Quantitation of emphysema with three-dimensional CT densitometry: comparison with two-dimensional analysis, visual emphysema scores, and pulmonary function test results

PURPOSE: To compare lung densitometric measurements that use a three-dimensional (3D) reconstruction of the lungs with those obtained from analysis of two-dimensional (2D) computed tomographic (CT) images, visual emphysema scores, and data from pulmonary function tests. MATERIALS AND METHODS: Thoracic helical CT scans were obtained in 60 adult patients (35 with no visual evidence of emphysema and 25 with emphysema). The lungs were reconstructed as a 3D model on a commercial workstation, with a threshold of -600 HU. By analysis of histograms, the proportions of lung volumes with attenuation values below -950, -910, and -900 HU were measured, in addition to mean lung attenuation. These values were compared with lung densitometric results obtained from 2D CT images, visual emphysema scores, and data from pulmonary function tests. RESULTS: Quantitation of emphysema with 3D reconstruction was efficient and accurate. Correlation was good among densitometric quantitation with 3D analysis, that obtained with 2D analysis (r = 0.98-0.99), and visual scoring (r = 0.74-0.82). Correlation was reasonable between 3D densitometric quantitation and the diffusing capacity of the lungs for carbon monoxide (DLCO) (r = -0.57 to -0.64), total lung capacity (r = 0.62-0.71), forced expiratory volume in 1 second (FEV1) (r = -0.57 to -0.60), and the ratio of FEV1 to forced vital capacity (FVC) (r = -0.75 to -0.82). The visual CT quantitation of emphysema correlated best with DLCO (r = -0.82) and FEV1/FVC (r = -0.89). CONCLUSION: Lung densitometry with 3D reconstruction of helical CT data is a fast and accurate method for quantifying emphysema.     

CT肺功能成像技术研究

目的探讨CT肺功能成像技术的可行性,着重研究CT肺功能参数与肺功能检查(pulmonary functional test, PFT)参数的相关性.方法共69例,包括PFT正常者21例,阻塞性通气功能障碍者37例,限制性通气功能障碍者9例,混合性功能障碍者2例,均在1周内完成PFT和胸部CT检查.采用最大吸气末和呼气末屏气螺旋CT扫描.扫描参数120 kV,175 mA,每层螺旋扫描时间1 s,床速20 mm/s,螺距2∶1.将CT图像经医学数字影像与通讯(DICOM)协议接口接到计算机上.利用自行研制的CT肺功能定量软件进行数据分析.结果通过吸气末CT测得的肺体积(Vin)与PFT的最大肺总量(TLC)存在明显相关性(r=0.866,P<0.001),呼气末CT测得的肺体积(Vex)与残气量(RV)有相关性 (r=0.833,P<0.001),呼吸比(Vex/Vin)与RV/TLC有相关性(r=0.590,P<0.001).吸气像平均CT值与第1秒量占预计值的百分比(FEV1%),第1秒用力呼吸量(FEV1)/用力肺活量(FVC)存在相关性(r=0.382, P<0.05 ; r=0.682, P<0.01).像素指数(PI)=-910～-950 HU与FEV1、FEV1%、 FVC%、FEV1/FVC均存在相关性,其中与FEV1/FVC的相关性最好(r=0.747～0.772,P<0.01).呼气像平均CT值与FEV1、FEV1%、FVC%、FEV1/FVC存在相关性(r=0.624, P<0.01; r=0.654, P<0.01; r=0.452, P<0.01 ; r=0.758, P<0.01).呼气像CT各阈值与PFT参数均存在相关性.结论最大吸气末和最大呼气末行螺旋CT扫描,可获得肺部解剖和肺功能情况的参数,与PFT结果相关性好,因此本法是行之有效的CT肺功能定量成像技术.     

