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Taking the lung view. A Boston University research team has built a theoretical model that advances current understanding of how changes in the sounds of inflating lungs relate to which part of the organ is receiving air, thus potentially allowing physicians to pinpoint malfunctioning areas. The team consists of ENG Assistant Biomedical Engineering Professor Bela Suki, CAS Research Associate Sergey Buldyrev, and CAS Physics Professor Gene Stanley, director of the Center for Polymer Studies, as well as graduate students from BU and colleagues from Hungary and Brazil.

As lungs inflate they generate explosive sound waves called "crackles." Examining changes in the character of crackles has long been a way to diagnose certain lung ailments. Team members found that they could analyze the crackles using the mathematical expression known as a "power law," which scientists often use in studying the size and regularity of catastrophic events such as earthquakes.

"There are many natural phenomena with power law distributions," says Suki. "The interesting thing is that the power law distribution indicates that the likelihood of so-called rare events is very high. This is true for earthquakes. The size distribution of earthquakes is a power law that says that the likelihood of a rare event is not negligible."

In studying crackles, the power law described how often big noise spikes happened in relation to smaller ones. Then the research team went a step further, relating the power law to the physical structure of the branched airways.

Air enters this network in "avalanches" of all sizes, moving anywhere from the next tube ahead to rushing deep into the network. "We developed a theoretical model of the lung, describing the treelike structure of the airways," explains Suki. "The avalanches produce crackles of correspondingly various sizes."

The model produced a power law very similar to the first one. "This suggests the model could be used to map the changes in the distribution of crackles to the changes in the accessibility of the lung passages," explains Suki. "Thus we could pinpoint the part of the malfunctioning lungs that are responsible for anomalous crackles."

The study was published in the October issue of Physical Review E.

Virtually easing medical testing. A new study by School of Medicine researchers has found that a "virtual colonoscopy" can detect precancerous colorectal polyps with 94 percent accuracy, comparable to conventional colonoscopy. The study appeared in the November 10 New England Journal of Medicine.

Colorectal cancer is common in the United States. Early diagnosis is crucial since numerous studies have indicated that the majority of cases arise from certain types of preexisting polyps, which may remain benign for months before becoming malignant.

Virtual colonoscopy uses standard computed tomography (CT) scanning equipment and software to create a image of the colon's interior. A traditional colonoscopy is an invasive procedure that requires sedation.

The study examined 100 patients at high risk for colorectal cancer. Participants had a virtual colonoscopy, then the conventional procedure.

"Our initial results indicated that the procedure is effective in detecting polyps over six millimeters in size and that if the virtual colonoscopy is negative, the chance of the patients' having a significant polyp or tumor is very unlikely," says senior author Dr. Joseph Ferrucci, MED professor and chair of the department of radiology. "This is a 15-minute procedure that poses no risk to the patients." He notes that the study results have yet to be widely reproduced at other medical centers.

"Research Briefs" is written by Joan Schwartz in the Office of the Provost. To read more about BU research, visit


15 May 2003
Boston University
Office of University Relations