Early detection of pulmonary emphysema in smokers by spiral chest CT

ABSTRACT

This study was carried out to assess the occurrence of pulmonary emphysema early among smokers [symptomatizing and non symptomatizing] by hellical chest CT and relating this finding to pulmonary function. In order to achieve this purpose 55 smokers [25 asymptomatic and 30 symptomatic] and 10 apparently healthy non smokers control subjects were in vestigated through I. Full detailed medical history with particular attention to smoking habits. II. Full clinical examination comprising both general and local chest examination. Ill. Plain chest X-ray, posterio-anterior [P A] and lateral views. IV. Pulmonary function tests, using computerized sensor medics 2450. [1] flow volume loop data, before and 20 minutes after inhalation of 4 puffs [400 micro g] of salbutamol using MDI to exclude asthmatic. [2] functional residual capacity [FRC] helium equilibration test. [3] pulmonary diffusing capacity [DL[co]] and pulmonary diffusing coefficient [DL[co]/VA] [alveolar volume VA]. V. High resolution chest CT [HRCT] .Analysis of the computed tomograms was performed visually according to Goddard et al. [5]. VI. Subjects proved to have other concomitant disease or known COPD were excluded from this study in asymptomatic smokers 16 out of 25 [64%] have emphysema by HRCT. Plain chest x-ray of those 16 smokers having emphysema by HRCT were normal in all [100%] and 9 of them [56.3%] have normal pulmonary functions in symptomatic smokers 27 out of 30 [90%] were having emphysema by HRCT. Twenty six percent of those symptomatic smokers having emphysema by HRCT showed normal plain chest x-ray. On comparing the validity of plain x-ray versus HRCT in the diagnosis of pulmonary emphysema plain x-ray has 35.5% sensitivity, 95.4% specificity, 95.0% predicted value positive, 46.7 predicted value negative and 61.5% accuracy. Correlation between pulmonary functions and emphysema score by HRCT in both asymptomatic and symptomatic smokers showed that there was only significant negative correlation between emphysema score and DL[co]/VA in asymptomatic smokers [P < 0.05] but in symptomatic smokers there is highly significant negative correlation with all parameters of pulmonary functions except total lung capacity [TLC]. residual volume [RV] RV/TLC and FRC [I] HRCT is the best mean for early detection of pulmonary emphysematous changes among smokers as it is better in this respect than pulmonary functions. [2] Plain chest X-ray is less sensitive than pulmonary functions in early detection of pulmonary emphysema. [3] DL[co]/V A is the most sensitive pulmonary function test to be affected early in pulmonary emphysema