Assessment of absolute metabolite concentrations in human tissue by ³¹P MRS in vivo. Part II: Muscle, liver, kidney

Abstract

Absolute metabolite concentrations were assessed in the muscle, the liver, and the kidney of healthy human volunteers by 31P MRS. Fully relaxed in vivo spectra were acquired with a surface coil and were localized with an adiabatic ISIS pulse sequence. The spectra were quantified with a subsequent measurement of a calibration phantom and were processed iteratively in the time domain. The following mean metabolite concentrations (mmol/liter) were measured in the resting male calf muscle (n = 9), in the fasting liver (n = 12), and in the orthotopic kidney (n = 5): [PME] = 2.0 +/- 0.6, 3.8 +/- 0.7, and 2.6 +/- 0.9, [Pi] = 2.9 +/- 0.3, 1.8 +/- 0.3, and 1.6 +/- 0.4, [PDE] = 3.8 +/- 0.8, 9.7 +/- 1.5, and 4.9 +/- 1.1, [PCr] = 22.0 +/- 1.2, 0, and 0, [NTP] = 5.7 +/- 0.4, 2.9 +/- 0.4, and 2.0 +/- 0.3, respectively. Several interesting findings are to be emphasized: The concentrations of Pi, PCr, and NTP were 20% lower in the muscle of women than of men. In addition, the pHi was significantly lower in female muscle (6.99 +/- 0.03) than in male muscle (7.05 +/- 0.03). The pHi in the liver (7.12 +/- 0.09) and in the kidney (7.09 +/- 0.08) were higher than in the muscle of both genders. The free magnesium concentration (mmol/liter) was higher in the liver (1.40 +/- 0.64) than in the kidney (0.79 +/- 0.39) and in the muscle (0.52 +/- 0.10).

Absolute quantification of human liver metabolite concentrations by localized in vivo 31P NMR spectroscopy in diffuse liver disease

“…5a,f (not drawn to the same scale). The relaxation rates for phosphorus resonances originating from muscle are considerably longer than those from liver [19], which adds to the discriminatory power of liver detection. Figure 5a, g (not drawn to the same scale) shows a typical image-guided spectrum of the human liver using volume selective excitation, although with worse than typical inclusion of PCr signal.…”

“…This is especially the case when the sequence is improved by adding more steps in the phase cycle in order to further improve the accuracy of the volume selection [22]. In any case many reports show spectra of apparently excellent volume selection, discriminating resonances obviously originating from peripheral muscle tissue [19].…”

Abnormal Hepatic Energy Homeostasis in Type 2 Diabetes†

“…[32][33][34][35][36][37] In addition to MRS-dependent differences, the great interindividual variability within and across these studies could be due to the nutritional status and variations of age and BMI. To overcome such influences, we controlled for dietary intake and matched the controls for age and BMI.…”

Phosphorus‐31 MR spectroscopy of normal adult human brain and brain tumours

“…It has already been demonstrated that this is, in principle, technically possible. 4,7,18 Due to the long acquisition times and the large measured volumes, these methods have not, as yet, been integrated into our clinical protocols.…”