Estimation of proton density fat fraction of the salivary gland

Objective:Our first objective was to prove the validity of the six-point Dixon method for estimating the proton density fat fraction (PDFF) of the salivary gland. The second objective was to estimate the salivary gland PDFF using Dixon method to evaluate the pathological conditions.Methods:At first, 12 volunteers underwent two types of sequences: single-voxel MRS and the Dixon method and the PDFFs obtained by the two methods were compared. Next, a total of 67 individuals (normal, n=46; Sjogren’s syndrome [SS], n=11; and IgG4-related dacryoadenitis and sialadenitis [IgG4-DS], n=4, parotitis, n=6) were enrolled to estimate the parotid gland (PG) and submandibular gland (SMG) PDFF using the Dixon method.Results:This volunteer study demonstrated excellent correlation between two methods (R2=0.964, slope=1.05). In the normal group, the PG-PDFF was correlated with the weight and body mass index (BMI) (ρ=0.38, P=0.0085; and ρ=0.63, P < 0.0001). The SMG-PDFF was also correlated with the weight, BMI, and serum tri...