CXCR4 and acute myeloid leukemia: Since CXCR4 expression is generally high among hematological malignancies, including non-Hodgkin lymphoma (NHL), multiple myeloma (MM), chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML), most experience with CXCR4-directed PET imaging is based on patients with these diseases [6].