Role of the chest radiography, spirometry, and high resolution computed tomography in the early diagnosis of the emphysema

The Egyptian Journal of Radiology and Nuclear Medicine (2010) 41, 509 515 Egyptian Society of Radiology and Nuclear Medicine The Egyptian Journal of Radiology and Nuclear Medicine www.elsevier.com/locate/ejrnm www.sciencedirect.com Role of the chest radiography, spirometry, and high resolution computed tomography in the early diagnosis of the emphysema Mohammed Mostafa Sayed Mostafa * Radiodiagnosis Department, Faculty of Medicine, Al-Azhar University, Al-Azhar, Egypt Received 16 August 2010; accepted 5 October 2010 Available online 9 December 2010 KEYWORDS High resolution computed tomography (HRCT); Forced expiratory volume in the first second (FEV1) in liters/second; Forced vital capacity (FVC) in liters/second; Forced expiratory volume in the first second/forced vital capacity% (FEV1/FVC%); Chronic obstructive pulmonary disease (COPD); Global initiative for chronic obstructive lung disease (GOLD); Emphysema Abstract Purpose: This study was performed to evaluate the role of the chest radiography pulmonary function tests, and HRCT in the early diagnosis of the emphysema. Materials and methods: The study included 50 patients who had emphysema. Average age varies between 40 and 60 years. All patients were subjected to full history, clinical examination, laboratory investigations, cardiac investigations, chest radiography, pulmonary function tests and HRCT. Results: I found high sensitivity of the HRCT in the early diagnosis of emphysema if compared with sensitivity of the chest radiography and pulmonary function tests. Conclusions: HRCT has much greater sensitivity than chest radiography in early diagnosing of emphysema. HRCT is also capable of differentiating between the various types of emphysema and assessing its severity. The presence of emphysema can be suspected on chest radiography but this is not a sensitive technique for diagnosis. Also the chest radiography is not a very good indicator for the severity of disease. In addition a precise characterization of the emphysema by HRCT is desirable for adequate therapy and monitoring as well as preoperative assessment of the patient before surgical treatment of emphysema. Compared to spirometry, HRCT shows regional assessment of compartments involved (airways, parenchyma and vasculature). Moreover spirometry has no definite sensitivity. Ó 2010 Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier B.V. All rights reserved. * Mobile: +20 0101966850. E-mail address: dr_mohamed_mos@yahoo.com 0378-603X Ó 2010 Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier B.V. Open access under CC BY-NC-ND license. Peer review under responsibility of Egyptian Society of Radiology and Nuclear Medicine. doi:10.1016/j.ejrnm.2010.10.007 Production and hosting by Elsevier 1. Introduction Pulmonary emphysema is a pathological term and is defined by the American Thoracic Society as an abnormal permanent enlargement of the air spaces distal to the terminal bronchiole, accompanied by the destruction of their walls (42). In a simplified way, obstructive air low limitation leads to air trapping with subsequent hyperinflation and later destruction of the lung parenchyma (1). Emphysema is one of the COPD. The etiology of pulmonary emphysema has not been fully established, but the prevailing concept is that lung inflammation

510 M.M.S. Mostafa is caused by cigarette smoke, environmental pollutants, or bacterial products (2). The diagnosis of emphysema is conventionally based upon spirometry, but during the early stage of the disease, conventional spirometry may reveal no abnormality (3). In particular, HRCT is an available tool for demonstrating the pathology of emphysema, even in subtle changes within secondary pulmonary lobules (4). 2. Patients and methods 2.1. Patients This study was performed at Chest and Radiology Departments, New Dammietta Hospital, Al Azhar University at the period from December 2008 to February 2010. The study was conducted on 50 patients (50 males). Their ages ranged from 40 to 60 years presenting to the out patients clinic chest department. 