Fig. 4.
Clavicular level axial slices from the cold scan of the subjects in Figs. 2 (top) and 3 (bottom). The dashed red line on the PET maximum intensity projection (MIP; left) indicates that the location of the axial slices displayed. The following 4 axial images are, in order, CT Hounsfield hnit (HU), PET standardized uptake value (SUV; g/ml) overlaid on the HU image, MRI-derived fat signal fraction (FSF) map (%), and MRI-derived R2* map (s−1). Note that whereas the region of clavicular adipose tissue is of comparable size on the CT HU image for both the normal-weight (top) and overweight (bottom) subject (total volume: 25.4 and 20.8 cm3, respectively), the clavicular adipose tissue in the normal weight subject has a higher SUV (7.1 ± 2.8 g/ml) over the entire region compared with the lower SUV (3.9 ± 1.3 g/ml) in the overweight subject. Additionally, the region of tissue on the MRI FSF image corresponding to the clavicular adipose tissue on the HU image has a slightly lower FSF in the normal-weight compared with the overweight subject (50.1 ± 15.2 vs. 63.3 ± 15.2%, respectively).