99mTc-hexakis methoxy isobutyl isonitrile MIBI scintigraphy and bronchoalveolar fluid lactic dehydrogenase in pulmonary tuberculosis.

In cases of chronic pulmonary tuberculosis (PTB) with negative sputum smears, particularly when they are symptomatic, physicians encounter problems in differentiating the active from the inactive stage of the disease. This study was undertaken to determine the usefulness of technetium-99m hexakis methoxy isobutyl isonitrile ((99m)Tc-MIBI) pulmonary scintigraphy and lactic dehydrogenase (LDH) in bronchoalveolar lavage fluid (BALF), in differentiating active from inactive PTB. According to the methods we used, BALF LDH level was measured in 12 patients with documented active PTB (Group 1) before of treatment and in 7 patients with treated PTB (Group 2) after treatment. Lung scan with (99m)Tc-MIBI was performed in 7/12 patients of Group 1 (Group 1a) and in all of Group 2. Five patients of Group 1 refused the lung scan (Group 1b). Five adults who had a normal myocardial perfusion scan were considered as normal lung cases (Group 3). Our results showed that the mean LDH level in BALF was not statistically higher in Group 1 (252.42+/-189.06 mIU/ml) than in Group 2 (106.28+/-139.99 mIU/ml). Very low values, less than 24 mIu/ml, excluded active PTB. Of the 7 patients of Group 1a, 6 had a positive lung scan (85.7%). Of the 7 patients of Group 2, 6 had negative lung scan (85.7%). Both tests had a positive correlation in differentiating active and inactive PTB. In conclusion, although none of the tests were specific for PTB, low BALF LDH of less than 24 mIUL and negative (99m)Tc-MIBI pulmonary scintigraphy, seemed to indicate inactive PTB. If our findings are confirmed by others with more related cases, these tests can be shown useful in the follow up of treated PTB patients.