Precision of MRI-based body composition measurements of postmenopausal women

Abstract

Objectives: To determine precision of magnetic resonance imaging (MRI) based fat and muscle quantification in a group of postmenopausal women. Furthermore, to extend the method to individual muscles relevant to upper-body exercise.

Materials and methods: This was a sub-study to a randomized control trial investigating effects of resistance training to decrease hot flushes in postmenopausal women. Thirty-six women were included, mean age 56 ± 6 years. Each subject was scanned twice with a 3.0T MR-scanner using a whole-body Dixon protocol. Water and fat images were calculated using a 6-peak lipid model including R2*-correction. Body composition analyses were performed to measure visceral and subcutaneous fat volumes, lean volumes and muscle fat infiltration (MFI) of the muscle groups' thigh muscles, lower leg muscles, and abdominal muscles, as well as the three individual muscles pectoralis, latissimus, and rhomboideus. Analysis was performed using a multi-atlas, calibrated water-fat separated quantification method. Liver-fat was measured as average proton density fat-fraction (PDFF) of three regions-of-interest. Precision was determined with Bland-Altman analysis, repeatability, and coefficient of variation.

Results: All of the 36 included women were successfully scanned and analysed. The coefficient of variation was 1.1% to 1.5% for abdominal fat compartments (visceral and subcutaneous), 0.8% to 1.9% for volumes of muscle groups (thigh, lower leg, and abdomen), and 2.3% to 7.0% for individual muscle volumes (pectoralis, latissimus, and rhomboideus). Limits of agreement for MFI was within ± 2.06% for muscle groups and within ± 5.13% for individual muscles. The limits of agreement for liver PDFF was within ± 1.9%.

Conclusion: Whole-body Dixon MRI could characterize a range of different fat and muscle compartments with high precision, including individual muscles, in the study-group of postmenopausal women. The inclusion of individual muscles, calculated from the same scan, enables analysis for specific intervention programs and studies.

Conflict of interest statement

Competing Interests: JW, TR, MB, and ODL receive salaries and are stockholders of Advanced MR Analytics AB. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. Segmentation of fat and muscle compartments.

Sample compartmental segmentation result, coronal and transverse sections of a 61-years-old woman. (a) Intensity-corrected water images with muscle segmentations using overlay colours, 1. abdominal muscles, 2. anterior thigh, 3. lower leg muscles, 4. posterior thigh, (b) intensity-corrected fat images with fat segmentations using overlay colours, 5. abdominal subcutaneous adipose tissue, 6. visceral adipose tissue.

Fig 2. Segmentation of individual muscles.

Sample individual muscle segmentation results of a 61-years-old woman. (a) Intensity-corrected water images with muscle segmentations using overlay colours, enlarged cutouts of central abdominal region 1. pectoralis major, 2. latissimus dorsi, 3. rhomboideus, (b) transverse sections covering the central abdominal region with muscle segmentations using overlay colours, and (c) sagittal cutouts of the central abdominal region with muscle segmentations using overlay colours.

Fig 3. Region of interest placements in the liver.

Water and proton density fat-fraction (PDFF) liver images with region of interest (ROI) placements to assess liver-fat, in (a-b) a subject with low liver-fat content, and (c-d) a subject with higher liver-fat content. (a, c) Water images and (b, d) PDFF images.

Fig 4. Bland-Altman plots of fat compartments.

Bland-Altman plots of (a) liver-fat, (b) visceral adipose tissue, and (c) abdominal subcutaneous adipose tissue. Note: Different ranges on y-axes.

Fig 5. Bland-Altman plots of muscle compartments and individual muscles.

Bland-Altman plots of (a) total thigh, (b) lower leg, (c) abdomen, (d) latissimus, (e) pectoralis, and (f) rhomboideus. For bilateral muscles (b-f) left and right sides are pooled in the plots. Note: Different ranges on y-axes.

Fig 6. Bland-Altman plots of muscle fat infiltration (MFI).

Bland-Altman plots of (a) total thigh, (b) lower leg, (c) abdomen, (d) latissimus, (e) pectoralis, and (f) rhomboideus. For bilateral muscles (b-f) left and right sides are pooled in the plots. Note: Different ranges on y-axes.