Body composition analyses for abdominal fat and muscles were performed from the reconstructed water and fat images, using the commercially available service AMRA® Profiler (Advanced MR Analytics AB, Linköping, Sweden). The methods used in AMRA® Profiler have been thoroughly described in earlier publications [10 (link), 11 (link), 15 (link), 33 ] but briefly the analysis consisted of the following steps: (1) image calibration to fat referenced images, (2) labels of fat and muscle compartments registered to the acquired volumes, (3) quality control of labels performed by trained analysis engineers at Advanced MR Analytics (Linköping, Sweden), and (4) quantification of fat and muscle volumes based on the calibrated images by integrating over the quality controlled labels. This process was described in detail in [11 (link)]. The included fat and muscle compartments were visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue (ASAT), posterior thigh muscles, anterior thigh muscles, lower leg muscles, and abdominal muscles, detailed definitions of the anatomical regions used for compartmental fat and muscle segmentations and quality control are listed in Table 1 . Finally, the individual muscles latissimus dorsi, pectoralis major, and rhomboideus were included.
Muscle fat infiltration was measured for each muscle. The MFI measurements were defined as the average PDFF of the muscle tissue, i.e. muscle tissue with an adipose tissue concentration of less than 50%. As the calibrated fat images are T1-corrected [20 (link)], and represent the adipose tissue concentration of the tissue, the MFI was calculated by scaling the adipose tissue concentration with the PDFF of adipose tissue. In this study a constant PDFF of 93.7% was assumed for adipose tissue to convert adipose tissue concentration to PDFF.
Based on water-fat images acquired with a 5° flip angle, the liver-fat was measured as the average PDFF of three 22x22x28 mm3 regions of interest (ROI) manually placed in right liver lobe, avoiding major vessels and bile ducts. The liver test and re-test scans were pooled and analysed in randomized order.
Muscle fat infiltration was measured for each muscle. The MFI measurements were defined as the average PDFF of the muscle tissue, i.e. muscle tissue with an adipose tissue concentration of less than 50%. As the calibrated fat images are T1-corrected [20 (link)], and represent the adipose tissue concentration of the tissue, the MFI was calculated by scaling the adipose tissue concentration with the PDFF of adipose tissue. In this study a constant PDFF of 93.7% was assumed for adipose tissue to convert adipose tissue concentration to PDFF.
Based on water-fat images acquired with a 5° flip angle, the liver-fat was measured as the average PDFF of three 22x22x28 mm3 regions of interest (ROI) manually placed in right liver lobe, avoiding major vessels and bile ducts. The liver test and re-test scans were pooled and analysed in randomized order.
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