Triplett William T, Baligand Celine, Forbes Sean C, Willcocks Rebecca J, Lott Donovan J, DeVos Soren, Pollaro Jim, Rooney William D, Sweeney H Lee, Bönnemann Carsten G, Wang Dah-Jyuu, Vandenborne Krista, Walter Glenn A
Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA.
Magn Reson Med. 2014 Jul;72(1):8-19. doi: 10.1002/mrm.24917. Epub 2013 Sep 4.
The relationship between fat fractions (FFs) determined based on multiple TE, unipolar gradient echo images and (1) H magnetic resonance spectroscopy (MRS) was evaluated using different models for fat-water decomposition, signal-to-noise ratios, and excitation flip angles.
A combination of single-voxel proton spectroscopy ((1) H-MRS) and gradient echo imaging was used to determine muscle FFs in both normal and dystrophic muscles. In order to cover a large range of FFs, the soleus and vastus lateralis muscles of 22 unaffected control subjects, 16 subjects with collagen VI deficiency (COL6), and 71 subjects with Duchenne muscular dystrophy (DMD) were studied. (1) H-MRS-based FF were corrected for the increased muscle (1) H2 O T1 and T2 values observed in dystrophic muscles.
Excellent agreement was found between coregistered FFs derived from gradient echo images fit to a multipeak model with noise bias correction and the relaxation-corrected (1) H-MRS FFs (y = 0.93x + 0.003; R(2) = 0.96) across the full range of FFs. Relaxation-corrected (1) H-MRS FFs and imaging-based FFs were significantly elevated (P < 0.01) in the muscles of COL6 and DMD subjects.
FFs, T2 , and T1 were all sensitive to muscle involvement in dystrophic muscle. MRI offered an additional advantage over single-voxel spectroscopy in that the tissue heterogeneity in FFs could be readily determined.
使用不同的脂肪-水分解模型、信噪比和激发翻转角，评估基于多回波时间、单极梯度回波图像测定的脂肪分数（FFs）与氢磁共振波谱（MRS）之间的关系。
采用单体素质子波谱（氢-MRS）和梯度回波成像相结合的方法，测定正常和营养不良肌肉中的肌肉FFs。为了涵盖较大范围的FFs，对22名未受影响的对照受试者、16名患有Ⅵ型胶原蛋白缺乏症（COL6）的受试者和71名患有杜兴氏肌营养不良症（DMD）的受试者的比目鱼肌和股外侧肌进行了研究。基于氢-MRS的FFs针对营养不良肌肉中观察到的肌肉氢水T1和T2值增加进行了校正。
在整个FFs范围内，源自拟合多峰模型并进行噪声偏差校正的梯度回波图像的配准FFs与经弛豫校正的氢-MRS FFs之间发现了极佳的一致性（y = 0.93x + 0.003；R² = 0.96）。在COL6和DMD受试者的肌肉中，经弛豫校正的氢-MRS FFs和基于成像的FFs显著升高（P < 0.01）。
FFs、T2和T1均对营养不良肌肉中的肌肉受累敏感。MRI相对于单体素质子波谱具有额外的优势，即可以很容易地确定FFs中的组织异质性。
