Dependent Lung Opacity at Thin-Section CT: Evaluation by Spirometrically-Gated CT of the Influence of Lung Volume.
- Author:
Ki Nam LEE
1
;
Seong Kuk YOON
;
Choon Hee SOHN
;
Pil Jo CHOI
;
W Richard WEBB
Author Information
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords: Lung, collapse; Lung, CT; Lung, density; Lung, function; Lung, ventilation
- MeSH: Adult; Female; Human; Lung/*radiography; Lung Volume Measurements; Male; Spirometry; Support, Non-U.S. Gov't; *Tomography, X-Ray Computed; Vital Capacity
- From:Korean Journal of Radiology 2002;3(1):24-29
- CountryRepublic of Korea
- Language:English
- Abstract: 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.
