Early diagnosis value of high-resolution CT in connective tissue disease complicated with interstitial pneumonia

Objective:To analyze the imaging features of lung high resolution CT(HRCT) in different connective tissue disease(CTD) complicated with interstitial pneumonia(ILD),and provide the basis for the HRCT in the early diagnosis of CTD complicated with ILD.Methods:Among 1388 patients with CTD,the imaging features of pulmonary HRCT in 143 patients with CTD complicated with ILD(total incidence rate for 10.3%) were investigated.The relationship between CT classification and different CTD laboratory indexes were analyzed.Results:Among 143 patients with CTD complicated with ILD,the systemic lupus erythematosus(SLE) in 53 cases,rheumatoid arthritis(RA) in 40 cases,sicca syndrome in 24 cases,polymyositis/dermatomyositis in 8 cases,systemic sclerosis(SSc) in 7 cases,mixed connective tissue disease(MTCD) and adult onset still's disease(AOSD) in 4 cases were identified.The imaging features of HRCT in patients with CTD complicated with ILD mainly included the septal thickening(88.1%),ground-glass opacity(78.3%),irregular linear opacities or subpleural line(74.1%),grid shadow(41.3%),bronchovascular bundle thickening(30.1%),thin-walled cyst(23.8%),honeycomb lung(19.6%),focal nodules(19.6%),mosaic perfusion opacities(10.5%),consolidation shadow(10.5%) and pulmonary bullae(5.6%).The ground-glass opacity and lobular interval thickening were the main imaging features of SLE,RA,SS and AOSD,and the grid shadow and honeycomb lung were the main imaging features of SSc,PM/DM and MCTD.The differences of the levels of ESR,CRP,C3 and C4 between different CT types of lung interstitial lesions were statistically significant(P<0.01).The ESR indexes in the grid shadow group,real shadow group,honeycomb lung group,ground-glass opacity and non-ILD group were higher than those in irregular line group or subpleural group(P<0.05 to P<0.01).The CRP indexes in the real shadow group,honeycomb lung group and ground-glass opacity group were higher than those in non-ILD group(P<0.05 to P<0.01).The C3 indexes in the irregular line group or subpleural group,thin-walled cysts group,bronchial tube bundle thickening group,honeycomb lung group,lobular interval thickening group and non-ILD group were lower than those in ground-glass opacity group(P<0.05 to P<0.01).The C3 indexes in irregular line group or subpleural group and real shadow group were higher than those in non-ILD group(P<0.05 to P<0.01).In addition to the pulmonary bullae group,the C4 index in other groups were significantly lower than those in ground-glass opacity group(P<0.01).Conclusions:Different CTD complicated with ILD have different imaging features,inflammation indexes and complement levels.The early lung HRCT examination is helpful to the early diagnosis of ILD,and predict the prognosis.