Lee Ki Nam, Yoon Seong Kuk, Sohn Choon Hee, Choi Pil Jo, Webb W Richard
Department of Diagnostic Radiology, Dong-A University College of Medicine, 3-1 Ga, Dong daesin-dong, Seo-gu, Pusan 602-103, Korea.
Korean J Radiol. 2002 Jan-Mar;3(1):24-9. doi: 10.3348/kjr.2002.3.1.24.
To evaluate the influence of lung volume on dependent lung opacity seen at thin-section CT.
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.
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).
Visual estimation and CT measurements of dependent opacity obtained by semiautomatic segmentation are significantly influenced by lung volume and are related to vascular diameter.
评估肺容积对薄层CT上所见的下垂肺模糊影的影响。
对13名健康志愿者，使用肺活量计门控CT在肺的三个层面（肺上部、中部和下部）以及不同肺容积（肺活量的10%、30%、50%和100%）进行薄层CT扫描。两名放射科医生使用三分制确定是否存在下垂模糊影，并估计其程度。使用半自动分割法确定膈上2 cm处的区域肺衰减，并在每个不同的肺活量下测量右下后基底段动脉分支的直径。
在所有三个解剖层面上，下垂模糊影在较低肺活量（10%、30%）时出现的频率显著高于肺活量为100%时（p = 0.001）。视觉估计的下垂模糊影与区域肺衰减显著相关（p < 0.0001），在下垂区域，随着肺活量降低，区域肺衰减逐渐增加（p < 0.0001）。下垂模糊影的存在以及下垂区域的区域肺衰减与段动脉分支直径增加显著相关（分别为r = 0.493，p = 0.0002；r = 0.486，p = 0.0003）。
通过半自动分割获得的下垂模糊影的视觉估计和CT测量受肺容积的显著影响，且与血管直径相关。
