Gevenois P A, De Vuyst P, Sy M, Scillia P, Chaminade L, de Maertelaer V, Zanen J, Yernault J C
Department of Radiology, Hôpital Erasme, Brussels, Belgium.
Radiology. 1996 Jun;199(3):825-9. doi: 10.1148/radiology.199.3.8638012.
To determine whether measurement of the relative area of lung with attenuation coefficients lower than a certain threshold on thin-section computed tomographic (CT) scans obtained during expiration is a valuable method of quantifying the extent of pulmonary emphysema.
Eighty-nine patients underwent CT (with 1-mm collimation) preoperatively during inspiration and expiration. Relative areas of lung with attenuation coefficients lower than various thresholds were calculated. These relative areas were compared with areas found macroscopically to have emphysema (59 patients [51 men, eight women; aged 40-77 years]) and with two microscopic indices (35 patients [29 men, six women; aged 42-77 years]) assessed on the resected specimens.
The valid expiratory CT thresholds were found to be -820 and 910 HU for microscopic and macroscopic emphysema, respectively. However, results of stepwise multiple regression analyses showed that the inspiratory threshold of -950 HU was superior for both macroscopically and microscopically quantified emphysema. The correlation coefficients in expiratory CT were higher for the pulmonary volumes but similar for the diffusing capacity.
Expiratory quantitative CT is not as accurate as inspiratory CT for quantifying pulmonary emphysema and probably reflects air trapping more than reduction in the alveolar wall surface.
确定在呼气期获得的薄层计算机断层扫描（CT）上，测量衰减系数低于特定阈值的肺相对面积是否是量化肺气肿程度的一种有价值的方法。
89例患者在术前吸气期和呼气期接受CT检查（准直1毫米）。计算衰减系数低于各种阈值的肺相对面积。将这些相对面积与肉眼可见有肺气肿的区域（59例患者[51名男性，8名女性；年龄40 - 77岁]）以及在切除标本上评估的两个微观指标（35例患者[29名男性，6名女性；年龄42 - 77岁]）进行比较。
发现微观和宏观肺气肿的有效呼气CT阈值分别为 - 820和 - 910HU。然而，逐步多元回归分析结果显示，对于宏观和微观量化的肺气肿，吸气阈值 - 950HU更优。呼气CT中肺容积的相关系数较高，但弥散能力的相关系数相似。
呼气定量CT在量化肺气肿方面不如吸气CT准确，并且可能更多地反映气体潴留而非肺泡壁表面积的减少。
