Table 6.
Test—retest results of muscle-associated lipid storage measured by MRS (n = 10) and CT (n = 6)
| Variable | Test (mean ± SD) |
Retest (mean ± SD) |
Between-subject CV% |
Within-subject CV% |
ICC |
|---|---|---|---|---|---|
| MRS (relative to oil phantom) | |||||
| Oil phantom (AU) | 17,842 ± 2314 | 17,565 ± 2342 | 12.87 | 2.72 | 0.96 |
| Soleus EMCL-CH2 (AU × 10-2) | 2.166 ± 1.00 | 1.83 ± 0.71 | 40.98 | 18.86 | 0.83 |
| Soleus IMCL-CH2 (AU × 10-2) | 2.59 ± 1.43 | 2.72 ± 1.47 | 54.10 | 7.25 | 0.98 |
| Soleus EMCL-CH3 (AU × 10-2) | 0.13 ± 0.09 | 0.13 ± 0.08 | 38.70 | 46.54 | 0.41 |
| Soleus IMCL-CH3 (AU × 10-2) | 0.45 ± 0.26 | 0.47 ± 0.24 | 53.17 | 10.05 | 0.97 |
| TA EMCL-CH2 (AU × 10-2) | 1.10 ± 0.70 | 1.20 ± 0.95 | 66.56 | 28.51 | 0.84 |
| TA IMCL-CH2 (AU × 10-2) | 0.38 ± 0.15 | 0.41 ± 0.18 | 40.58 | 10.86 | 0.93 |
| TA EMCL-CH3 (AU × 10-2) (n = 9) | 0.13 ± 0.06 | 0.16 ± 10 | 41.78 | 42.77 | 0.49 |
| TA IMCL-CH3 (AU × 10-2) (n = 9) | 0.08 ± 0.03 | 0.08 ± 0.03 | 44.89 | 20.02 | 0.83 |
| MRS (relative to internal water peak) | |||||
| Soleus internal water peak (AU) | 12,329.9 ± 1253.1 | 12,415.9 ± 1058.7 | 9.03 | 2.49 | 0.93 |
| Soleus EMCL-CH2 (AU × 10-2) | 2.84 ± 1.29 | 2.57 ± 1.03 | 39.37 | 17.87 | 0.82 |
| Soleus IMCL-CH2 (AU × 10-2) | 3.81 ± 2.32 | 3.85 ± 2.23 | 59.00 | 6.30 | 0.99 |
| Soleus EMCL-CH3 (AU × 10-2) | 0.18 ± 0.11 | 0.19 ± 0.14 | 51.77 | 41.74 | 0.61 |
| Soleus IMCL-CH3 (AU × 10-2) | 0.66 ± 0.42 | 0.67 ± 0.35 | 57.29 | 10.53 | 0.97 |
| TA internal water peak (AU) | 10,318.2 ± 1232.3 | 10,515.6 ± 998.7 | 10.58 | 2.19 | 0.96 |
| TA EMCL-CH2 (AU × 10-2) | 1.87 ± 1.22 | 1.95 ± 1.61 | 69.75 | 26.83 | 0.87 |
| TA IMCL-CH2 (AU × 10-2) | 0.67 ± 0.29 | 0.68 ± 0.31 | 43.86 | 10.26 | 0.95 |
| TA EMCL-CH3 (AU × 10-2) (n = 9) | 0.20 ± 0.12 | 0.24 ± 0.16 | 49.28 | 42.74 | 0.57 |
| TA IMCL-CH3 (AU × 10-2) (n = 9) | 0.13 ± 0.07 | 0.12 ± 0.07 | 50.97 | 19.03 | 0.88 |
| MRS (relative to internal Cr peak) | |||||
| Soleus internal Cr peak (AU) | 66.21 ± 14.73 | 67.12 ± 14.84 | 18.74 | 11.57 | 0.72 |
| Soleus EMCL-CH2 (AU × 10-2) | 17.40 ± 10.51 | 15.86 ± 9.44 | 54.20 | 25.65 | 0.82 |
| Soleus IMCL-CH2 (AU × 10-2) | 23.80 ± 18.91 | 24.00 ± 17.51 | 74.59 | 15.46 | 0.96 |
| Soleus EMCL-CH3 (AU × 10-2) | 0.98 ± 0.54 | 1.08 ± 0.86 | 44.64 | 52.64 | 0.42 |
| Soleus IMCL-CH3 (AU × 10-2) | 4.14 ± 3.33 | 4.15 ± 2.77 | 70.96 | 20.0 | 0.93 |
| CT | |||||
| Soleus mean MA (HU) | 49.6 ± 5.2 | 50.0 ± 5.4 | 10.22 | 1.96 | 0.96 |
| TA mean MA (HU) | 57.5 ± 2.7 | 57.6 ± 2.4 | 3.4 | 4.05 | 0.41 |
MRS, magnetic resonance spectroscopy; CT, computed tomography; SD, standard deviation; CV, coefficient of variation; ICC, intraclass correlation; AU, arbitrary unit; EMCL, extramyocellular lipid; IMCL, intramyocellular lipid; CH2, methylene; CH3, methyl; TA, tibialis muscle; Cr, creatine; HU, Hounsfield unit.