Scientists use PET scans to monitor lung inflammation noninvasively

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Scientists use PET scans to monitor lung inflammation noninvasively



Traditional methods are more invasive and unpleasant



By Purdy



March 7, 2006 -- A noninvasive approach for assessing lung

inflammation should accelerate efforts to develop drugs for

inflammatory lung conditions like cystic fibrosis and pneumonia,

scientists at Washington University School of Medicine in St. Louis

report.

Researchers have used positron emission tomography (PET) scans to

monitor artificially induced inflammation in the lungs of healthy

volunteers. The new imaging process may help doctors monitor the

conditions of patients with inflammatory lung diseases and should

make it easier to test potential anti-inflammatory drugs in trials.

" Until now, when we wanted to assess whether a new drug decreased

lung inflammation, the options for specifically measuring active

inflammation were not pleasant, " says lead author Delphine Chen,

M.D., chief resident in nuclear medicine at the medical school's

Mallinckrodt Institute of Radiology. " We could perform a bronchoscopy

and gather samples directly from the breathing passages, or we could

have patients inhale a saline solution and cough it back up. "

To make it possible to detect lung inflammation with PET, Chen and

her colleagues employed an imaging technique commonly used to

diagnose cancer and monitor its treatment. Scientists reported the

results in a paper published online by The Journal of Applied

Physiology.

Senior author P. Schuster, M.D., professor of medicine and of

radiology, hopes the new imaging process will make it possible to

give new drugs trial runs.

" Full-scale clinical trials are costly in terms of both time and

dollars spent, and right now it's very difficult to find intermediate

steps that allow us to build confidence in a drug's effectiveness

before taking that plunge, " Schuster says.

With the new PET procedure, Schuster says, researchers developing

anti-inflammatory drugs can test the drugs' effects in less expensive

trials involving smaller groups of healthy volunteers and patients.

" If the drug passes those tests, then you can say, okay, let's see in

a full-scale trial if the drug actually has an impact on some

important patient-centered outcome like mortality or disease

progression, " he says.

To create areas of limited lung inflammation in healthy volunteers,

researchers used a technique originally developed by scientists at

the National Institutes of Health. It involves the injection, via

bronchoscope, of a small amount of endotoxin into a lung segment.

" Endotoxin is a purified bacterial substance that triggers

inflammation, " Schuster says. " The technique we used keeps that

inflammation compartmentalized to a small region in the lung,

ensuring that the inflammation doesn't become systemic. "

Another research group previously had shown that this artificial

inflammation could be used to test potential drugs, but they followed

the effects of the drugs via a second insertion of the bronchoscope

into the volunteers' tracheas.

Chen and her colleagues instead injected volunteers with

fluorodeoxyglucose (FDG), a form of sugar readily detectable by PET,

and continuously monitored the lungs for 60 minutes to see how much

FDG appeared there.

Scientists already have completed a trial to test the new imaging

procedure's ability to detect inflammation in cystic fibrosis

patients that will be published soon in The American Journal of

Respiratory and Critical Care Medicine.

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