The role of 67gallium scintigraphy and high resolution computed tomography as predictors of disease activity in sputum smear-negative pulmonary tuberculosis.

SETTING

University Hospital, Kuala Lumpur, Malaysia.

OBJECTIVE

To determine whether 67Gallium (Ga) scintigraphy and high resolution computed tomography (HRCT) of the lung improve the diagnostic accuracy of sputum smear-negative active pulmonary tuberculosis.

DESIGN

Patients suspected of having active pulmonary tuberculosis but who were sputum smear-negative underwent 67Ga scintigraphic and HRCT scanning of the lung. Results of these scans were correlated with results of bacteriology and histopathology as well as clinical data on follow-up.

RESULTS

Although none of the patients was culture-positive for Mycobacterium tuberculosis, 14 were considered to have active disease either because of positive direct smears of respiratory tract specimens other than sputum, positive histopathology, or clinical and radiological improvement following antituberculosis chemotherapy. A positive 67Ga scan had a sensitivity of 100% and a specificity of 83% for active pulmonary tuberculosis. Of the HRCT findings, the presence of centrilobular lesions had a 93% sensitivity and 100% specificity in determining disease activity in this group of patients.

CONCLUSION

Both 67Ga scintigraphic and HRCT scans are helpful in determining disease activity in sputum smear-negative pulmonary tuberculosis.