What does "the marrow signal in the cervical spine is decreased" mean? it says it can be correlated with a cbc. from mri scan from 2007. concerns?

Not much: Each of the tissues in an MRI gives if a characteristic signal, which then makes it a certain appearance on the image. So the marrow signal was lower than average. This could be a normal variant, but is sometimes seen in patients with abnormalities of the marrow system which produces our blood cells; thus the recommendation to correlate with a CBC. I would just mention to your MD.