Challenges in Imaging Obese Patients
Challenges in Imaging Obese Patients
As obesity rates continue to rise in the United States, radiologists and technologists face challenges imaging larger patients, despite the effort of manufacturers making machines better able to accommodate them. What are these challenges and what is the industry doing to help?
If current trends continue, 44 percent of U.S. adults will be obese within 20 years, with rates exceeding 60 percent in 13 states.
For geographic areas with less of an obesity problem, the solution is usually solved by purchasing machines that can accommodate 450-500 pounds, Raul Uppot, MD, interventional radiologist at Massachusetts General Hospital and assistant professor at Harvard Medical School told Diagnostic Imaging. “But even if you have trouble getting one person on the machine, this is a problem,” he said.
Statistics are one thing, but for radiological technologists like Curtis Carpenter in Vero Beach, Fla., the problem seems to be growing. “It’s a major problem not only for seasoned technologists, but for students coming out of school who don’t know what to do when they have someone who is so large,” he said.
Carpenter’s current employer just purchased a new lithography machine because the previous one wasn’t robust enough. “We kept canceling patients because they exceeded the 300 pound weight limit,” Carpenter said. “We had to make a $650,000 expenditure because of the obesity problem.”
It’s an issue for everyone involved in imaging, said Uppot. As the front-line people moving the patients onto the scanner tables or turning over patients during an ultrasound, technologists have to worry about injury. Newer equipment with pulleys help do this more safely.
MRI scanners tend to have a lower weight limit and smaller gantry, while CT machines are slightly larger. “The most common point at which hospitals get into an issue, is when the patient can’t fit into the CT scanner,” Uppot said. Some outpatient open MRI units can support a slightly larger weight limit. And ultrasounds can be used if the patient isn’t mobile, but due to tissue amount, you can’t always get a good image.
When this happens, you revert to pre-imaging days, relying on a physical and clinical exam, said Uppot, to help determine the diagnosis. “With imaging, we’ve been spoiled. They come in, and we scan them for an answer,” he said. “If imaging equipment isn’t available, you have to revert back to your clinical skills.” It might result in the patient getting exploratory surgery, which is already more difficult on bariatric patients. If the patient is stable, Uppot said, they’d be observed after a clinical exam and treated empirically.
While making larger machines is a business opportunity, it’s also a challenge. And they’re not just creating these machines to handle obese patients, but also to accommodate those who are tall, athletic or pregnant, all of whom can be difficult to image said Michael Wendt, senior vice president of the imaging and therapy systems division at Siemens Healthcare in the U.S. and Canada. “We’re not singling out or making products purely for obese patients, but a wider population,” he said.
The most limiting part of the anatomy isn’t fat, but the shoulders, said Lawrence Murphy, chief designer at GE Healthcare. A 65–70 cm bore often restricts the shoulders more than a large abdomen. When people lie down, they puddle, meaning their body relaxes and tissue spreads out, helping them fit into the machine, said Murphy. However, large and athletic people have large shoulders, making it difficult to fit them into the bore.
Newer imaging machine design specifications include several categories, Wendt said, including table weight capacity, gantry size and image quality/patient safety. While increasing table weight capability, the machine must still be able to lift, tilt and advance accurately. Patients have to fit in the gantry. And image quality must be sufficient and uniform enough for diagnostic-quality images, without increasing the radiation dose to unsafe levels.