FDG-PET correlation with CT

The section on FDG-PET mentions that correlation with CT is warranted for new lesions, and that PD should be declared if the hot spot on PET corresponds to a progressing lesion on CT.

If the hot spot on PET corresponds to a target lesion that has enlarged, but the sum of the target measurements does not show an increase that is sufficient for PD (other target lesions have not enlarged or have actually decreased), the FDG-PET does not override the assessment following the measurement rules of RECIST 1.1. FDG-PET in RECIST 1.1 is considered to complementary.

Similarly, if there is a hot spot on FDG-PET (baseline PET was not available) that is not associated with a new CT (or MRI) lesion, the response should be assigned based on the results of the CT (MRI) imaging.