吸烟人群肺部MDCT形态和容积量化评估及与肺功能的相关性研究

目的 分析吸烟人群肺部多排螺旋CT(MDCT)形态学特点,测量CT肺容积量化参数,研究二者与肺功能检查(PFT)指标的相关性.方法 选取59例吸烟者,其中14例为慢性阻塞性肺疾病(COPD)患者,另纳入39例不吸烟者作为对照组.所有受试者接受MDCT双气相扫描及PFT.分析并比较3组人群中与吸烟相关的11种肺部CT征象.测量肺气肿指数(EI)和平均肺密度(MLD).分析上述参数与PFT指标的相关性.结果 ①小叶中心型肺气肿、间隔旁型肺气肿、支气管扩张或管壁增厚的评分及发生率在3组间存在统计学差异(P均＜0.01).②吸烟COPD患者间隔旁型肺气肿与一氧化碳弥散量(DLCO)/肺泡容积(VA),支气管扩张或管壁增厚与DLCO实测值与预计值比值[DLCO SB(％P)]、DLCO与VA比值的实测值与预计值之比[DLCO/VA(％P)],EI与25％最大呼气量实测值与预计值的比值[MEF25％(％P)]、DLCO SB(％ p)、DLCO/VA(％P)均呈负相关.吸烟非COPD者小叶中心型肺气肿与第1秒用力呼气量与用力肺活量的比值(FEV1/FVC)、MEF25％(％P)、50％最大呼气量实测值与预计值的比值[MEF5％(％P)]、DLCO SB(％P)及DLCO/VA(％P),间隔旁型肺气肿与DLCO SB(％P)、DLCO/VA(％P),支气管扩张或管壁增厚与DLCO/VA(％P),EI与FEV1/FVC、MEF5％(％P)均呈负相关,MLD与FEV1(％P)、MEF25％ (％P)呈正相关.结论 MDCT可用于分析吸烟人群的肺部形态异常,其形态学特点及容积量化参数对肺功能有很好的预测价值.     

Quantitatively assessed dynamic contrast-enhanced magnetic resonance imaging in patients with chronic obstructive pulmonary disease: correlation of perfusion parameters with pulmonary function test and quantitative computed tomography

OBJECTIVES: The purpose of this study is to evaluate the correlation of the perfusion parameters of 3-dimensional, contrast-enhanced magnetic resonance (MR) imaging (3D CEMRI) with pulmonary function test (PFT) and quantitative computed tomography (CT) parameters in patients with chronic obstructive pulmonary disease (COPD). MATERIALS AND METHODS: In 14 patients with COPD, 3D CEMRI was performed. From the signal intensity-time curves, pulmonary blood flow (PBF), pulmonary blood volume (PBV), and mean transit time of each pixel was calculated. From the volumetric CT data, the quantitative parameters including the volume fraction of the lung below -950 Housefield Units (V(-950)) and mean lung density were assessed. The correlation between the MR perfusion parameters and the parameters from quantitative CT and PFT was assessed using Spearman correlation analysis. The correspondence of the regional impairment of perfusion on MR perfusion maps to the areas of emphysema on quantitative CT maps in each patient was assessed qualitatively using a 4-class visual scoring method by 2 readers. RESULTS: All 3D CEMRI examinations were successfully completed and MR perfusion parameters were obtained in all patients. The Spearman correlation test showed that PBF positively correlated with forced expiratory volume in 1 second (FEV(1))/forced vital capacity (FVC) (R = 0.49, P = 0.044), PBV positively correlated with FEV(1)/FVC (R = 0.69, P = 0.006) and negatively correlated with V-950 (R = -0.61, P = 0.020), and mean transit time positively correlated with FEV(1) (R = 0.63, P = 0.017) and FEV(1)/FVC (R = 0.76, P = 0.002). The areas of perfusion impairment on PBF and PBV maps were relatively well correlated with the areas of emphysema on CT maps [very good or good: PBF 71.5% (reader 1) and 64.3% (reader 2) of the patients, kappa = 0.47 (P < 0.001); PBV 78.6% (reader 1) and 78.6% (reader 2) of the patients, kappa = 0.89 (P < 0.001)]. CONCLUSIONS: This study shows that the deterioration of perfusion parameters measured on MR in patients with COPD, correlates with worsening of airflow limitation on PFT and emphysema index on CT. Regional heterogeneity of emphysema on CT matches with the decreased perfusion on MR.     

