A weighty issue for medical imaging

As the prevalence of obesity in developed countries increases, radiologists are faced with the reality of imaging large patients. The most sophisticated equipment will do no good if patients cannot fit in the scanner or if they weigh so much that they break the imaging table. Body fat also can prevent imaging systems from providing a view of internal anatomy, and extra weight can make it difficult to wheel patients to the radiology department. Dr. Raul N. Uppot and others from Massachusetts General Hospital and Harvard Medical School in Boston have reviewed the impact of obesity on radiological procedures.

They note several ways to accommodate obese patients, suggesting that hospitals keep larger wheelchairs and stretchers available. They also say that the aperture size and weight limits of each imaging machine should be made readily available to health care professionals.

The reviewers list problems that body fat can present for several imaging modalities. In general, it limits the penetration of imaging techniques, and it scatters photons, resulting in noisy images. CT and MRI scanners may provide a limited field of view because patients with a large girth may occupy a larger field of view than the scanners allow. Open-bore MRI can accommodate extremely heavy patients (more than 500 pounds), but it produces images with a lower resolution than closed-bore MRI.

The reviewers suggest numerous solutions for these problems and conclude that radiologists and technologists must know the limitations of imaging equipment and must make procedural adjustments accordingly. They also state that imaging equipment manufacturers now are making larger machines to accommodate obese patients.