Helium can light the way to diagnoses deep within the body

Helium can light the way to diagnoses deep within the body

By LAURAN NEERGAARD

WASHINGTON (September 8, 1999 5:00 p.m. EDT http://www.nandotimes.com) - In a laboratory at the University of Virginia, a handful of patients inhaled a deep breath of helium and watched their lungs light up.

Scientists are exploring a dramatic new way to peer into patients' bodies: using specially treated gases that let doctors watch, for the first time, how breath flows through the lungs.

But the technology isn't just for lungs. It also promises to light up other organs now difficult to see with conventional scanning. Researchers are poised to try it as a colon cancer test, and say it might also offer better images of the brain or a woman's reproductive tract, without the discomfort or radiation of some of today's tests.

"It really looks like it's going to help people," said James R. Brookeman, a professor of radiology at UVA.

These so-called hyperpolarized gases are still highly experimental, experts caution. But radiologists compare the black blob an MRI pictures as a lung with the brightly lit image of helium-filled lungs, and say the need is great.

"It's a new idea and a new technique" that provides "very striking" images, said James MacFall, a Duke University medical physicist who also has tested the gases.

Scanners like magnetic resonance imaging, or MRI, provide incredible illumination of parts of the body. But they don't image some organs well. They don't picture airflow through the lungs, for instance. Tracking airflow could help treat emphysema, cystic fibrosis, asthma, even monitor how well a transplanted lung is adapting.

But inhale a hyperpolarized gas into the lungs, just like you would inhale oxygen, and an MRI shows a bright image of plump lungs. Where there's an obstruction - where the lungs aren't doing their job - the image is dark.

Tom Daniel, a UVA lung surgeon, uses hyperpolarized helium to help perform a tricky surgery for emphysema patients: slicing away dead portions of lung so the remaining good lung tissue moves and breathes more freely. It's called lung-reduction surgery, and picking just which spot to cut is difficult but key.

"It told me with a lot more confidence what part of her lung was not getting oxygen," Daniel said in describing a woman he operated on last month.

The gas provides "a very beautiful picture of the abnormal pathology in emphysema. It was just a no-brainer" to try, he said.

Molecules of substances like gas normally spin randomly. Physicists can fire a laser at certain gases, and the molecules temporarily spin in the same direction, called hyperpolarization.

Two Princeton University physicists were researching hyperpolarized gases for the military when one of them needed an MRI - and wondered if the research might also help medicine.

Experiments showed the lined-up molecules of hyperpolarized helium-3 produced an MRI signal thousands of times stronger than today's technology.

Helium is benign - divers routinely breathe it, and a helium-induced high-pitched voice is an old comedian's trick. The isotope helium-3, a byproduct of the tritium used in hydrogen bombs, is the version that can be hyperpolarized. Simply gulp a lungful and hold your breath for 10 seconds while the MRI scans.

Now New Jersey-based Nycomed Amersham Imaging is preparing clinical trials necessary to prove to the Food and Drug Administration that hyperpolarized helium lung scans are safe and useful. In addition to UVA's ongoing study, Nycomed hopes to begin other studies by year's end.

But helium's not the only choice. Xenon-129 also can be hyperpolarized. It can penetrate into the brain - giving it an anesthetic effect - and thus might give better brain scans. It's also more abundant than helium-3, which Nycomed now must buy from the former Soviet Union because the Defense Department won't sell its supplies.

Those aren't the only potential uses.

Next year, Brookeman plans to study inflating people's colons with helium to hunt for cancer. Everyone over age 50 now is supposed to get a colonoscopy in which a fiber-optic tube is threaded through the intestine. Using helium to just light up precancerous colon polyps promises to be less uncomfortable, says Brookeman, who has successfully tried the experiment in dogs.

The technique could also be used to tell if a woman's fallopian tubes are blocked without an X-ray's radiation, Brookeman said. A common test now to check for infertility is to inject an oily substance into a woman's fallopian tubes and then X-ray her abdomen.