Correlation of pulmonary perfusion volume analysis with pulmonary function in emphysema

Pulmonary perfusion single photon emission tomography with 99mTc MAA was performed on 13 pulmonary emphysema patients and 6 controls. We calculated perfusion volume with lower 10%, 20%, 30%, 40% and 50% of the highest counts/boxels in the lung cut-off. And perfusion index (PI) was defined as follows; PI = ((A% cut-off volume) - (B% cut-off volume))/(A% cut-off volume); A and B take 10 to 50, A < B. The correlation of each PI and pulmonary function test results (FEV1, FEV1%, VC, VC%, FVC, FVC%, PaO2 and PaCO2) was examined. There were significant correlation between every PI and FEV1 or FEV1% (p < 0.05), and any PI had no significant correlation with other functional results. When A = 10 and B = 40, the PI showed the best correlation with FEV1 (r = 0.680) and FEV1% (r = 0.830). And the PI showed an increasing tendency along with the rise of the emphysema severity. The PI may have the clinical utility of the evaluation of pulmonary function. Moreover, we showed the lung CT painted the area where the uptake counts/boxels was more than 10% and less than 40% of the highest counts/boxels. This makes it easy to understand the severe emphysematous area.     

Texture-based quantification of pulmonary emphysema on high-resolution computed tomography: comparison with density-based quantification and correlation with pulmonary function test

PURPOSE: To develop a system for texture-based quantification of emphysema on high-resolution computed tomography (HRCT) and to compare it with density-based quantification in correlation with pulmonary function test (PFT). MATERIALS AND METHODS: Two hundred sixty-one circular regions of interest (ROI) with 16-pixel diameter [66 ROIs representing typical area of normal lung; 69 representing bronchiolitis obliterans (BO); 64, mild emphysema (ME); and 62, severe emphysema (SE)] were used to train the automated classification system based on the Support Vector Machine classifier and on variable texture and shape features. An automated quantification system was developed with a moving ROI in the lung area, which classified each pixel into 4 categories. To validate the system, the HRCT and standard-kernel-reconstructed volumetric CT data of 39 consecutive patients with emphysema were included. Using this system, the whole lung area was evaluated, and the area fractions of each class were calculated (normal lung%, BO%, ME%, SE%, respectively). The emphysema index (EI) of texture-based quantification was defined as follows: (0.3 x ME% + SE%) (TEI). EIs from density-based quantification with a threshold of -950 Hounsfield Units, were measured on both HRCT (DEI_HR_2D) and on volumetric CT (DEI_standard_3D). The agreement between TEI, DEI_HR_2D, and DEI_standard_3D was assessed using interclass correlation coefficients (ICC). Correlation of the results on the TEI with the PFT results was compared with the results of the DEI_standard_3D and the DEI_HR_2D with Spearman's correlation test. To evaluate the contribution of each texture-based quantification lesion (BO%, ME%, SE%) on PFT, multiple linear regression analysis was performed. RESULTS: The calculated TEI (19.71% +/- 17.98%) was well correlated with the DEI_standard_3D (19.42% +/- 14.30%) (ICC = 0.95), whereas the ICC with DEI_HR_2D (37.22% +/- 9.42%) was 0.43. TEI showed better correlation with PFT than DEI_standard_3D or DEI_HR_2D did [R = 0.71 vs. 0.67 vs. 0.61 for forced expiratory volume in 1 second (FEV(1))/forced vital capacity (FVC); 0.54 vs. 0.50 vs. 0.43 for diffusing capacity (DLco), respectively]. Multiple linear regression analysis revealed that the BO% and SE% areas were independent determinants of FEV(1)/FVC, whereas the ME% and the SE% were determinants of DLco. CONCLUSION: Texture-based quantification of emphysema using an automated system showed better correlation with the PFT results than density-based quantification. Separate quantification of the BO, ME, and SE areas showed a different contribution of each component to the FEV(1)/FVC and the DLco. The proposed system can be successfully used for detailed regional and global evaluation of lung lesions on HRCT scanning for emphysema.     

Pulmonary sarcoidosis. Correlation of expiratory high-resolution CT findings with inspiratory patterns and pulmonary function tests

Purpose: To assess the presence and extent of air trapping (AT) on chest high-resolution CT (HRCT) in sarcoidosis and to correlate such findings with patterns, lesion extent on inspiratory CT and pulmonary function tests (PFT).Material and Methods: Thirty patients with sarcoidosis underwent inspiratory and expiratory HRCT and PFT. HRCT images were evaluated for presence, distribution and AT extent as well as the predominant HRCT pattern and the extent of lesions at inspiration. Attenuation difference in the AT regions at expiration and at inspiration were calculated. The presence and extent of AT were correlated with PFT, extent of involvement and predominant inspiratory patterns.Results: AT was present in 25/30 patients with no lung zone predilection. AT was the only CT indication of pulmonary sarcoidosis in 3/30 patients who also had normal PFT. Attenuation difference between inspiration and expiration ranged from -40 HU to 106 HU. In 2 patients, a paradoxical decrease of lung attenuation was observed at expiration. A significant correlation was found between AT extent at expiration, with residual volume-total lung capacity ratio and residual volume.Conclusion: AT is an additional HRCT finding in sarcoidosis. AT may involve any lung zone, including costophrenic angles and may be the only CT feature of pulmonary sarcoidosis. Strong correlation is only found with PFT values that are specific for incomplete lung emptying at expiration.     

