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Radiology
Low-attenuation areas on computed tomography are believed to reflect areas of emphysema. The distribution of the cumulative sizes of clusters of low-attenuation areas follows a power law function characterized by exponent D, which is closely related to a fractal dimension and reflects terminal airspace enlargement in early emphysema. Mitsunobu and coworkers
examined the size distribution of clusters of low-attenuation areas in 105 patients with asthma (30 smokers and 75 nonsmokers) and 23 nonsmoking healthy subjects. In nonsmoking patients with asthma, the percentage of low-attenuation areas was higher in patients with moderate versus mild asthma, and the percentage was further increased in patients with severe asthma. Exponent D was lower in patients with severe asthma than in the other groups, but exponent D did not differ between patients with mild asthma and moderate asthma. The percentage of low-attenuation areas was correlated with exponent D in smokers with asthma (r = -0.91), but not in the nonsmokers. The authors conclude that exponent D, a measure of the complexity of terminal airspace geometry that reflects fractal properties, is mostly related to emphysematous changes, and that measurement of exponent D and the percentage of low-attenuation areas on computed tomography may discriminate between emphysema and hyperinflation in patients with asthma.
1 Citation displayed.
Complexity of Terminal Airspace Geometry Assessed by Computed Tomography in Asthma
- Fumihiro Mitsunobu, Kozo Ashida, Yasuhiro Hosaki, Hirofumi Tsugeno, Makoto Okamoto, Kazunori Nishida, Shingo Takata, Tadashi Yokoi, Michiaki Mishima, and Yoshiro Tanizaki
Am. J. Respir. Crit. Care Med. 167: 411-417.
[Abstract]
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