Inductively coupled helmholtz coil on a dedicated imaging platform for the in vivo¹H‐MRS measurement of intramyocellular lipids in the hind leg of rats

Abstract

Skeletal muscle triglycerides are markers for insulin resistance in type 2 diabetes. Recently, MR spectroscopy was adapted for in vivo measurement of triglycerides in animal models and for the characterization of new therapeutic approaches. Because of small MR spectroscopy voxel sizes used in skeletal muscles, surface coils are used for signal reception. Furthermore, to obtain well-resolved and undistorted lipid spectra, muscle fibers must be aligned parallel to the magnetic field. Consequently, to achieve a high signal-to-noise ratio and spectral quality, a coil setup must combine high sensitivity with a reliable and reproducible positioning of muscle and voxel. These demands are difficult to match using surface coils. Here, a coil platform is described, which uses inductively coupled Helmholtz coil setup combined with a leg retainer system for rats. The new system allows for measurement of intramyocellular lipids with high signal-to-noise ratio and for significantly improved animal handling, positioning, and throughput. Magn

Inhibition of acetyl-CoA carboxylase 2 enhances skeletal muscle fatty acid oxidation and improves whole-body glucose homeostasis in db/db mice

“…Intramyocellular lipid For signal reception a custom-made Helmholtz coil mouse set-up was used (adapted from Neumaier et al [28]). The MR spectroscopy (MRS) voxel was positioned in the tibialis anterior muscle using a T 1 -weighted pilot scan with packages of horizontal and axial slices (repetition time (TR) 120 ms, echo time (TE) 4 ms, flip angle 55°, four averages, field-of-view 2.5×2.5 cm, slice thickness 1.0 mm, interslice distance 1.2 mm, matrix 192 2 (zero-filled to 256 2 ), measuring time 92 s).…”

Diffusion‐weighted magnetic resonance spectroscopy: A novel approach to investigate intramyocellular lipids

“…Thus, it can be used when examining IMCL in various muscles including vastus muscle, or a large muscle volume to achieve high spectral signal to noise ratio (SNR). It has been shown in earlier animal and human studies that carefully positioned small voxels could yield well‐resolved IMCL and EMCL spectra in certain muscles even at short TE to investigate specific muscle physiology (39–42). In the present study, large voxels were chosen to gain SNR for in vivo demonstration, permitting 2‐min DW‐MRS acquisition with reasonable SNR.…”

High‐field (11.75T) multimodal MR imaging of exercising hindlimb mouse muscles using a non‐invasive combined stimulation and force measurement device

“…While conventional T 1 ‐ and T 2 ‐weighted MR images can easily provide important clues regarding resting muscle (e.g. muscle volume), investigation of exercising small animals muscle requires more advanced MR techniques allowing evaluation of muscle activation via T 2 mapping , muscle oxygenation using blood oxygenation level‐dependent techniques , muscle perfusion through arterial spin labeling (ASL) and dynamic contrast‐enhanced techniques , muscle architecture using diffusion tensor imaging and muscle metabolism via 1 H and 31 P‐magnetic resonance spectroscopy (MRS) . Given that most of these techniques are limited by their low sensitivity, they would benefit from the larger signal‐to‐noise ratio (SNR) provided by both high‐field magnets (>7T) and the availability of high‐performance gradient systems (e.g.…”