Detection of emphysema with computed tomography. Correlation with pulmonary function tests and chest radiography

We studied 60 male patients who had concurrent chest films (CXR), computed tomography scans (CT) and pulmonary function tests (PFT) to assess the sensitivity of CT and conventional films in detecting emphysema compared with PFT. We also sought to determine whether emphysema could be diagnosed by CT in patients with normal pulmonary function. Using a method similar to that proposed by Bergin, we scored the severity of emphysema depicted by CT, and using arterial deficiency and bullae as criteria, we estimated the degree of emphysema on CXR. There was a significant inverse correlation between CT scores for emphysema and percentage predicted values of DLco/VA (r = -0.650), FEV1 (r = -0.552), and FVC (r = -0.409), (P less than 0.001). A significant but smaller correlation also was noted with the CXR scores and percentage predicted: DLco/VA (r = -0.564), FEV1 (r = -0.454), and FVC (r = -0.355), (P less than 0.005). When decreased diffusion capacity and airway obstruction were used as functional criteria of emphysema, CT was as sensitive as PFT and more sensitive than CXR in detecting emphysema (96% vs. 68%). There was CT evidence of emphysema in 69% (24/35) of patients who did not have functional findings of emphysema. In 12 pathologic specimens available for review, 11 had emphysema by CT and pathologic examination; one patient had centrilobular emphysema undetected by CT. We conclude that CT is as sensitive as PFT in detecting emphysema and more sensitive than conventional radiography. CT may be more sensitive than PFT in detecting mild emphysema.(ABSTRACT TRUNCATED AT 250 WORDS)     

Chronic tuberculous empyema: relationships between preoperative CT findings and postoperative improvement measured by pulmonary function testing

AIMS: To evaluate whether preoperative computed tomography (CT) findings correlate with postoperative improvements in forced vital capacity (FVC) and forced expiratory volume during 1s (FEV1) in persons who have undergone unilateral decortication because of unilateral chronic tuberculous empyema. METHODS: A retrospective study was carried out of 67 individuals who had undergone decortication because of chronic tuberculous empyema between January 1996 and December 2000. Of these, 13 subjects who had had preoperative chest CT and preoperative and postoperative pulmonary function tests (PFTs) were included in the investigation. On preoperative CT, the degree of volume reduction of the affected side was compared with that of the contralateral normal lung. The relative volume of empyema was calculated by dividing the volume occupied by the empyema by the sum of the total volume of the ipsilateral lung and the empyema volume. The thicknesses of pleura and extrapleural fat in the involved hemithorax were measured by CT at their thickest points, and the degree of atelectasis adjacent to the empyema in the diseased lung was assessed and classified. These five CT parameters and the ages of the patients were compared with preoperative and postoperative FVC and FEV1 changes. RESULTS: A significant negative correlation was found between FVC changes and the relative volume of the affected lung (FVC: p = 0.039, RS = -0.58). FVC and FEV1 were found to be significantly and positively correlated with the relative volume of the empyema (FVC: p = 0.005, RS = 0.72; FEV1: p = 0.014, RS = 0.66) and the degree of atelectasis (FVC: p = 0.007, RS = 0.71; FEV1: p = 0.029, RS = 0.60) by Spearman's nonparametric correlation test. Other CT parameters and the ages of the patients were not found to be correlated with PFT changes. CONCLUSION: The relative volume of the affected side, the relative volume of empyema and the degree of atelectasis can predict improvements in FVC and FEV1 after decortication in patients with chronic tuberculous empyema.     

