Lucidarme O, Coche E, Cluzel P, Mourey-Gerosa I, Howarth N, Grenier P
Department of Radiology, Université Pierre et Marie Curie, Hôpital de la Pitié-Salpêtrière, Paris, France.
AJR Am J Roentgenol. 1998 Feb;170(2):301-7. doi: 10.2214/ajr.170.2.9456933.
The purpose of our study was to correlate findings on expiratory CT scans with results of pulmonary function tests (PFTs) and to determine whether these techniques may be complementary in assessing airway obstruction.
Seventy-four patients with suspected chronic airway disease and 10 healthy nonsmokers underwent inspiratory and expiratory CT scans and PFTs. An air trapping score, corresponding to the ratio of the cross-sectional air trapping area versus the total cross-sectional lung area on expiratory CT, and a reduction score, representing the change in cross-sectional lung area at inspiration and expiration, were calculated using a quantitative grid. The two scores were then correlated with the results of the PFTs.
Expiratory air trapping was seen in 18 (51%) of 35 patients with severe airway obstruction (forced expiratory volume in 1 sec [FEV1]:vital capacity < 80%) (group A), in 21 (72%) of 29 patients with predominantly small airways obstruction (abnormal flow-volume curve and FEV1:vital capacity > or = 80%) (group B1), and in four (40%) of 10 patients with normal PFT results (group B2). Expiratory air trapping was never seen in the 10 healthy subjects. Air trapping scores were 27%, 12%, and 8% for groups A, B1, and B2, respectively, with significant negative correlations with FEV1 (r = -.45), FEV1:vital capacity (r = -.31), and forced expiratory flow at 25% of vital capacity (r = -.57). Reduction scores were 18%, 30%, 35%, and 43%, for the groups A, B1, B2, and the healthy group, respectively, with significant correlations with all the PFT indexes (r = .35 to .66) except total lung capacity.
Air trapping may permit detection of airway obstruction in patients with clinically suspected chronic airway disease even when PFTs are normal. Furthermore, expiratory CT allows one to calculate a reduction score for a cross-sectional lung area that appears to be better correlated with the degree of airway obstruction measured on PFTs.
本研究的目的是将呼气CT扫描结果与肺功能测试（PFT）结果相关联，并确定这些技术在评估气道阻塞方面是否具有互补性。
74例疑似慢性气道疾病患者和10名健康非吸烟者接受了吸气和呼气CT扫描以及PFT。使用定量网格计算空气潴留评分（对应于呼气CT上空气潴留横截面积与肺总横截面积之比）和缩小评分（代表吸气和呼气时肺横截面积的变化）。然后将这两个评分与PFT结果相关联。
35例严重气道阻塞患者（第1秒用力呼气量[FEV1]：肺活量<80%）（A组）中有18例（51%）出现呼气空气潴留，29例主要为小气道阻塞患者（流量-容积曲线异常且FEV1：肺活量>或 = 80%）（B1组）中有21例（72%）出现呼气空气潴留，10例PFT结果正常的患者（B2组）中有4例（40%）出现呼气空气潴留。10名健康受试者中未见呼气空气潴留。A组、B1组和B2组的空气潴留评分分别为27%、12%和8%，与FEV1（r = -0.45）、FEV1：肺活量（r = -0.31）和肺活量25%时的用力呼气流量（r = -0.57）呈显著负相关。A组、B1组、B2组和健康组的缩小评分分别为18%、30%、35%和43%，与除肺总量外的所有PFT指标（r = 0.35至0.66）呈显著相关。
即使PFT结果正常，空气潴留也可能有助于检测临床疑似慢性气道疾病患者的气道阻塞。此外，呼气CT能够计算肺横截面积的缩小评分，该评分似乎与PFT测量的气道阻塞程度具有更好的相关性。
