Technetium-99m-tetrofosmin scintigraphy in pulmonary tuberculosis

Technetium-99m-tetrofosmin, an agent that is widely used in myocardial imag ing, has been reported to accumulate in several types of malignancies, incl uding lung tumors. Yet, there is limited knowledge about its role in imagin g infection or inflammatory lesions. The aim of this study was to investiga te the role of Tc-99m-tetrofosmin scintigraphy in pulmonary tuberculosis in cases with active and inactive tuberculosis in comparison with radiologica l and microbiological findings. Methods: Twenty-seven patients with active pulmonary tuberculosis (APTB) and 6 patients with inactive pulmonary tuberc ulosis (IPTB), proven by sputum smears and cultures, were included in this study. Mean age of the group was 42.6 +/- 13 yr. Nine months after therapy, Tc-99m-tetrofosmin scintigraphy was repeated in 6 patients with APTB to ev aluate response to therapy. Ten-minute anterior and posterior chest images were acquired 20 and 60 min after the injection of 370 MBq (10 mCi) Tc-99m- tetrofosmin. The images were evaluated both visually and semiquantitatively by two blinded nuclear medicine physicians. For semiquantitative evaluatio n, regions of interest (ROIs) were drawn over the lesion (L) and nonlesion areas (NL). The mean count values of ROIs were obtained and L/NL ratios wer e calculated. Results: According to the visual evaluations, Tc-99m-tetrofos min uptake was Grade (+) in 4 (15%) and Grade (+ +) in 23 (85%) patients wi th APTB. Technetium-99m-tetrofosmin uptake was negative in 5 patients with IPTB. Grade (+) Tc-99m-tetrofosmin uptake was observed in only one inactive case. After therapy, there was no Tc-99m-tetrofosmin uptake in 3 patients, which correlated well with chest radiography and clinical findings. In the other 2 patients, Tc-99m-tetrofosmin uptake was slightly decreased when co mpared with a previous scan that correlated with radiological and clinical findings. In 1 patient with bilateral lung disease, Tc-99m-tetrofosmin upta ke decreased on the right lung lesions, whereas the left lung lesions persi sted with no change. The mean early and delayed L/NL ratios of APTB were 1. 53 +/- 0.22 and 1.45 +/- 0.21, respectively. Although Tc-99m-tetrofosmin up take in APTB lesions was more visually marked in early images than that in delayed images, there was no statistically significant difference between t hese two sets of images. Conclusion: Technetium-99m-tetrofosmin scintigraph y showed increased uptake in APTB lesions related to disease activity. Afte r treatment, Tc-99m-tetrofosmin uptake disappeared or decreased, correlatin g well with radiological and clinical findings. Technetium-99m-tetrofosmin scintigraphy may have a complementary role in the assessment of APTB as wel l as in follow-up treatment.