Automatic evaluation of total lung capacity and of emphysema involvement with spiral computerized tomography (CT) in obstructive pneumonia

OBJECTIVE: To evaluate, in patients with chronic obstructive lung disease or chronic bronchitis, inspiratory helical CT with 3D postprocessing, to measure lung volumes and the amount of emphysema and to compare these measurements with lung function tests. MATERIAL AND METHODS: Seventeen patients with chronic obstructive lung disease disease or chronic bronchitis underwent pulmonary function tests and helical CT after a full inspiration with 3D postprocessing (lower threshold -1024 HU, upper thresholds -200, -300 and -400 HU). Lung inspiratory volumes (TLC-CT) were determined for each model; the amount of emphysema was evaluated by means of an automatic score and a visual score with HRCT. RESULTS: There is a good correlation between automatic and visual scores (p < 0.001); the automatic score had a good correlation with lung function tests, above all with total lung capacity (r = -0.56; p = 0.01) but the visual score had a much closer correlation with DLCO (r = -0.70; p < 0.001). TLC-CT had a significant correlation with pletismographic TLC (TLC-P); the upper threshold -200 HU was more correct (TLC-P = 8011 cc.; TLC-CT 200 = 7138 cc.; r = 0.83; p < 0.001). The volume change of 3D model was about 230 cc. per 100 HU (p < 0.001) modifying upper thresholds, but no change was observed in the volume occupied by emphysema and the percentage of emphysema presented minimal, clinically non significant modifications. DISCUSSION AND CONCLUSIONS: In emphysematous patients, the helical CT with 3D model construction is a good technique to evaluate lung volumes and to quantify emphysema with automatic score; this one, however, probably underscores the extent of pathology; therefore, the addition of a visual score with HRCT is probably worthwhile.     

Quantitative assessment of peripheral airway obstruction on paired expiratory/inspiratory thin-section computed tomography in chronic obstructive pulmonary disease with emphysema

OBJECTIVES: We examined the hypothesis that paired inspiratory/expiratory computed tomography (CT) scans in a limited-lung area that excludes emphysema may provide a more accurate evaluation of peripheral airway obstruction in patients with chronic obstructive pulmonary disease (COPD) with emphysema. MATERIALS AND METHODS: This study included 32 patients with COPD. The cross-sectional area between -500 and -1024 HU was segmented as whole-lung. The relative areas (RA) less than -950 HU for the whole-lung (RA<-950) were segmented as emphysema, and pixels less than -900 HU for the whole-lung (RA<-900) were segmented to evaluate air trapping. Next, the cross-sectional area between -500 and -950 HU that excludes emphysema was segmented as limited-lung, and pixels between -900 and -950 HU for the limited-lung (RA900-950) were segmented. The changes in RA<-900 (RA<-900-change) and RA900-950 (RA900-950-change) between inspiration and expiration were calculated. Correlations between CT measurements and the results of pulmonary function tests (PFT) were evaluated. RESULTS: There was no significant difference between the mean inspiratory RA<-950 and expiratory RA<-950 (P = 0.245), but the mean expiratory RA900-950 decreased significantly compared with the mean inspiratory RA900-950 (P < 0.001). The correlation coefficients between PFT parameters and the RA900-900-change in the limited-lung without emphysema were higher than that of the RA<-900-change in the whole-lung. CONCLUSIONS: The paired inspiratory/expiratory CT measurements in the limited-lung without emphysema correlated more closely with the PFTs. Our observations suggest that paired inspiratory/expiratory CT scans in the limited-lung excluding emphysema are sensitive for the evaluation of airway obstruction in COPD with emphysema.     

COPD患者肺气肿程度对气道径线与肺功能相关性的影响

目的：定量分析肺气肿程度对气道径线及其与肺功能相关性的影响。方法对73例慢性阻塞性肺疾病(COPD)患者行呼气相 CT 扫描,测量肺气肿指数(LAA%)以及右肺上叶尖段(RB1)、右肺下叶后基底段(RB10)、左肺上叶尖后段(LB1)、左肺下叶后基底段(LB10)亚段支气管的气道径线,包括管壁厚度(WT),管壁厚度/气道直径(WT/AD),管壁面积比值(WA%);以 LAA%=15%为界限,将 COPD 患者分为2组,即轻度肺气肿组(34例)和重度肺气肿组(39例)。分别比较不同亚段支气管的轻度、重度肺气肿组 WA%、WT/AD、WT 与 FEV1%的相关性。结果除外 RB10亚段支气管的轻度肺气肿组中 WT 及重度肺气肿组的气道径线与 FEV1%无明显相关(P >0.05),其余各亚段支气管(RB1,LB1,LB10)的轻度肺气肿组气道径线指标与 FEV1%均呈负相关(r=-0.382~-0.799,P <0.05),均优于重度肺气肿组(r =-0.371~-0.687,P <0.05)。RB1、LB1、LB10气道径线均与FEV1%呈负相关,其中 RB1的气道径线与 FEV1%相关性最好;各亚段支气管中轻度肺气肿组气道径线与 FEV1%的相关性均优于重度肺气肿组。结论肺气肿的严重程度会影响气道径线与气流受限的相关性,在 COPD 患者的 CT 定量研究中,需将这一相互影响的过程考虑入内。     

