Abstract: Objective  To explore the CT characteristics of interstitial changes in patients with secondary pulmonary tuberculosis and analyze the value of CT manifestations to evaluate the effects of anti-tuberculosis therapy. Methods  Forty-three patients who were diagnosed as tuberculosis by clinical or pathology were enrolled into our study (male: 23, female: 20; age: 19-54 years old, average age （29±11.4）years old). All the cases showed interstitial changes on CT imaging. Twenty-nine cases were testified by sputum smear, and the other cases were testified by sputum culture, bronchoscopy, biopsy or clinical follow-up. All the cases underwent CT scans before and after anti-tuberculosis therapy. Double-blind method was used to analyze the dynamic changes and outcomes of CT appearances.  Results  The most common location of this kind of tuberculosis was in the bilaterally upper pulmonary lobes (30/43), mostly distributed in segments, in the form of a small lesion or large fusion lesion. The CT appearances of interstitial changes were mainly intra-lobular reticular reticulation (43/43, 100.0%), micro-nodule (43/43, 100.0%), tree-in-bud (33/43, 76.7%), ground-glass opacity (27/43, 62.8%), thickening of inter-lobular septa (23/43, 53.5%) and thickening of the airway wall (24/43, 55.8%). The most cases showed clear boundary between the interstitial lesion and the normal lung tissue. The interstitial appearances improved after the anti-tuberculosis treatment, and more than 93% of the later four signs disappeared after the consolidation phase therapy (6 months). Conclusion  It was a special kind of secondary tuberculosis which mainly manifested interstitial changes. The CT image could show us clear characteristics, and was helpful in detecting tuberculosis in the early phase, and evaluating the outcomes after therapy.

Key words: Tuberculosis,pulmonary/radiography, Tomography,X-ray computed, Treatment outcome