Author Contributions
Conceptualization, T.B., D.C.K., D.F.; Methodology, J.S., C.H., T.D., H.H., T.B., D.C.K.; Validation, T.B., D.C.K.; Formal Analysis, E.B., T.B., D.C.K., D.F.; Investigation, Resources, E.B., J.S., C.H., T.D., H.H., D.F.; Writing—Original Draft Preparation, E.B.; Writing—Review & Editing, E.B., J.S., C.H., T.D., J.S.K., C.Z., E.J.R., H.H., D.C.K., T.B., D.F.; Visualization, E.B., D.F.; Supervision, T.B.; Project Administration, T.B., D.F.; Funding Acquisition, J.S.K., D.C.K.
Figure 1.
Representative segmentation of the abdominal muscles, psoas muscle, and erector spinae muscle in the proton density fat fraction (PDFF) map of a 40-year-old woman. The rectus abdominis muscle and internal oblique muscle (1), psoas muscle (2), and erector spinae (3) are segmented at the level of L4.
Figure 1.
Representative segmentation of the abdominal muscles, psoas muscle, and erector spinae muscle in the proton density fat fraction (PDFF) map of a 40-year-old woman. The rectus abdominis muscle and internal oblique muscle (1), psoas muscle (2), and erector spinae (3) are segmented at the level of L4.
Figure 2.
Representative PDFF maps on the level of L4 of a 39-year-old man (A) BMI: 24.92 kg/m2; mean PDFF abdominal muscles: 3.152%; mean PDFF psoas muscle: 0.764%; mean PDFF erector spinae: 6.332%; and a 37-year-old man (B) BMI: 30.68 kg/m2; mean PDFF abdominal muscles: 17.789%; mean PDFF psoas muscle: 12.678%; mean PDFF erector spinae: 11.386%.
Figure 2.
Representative PDFF maps on the level of L4 of a 39-year-old man (A) BMI: 24.92 kg/m2; mean PDFF abdominal muscles: 3.152%; mean PDFF psoas muscle: 0.764%; mean PDFF erector spinae: 6.332%; and a 37-year-old man (B) BMI: 30.68 kg/m2; mean PDFF abdominal muscles: 17.789%; mean PDFF psoas muscle: 12.678%; mean PDFF erector spinae: 11.386%.
Figure 3.
Representative PDFF maps on the level of L4 of a 23-year-old woman (A) BMI: 22.81 kg/m2; mean PDFF abdominal muscles: 1.569%; mean PDFF psoas muscle: 3.320%; mean PDFF erector spinae: 9.547%; and a 77-year-old woman (B) BMI: 23.39 kg/m2; mean PDFF abdominal muscles: 13.992%; mean PDFF psoas muscle: 3.162%; mean PDFF erector spinae: 29.698%.
Figure 3.
Representative PDFF maps on the level of L4 of a 23-year-old woman (A) BMI: 22.81 kg/m2; mean PDFF abdominal muscles: 1.569%; mean PDFF psoas muscle: 3.320%; mean PDFF erector spinae: 9.547%; and a 77-year-old woman (B) BMI: 23.39 kg/m2; mean PDFF abdominal muscles: 13.992%; mean PDFF psoas muscle: 3.162%; mean PDFF erector spinae: 29.698%.
Figure 4.
Proton density fat fraction (PDFF) of the abdominal muscle compartments. This figure plots the PDFF of the abdominal muscle, psoas muscle, and erector spinae against age for men (A,C,E) and women (B,D,F), respectively. The areas between the dotted lines represent the 95% confidence band of the best-fit line. Triangles represent x/y values for men and dots for women.
Figure 4.
Proton density fat fraction (PDFF) of the abdominal muscle compartments. This figure plots the PDFF of the abdominal muscle, psoas muscle, and erector spinae against age for men (A,C,E) and women (B,D,F), respectively. The areas between the dotted lines represent the 95% confidence band of the best-fit line. Triangles represent x/y values for men and dots for women.
Figure 5.
Proton density fat fraction (PDFF) of the abdominal muscle compartments. This figure plots the PDFF of the abdominal muscle, psoas muscle and erector spinae against BMI for men (A,C,E) and women (B,D,F), respectively. The areas between the dotted lines represent the 95% confidence band of the best-fit line. Triangles represent x/y values for men and dots for women.
Figure 5.
Proton density fat fraction (PDFF) of the abdominal muscle compartments. This figure plots the PDFF of the abdominal muscle, psoas muscle and erector spinae against BMI for men (A,C,E) and women (B,D,F), respectively. The areas between the dotted lines represent the 95% confidence band of the best-fit line. Triangles represent x/y values for men and dots for women.
Table 1.
