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First Proof of Secondhand Smoke Damage

MRI analysis provides evidence

For the first time, the effects of secondhand smoke can be plainly seen, and the picture isn’t pretty. Using a special type of magnetic resonance imaging, researchers have produced evidence of microscopic structural damage in the lungs caused by secondhand cigarette smoke. While cigarette smoke has long been suspected to cause physical damage to the lungs in nonsmokers, previous methods of analyzing changes in the lung have not been sensitive enough to detect it.

The research team was led by Chengbo Wang of the Children’s Hospital of Philadelphia, formerly a magnetic resonance physicist at UVA. He collaborated with radiology researchers at UVA, where they acquired MRIs from adult smokers and nonsmokers.

Wang and his colleagues studied the lungs of 60 adults between the ages of 41 and 79, 45 of whom had never smoked. The 45 subjects were divided into groups with low and high exposure to secondhand smoke. Those considered high-exposure subjects had lived with a smoker for at least 10 years, often during childhood, or had worked in a bar for at least a decade. The control group consisted of 15 current or former smokers.

Early lung damage was detected in 67 percent of smokers and 27 percent of nonsmokers with heavy exposure to secondhand smoke. 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.

Patients inhaled a specially prepared helium-nitrogen mixture whose movement could be traced by the MRI machine as it spread through the lungs in a matter of seconds. In those patients with prolonged exposure to cigarette smoke, the helium moved a greater distance, indicating the presence of holes and extended spaces within the lung’s tiny air sacs called alveoli—early signs of emphysema. In the images using helium MRI, the lungs of healthy subjects are red. In those with prolonged exposure to smoke, the lungs are heavily speckled with yellow.

The findings were presented at the November annual meeting of the Radio-logical Society of North America.