2.2. Methods All the patients were subjected to the following: (A) History including: Personal history, occupation and special habits (smoking history was obtained and cumulative pack years of exposure were calculated). History of dyspnea that was irreversible air flow limitation (post-inhalation bronchodilator FEV1 less than 80% of the predicted value in combination with FEV1/FVC not more than 70% of the predicted value). They had an increase in FEV1 less than 200 ml or less than 12% of the baseline value 20 min after inhalation bronchodilator in accordance with the GOLD guidelines. (B) Exclusion criteria: Patients with one of the following criteria were excluded from the study: the patients who had bronchiectasis, cystic disease, TB, chest infection, bronchial asthma, interstitial lung disease, chest tumour, previous thoracotomy, coronary and cerebral diseases, as well as patients with past history of DM, sarcoidosis and uremia. (C) Clinical examination: General and local examinations. (D) Laboratory investigations: Routine laboratory investigations as CBC, blood sugar, liver and renal functions tests. (E) Cardiac investigations: ECG and echocardiography. (F) Chest radiography: Posterior anterior and left lateral views. (G) Pulmonary function tests: We do pulmonary function tests before and 20 min after inhalation of bronchodilator (three trials were done and the best were taken)and the following data recorded: Forced expiratory volume in the first second (FEV1) in liters/second. Forced vital capacity (FVC) in liters/second. Forced expiratory volume in the first second/forced vital capacity% (FEV1/FVC%). (H) High resolution CT: All scans were obtained by using a CT Hi speed advantage scanner (SIEMENS) Somatom. HRCT scanning without contrast was done at full inspiration with 1 mm collimation at (120 KVP, 200 MAS), matrix size of 512 512, scans were taken at 10 mm interval with window setting appropriate for the lungs (widow level from 700 to 900 HU, width from 800 to1000 HU). The following features were evaluated using HRCT: 3. Results 1. Tracheal index: A ration of transverse to anteroposterior diameter at a plane 1 cm above the aortic arch. Saber sheath trachea was described as when the tracheal index was less than 2/3. 2. Thoracic cage ratio: A ration antero-posterior to transverse diameter. It was evaluated at two planes: (A) carina and (B) 5 cm below carina. 3. Sterno-aortic distance: Distance from posterior surface of the sternum to anterior margin of the aortic at carinal level. 4. Thoracic cross sectional area: Thoracic cross sectional area was measured on HRCT images made 1 cm below the top of aortic arch. The ratio of TCSA to the square of height (TCSA/height 2 ) was calculated for each patient. 5. Vascular attenuation: Vascular attenuation was considered when there was thinning of pulmonary vessels and reduction in their number. 6. Vascular distortion: Vascular distortion was considered as increased angles and/or excessive straightening of pulmonary vessels. 7. Mosaic attenuation pattern: Mosaic attenuation mean non homogenous lung density, the latter was described as areas that remain relatively lucent interspersed with areas of normal or higher lung density. 8. Direct visible small airways: The airways with internal diameter not more than 2 mm. This study includes 50 patients of emphysema. There were 50 males. The patients characteristics were as shown in Table 1. Their age ranged from 40 to 60 years (mean 52.34 ± 633). The duration of the disease ranged from 3 to 23 years (mean 18.76 ± 5.49). The dyspnea scale ranged from 1 to 5 years (mean 2.78 ± 1.282). The smoking pack years ranged from 10 to 50 years (mean 35 ± 14.743). Table 1 also shows the quantitative HRCT features. The tracheal index (1 cm above aortic arch) ranged from 0.45 to 0.93 (mean 0.696 ± 0.143). The thoracic cage ratio at carina ranged from 62.15 to 79.12 (mean 70.657 ± 6.58). The thoracic cage ratio at 5 cm below carina ranged from 63.8 to 85.1 (mean 73.988 ± 7.773). The sterno aortic distance at carinal level (cm) ranged from 1.45 to 4.9 (mean 3.898 ± 0.9507). The thoracic cross sectional area 1 cm below the top of aortic arch ranged from 62.1 to 105.1 (mean 89.272 ± 14.423). The lung function tests are shown in Table 2. The baseline FEVI ranged from 0.4 to 10.3 l/s (mean 2.3339 ± 2.455) pre-inhalation bronchodilator and ranged from 0.5 to 5.1 l/s (mean 1.926 ± 1.317) post-inhalation bronchodilator. The baseline FVC ranged from 1 to 6.1 l/s (mean 2.570 ± 1.357) pre-inhalation bronchodilator and ranged from 1 to 6.3 (mean 2.784 ± 1.319) post-inhalation bronchodilator. The baseline FEVI/FVC ratio ranged from 38% to