慢性阻塞性肺部疾病的电子束CT动态扫描

目的评价慢性阻塞性肺部疾病（ＣＯＰＤ）在肺部电子束ＣＴ（ＥＢＣＴ）动态扫描时的表现。材料与方法对３２例临床和肺功能检查确诊的ＣＯＰＤ病人及正常对照组２４例健康男性，使用ＥＢＣＴ分别进行了不同呼吸时相的连续容积模式扫描，将全肺等分为上、中、下三个肺区后测量和计算肺野密度和体积值，以及像素值＜－９００ＨＵ的肺区所占比例，即像素指数（ＰＩ）。对两组的结果作了比较。结果ＣＯＰＤ组在深吸气末的ＣＴ值与正常组相似，分别为－８１９ＨＵ和－８１６ＨＵ，但在深呼气末时则明显低于正常组（分别为－７５１ＨＵ和－６１９ＨＵ），吸、呼气间的差值两组分别为６８ＨＵ和１９７ＨＵ。在呼气ＣＴ上ＣＯＰＤ组体积仅缩少２５．９０％，为正常组（５４．９０％）的一半，ＣＯＰＤ组呼气ＣＴ上８７．５０％检出了＜－９００ＨＵ的像素，其ＰＩ值平均为１０．７６％，正常组仅４例（１６．６７％），平均ＰＩ值为０．１２％。上述表现提示ＣＯＰＤ患者中多数有空气贮留。结论ＣＯＰＤ患者较正常人有明显的空气贮留，可用肺部动态ＣＴ扫描加以诊断和定量，后者是一种可取的，有发展前途的检查方法。     

慢性阻塞性肺疾病各中医证型的CT肺功能评估及临床肺功能检查参数分析

目的:对慢性阻塞性肺疾病(COPD)患者行CT肺功能评估,探究其与肺功能检查的相关性,并分析比较COPD各中医证型的肺功能参数与CT肺功能评估结果,为COPD中医辨证提供参考依据。方法:根据COPD中医诊断标准对其进行分型,完成肺功能、CT检查,并对CT图像进行三维重建,计算肺气肿指数(LAA%)。结果:痰浊壅肺证、痰热蕴肺证、痰瘀阻肺证、肺肾气虚证之间第1秒用力呼气容积占预计值百分比(FEV1占预计值%)及第1秒用力呼气容积占用力肺活量的百分比(FEV1/FVC%)比较差异均有统计学意义(均P<0.01),FEV1占预计值%、FEV1/FVC%由痰浊壅肺证→痰热蕴肺证→痰瘀阻肺证→肺肾气虚证逐渐变小;LAA%由痰浊壅肺证→痰热蕴肺证→痰瘀阻肺证→肺肾气虚证逐渐增大。LAA%与FEV1占预计值%呈负相关(r=-0.775,P=0.001);LAA%与FEV1/FVC%呈负相关(r=-0.458,P=0.001)。结论:CT肺功能评估与临床肺功能检查之间呈负相关,随着肺通气功能的降低,COPD患者的LAA%随之升高,说明CT评估肺功能是可行的。COPD各中医证型之间LAA%、肺功能参数存在差异,可为COPD辨证分型提供一定的参考价值。     

CT attenuation of paired HRCT scans obtained at full inspiratory/expiratory position: comparison with pulmonary function tests