Subject characteristics (age and body mass index (BMI)), PDFF values, and cross-sectional area (CSA) of abdominal muscles, psoas muscle, and erector spinae. Parameters were compared between the two groups with Mann–Whitney tests (p-values).
Table 1.
Subject characteristics (age and body mass index (BMI)), PDFF values, and cross-sectional area (CSA) of abdominal muscles, psoas muscle, and erector spinae. Parameters were compared between the two groups with Mann–Whitney tests (p-values).
| Subjects | n | Mean | SD | p |
---|
age | men | 26 | 38.85 | 10.38 | 0.665 |
(years) | women | 53 | 39.51 | 15.03 | |
BMI | men | 20 | 26.37 | 5.30 | 0.455 |
(kg/m2) | women | 48 | 25.67 | 5.46 | |
PDFFabdominal muscles | men | 26 | 6.16 | 8.26 | 0.262 |
(%) | women | 53 | 6.96 | 6.52 | |
CSAabdominal muscles | men | 26 | 43.83 | 9.87 | <0.0001 |
(a.u.) | women | 53 | 27.78 | 6.56 | |
PDFFpsoas muscle | men | 26 | 4.45 | 2.76 | 0.650 |
(%) | women | 53 | 3.93 | 1.79 | |
CSApsoas muscle | men | 26 | 17.88 | 4.11 | <0.0001 |
(a.u.) | women | 53 | 10.81 | 2.48 | |
PDFFerector spinae | men | 26 | 7.99 | 6.36 | 0.011 |
(%) | women | 53 | 14.87 | 31.74 | |
CSAerector spinae | men | 26 | 37.40 | 6.77 | <0.0001 |
(a.u.) | women | 53 | 25.02 | 4.74 | |
Table 2.
This table illustrates the results of the correlation of age, body mass index (BMI), and proton density fat fraction (PDFF) in the abdominal muscles, psoas muscle, and erector spinae in men. Spearman’s rho correlation coefficients are provided for each correlation, and p-values indicate statistical significance of the respective correlation (n.s.: not significant).
Table 2.
This table illustrates the results of the correlation of age, body mass index (BMI), and proton density fat fraction (PDFF) in the abdominal muscles, psoas muscle, and erector spinae in men. Spearman’s rho correlation coefficients are provided for each correlation, and p-values indicate statistical significance of the respective correlation (n.s.: not significant).
| | Age | BMI | PDFFabdominal muscles | PDFFpsoas muscle | PDFFerector spinae |
---|
age | Spearman’s rho | 1 | | 0.638 | | |
(years) | p | - | n.s. | 0.0001 | n.s. | n.s. |
BMI | Spearman’s rho | | 1 | 0.510 | | |
(kg/m2) | p | n.s. | - | 0.022 | n.s. | n.s. |
PDFFabdominal muscles | Spearman’s rho | 0.638 | 0.510 | 1 | 0.543 | 0.395 |
(%) | p | 0.0001 | 0.022 | - | 0.004 | 0.046 |
PDFFpsoas muscle | Spearman’s rho | | | 0.543 | 1 | 0.506 |
(%) | p | n.s. | n.s. | 0.004 | - | 0.008 |
PDFFerector spinae | Spearman’s rho | | | 0.395 | 0.506 | 1 |
(%) | p | n.s. | n.s. | 0.046 | 0.008 | - |
Table 3.
In this table Spearman’s rho correlation is depicted for age, BMI, and PDFF in the different muscle compartments in women.
Table 3.
In this table Spearman’s rho correlation is depicted for age, BMI, and PDFF in the different muscle compartments in women.
| | Age | BMI | PDFFabdominal muscles | PDFFpsoas muscle | PDFFerector spinae |
---|
age | Spearman’s rho | 1 | 0.324 | 0.709 | | 0.674 |
(years) | p | - | 0.025 | 0.0001 | n.s. | 0.0001 |
BMI | Spearman’s rho | 0.324 | 1 | 0.512 | | 0.340 |
(kg/m2) | p | 0.025 | - | 0.0001 | n.s. | 0.018 |
PDFFabdominal muscles | Spearman’s rho | 0.709 | 0.512 | 1 | | 0.653 |
(%) | p | 0.0001 | 0.001 | - | n.s. | 0.0001 |
PDFFpsoas muscle | Spearman’s rho | | | | 1 | |
(%) | p | n.s. | n.s. | n.s. | - | n.s. |
PDFFerector spinae | Spearman’s rho | 0.674 | 0.340 | 0.653 | | 1 |
(%) | p | 0.0001 | 0.018 | 0.0001 | n.s. | - |
Table 4.
