We studied about the The different features of high-resolution CT (HRCT) findings of active pulmonary tuberculosis(TB) were studied between acid fast bacilli(AFB) smear or culture positive and negative group.

We prospectively evaluated 36 patients who had been confirmed for active pulmonary tuberculosis by the smear or culture of AFB in sputum(n=25), and changes on serial chest radiographs(n=11). The patient were divided into 3 groups by the results on sputum AFB stain and culture. Group 1(n=11) is negative in both AFB stain and culture ; group 2(n=13) is negative in AFB stain but positive in culture ; and group 3(n=12)is positive in both AFB stain and culture. We evaluated the findings of HRCT in each group randomly.

On the HRCT scans, acinar nodule(100%), macronodule(75%), and cavity(75%) in group 3 were more frequently found than group 1(63%, 18%, 9%) and group 2(46%, 15%, 23%)(p<0.05). The centrilobular nodule and branching structure in group 3(92%) was more frequently observed were more frequently observed in group 3 (92%) than in group 1(54%)(p<0.05), but not different than were similarly observed in group 2(77%)(p>0.05). AFB positive group was statistically different than the negative group in the HRCT findings such as with respect to acinar nodule(100% vs 54%), macronodule(75% vs 17%), and cavity(75% vs 17%)(p<0.05). TB culture positive group was statistically different than the negative group in the HRCT findings such as with respect to acinar nodule(72% vs 45%) and cavity(48% vs 9%)(p<0.05).

HRCT scans are helpful in determining disease acitivity in sputum AFB stain- negative pulmonary tuberculosis. When HRCT shows centrilobular nodule and branching structure, acinar nodule, macronodule, cavity, we are able to decide more study such further studies as sputum induction and bronchoscopy for determination of can be performed to determine the presence of bacilli in patients of AFB stain-negative tuberculosis.