After multiple trial and error attempts, for the first time, researchers say they have evidence that long-term exposure to secondhand smoke can cause structural damage in the lungs that is indicative of emphysema.

Their study also suggests that the modified magnetic resonance imaging (MRI) technique used to detect the lung damage may be able to spot emphysema long before symptoms occur.

The researchers used global helium-3 diffusion MRI to study the lungs of 13 current or former smokers and 45 people who had never smoked. Of the nonsmokers, 22 had heavy exposure to secondhand smoke, meaning they lived with a smoker or worked in a bar for at least a decade. None had symptoms of lung disease.

The modified MRI detected signs of early lung damage in 67 percent of smokers and 27 percent of nonsmokers with heavy exposure to secondhand smoke, says researcher Chengbo Wang, Ph.D., of the Children's Hospital of Philadelphia.

In contrast, only 4 percent of nonsmokers who had never smoked and had fewer than 10 years of exposure appeared to have signs of early lung damage, he says.

The research was presented here at the annual meeting of the Radiological Society of North America (RSNA).