This table illustrates the results of the correlation of age, body mass index (BMI), and cross-sectional area (CSA) in the abdominal muscles, psoas muscle, and erector spinae in men.
Table 4.
This table illustrates the results of the correlation of age, body mass index (BMI), and cross-sectional area (CSA) in the abdominal muscles, psoas muscle, and erector spinae in men.
| | Age | BMI | CSAabdominal muscles | CSApsoas muscle | CSAerector spinae |
---|
age | Spearman’s rho | 1 | | | | |
(years) | p | - | n.s. | n.s. | n.s. | n.s. |
BMI | Spearman’s rho | | 1 | | | 0.599 |
(kg/m2) | p | n.s. | - | n.s. | n.s. | 0.005 |
CSAabdominal muscles | Spearman’s rho | | | 1 | | |
(a.u.) | p | n.s. | n.s. | - | n.s. | n.s. |
CSApsoas muscle | Spearman’s rho | | | | 1 | |
(a.u.) | p | n.s. | n.s. | n.s. | - | n.s. |
CSAerector spinae | Spearman’s rho | | 0.599 | | | 1 |
(a.u.) | p | n.s. | 0.005 | n.s. | n.s. | - |
Table 5.
This table illustrates the results of the correlation of age, body mass index (BMI), and cross-sectional area (CSA) in the abdominal muscles, psoas muscle, and erector spinae in women.
Table 5.
This table illustrates the results of the correlation of age, body mass index (BMI), and cross-sectional area (CSA) in the abdominal muscles, psoas muscle, and erector spinae in women.
| | Age | BMI | CSAabdominal muscles | CSApsoas muscle | CSAerector spinae |
---|
age | Spearman’s rho | 1 | 0.324 | | | |
(years) | p | - | 0.025 | n.s. | n.s. | n.s. |
BMI | Spearman’s rho | 0.324 | 1 | | | |
(kg/m2) | p | 0.025 | - | n.s. | n.s. | n.s. |
CSAabdominal muscles | Spearman’s rho | | | 1 | 0.558 | 0.424 |
(a.u.) | p | n.s. | n.s. | - | 0.0001 | 0.002 |
CSApsoas muscle | Spearman’s rho | | | 0.558 | 1 | |
(a.u.) | p | n.s. | n.s. | 0.0001 | - | n.s. |
CSAerector spinae | Spearman’s rho | | | 0.424 | | 1 |
(a.u.) | p | n.s. | n.s. | 0.002 | n.s. | - |
Table 6.
Partial correlations for men with age as a control variable.
Table 6.
Partial correlations for men with age as a control variable.
| | BMI | PDFFabdominal muscles | PDFFpsoas muscle | PDFFerector spinae |
---|
BMI | r | 1 | 0.555 | | |
(kg/m2) | p | - | 0.014 | n.s. | n.s. |
PDFFabdominal muscles | r | 0.510 | 1 | 0.618 | 0.555 |
(%) | p | 0.022 | - | 0.005 | 0.014 |
PDFFpsoas muscle | r | | 0.618 | 1 | 0.620 |
(%) | p | n.s. | 0.005 | - | 0.005 |
PDFFerector spinae | r | | 0.464 | 0.620 | 1 |
(%) | p | n.s. | 0.045 | 0.005 | - |
Table 7.
Partial correlations for women with age as a control variable.
Table 7.
Partial correlations for women with age as a control variable.
| | BMI | PDFFabdominal muscles | PDFFpsoas muscle | PDFFerector spinae |
---|
BMI | r | 1 | 0.308 | | |
(kg/m2) | p | - | 0.014 | n.s. | n.s. |
PDFFabdominal muscles | r | 0.308 | 1 | | |
(%) | p | 0.014 | - | n.s. | n.s. |
PDFFpsoas muscle | r | | | 1 | |
(%) | p | n.s. | n.s | - | n.s. |
PDFFerector spinae | r | | | | 1 |
(%) | p | n.s. | n.s. | n.s. | - |
Table 8.
Partial correlations for women with BMI as a control variable.
Table 8.
Partial correlations for women with BMI as a control variable.
| | Age | PDFFabdominal muscles | PDFFpsoas muscle | PDFFerector spinae |
---|
age | r | 1 | 0.631 | | |
(kg/m2) | p | - | <0.0001 | n.s. | n.s. |
PDFFabdominal muscles | r | 0.631 | 1 | 0.293 | |
(%) | p | <0.0001 | - | 0.046 | n.s. |
PDFFpsoas muscle | r | | 0.293 | 1 | 0.538 |
(%) | p | n.s. | 0.046 | - | 0.017 |
PDFFerector spinae | r | | | | 1 |
(%) | p | n.s. | n.s. | n.s. | - |