To further determine whether noninvasive NIS imaging could be used to evaluate the density and heterogeneity of intratumoral virus distribution after intravenous VSV-mIFNβ-NIS administration, imaging studies performed on tumor-bearing mice imaged 24 hours after intravenous administration of varying doses of VSV-mIFNβ-NIS were compared. The gene discussed is SLC5A5; the disease is neoplasm.