Figure 2

Maximum instensity projection (MIP) of PET images of six different patients progressively aligned from left to right, according to the extent of bone involvement, as stated by a subjective visual analysis of PET images: negative/mild (the two images on the left), moderate (the two central images) and marked bone involvement (the two images on the right). Note that the Intensity of Bone Involvement (IBI) score increases progressively, so that the bone/bone marrow involvement can be evaluated as a continuous numerical variable.