The purpose of this prospective study was to measure lung attenuation at paired HRCT obtained at full inspiratory/expiratory position, to correlate with pulmonary function tests (PFTs) and to characterize different types of ventilatory impairment. One hundred fifty-five patients with and without pulmonary disease underwent paired HRCT obtained at full inspiratory/expiratory position. Three scan pairs were evaluated by densito- and planimetry using dedicated software. The PFTs were available for correlation in all patients (mean interval 5 days). Mean lung density (MLD) at full inspiration was –813 HU, and MLD at full expiration was –736 HU; both, as well as the expiratory attenuation increase, demonstrated significant correlations with static and dynamic lung volumes: up to r=0.68, p<0.05 for residual volume. The MLD and emphysema indices correlated markedly better for scans obtained at full expiration than at full inspiration, e.g. correlation with the residual volume: r=0.68 compared with r=0.55. Even better correlations were obtained for the lung area (229 cm² at inspiration, 190 cm² at expiration), up to r=0.74 for the lung area in expiration and the intrathoracic gas volume. Inspiratory MLD and the expiratory attenuation increase were able to differentiate obstructive and restrictive ventilatory impairment from normal subjects, the best results were obtained from scans obtained at full expiratory position (p<0.05). In conclusion, scans obtained at full expiratory position reveal more functional information than scans obtained at full inspiratory position. Quantitative analysis of CT obtained at full expiratory position provides good estimations of static and dynamic lung volumes as well as significant differences between normal subjects and patients with ventilatory impairment. Electronic Publication     

MDCT assessment of lung volume in patients undergoing bronchial stenting for treatment of pulmonary emphysema: correlation with respiratory tests and personal experience

PURPOSE: The aid of this study was to evaluate lung volume reduction with multidetector-row computed tomography (MDCT) in patients with emphysema who have undergone endobronchial valve placement. MATERIALS AND METHODS: Nine patients with emphysema were studied by low-dose chest MDCT (64-slice Somatom Sensation Cardiac, Siemens) with a collimation of 64 x 0.6 mm and a slice thickness of 1 mm. After treatment, MDCT scans were repeated at 7 and 30 days. A single observer calculated the volume of the treated lobe and of both lungs on a dedicated console. Volume calculations were then compared with the results of lung function tests. RESULTS: Four patients in whom MDCT showed severe emphysema of the right upper lobe (RUL) were selected for endobronchial valve insertion. Volume assessment at 30 days showed a 29% reduction in RUL volume in patient A, a 15% reduction in patient B, a <1% reduction in patient C and a 30% reduction in patient D. Correlation with lung function tests confirmed a major reduction of forced expiratory volume in 1 s (FEV(1)) and vital capacity (VC) and improved walking test results after 7 and 30 days. CONCLUSIONS: In patients undergoing endobronchial valve placement, MDCT with dedicated software allows for a better evaluation of volume reduction of a single lobe and of the whole lung.     

New Method for Combined Quantitative Assessment of Air-Trapping and Emphysema on Chest Computed Tomography in Chronic Obstructive Pulmonary Disease: Comparison with Parametric Response Mapping

ObjectiveEmphysema and small-airway disease are the two major components of chronic obstructive pulmonary disease (COPD). We propose a novel method of quantitative computed tomography (CT) emphysema air-trapping composite (EAtC) mapping to assess each COPD component. We analyzed the potential use of this method for assessing lung function in patients with COPD.Materials and MethodsA total of 584 patients with COPD underwent inspiration and expiration CTs. Using pairwise analysis of inspiration and expiration CTs with non-rigid registration, EAtC mapping classified lung parenchyma into three areas: Normal, functional air trapping (fAT), and emphysema (Emph). We defined fAT as the area with a density change of less than 60 Hounsfield units (HU) between inspiration and expiration CTs among areas with a density less than −856 HU on inspiration CT. The volume fraction of each area was compared with clinical parameters and pulmonary function tests (PFTs). The results were compared with those of parametric response mapping (PRM) analysis.ResultsThe relative volumes of the EAtC classes differed according to the Global Initiative for Chronic Obstructive Lung Disease stages (p < 0.001). Each class showed moderate correlations with forced expiratory volume in 1 second (FEV₁) and FEV₁/forced vital capacity (FVC) (r = −0.659–0.674, p < 0.001). Both fAT and Emph were significant predictors of FEV₁ and FEV₁/FVC (R² = 0.352 and 0.488, respectively; p < 0.001). fAT was a significant predictor of mean forced expiratory flow between 25% and 75% and residual volume/total vital capacity (R² = 0.264 and 0.233, respectively; p < 0.001), while Emph and age were significant predictors of carbon monoxide diffusing capacity (R² = 0.303; p < 0.001). fAT showed better correlations with PFTs than with small-airway disease on PRM.ConclusionThe proposed quantitative CT EAtC mapping provides comprehensive lung functional information on each disease component of COPD, which may serve as an imaging biomarker of lung function.     

