In vivo 1D and 2D correlation MR spectroscopy of the soleus muscle at 7T

Abstract

Aim This study aims to (1) undertake and analyse 1D and 2D MR correlation spectroscopy from human soleus muscle in vivo at 7T, and (2) determine T1 and T2 relaxation time constants at 7T field strength due to their importance in sequence design and spectral quantitation. Method Six healthy, male volunteers were consented and scanned on a 7T whole-body scanner (Siemens AG, Erlangen, Germany). Experiments were undertaken using a 28 cm diameter detunable birdcage coil for signal excitation and an 8.5 cm diameter surface coil for signal reception. The relaxation time constants, T1 and T2 were recorded using a STEAM sequence, using the ‘progressive saturation’ method for the T1 and multiple echo times for T2. The 2D L-Correlated SpectroscopY (L-COSY) method was employed with 64 increments (0.4 ms increment size) and eight averages per scan, with a total time of 17 min. Results T1 and T2 values for the metabolites of interest were determined. The L-COSY spectra obtained from the soleus muscle provided information on lipid content and chemical structure not available, in vivo, at lower field strengths. All molecular fragments within multiple lipid compartments were chemically shifted by 0.20–0.26 ppm at this field strength. 1D and 2D L-COSY spectra were assigned and proton connectivities were confirmed with the 2D method. Conclusion In vivo 1D and 2D spectroscopic examination of muscle can be successfully recorded at 7T and is now available to assess lipid alterations as well as other metabolites present with disease. T1 and T2 values were also determined in soleus muscle of male healthy volunteers.

Glycosidic intermediates identified in 1H MR spectra of intact tumour cells may contribute to the clarification of aspects of glycosylation pathways

“…Nevertheless, relative concentration changes may be detected on the basis of the assumption that relevant changes in T 2 relaxation times of the compounds of interest are not expected in the observed pools. Recent papers have shown that 2D NMR may play an important role in the detection and quantification of selected metabolites either in vitro (46) or in vivo (47). Variations in (Table 1) agree not only with those deriving from the solution of commercial products (Table 2), but also with those of isolated phosphocompounds of prokaryote origin (37,38).…”

Adiabatic localized correlation spectroscopy (AL‐COSY): Application in muscle and brain

“…All slice selective RF pulses are surrounded by spoilers, with a resultant spoiler gradient vector applied along the magic angle. mm 3 and located at isocenter. Experimental parameters were as follows: TR; 2000 ms, TE; 50 ms, dummy scans; 4, averages; 4, acquisition duration; 512 ms, acquired vector size; 1024 points, bandwidth; 2000 Hz, RF offset frequency was set to water resonance frequency, and water suppression routine ''WET'' was turned off (27).…”

Effect of J‐coupling on lipid composition determination with localized proton magnetic resonance spectroscopy at 9.4 T

“…During the PRESS echo time, TE, the signal of each lipid resonance decays due to transverse relaxation according to a T 2 constant characteristic of the protons contributing to that peak. Furthermore, all lipid protons are involved in scalar coupling (J-coupling) interactions (21)(22)(23), which cause their response to PRESS to be modulated as a function of TE. Efforts have been made to correct for T 2 losses (11,12,18); however, to our knowledge signal correction for J-coupling evolution has not been performed when establishing lipid compositions using in vivo sequences.…”

“…1b shows the corresponding peaks of corn oil. At 9.4 T, the 2.1 ppm protons are weakly coupled to neighboring 1.3 and 5.4 ppm protons; the 2.8 ppm protons are weakly coupled to neighboring 5.4 ppm protons, and the 2.3 ppm protons are weakly coupled to neighboring 1.6 ppm protons (23). The oils studied in this work consisted primarily of saturated (SFA), monounsaturated (MUFA), and diunsaturated fatty acids (DUFA); specifically, the main MUFA and DUFA constituents are oleic and linoleic acid, respectively.…”