Role of the chest radiography, spirometry, and highresolution computed tomography 511 Table 1 Patient characteristics (No. of patients 50). Parameter Minimum Maximum Mean SD Age in years 40 60 52.34 6.33 Duration of disease 3 23 18.76 5.49 Dyspnea scale 1 5 2.78 1.282 Pack years of cigarette smoking 10 50 35 14.743 Tracheal index (1 cm above aortic arch) 0.45 0.93 0.696 0.143 Thoracic cage ratio at carina 62.15 79.12 70.657 6.58 Thoracic cage ratio at 5 cm below carina 63.8 85.1 73.988 7.773 Sterno aortic distance at carinal level (cm) 1.45 4.9 3.898 0.9507 Thoracic cross sectional area 1 cm below the top of aortic arch 62.1 105.1 89.272 14.423 Table 2 Pulmonary function tests (No. of patients 50). Baseline FEV1 L/S Paired t-test Range Mean ± SD t P-value FEV1 L/S Pre-inhalation bronchodilator 0.4 10.3 2.339 ± 2.455 Post-inhalation bronchodilator 0.5 5.1 1.926 ± 1.317 1.332 0.189 Predicted FEV1 L/S Pre-inhalation bronchodilator 16.0 119.0 53.400 ± 29.107 Post-inhalation bronchodilator 20.0 120.0 58.540 ± 28.414 9.416 0.000 FVC L/S Baseline FVC L/S Pre-inhalation bronchodilator 1.0 6.1 2.570 ± 1.357 Post-inhalation bronchodilator 1.0 6.3 2.784 ± 1.319 8.359 0.000 Predicted FVC L/S Pre-inhalation bronchodilator 30.0 115.0 62.880 ± 21.473 Post-inhalation bronchodilator 39.0 118.0 68.940 ± 19.999 8.441 0.000 FEV1/FVC% Baseline FEV1/FVC% Pre-inhalation bronchodilator 38.0 88.0 63.300 ± 13.737 Post-inhalation bronchodilator 47.0 90.0 66.864 ± 11.722 5.824 0.000 88% (mean 63.3 ± 13.737) pre-inhalation bronchodilator and ranged from 47% to 90% (mean 66.864 ± 11.722) post-inhalation bronchodilator. In our study the sensitivity of the chest radiography in the early diagnosis of the emphysema was 40%. In our study the sensitivity of the spirometry in early diagnosis of the emphysema was 80%. In our study the sensitivity of the HRCT in early diagnosis of the emphysema was 100%. The HRCT features in individual patients were as shown in (Table 3). The tracheal index was less than 0.67% and was found in 27 patients (54%). Abnormal thoracic cage ratio was more common at 5 cm below carina and was found in 27 patients (54%) than at carina in 22 patients (44%). Sterno aortic distance 4 cm or more was found in 33 patients (66%). A large ratio of thoracic cross sectional area/height 2 was presented in 38 patients (76%). Direct visible small airways was the most common finding that was presented in 38 patients (76%) followed by vascular attenuation in 27 patients (54%), mosaic attenuation pattern in 18 patients (36%) and vascular distortion in 10 patients (20%). Among the four types of emphysema, centriacinar emphysema was observed most frequently in 16 patients (32%), panacinar emphysema in 10 Table 3 HRCT features in individual patients (No. of patients 50). HRCT features No. of patients Percentage of patients (%) Tracheal index <0.67 27 54 Thoracic cage ratio at carina 22 44 >0.75 Thoracic cage ratio at 5 cm below 27 54 carina >0.75 Sterno aortic distance 64cm 33 66 Thoracic cross sectional area/ 38 76 height 2 >80cm 2 /m 2 Vascular attenuation 27 54 Vascular distortion 10 20 Mosaic attenuation pattern 18 36 Directly visible small airways 38 76 Centriacinar emphysema 16 32 Panacinar emphysema 10 20 Distal acinar emphysema 7 14 All types of emphysema 17 34 Associated chronic bronchitis 15 30

512 M.M.S. Mostafa Table 4 Chest radiographic features in individual patients (No. of patients 50). Chest radiographic features patients (20%), distal acinar emphysema in 7 patients (14%). All of above types of emphysema was presented in 17 patients (34%). In our study, the emphysema was associated with chronic bronchitis in 15 patients (30%). The chest radiographic features in individual patients were as shown in (Table 4). The posterior anterior view shows low flat diaphragm, hyperinflated lungs, attenuated peripheral blood vessels and tubular heart. Lateral view shows large retrosternal space and barrel chest. All those manifestations were presented in 20 patients (40%) of all the cases. In addition all these patients have been shown manifestations of emphysema on HRCT. 4. Discussion No. of patients Low flat diaphragm in P.A. view 2 4 