Association between gallium-67 uptake by lung foci and sputum smear status in patients with pulmonary tuberculosis

OBJECTIVES Rapid determination of the inflammatory and sputum smear status in patients with pulmonary tuberculosis (PTB) is crucial for clinical decision making. The purpose of this study was to assess the relationship between gallium-67 (Ga-67) uptake by lung foci and sputum smear status in patients with PTB. We also attempted to predict the patients with acid-fast bacilli (AFB) smear-positive PTB by means of a semiquantitative measurement of Ga-67 uptake ratio using single-photon emission computed tomography images. PATIENTS AND METHODS Ninety-five patients with PTB were enrolled in this retrospective study. A volume-of-interest method was used to quantify Ga-67 uptake in single-photon emission computed tomography images. The Ga-67 uptake ratio was defined as the maximum voxel value of the pulmonary lesion divided by the maximum voxel value of normal lung tissue. RESULTS The Ga-67 uptake ratio was higher in patients with active PTB than in those with inactive PTB (3.11 ± 1.52 vs. 1.42 ± 0.14, P