Technetium-99m-MIBI scintigraphy in pulmonary tuberculosis

We investigated the usefulness of ^99mTc-methoxyisobutylisonitrile scintigraphy in patients with known or suspected pulmonary tuberculosis (PTB) in comparison with radiological and bacteriological findings. Methods: Thirty-six patients aged 13-59 yr were scanned 15 and 60 min after intravenous injection of 370 MBq (10 mCi) ^99mTc-methoxyisobutylisonitrile. Twenty-four patients had active PTB proven by chest radiograph and sputum examinations, two had miliary tuberculosis and ten were suspected of having relapsed PTB with negative sputum examinations and indeterminate chest radiographs. In 12 patients ^99mTc-MIBI imaging was repeated 1-3 mo after chemotherapy. Results: Of 24 patients with active localized PTB, 22 (92%) showed increased focal uptake of ^99mTc-MIBI, but two patients with minimal infiltration on chest radiographs had no accumulation of ^99mTc-MIBI. Both patients with miliary PTB showed diffuse ^99mTc-MIBI uptake in the lungs. Among 10 patients with suspicion of relapse, ^99mTc-MIBI scans were true- positive in 4 of 5 patients (80%) with culture-proven tuberculosis and false- positive in 2 of 5 (40%) patients with negative sputum cultures. For repeat imaging, 6 of 10 patients with active localized PTB showed reduced MIBI uptake, which correlated with chest radiograph findings, and one patient had increased MIBI uptake again concordant with clinical and radiological findings which were suggestive of resistance to first line chemotherapy of tuberculosis. The other three patients showed no significant scintigraphic changes despite clinical and partial radiological regression. Conclusion: Active PTB granulomas generally present considerable ^99mTc-MIBI uptake that is most probably related to disease activity. Therefore, ^99mTc-MIBI scanning could be used in the detection and follow-up of active PTB as a complement to routine techniques.