invasive surgery. “[It] can lead to further tests and increased hospitalization,” writes Uppot, who added that this places an additional economic and social burden on obese patients, not to mention complications resulting from a delay in diagnosis.

“The public should know that obesity not only affects health, but their doctor’s ability to make a diagnosis,” Uppot added.