Hyperinflated lungs in P.A. view 2 4 Attenuated peripheral blood 1 2 vessels in P.A. view Tubular heart in P.A. view 2 4 Large retrosternal space in lateral view 3 6 Barrel chest in lateral view 3 6 All of above features in 7 14 P.A. and lateral views Total 20 40 Percentage of patients (%) Regarding patient sex all patients in our study are males. This result was in agreement with Wang et al. (5) who found that the prevalence of emphysema was higher in man than in women and that when present it was more severe among man. Regarding pack years of cigarette smoking and the severity of CT emphysema Mark et al. (6) found a distinct correlation between smoking and the prevalence of emphysema, indexes of smoke exposure did not correlate with the extent of CT abnormalities. Gillooly and Lamb (7) also reported no correlation between smoking habits and the extent of microscopic emphysema. In our study, the correlation between HRCT and spirometry in the early diagnosis of the emphysema is considered moderate. Nakano et al. (8) reported that an effort has been made to correlate HRCT of emphysema as well as airway abnormalities with spirometry that are moderate. Cerveri et al. (9) showed that lung function tests are a better predictor of emphysema as measured by HRCT scans explaining 71% of the variability in its extent. Nakano et al. (10) and Fishman et al. (11) mentioned emerging data that suggest that CT localization of emphysema can be used to predict the response to lung volume reduction surgery and to help select candidates for the procedure. COPD Guidelines Group (12) also mentioned emphysema is a pathological diagnosis. The diagnosis of emphysema during life is based on a combination of clinical, functional and radiological findings, but this is a combination that is insensitive to mild emphysema. The functional hall mark of emphysema is decreased airflow at spirometry, but patients may have up to 30% of their lung involved with emphysema and have no evidence of functional impairment. Gold (3) also mentioned that during the early stage of the COPD conventional spirometry may reveal no abnormality as the earliest changes affect the alveolar walls and small airways. Muller (13) mentioned that emphysema can involve 30% of the lung parenchyma without air flow obstruction being present. In our study, tracheal index <0.67% Case 5 was presented in 27 patients (54%). Trigaux et al. (14) mentioned that saber sheath trachea is a basically a sign of hyperinflation. Trigaux et al. (15) also found that saber sheath trachea was established as a specific radiographic diagnostic parameter in the diagnosis of emphysema specificity (92.95), although the sensitivity (39.1%) was low. I found saber sheath trachea in 27 patients, sensitivity (54%). In our study, stern aortic distance 64 cm was presented in 33 patients (66%). Hagen and Kolbenstvedt (16) reported that stern aortic distance was measured in CT sections at the carinal level if 4 cm or more is characteristic for emphysema. In our study, the main vascular abnormalities were seen to include vascular attenuation and distortion Case 6. Szilasi et al. (17) reported that the pulmonary arteries show intimal thickening, smooth muscle hypertrophy and inflammation finally leading to vascular remodeling. Crofton and Douglas (18) also mentioned the vascular changes associated with emphysema include, reduction in size and number of pulmonary vessels particular at the peripheral third of lung zone, vessel distortion producing increased branching angles, excess straightening or bowing of vessels and areas of low attenuation. Kalender (19) additionally noted attenuation and pruning of the vascular tree and abnormal vascular configurations are seen in emphysema. Rosenkranz (20) also mentioned that the direct vascular changes and hyperinflation lead to the pre-capillary type of pulmonary hypertension. In our study, vascular distortion was presented in advanced cases of the emphysema. Mac Nee et al. (21) mentioned that vascular distortion is present in very advanced cases of emphysema and in those with severely deranged pulmonary functions. In our study, mosaic attenuation pattern is present in only 18 patients (36%). Arakawa and Webb (22) mentioned that mosaic attenuation is more pronounced on scans obtained at end expiration compared to that found at end