2nd PET SCAN vs 1st PET SCAN

My 2nd Pet Scan (3/10) said: The mass is slightly decreased in size. Centrally, there is decreased FDG activity within the mass. However, at the periphery of the mass there is increased FDG activity. The maximum SUV values is increased, now measuring 18.3. (The 1st pet scan 9/09) said the SUV values ranged up to 5.6. There is no evidence of metastatic mediastinal lymphadenopaty. There are no pulmonary metastases. There is no infiltrate or pleural effusion.

Can someon knowledgable explain all this to me? I have been on Chemo treatments for 5 cycles.

Thank you,

Charlotte