在7T磁场下，采用自由感应衰减与长回波时间采集相结合的二维光谱成像（FID回波光谱成像，FIDESI）检测小腿肌肉中的肌内脂质。

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.

作者信息

Just Kukurova Ivica, Valkovič Ladislav, Bogner Wolfgang, Gajdošík Martin, Krššák Martin, Gruber Stephan, Trattnig Siegfried, Chmelík Marek

机构信息

MR Centre of Excellence, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Department of NMR and MS, Faculty of Chemical and Food Technology, Slovak University of Technology, Bratislava, Slovakia.

出版信息

NMR Biomed. 2014 Aug;27(8):980-7. doi: 10.1002/nbm.3148. Epub 2014 Jun 9.

DOI:10.1002/nbm.3148

PMID:24912448

Abstract

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-CH3 ratio, and a polyunsaturation index (pUI) of the diallylic-H (2.77 ppm) to -CH3 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.

摘要

本研究的目的是引入一种二维化学位移成像（2D CSI）序列，该序列可同时采集自由感应衰减（FID）和长回波时间（TE），用于在7T场强下检测和定量小腿中的肌内脂质（IMCL）。在体模和志愿者（n = 5）中评估了新的2D CSI序列的可行性，该序列在一次测量中采集FID（采集延迟，1.3毫秒）和一个回波（长TE）：重复时间/有效回波时间/回波时间 = 800/1.3/156毫秒；48×48矩阵；视野，200×200×20毫米³；汉明滤波器；不进行水抑制；测量时间，22分2秒。评估了IMCL浓度和皮下脂质污染情况。分析了胫骨前肌（TA）、腓肠肌（GM）和比目鱼肌（SOL）的光谱。将FID采集得到的水信号用作内部浓度参考。在皮下脂肪组织（SUB）和骨髓（BM）的光谱中，计算了乙烯基-H（5.3 ppm）与甲基-CH₃ 之比的不饱和指数（UI），以及二烯丙基-H（2.77 ppm）与-CH₃ 之比的多不饱和指数（pUI）。来自肌肉的长TE光谱显示出简化的光谱模式，在同一次扫描中，几个肌肉群的IMCL分离良好。IMCL与水的比率在SOL中最大（0.66%±0.23%），在GM中较低（0.37%±0.14%），在TA中更低（0.36%±0.12%）。SUB的UI和pUI分别为0.65±0.06和0.18±0.04，BM的UI和pUI分别为0.60±0.16和0.18±0.08。这个新序列，命名为“自由感应衰减回波光谱成像”（FIDESI），在临床可接受的测量时间内，提供了小腿不同组织中特定脂质共振和水信号的信息，具有高光谱和空间分辨率，以及最小的体素渗漏和皮下脂质污染。