Zoos Stretched to Limit as Providers Seek Supersized Scanners for Morbidly Obese Patients
When 407-pound Jennifer Walters kept complaining of acute back and leg pain, her doctor made an unorthodox referral for a diagnostic scan: Go to the zoo.
Aware that the New York City woman was too large to squeeze into an MR scanner, the physician reasoned that if the nearby Bronx Zoo could image hippopotami, elephants, rhinos, and other large animals, surely it could accommodate her.
Outraged, Walters complained to the New York Post, whose editors promptly turned her private humiliation into a public joke that circled the globe. One media source spoke for the insensitivity of many when it ran the headline: "Fat Lady Sent to Zoo for MRI." [editor's note: ACR chose not to link to that particular article] "It's humiliating," Walters would later tell a reporter. "It was like I was an animal."
The story doesn't surprise Chicago's Lincoln Park Zoo veterinary technician Joel Pond. As executive director of the Association of Zoo Veterinary Technicians (AZVT), he routinely fields calls from radiologists and other physicians looking for supersized scanners for their plus-sized patients. Individually, the calls typically don't annoy Pond, but they add up. It didn't help when the NBC television comedy "Scrubs" recently depicted a morbidly obese character being told to go to a zoo for a diagnostic scan.
Fed up, on July 18, Pond sent an open letter addressed to the nation's "radiographers and their instructors." His message? Jumbo-sized zoo scanners are an urban legend.
"Very few zoos own a CT machine — only one of which is known to me — and none own MRIs," Pond says. "And that one zoo, along with veterinary specialty practices that do have this larger equipment, obtained them from the human side. Zoos do not have any special imaging equipment for large animals that is not already available in the human field. Our 400-pound gorillas are imaged with standard radiograph machines and would not fit into any CT or MRI we could currently use. No matter how you slice it (pun intended), a 40-inch-wide ape will not fit through a 27-inch opening in a CT scanner."
Nor, as greater numbers of radiologists are finding out, will a morbidly obese person fit into the relatively small gantry of a conventional CT or MR unit. Although the term "morbidly obese" describes a person 100 or more pounds above his or her target body weight, many tip the scales at 400, 500, 600, 700, or more pounds.
Pond, 53, has been repeating the same talking points since the 1980s, but this urban legend seems bulletproof. "We probably get on average one call a month," he says. "Some zoos get calls all the time, others a couple of times a year." He says "a record number of postings" on the Association's message board reveals that zoos across the nation are receiving these requests. "Even at SeaWorld Orlando," Pond says.
Officials at SeaWorld Orlando, home to Shamu the killer whale, say they have received "quite a few" inquiries about imaging obese humans, even though SeaWorld Orlando has no such scanner.
Martha Larson, DVM, is professor of the radiology department of Small Animal Clinical Sciences at VA-MD Regional College of Veterinary Medicine at Virginia Tech University. She says her colleagues "occasionally" receive such calls. Her facility can't accept human patients for reasons that include insurance liability, lack of FDA approval, and the fact that the accidental dropping of a 575-pound human "patient" inside an accredited vet college isn't likely to score points with the university's trustees. Larson notes that Virginia Tech does possess an equine CT scanner rated to hold 2,500 pounds, but the gantry opening is no larger than on human CT scanners. Consequently only "certain equine body parts" can be imaged.
Recollecting one incident, Pond comments, "A radiologist called and said, ‘We have a large person that we'd like to bring over to see your CT.' I told him we don't have one. There was this silence, and then he said, ‘Well, my colleague here, Dr. So and So, said they brought patients to your zoo all the time. And I said, ‘No, you can't bring patients to a machine that we don't have.'" Pond says some physicians offer to airlift or transport their patients themselves. When Pond politely turns them down, some get angry.
Pond traces some of this legend to instructors. "I just spoke with a [medical] resident working on a paper on the morbidly obese. She said she has been told numerous times during her residency that [our] zoo had the capability to do these tests, because we do them on the elephants all the time." Untrue, Ponds says.
All of which raises the inevitable question: How does one image a 5,000-pound elephant? While the obvious answer is "very carefully," Pond chuckles, "Well, that's just it, we don't. First, you've got to get the animal inside the imaging facility. Next you have to get its leg into the machine. And then you have to be able to manipulate the leg, which is going to be impossible. You're not going to sedate an elephant inside an MR scanner." If "lucky," he and his team might be able to "shoot the very distill portion of the feet with our portable unit, but there still isn't any machinery that will go through, let's say, the thorax of an elephant," he says. "In order to put that much radiation into something, it would probably do too much damage."
The upper limit on the Chicago Zoo's X-ray machine, Pond notes, is "probably a 400- or 500-pound gorilla." They've also imaged the zoo's polar bear and have even turned to a local hospital for its CT, though usually it's used on infant animals, not on adults. He notes that manufacturers of human imaging equipment have recently upsized their weight and size capacities, and that veterinary practices in some large cities offer this equipment for animal use, but he describes his zoo's equipment as "pretty much hand-me-down technology from the human side — in the veterinary field." Another problem: Pond guesses that there are few experts who could make much sense out of a hippopotamus CT or MR scan.
At the least, Pond hopes that radiologists will lobby manufacturers to start designing mega-sized machines that will accommodate the largest of the large — man or beast.