Assessment of Tc-99m sestamibi tumor tissue uptake under the influence of increased arterial oxygen saturation.

The aim of this study is to investigate the potential effect of increased arterial saturation of oxygen in the magnitude of technetium-99m-hexakis-isobutyl-isonitrile (99mTc-MIBI) uptake in tumor tissue and to compare the results with those of conventional 99mTc-MIBI tumor imaging in the same patient with lung cancer. A total of 26 lung cancer patients underwent initial SPECT (I-SPECT) and after oxygen inhalation SPECT (O2-SPECT). The early (ER) and delayed ratios (DR) of O2-SPECT mean+/-S.D. were significantly higher than those of I-SPECT mean+/-S.D. (2.07+/-0.57 vs. 1.90+/-0.48 and 2.02+/-0.45 vs. 1.83+/-0.39, respectively). There are increased rates for the relative tumor uptake of 99mTc-MIBI by 9% for ER and 10% for DR on the O2-SPECT compared to I-SPECT. We found that 99mTc-MIBI uptake increased significantly in the tumor tissue with O2-SPECT compared to I-SPECT. In conclusion, 99mTc-MIBI scintigraphy is one of the main methods for differentiating viable and nonviable tissue fractions in tumors. We consider that 99mTc-MIBI uptake increase after oxygen inhalation is an indicator of positive acute cellular response of the tumor tissue to the rising tissue oxygen level.