inspiration. This is the probable reason for detection of mosaic attenuation pattern in only 18 patients (36%). Copley et al. (23) mentioned that mosaic attenuation pattern in association with other HRCT features is observed to be helpful in distinguishing different disease entities grouped under COPD. As regarding air way abnormality, (Case 4) in our study, directly visible small airways were observed as the most prevalent HRCT features of 38 patients (76%). Vignola et al. (24) reported that HRCT has allowed the demonstration of several airway wall abnormalities, whose extent significantly correlated with the clinical severity of the disease. Tell et al. (25) mentioned that despite a decreased radius of small airways, air flow resistance is not significantly increased because of the large number of these peripheral bronchioles. Hence not worth disease must be present at the level of peripheral airways, to be detected on pulmonary function tests. Here HRCT scan play an infallible role in a diagnosis of involvement of small airways. Reilly (26) mentioned that the HRCT has allowed for greater definition of both parenchymal and airway abnormalities in emphysema. In our study, all types of emphysema were presented in 17 patients (34%) among these the centriacinar emphysema (Case 1) is the comments type of emphysema which was presented in 16 patients (32%) and is involved in the upper lobes.

Role of the chest radiography, spirometry, and highresolution computed tomography 513 Case 1 Axial HRCT image in patient with centriacinar emphysema in the upper lobe shows multiple round lucent areas of various sizes surrounded by normal parenchyma. Case 3 Axial HRCT image in patient with centriacinar emphysema in the right upper lobe shows emphysematous bulla at the medial posterior aspect and small distal acinar emphysema at the lateral aspect. Case 2 Axial HRCT image in patient with panacinar emphysema in the upper lobe shows diffuse low attenuation the lung field. These results were in agreement with Takahashi Masashi et al. (4) who reported that centriacinar emphysema is the comments type of pulmonary emphysema and with the Wright (27) who mentioned that type is more common in the upper lung zones of the upper and lower lobes. In our study, panacinar emphysema (Case 2) was presented in 10 patients (20%) and is involved in the lower lobes. Lamb (28) mentioned that this type of emphysema is more prominent at the bases. Copley et al. (29) also mentioned the same previous two results. In our study, distal acinar emphysema Case 3 was presented in 7 patients (14%) and is involved the upper lobes and is the less common type of emphysema. Thurlback (30) mentioned that this type of emphysema is less common than centriacinar or panacinar emphysema and is usually of little clinical significant except when it occurs extensively in subpleural position and may be associated with pneumothorax. Lesur et al. (31) mentioned that this type of emphysema is usually limited in extent, occurs most commonly along the dorsal surface of the upper lung. In our study, bulbous emphysema (Case 3) is seen associated with distal acinar and centriacinar emphysema. Richard Case 4 Axial HRCT image in patient with centriacinar emphysema in the right upper lobe shows thickening of the bronchial wall and mild narrowing of the lumen (arrow). Webb et al. (32) mentioned that bullae are most common with distal acinar and centriacinar emphysema. Snider (33) CT allows for an assessment not only of the extent of bulbous disease but also the degree of compression and the severity of emphysema in the remaining lung parenchyma. As regarding the last type of emphysema scare or irregular emphysema no cases could be detected. In our study, the emphysema was associated with chronic bronchitis in 15 patients (30%). Muller and Thurlbeck (34) mentioned that partially the lack of close

