Air Trapping on HRCT in Asthmatics: Correlation with Pulmonary Function Test

PURPOSE: To evaluate on the basis of the pulmonary function test the correlation between the extent of air trapping on HRCT with the severity of airway obstruction and also to identify the prognostic effect of the extent of air trapping after treatment of asthma. MATERIALS AND METHODS: Thirty five patients with clinically diagnosed bronchial asthma and air trapping, as seen on HRCT, were included in this study. We quantitatively analysed on HRCT the extent of air trapping and then statistically compared this with the clinical parameters of the pulmonary function test. We classified the patients into two groups on the basis of the pulmonary function test and clinical status : Group 1(N=35), the total number of asthmatic patients ; Group 2(N=18), relatively stable asthmatics without acute asthmatic attack who showed FEV1 of more than 80% of the predicted value. Using the functional parameters of PEFR, one of the objective indications of improvement in airway obstruction, we also classified the patients into three groups on the basis of interval between treatment and clinical improvement. The result of this was as follows ; group 1, asymptomatic group(initial PEFR within normal limit, N=7) ; group 2, early responder(improvement of PEFR within three hospital days, N=18) ; group 3, late responder(improvement of PEFRwithin fourteen hospital days should there be a number here). Using HRCT, we then statistically analysed the differences between the three groups in the extent of air trapping. RESULTS: Among the total of 35 asthmatics, the extent of air trapping on HRCT showed significant correlation with the FEV1(r=-0.6161, p<0.001) and MEFR(r=-0.6012, p<0.001). Among the relatively stable asthmatics who showed FEV1 of more than 80% of the predicted value, MEFR(r=-0.7553, p<0.001) and FEF75(r=-0.7529, p=0.012) showed statistically significant correlation with the extent of air trapping on HRCT, but there was no significant corrlation between air trapping on HRCT and FEV1. In the three groups of asthmatics classified on the basis of interval between treatment and clinical improvement, the extents of air trapping on HRCT in the asymptomatic, early responder and late responder groups was as follows: (mean valuse) 9.31%, 21.50% and 27.89%, respectively ; these differences were statistically significant. CONCLUSION: The extent of air trapping on HRCT in asthmatics showed positive correlation with FEV1 and MEFR. Quantitative analysis of air trapping on HRCT also provides prognostic information about a patient's response to treatment.

Pulmonary Tuberculosis with Airspace Consolidation vs Mycoplasma Pneumonia in Adults: High-Resolution CT Findings

PURPOSE: To analyse and compare high-resolution CT findings of pulmonary tuberculosis with consolidation and mycoplasma pneumonia. MATERIALS AND METHODS: Twenty patients with pulmonary tuberculosis [confirmed by sputum culture (n=9) and bronchoscopic biopsy (n=11)] and airspace consolidation on high-resolution CT and 17 patientswith mycoplasma pneumonia, confirmed by serologic test, were included in this study. High-resolution CT findings were analyzed in terms of ground-glass opacities, distribution of consolidation, type of nodules, cavities, interlobular septal thickening, bronchial dilatations, bronchial wall thickening and pleural effusion. RESULTS: In patients with tuberculsis, average age was 33.5 years (range, 20-67) ; in those with mycoplasma pneumonia it was 32.5 years (range, 17-74). Segmental and subsegmental distributions were most common in both diseases ; the preferred site of consolidation was different, however ; for tuberculosis it was the upper lobes (13 cases, 65% ; bilateral involvement, 7 cases) ; for mycoplasma pneumonia it was the lower lobes (11 cases, 64.7%). Non-segmental (diffuse and random) distribution of ground-glass opacities were seen in two patients(11.8%) with mycoplasma pneumonia. Centrilobular nodules, branching linear opacities and alveolar nodules were not different in both diseases, but there were nodules above 10mm in 14 cases of tuberculosis and in only one case of mycoplasma pneumonia. Tree-in-bud appearances were seen in five cases of tuberculosis. Cavities without air-fluid level were noted in ten cases of tuberculosis. Other interlobular septal thickening, bronchial wall thickening, bronchial dilatation and pleural effusion were not different in both diseases. CONCLUSION: There was considerable overlap between high resolution CT findings of tuberculosis with airspace consolidation and those of mycoplasma pneumonia. The location of consolidation, type of nodules, and the presence of tree-in-bud appearance and cavities help in the differentiation of the two diseases, however.