is a disease of WBC`s, so if your peripheral blood smear and bone marrow
aspiration is normal, your in remission i.e without the evidence of disease in the body. as the MRI
is showing infiltration you need to be on close follow up with your doctor to detect early recurrence if at all it recur. as of my knowledge PET scan is not validated in leukemias. leukemia is a very aggressive diasease, so it is unlikely to remain inactive.