Effect of zebularine on a mouse model of gamma-induced thymic lymphoma determined by overall survival, NMR, and PET. (A) Schematic diagram of the gamma-induced mouse model of lymphomagenesis, zebularine treatment, and NMR and PET imaging follow-up. (B) Up indicates Kaplan-Meier survival curve; γ, gamma irradiation; Tb, start of zebularine treatment; and Te, end of zebularine treatment. Black and gray straight lines show nonirradiated control mice treated with PBS and zebularine (Zeb), respectively; ♦ line shows irradiated and PBS treated animals; and ▪ line shows irradiated and zebularine treated mice. Below, summary of total number of animals used in the study (n) and the surviving animals (alive). (C) Follow-up of thymus and thymic lymphoma sizes by NMR using a Bruker Biospec spectrometer/Magnex 4.7 Teslas 40-cm bore horizontal magnet MRI system. Image analysis and tumor volume measurements were performed with the public domain software ImageJ (NIH, http://rsb.info.nih.gov/ij). A marked volume reduction in the thymic mass is observed in zebularine-treated mice. (D) Metabolic activity in FDG-PET imaging; PET image shows a significant “hot spot” (yellow) confined in the thymic lymphoma that is lost in the zebularine-treated mice.