An Increasing Obstacle to Medical Diagnosis

Not everyone fits into the
hole in the doughnut; © NCI

In an effort to quantify how obesity affects diagnostic imaging quality, ," said Raul N. Uppot, M.D., lead author and staff radiologist at Massachusetts General Hospital (MGH). and colleagues analysed radiology records from a 15-year span at MGH. They searched for incomplete exams that carried the label "limited by body habitus," meaning limited 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 Uppot. "Americans need to know that obesity can hinder their medical care when they enter a hospital."

By 2003, the modality that yielded the most difficulties in rendering a diagnosis 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).

CT and MRI can be problematic because of weight limitations of the imaging table and the size of the opening on the imager (patients are inserted through a small "hole in the doughnut"). 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.

For exams that require radiation exposure, such as x-rays and CT, the power can be increased on standard machines in an attempt to acquire a higher-quality image. However, this leads to an undesirable increase in radiation dose. Incomplete examinations related to obesity can lead to serious consequences for the patient, as in the case of misdiagnosis or failure to be able to assign a diagnosis at all.; Source: Radiological Society of North America