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Two‐dimensional spectroscopic imaging with combined free induction decay and long‐TE acquisition (FID echo spectroscopic imaging, FIDESI) for the detection of intramyocellular lipids in calf muscle at 7 T
Author(s) -
Just Kukurova Ivica,
Valkovič Ladislav,
Bogner Wolfgang,
Gajdošík Martin,
Krššák Martin,
Gruber Stephan,
Trattnig Siegfried,
Chmelík Marek
Publication year - 2014
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3148
Subject(s) - chemistry , analytical chemistry (journal) , triglyceride , degree of unsaturation , nuclear magnetic resonance , nuclear medicine , chromatography , medicine , cholesterol , biochemistry , physics
The aim of this study was to introduce a two‐dimensional chemical shift imaging (2D CSI) sequence, with simultaneous acquisition of free induction decay (FID) and long TEs, for the detection and quantification of intramyocellular lipids (IMCLs) in the calf at 7 T. The feasibility of the new 2D CSI sequence, which acquires FID (acquisition delay, 1.3 ms) and an echo (long TE) in one measurement, was evaluated in phantoms and volunteers ( n = 5): TR/TE*/TE = 800/1.3/156 ms; 48 × 48 matrix; field of view, 200 × 200 × 20 mm 3 ; Hamming filter; no water suppression; measurement time, 22 min 2 s. The IMCL concentration and subcutaneous lipid contamination were assessed. Spectra in the tibialis anterior (TA), gastrocnemius (GM) and soleus (SOL) muscles were analyzed. The water signal from the FID acquisition was used as an internal concentration reference. In the spectra from subcutaneous adipose tissue (SUB) and bone marrow (BM), an unsaturation index (UI) of the vinyl‐H (5.3 ppm) to methyl‐CH 3 ratio, and a polyunsaturation index (pUI) of the diallylic‐H (2.77 ppm) to ‐CH 3 ratio, were calculated. Long‐TE spectra from muscles showed a simplified spectral pattern with well‐separated IMCL for several muscle groups in the same scan. The IMCL to water ratio was largest in SOL (0.66% ± 0.23%), and lower in GM (0.37% ± 0.14%) and TA (0.36% ± 0.12%). UI and pUI for SUB were 0.65 ± 0.06 and 0.18 ± 0.04, respectively, and for BM were 0.60 ± 0.16 and 0.18 ± 0.08, respectively. The new sequence, with the proposed name ‘free induction decay echo spectroscopic imaging’ (FIDESI), provides information on both specific lipid resonances and water signal from different tissues in the calf, with high spectral and spatial resolution, as well as minimal voxel bleeding and subcutaneous lipid contamination, in clinically acceptable measurement times. Copyright © 2014 John Wiley & Sons, Ltd.