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KMID : 0880420020030010024
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Korean Journal of Radiology
2002 Volume.3 No. 1 p.24 ~ p.29
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Dependent Lung Opacity at Thin-Section CT: Evaluation by Spirometrically-Gated CT of the Influence of Lung Volume
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Ki Nam Lee/Ki Nam Lee
Seong Kuk Yoon/Choon Hee Sohn/Pil Jo Choi/W. Richard Webb
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Abstract
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Objective : To evaluate the influence of lung volume on dependent lung opacity seen at thin-section CT.
Materials and Methods : In thirteen healthy volunteers, thin-section CT scans were performed at three levels (upper, mid, and lower portion of the lung) and at different lung volumes (10, 30, 50, and 100% vital capacity), using spirometric gated CT. Using a three-point scale, two radiologists determined whether dependent opacity was present, and estimated its degree. Regional lung attenuation at a level 2 cm above the diaphragm was determined using semiautomatic segmentation, and the diameter of a branch of the right lower posterior basal segmental artery was measured at each different vital capacity.
Results : At all three anatomic levels, dependent opacity occurred significantly more often at lower vital capacities (10, 30%) than at 100% vital capacity (p = 0.001). Visually estimated dependent opacity was significantly related to regional lung attenuation (p < 0.0001), which in dependent areas progressively increased as vital capacity decreased (p < 0.0001). The presence of dependent opacity and regional lung attenuation of a dependent area correlated significantly with increased diameter of a segmental arterial branch (r = 0.493 and p = 0.0002; r = 0.486 and p = 0.0003, respectively).
Conclusion : Visual estimation and CT measurements of dependent opacity obtained by semiautomatic segmentation are significantly influenced by lung volume and are related to vascular diameter.
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KEYWORD
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Lung, collapse, Lung, CT, Lung, density, Lung, function, Lung, ventilation,
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