CHICAGO, Nov. 26 /PRNewswire/ -- For the first time, researchers have
identified structural damage to the lungs caused by secondhand cigarette
smoke.
The results of the study, conducted by researchers at the University of
Virginia School of Medicine in Charlottesville and The Children's Hospital
of Philadelphia in Pennsylvania, were presented today at the annual meeting
of the Radiological Society of North America (RSNA).
"It's long been hypothesized that prolonged exposure to secondhand
smoke may cause physical damage to the lungs, but previous methods of
analyzing lung changes were not sensitive enough to detect it," said
Chengbo Wang, Ph.D., magnetic resonance physicist in the Department of
Radiology at The Children's Hospital of Philadelphia.
In recent years, secondhand smoke has emerged as a public health
threat. It has been classified as a carcinogen by the Environmental
Protection Agency and has been linked to heart disease, lung cancer and a
number of respiratory ailments, including asthma and chronic bronchitis.
Children are particularly susceptible to the harmful effects of secondhand
smoke. According to the American Lung Association, 35 percent of American
children live in homes where regular smoking occurs.
Dr. Wang and colleagues used long-time-scale, global helium-3 diffusion
magnetic resonance imaging (MRI) to study the lungs of 43 volunteers,
including seven current and former smokers and 36 people who had never
smoked, 18 of whom had a high level of exposure to secondhand smoke.
Helium-3 diffusion MRI differs from conventional MRI in that the
patient inhales a specially prepared helium gas prior to imaging, and the
scanner is adjusted to collect images showing this helium gas in tissue. MR
measures how far the helium atoms move, or diffuse, inside the lungs during
a specific time period -- 1.5 seconds in this study. Using this method,
radiologists and physicists can detect changes deep in the small airways
and sacs in the lungs, which can break down, become enlarged and develop
holes after prolonged exposure to cigarette smoke. Helium-3 diffusion MRI
identifies this damage by measuring the increased distance the helium atoms
move.
"With this technique, we are able to assess lung structure on a
microscopic level," Dr. Wang said.
For the study, measurements were translated into scores called apparent
diffusion coefficient (ADC) values for each of the participants. An
increased ADC value indicates that the helium atoms were able to travel
farther during the measurement time. Fifty-seven percent of the smokers and
33 percent of the nonsmokers with high exposure to secondhand smoke had ADC
values greater than 0.024, suggesting that early lung damage was present.
In addition, 14 percent of smokers, 67 percent of high-exposure nonsmokers,
and 39 percent of low-exposure nonsmokers had ADC values below 0.0185.
Relatively low ADC values in adults are a possible indication of a
developing respiratory problem, such as chronic bronchitis or asthma.
"These findings suggest that breathing secondhand smoke can injure your
lungs," Dr. Wang said. "Since legislation to limit public exposure to
secondhand smoke is still being considered in many states, we hope that our
work can be used to add momentum to the drive to pass such legislation."
Co-authors are T.A. Altes, M.D., G.W. Miller, Ph.D., E.E. de Lange,
M.D., K. Ruppert, Ph.D., J.F. Mata, Ph.D., and G.D. Cates, Ph.D.
AT A GLANCE
-- Helium-3 diffusion MRI shows lung damage caused by secondhand smoke.
-- One-third of nonsmokers with high levels of exposure to secondhand
smoke exhibited structural changes in the lung similar to those in
smokers.
-- Thirty-five percent of U.S. children live in homes where regular
smoking occurs.
Note: Copies of RSNA 2007 news releases and electronic images will be
available online at RSNA.org/press07 beginning Monday, Nov. 26.
RSNA is an association of more than 41,000 radiologists, radiation
oncologists, medical physicists and related scientists committed to
excellence in patient care through education and research. The Society is
based in Oak Brook, Ill. (RSNA.org)
Editor's note: The data in these releases may differ from those in the
printed abstract and those actually presented at the meeting, as
researchers continue to update their data right up until the meeting. To
ensure you are using the most up-to-date information, please call the RSNA
Newsroom at 1-312-949-3233.
SOURCE Radiological Society of North America
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