CT定量分析COPD患者气流受限的影响因素

目的 比较肺气肿及支气管壁厚度对慢性阻塞性肺疾病(COPD)患者气流受限影响的相关性.方法 40例COPD患者为观察组及40健康者为对照组,同期接受肺功能检查后行吸气相MSCT检查.应用Thoracic VCAR软件测量观察组及对照组肺野内支气管管腔面积为8 mm2的管壁面积的平方根(Ai8).同时测量肺气肿患者全肺及各个肺叶肺气肿区域百分比(LAV%).用SPSS2.2统计学软件分析观察组与对照组Ai8.比较观察组全肺及各个肺叶LAV%及Ai8对肺气流受限指标第1秒用力呼气量实测值与预测值的百分比(FEV1%)及第1秒用力呼气量/用力肺活量(FEV1/FVC)的相关性.结果 观察组与对照组Ai8有明显统计学差异.气流受限指标与全肺LAV%和全肺Ai8都有相关性(P<0.05).在各肺叶中,仅右肺下叶的Ai8与气流受限指标有较强相关性.各个肺叶的LAV%对气流受限指标的相关性均大于右肺下叶Ai8.结论 观察组与对照组Ai8有明显统计学差异.LAV%和Ai8都会独立影响气流受限指标;LAV%对COPD患者气流受限的影响大于Ai8, 其顺序为LAV%>右肺下叶Ai8>其他肺叶Ai8.     

Silicosis in 76 men: qualitative and quantitative CT evaluation--clinical-radiologic correlation study

PURPOSE: To use qualitative and quantitative computed tomography (CT) to test the hypothesis that impaired lung function with silicosis is due to progressive massive fibrosis (PMF) and associated emphysema. MATERIALS AND METHODS: Seventy-six men with silicosis underwent volumetric and thin-section CT of the thorax. Lung function, Borg scale dyspnea grade, silica exposure duration, and cigarette consumption were determined. Nodular profusion (NP) at chest radiography was graded according to the International Labor Organization radiographic classification system; NP and PMF at CT were visually graded by using five-point (ie, grades 0-4) and four-point (grades 0-3) scales, respectively. Emphysema and NP, which together are defined as the NP index, were quantified by using attenuation threshold values of less than -950 HU and greater than -100 HU, respectively. Mean lung attenuation was also determined. Relationships among the CT, chest radiographic, and clinical parameters were analyzed by using Spearman correlation. RESULTS: NP at chest radiography correlated (r > 0.50) with all CT parameters of nodularity. CT PMF had the highest correlation with emphysema (r = 0.58, P <.001). NP at chest radiography and all CT parameters were inversely related to lung function. At multiple regression analysis, PMF and emphysema index (both at CT) were significant determinants of forced expiratory volume in 1 second (FEV1) (P =.006 and.03, respectively) and FEV1 to forced vital capacity (FVC) ratio (P =.007 and.02, respectively). Mean lung attenuation remained related to FVC (P =.03), diffusing capacity of lung for carbon monoxide (P =.04), and Borg scale grade (P =.01). Cigarette consumption and silica exposure duration had no independent effects on lung function. CONCLUSION: Qualitative and quantitative CT parameters can be used as indirect measures of functional impairment in silicosis. PMF and emphysema are independently related to airflow obstruction, whereas mean lung attenuation is related to clinical dyspnea and reduced lung volume.     

周围型肺癌阻塞性病变的CT表现(附18例分析)

目的:确定深呼吸时相CT扫描对周围型肺癌诊断敏感性。材料与方法:18例周围型肺癌(13例经病理证实,5例由其它方法证实)和12例良性肺肿块对照者(炎性假瘤和结核球等)均经常规CT扫描,除2例炎性假瘤患者外,其余所有病人并经肿块部位及其上下一层的深呼吸时相CT扫描。结果:周围型肺癌深呼吸时相CT扫描所见的阻塞性病变计有4例肺不张,12例阻塞性肺炎(按其帮位进而可分为远离肿块的和邻近肿块的阻塞性肺炎),1例阻塞性肺气肿,以及1例肺静脉癌栓。周围型肺癌的这些CT表现,在良性肺肿块对照者中不复被看到。结论:深呼吸时相CT扫描所见的远离肿块的阻塞性肺炎及肿块外侧的阻塞性肺气肿,可被看作是周围型肺癌的特有表现而且是其早期诊断的依据。