Obesity has doubled the likelihood of inconclusive imaging

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Over the past 15 years, obesity in the United States has doubled the instances of inconclusive imaging exams, according to a study featured in the August issue of Radiology. Current Department of Health and Human Services estimates indicate that nearly 66 percent of adults in this country are overweight.
The study took place at Massachusetts General Hospital (MGH) between 1989 and 2003 where researchers did assessments of all radiology exams during that period. Specifically, they looked for the "limited by body habitus" on exams which indicated limitations in quality due to patient size.

"While 0.10 percent of inconclusive exams were due to patient size in 1989, by 2003 the number had jumped to 0.19 percent, despite advances in imaging technology," said Raul N. Uppot, MD, lead author and staff radiologist at MGH. "Americans need to know that obesity can hinder their medical care when they enter a hospital."
Overall, the modality impacted the most by patient obesity was abdominal ultrasound (1.90 percent), followed by chest x-rays (0.18 percent), abdominal computed tomography (CT), abdominal x-rays, chest CT and magnetic resonance imaging (MRI) (all anatomic regions included), according to the study.
CT and MRI can be problematic because of weight limitations of the imaging table and the size of the opening on the imager. Standard CT tables can accommodate patients weighing up to 450 pounds, and MRI machines can typically obtain diagnostic-quality images in patients weighing up to 350 pounds.
Certain modalities, like x-rays and CTs, can adjust through power increases to compensate for patient size. This is not ideal because the increase in radiation dose is not desirable.
Other unpleasant consequences of inconclusive exams are misdiagnosis, further costly testing, and more wear on imaging systems, according to the study.