Predictors of Chemotherapeutic Response of Lung Cancer Patients in Sequential Tc-99m MIBI Scintigraphy: Perfusion Index, Tumor Uptake, and Washout RatePredictors of Chemotherapeutic Response of Lung Cancer Patients in Sequential Tc-99m MIBI Scintigraphy: Perfusion Index, Tumor Uptake, and Washout RatePredictors of chemotherapeuric response of lung cancer patients in sequential Tc-99m MIBI scintigraphy: perfusion index, tumor uptake and washout rate