A helium-based imaging technique may help doctors detect smoking-related lung damage in healthy smokers sooner and more accurately than existing imaging methods, according to a study by researchers at the University of Wisconsin-Madison.

The University of Wisconsin is one of three sites that have applied helium MRI to lung disease since 2001. “We’ve been looking at the ability of the technique to detect disease both in asthma and chronic obstructive pulmonary disease, a common disease that occurs due to excessive smoking,” said Sean Fain, UW-Madison assistant professor of medical physics and radiology. COPD includes emphysema, bronchitis and asthma.

The technique uses an isotope of helium, helium-3, that is a harmless gas that can be inhaled and detected by an MRI. By tracking helium’s movement in the lungs, researchers were able to show structural changes in the lungs from smoking before people began to show symptoms. The conventional methods for detecting lung damage, CT scan and spirometry, failed to detect the same structural changes at an early stage in the same subjects.

“It’s one thing to see a [lung] disease that was already diagnosed, but another to see changes that no one predicted were there,” said Fain. “This approach allows us to look at lung microstructures that are on the scale of less than a millimeter.”

This imaging technique has several advantages. Helium-based MRI provides regional information about the location and severity of disease in the event the patient needs surgery, Fain said. Helium-based imaging could one day help to evaluate drugs in development for suspending and potentially reversing the process of emphysema, he added.

The technique also has the potential to show who is most genetically vulnerable to develop emphysema, said Fain. “We’re interested in the underlying genotype that makes one vulnerable to disease and imaging provides us with a very early diagnostic tool to determine those people who show greater propensity for the disease and we can target those individuals to see if they have markers for the disease.”

The researchers conducted another study with the University of Virginia and University of Nottingham in England that looked at age-dependent changes in nonsmokers. “There are similar but less severe structural changes in the lungs of nonsmokers just due to the aging process,” Fain said. Smokers seem to be accelerating this natural process.

Fain would also like to look more closely at genetic markers and collaborate with other sites to combine data and draw strength in conclusions, Fain said. “We still need to validate the technique with histology and more modern CT imaging because CT has also gone through technical improvements.”

In the future the helium-based imaging technique may help researchers evaluate the progression of lung cancer and the effectiveness of targeted cancer therapies designed to treat the lesion while sparing healthy tissue, he said.

Clinicians are enthusiastic about the technique as well. “MRI promises to reveal functional information previously unavailable to us about the lung damage caused by smoking,” said Dr. John Anastos, chairman of the department of radiology at Advocate Lutheran General Hospital. “The ultimate goal of this research is to develop drug therapies to treat the effects of lung disease before the signs and symptoms become apparent.

“MRI offers greater sensitivity in imaging the smallest portions of the lung compared with other techniques such as computed tomography,” Anastos continued. “It will likely be applied to other lung diseases such as asthma within the next few years to better evaluate and monitor lung function.”

By Terri Yablonsky Stat

Special to the Tribune