514 M.M.S. Mostafa Case 5 Axial HRCT image in patient with centriacinar emphysema in the upper lobes show Saber sheath trachea sagittal and coronal diameter of the trachea are illustrated. Tracheal parameters were sagittal diameter, 21.1 mm; coronal diameter, 12.2 mm; tracheal index, 0.58. are normal in 20% or more of cases denoting less sensitivity. Richard Webb (32) mentioned that standard chest radiography and pulmonary function tests are insensitive for the early diagnosis of emphysema. CT is undoubtedly more sensitive than chest radiographs in diagnosis emphysema and in determining its type and extent. HRCT is also advantageous relative to conventional CT. If significant emphysema is found on HRCT, no further evaluation is necessary specifically, lung biopsy is not needed. In a study by Klein et al. (36), the sensitivity of chest radiography in the diagnosis of emphysema was 34%. Thurlbeck et al. (37) and COPD Guide Lines Group (12) mentioned that mild emphysema is difficult to detect on chest radiography. In our study, the sensitivity of the spirometry in early diagnosis of the emphysema was 80%. Hardie et al. (38) mentioned that spirometry is used as a confirmatory test as well as a screening test for COPD, no gold standard exists for comparison to provide precise estimation of sensitivity. In our study, the sensitivity of the HRCT in early diagnosis of the emphysema was 100%. Richard Webb et al. (32) mentioned that in averaging the results of several studies, the sensitivity of the HRCT for detecting emphysema is approximately 94%. Bonelli et al. (39) mentioned that in a retrospective review of HRCT findings in patients who had pathologically proven cystic lung diseases including emphysema the sensitivity of HRCT is 95% in the diagnosis of emphysema. Webb (43) mentioned that HRCT has excellent sensitivity in the diagnosis of COPD. Sanders et al. (40) mentioned that CT is a more sensitive measure of mild emphysema than conventional lung function tests. Gurney et al. (41) studied 59 smokers and found that 40% of the patients had HRCT evidence of emphysema but no functional evidence of emphysema. This showed the sensitivity of HRCT for detecting emphysema. Emphysema in the lower lobes had a better correlation with abnormal pulmonary function tests than did emphysema in the upper lobes. The authors pointed out that upper lobe emphysema is relatively silent. 5. Conclusions Case 6 Axial HRCT image in patient with panacinar emphysema shows vascular distortion characterized by increased branching angles and straightening of pulmonary vessels. correlation between emphysema extent and airways obstruction reflects the fact that emphysema is often associated with chronic bronchitis, which may also contribute to lung function abnormalities in patients who have COPD and is more likely responsible for airways obstruction. In a study by Gevenois et al. (35) using inspiratory and expiratory HRCT, inspiratory scans were found to be most accurate in showing the extent of pathological emphysema, where as expiratory scans correlated best with pulmonary function tests measures of airways obstruction, fact which may be related to the presence of associated airways disease. Richard Webb et al. (32) mentioned that many patients who have emphysema also have chronic bronchitis. In our study chest radiography detected emphysema in 20 patients (40%) so its sensitivity was 40%. Because our study was done for early diagnosis of emphysema chest radiographs show low sensitivity in diagnosis since a positive diagnosis depends on the severity of disease. Muller (13) mentioned that patients who have emphysema chest radiography HRCT has much greater sensitivity than chest radiography in early diagnosing of emphysema. HRCT is also capable of differentiating between the various types of emphysema and assessing its severity. The presence of emphysema can be suspected on chest radiography but this is not a sensitive technique for diagnosis. Also the chest radiography is not a very good indicator for the severity of disease. In addition a precise characterization of the emphysema by HRCT is desirable for adequate therapy and monitoring as well as a preoperative assessment of the patient before surgical treatment of emphysema. Compared to spirometry, HRCT shows the regional assessment of compartments involved (airways, parenchyma and vasculature). Moreover spirometry has no definite sensitivity. References (1) Julia Ley, Zaporozhain Sebastian Ley Hans, Ulrich Kauczor. Morphological and functional imaging in COPD with CT and MRI: present and future. Eur Soc Radiol 2008:510 511. (2) Tuder RM, Yoshida T, Arap W, et al. State of the art. Cellular and molecular mechanisms of alveolar destruction in emphysema: an evolutionary perspective. Proc Am Thorac Soc 2006;3:503 10.

