Male and female patients at least 18 years of age with untreated Non-small Cell Lung Cancer who have non-incisional biopsy definitive evidence of disease (or from cytology results from a bronchoscope procedure) and who have been previously certified (per centers for Medicare and Medicaid Services requirements) by their physicians will be consented for the study. The study consists of a screening visit, gold-standard 18F-FDG PET/CT imaging followed by the investigational agent 99m Tc-Ec-DG SPECT/CT. The study procedures can be performed within 5-7 days of signing the informed consent. [To better meet the standard of care at each clinical location, the PET/CT can be performed as part of pre-study procedures on a PET/CT camera previously qualified by the site to meet the standards required for the study. If this occurs, the SPECT/CT must be performed within 45 days of the PET/CT imaging procedures.] Patients will be seen 24 hours after the 99m Tc-Ec-DG injection for safety. A 21-day follow-up period (after the SPECT/CT image) will allow the investigator to acquire additional imaging, surgical, pathology and treatment documentation. [An actual patient visit is NOT required at the 21-day follow-up time point.]