Abstract: Objective To explore CT imaging characteristics in three kinds of active pulmonary tuberculosis (TB). Methods Spiral CT scan was applied to 51 newly diagnosed TB cases, 54 relapsed TB cases and 34 chronic TB cases. The difference of the CT imaging among the three kinds of TB cases were observed. Results Active CT imaging: the check-out rates of ground-glass opacity, centrilobular nodules with segmental distribution, tree in bud, segmental or lobar consolidation,thickening of the bronchial walls and thick-walled cavity was 88.2%, 82.4%, 66.7%, 27.5%, 37.3% respectively in newly diagnosed cases; 92.6%, 72.2%, 59.3%, 33.3%, 24.1% respectively in relapsed cases and 38.2%, 41.2%, 32.3%, 8.8%, 76.4% respectively in chronic cases. There was not significant difference of the above check-out rates between new and relapsed cases ( P＞0.05) , while the check-out rates in new and relapsed cases were all obvious higher than those in the chronic cases ( P＜ 0.01) . The check-out rate of thick-walled cavity was obvious more higher than new diagnosed cases and relapse case. Inactive CT imaging: the check-out rates of fibre rope band and bronchial flection were 5.9% and 17.6% in newly diagnosed case, 48.1% and 40.7% in relapsed cases and 88.2% and 85.3% in chronic cases respectively. The difference was significant among three kinds of TB cases ( P＜ 0.01). Conclusion The check-out rates of active CT Image is different among newly diagnosed case, relapsed case and chronic case. CT is helpful to their differential diagnosis, while carefully considering the clinical symptoms and sputum examinations at the same time.

Key words: Pulmonary tuberculosis/radiography, Tomography,X-ray computed