Role of the chest radiography, spirometry, and highresolution computed tomography 515 (3) Gold. Global strategy for the diagnosis, management, and prevention of COPD; 2006 (4) Takahashi Masashi, Fukvoka Junya, Nitta Norihisa, Takazakura Ryutaro, et al. Imaging of pulmonary emphysema: a pictorial review. Int J COPD 2008;3(2):193 203. (5) Wang Q, Takashima S, Wang JC, et al. Prevalence of emphysema in individuals who underwent screening CT for lung cancer in Nagano prefecture of Japan. Respiration 2001;68:352 6. (6) Dransfield Mark T, Washko George R, et al. Gender differences in the severity of CT emphysema in COPD, American College of Chest Physicians. Chest 2007;132:464 70. (7) Gillooly M, Lamb D. Microscopic emphysema in relation to age and smoking habit. Thorax 1993;48:491 5. (8) Nakano Y, Muro S, Sakai H, et al. CT measurements of airway dimensions and emphysema in smokers: correlation with lung function. Am J Respir Crit Care Med 2000;162:1102 8. (9) Cerveri I, Dore R, Corsico A, et al. Assessment of emphysema in COPD: a functional and radiological study. Chest 2004;125: 1714 8. (10) Nakano Y, Coxson Ho, Bosan S, et al. Core to rind distribution of severe emphysema predicts outcome of lung volume reduction surgery. Am J Respir Crit Care Med 2001;164:2195 9. (11) Fishman A, Martinez F, Naunheim K, et al. National emphysema treatment trial research group: a randomized trial comparing lung volume reduction surgery with medical therapy for severe emphysema. N Engl J Med 2003;348:2059 73. (12) COPD Guidelines Group of the Standards of Care Committee of the British Thoracic Society. BTS guidelines for management of COPD. Thorax 1997;52(Supp. 5):51 8. (13) Muller NL. Clinical value of HRCT in chronic diffuse lunge disease. AJR Am J Roentgenol 1991;157:1163 70. (14) Trigaux Jean Paul, Hermes G, Dubois P, Van Beers B, Delaunois L, Jamart J. CT of Saber Sheath Trachea correlation with clinical, chest radiographic and functional findings; 1994. (15) Trigaux JP, Hermes G, Dubois P, Van Beers B, Delaunois L, Jamart J. CT of saber sheath trachea correlation with clinical, chest radiographic and functional findings. Acta Radiol 1994;35: 247 50. (16) Hagen G, Kolbenstvedt Alf. CT measurement of mediastinal anterior line in emphysema patients. J Acta Radiol 1993;34(2): 194 5. (17) Szilasi M, Dolinay T, Nemes Z, Strausz J. Pathology of COPD. Pathol Oncol Res 2006;12:52 60. (18) Crofton, Douglas. Respiratory disease text book. 5th ed. Blackwell Scientific Publication; 2000, p. 616 696. (19) Kalender WA. CT Munich: Publicis MCD Verlag; 2000. (20) Rosenkranz S. Pulmonary hypertension: current diagnosis and treatment. Clin Res Cardiol 2007;96:527 41. (21) Mac Nee W, Gould G, Lamb D. Quantifying emphysema by CT scanning: clinical pathological correlates. Ann N Y Acad Sci 1991;624:179. (22) Arakawa H, Webb WR. Air trapping on expiratory HRCT scans in the absence of inspiratory scan abnormalities: correlation with pulmonary function tests and differential diagnosis. AJR Am J Roentgenol 1998;170:1349 53. (23) Copley SJ, Well AV, Muller NL, Rubens