Our comprehensive diagnostic criteria for IgG4-RD are practically useful for general physicians and nonspecialists.

Our comprehensive diagnostic criteria for IgG4-RD are practically useful for general physicians and nonspecialists.

Chronic obstructive pulmonary disease (COPD) is characterized by the presence of airflow obstruction caused by emphysema or airway narrowing, or both. Low attenuation areas (LAA) on computed tomography (CT) have been shown to represent macroscopic or microscopic emphysema, or both. However CT has not been used to quantify the airway abnormalities in smokers with or without airflow obstruction. In this study, we used CT to evaluate both emphysema and airway wall thickening in 114 smokers. The CT measurements revealed that a decreased FEV(1) (%predicted) is associated with an increase of airway wall area and an increase of emphysema. Although both airway wall thickening and emphysema (LAA) correlated with measurements of lung function, stepwise multiple regression analysis showed that the combination of airway and emphysema measurements improved the estimate of pulmonary function test abnormalities. We conclude that both CT measurements of airway dimensions and emphysema are useful and complementary in the evaluation of the lung of smokers.

Increases in the low attenuation areas (LAA) of chest x-ray computed tomography images in patients with chronic obstructive pulmonary disease (COPD) have been reported to ref lect the development of pathological emphysema. We examined the statistical properties of LAA clusters in COPD patients and in healthy subjects. In COPD patients, the percentage of the lung field occupied by LAAs (LAA%) ranged from 2.6 to 67.6. In contrast, LAA% was always <30% in healthy subjects. The cumulative size distribution of the LAA clusters followed a power law characterized by an exponent D. We show that D is a measure of the complexity of the terminal airspace geometry. The COPD patients with normal LAA% had significantly smaller D values than the healthy subjects, and the D values did not correlate with pulmonary function tests except for the diffusing capacity of the lung. We interpret these results by using a large elastic spring network model and find that the neighboring smaller LAA clusters tend to coalesce and form larger clusters as the weak elastic fibers separating them break under tension. This process leaves LAA% unchanged whereas it decreases the number of small clusters and increases the number of large clusters, which results in a reduction in D similar to that observed in early emphysema patients. These findings suggest that D is a sensitive and powerful parameter for the detection of the terminal airspace enlargement that occurs in early emphysema.High-resolution computed tomography (CT) is a sensitive and noninvasive tool for assessing alterations in lung structure induced by various disease processes. Increases in the low attenuation areas (LAA) in the lung regions of chest x-ray CT images in patients with chronic obstructive pulmonary disease (COPD) have been reported to reflect the development of pathological emphysema (1-4). Nevertheless, previous methods of analyzing lung CT images are limited for general clinical diagnostic purposes (5) because the size and spatial distribution of LAAs are not taken into account. Recently, Uppaluri et al. (6) found that a texture-based adaptive multiple feature method could differentiate between normal and emphysematous tissue with 100% accuracy. However, it is not clear whether this method would detect early emphysema. More recently, Shimizu et al. (7) proposed a promising fractal analysis method for assessing ground-glass opacities in lung CT images. Their approach was able to successfully differentiate between fibrotic and nonfibrotic disease processes.The concept of fractal geometry was developed by Mandelbrot (8) to quantitatively describe the random variations in size and shape seen in natural objects. A fractal object is said to be scale-free because its characteristics are invariant under isotropic scale transformations. Such scale-invariance can be achieved if the object is formed by parts that are similar to the whole. In other words, fractals are self-similar and hence are characterized by power law functions (the only mathematical functions obeying s...