MB, Holling NP, Cleverley JR, et al. Thin section CT in obstructive pulmonary disease: discriminatory value. Radiology 2002;223:812 9. (24) Vignola AM, Paganin F, Capieu L, Scichilone N, et al. Airway remodeling assessed by sputum and HRCT is asthma and COPD. Eur Respir J 2004;24:910 7. (25) Tell GS, Engeler CE, Tashijian JH. Imaging of small airways disease. Radiographics 1996;16:27 41. (26) Reilly J. Using CT scanning to advance understanding of COPD Pro. Am Thorac Soc 2006;3:450 5. (27) Wright JL. Emphysema concepts under change. A pathologists prospective. Med Pathol 1995;8:873 80. (28) Lamb D. Chronic bronchitis, emphysema, and the pathological basis of COPD. In: Hazleton P, editor. Spencer s pathology of the lung. New York: Mc Graw Hill; 1996. p. 597 630. (29) Copley Susan J, Wells Athol U, Muller Nestor L, et al. Thin section CT in obstructive pulmonary disease: discriminatory value. Radiology 2002;223:818. (30) Thurlebeck WM. Pathology of chronic airflow obstruction. In: Cherniack NS, editor. COPD. Philadelphia: W.B. Saunders; 1991. p. 3 20. (31) Lesur O, Delorme N, Fromaget JM, et al. CT in the etiologic assessment of idiopathic spontaneous pneumothorax. Chest 1990;98:341 7. (32) Richard Webb W, Muller Nestor L, Naidich David P. Text book HRCT of the lung. 3rd ed. Diseases characterized primarily by cysts and emphysema. Lippincott Williams and Wilkins: 530 Walnut Street Philadelphia, PA 19106 VSA LWW.com; 2001. p. 455 457 [chapter 7] (33) Snider GL. Reduction pneumoplasty for giant bullous emphysema: Implications for surgical treatment of non bullous emphysema. Chest 1996;109:540 8. (34) Muller NL, Thurlbeck WM. Thin section CT, emphysema, air trapping and airway obstruction. Radiology 1996;199:621 2. (35) Gevenois PA, De Vuyst P, Sy M, et al. Pulmonary emphysema: quantitative CT during expiration. Radiology 1996;199:825 9. (36) Klein JS, Gamsu G, Webb WR, et al. HRCT diagnosis of emphysema in a symptomatic patients with normal chest radiographs and isolated low diffusion capacity. Radiology 1992;182: 817 21. (37) Thurlbeck WM, Muller NL, Emphysema. Definition, imaging and quantification. AJR Am J Roentgenol 1994;163:1017 25. (38) Hardie JA, Buist AS, Vollmer WM, Ellingsen I, Bakke PS, Mørkve O. Risk of over-diagnosis of COPD in asymptomatic elderly never-smokers. Eur Respir J 2002;20:1117 22. (39) Bonelli FS, Hartman TE, Swensen SJ, et al. Accuracy of HRCT in diagnosing lung diseases. AJR Am J Roentgenol 1998;170: 1507 12. (40) Sanders C, Nath PH, Bailey WC. Detection of emphysema with CT: correlation with pulmonary function tests and chest radiography. Invest Radiol 1988;155:1290 4. (41) Gurney JW, Jones KK, Robbins RA, Gossman GL, Nelson KJ, Daughton D, et al. Regional distribution of emphysema: correlation of HRCT with pulmonary function tests in unselected smokers. Radiology 1992;183:457 63. (42) Mannino DM. COPD epidemiology, prevalence, morbidity and mortality and disease heterogeneity. Chest 2002;121:121S 6S. (43) Webb WR. High resolution computed tomography of obstructive lung disease. Radiol Clin North Am 1994;32:745 57.