在11.7T磁共振成像（MRI）下对小鼠骨骼肌进行肌酸化学交换饱和转移（CrCEST）成像。
Mouse skeletal muscle creatine chemical exchange saturation transfer (CrCEST) imaging at 11.7T MRI.
作者信息
Takahashi Yusuke, Saito Shigeyoshi, Kioka Hidetaka, Araki Rikita, Asano Yoshihiro, Takashima Seiji, Sakata Yasushi, Yoshioka Yoshichika
机构信息
Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Department of Medical Physics and Engineering, Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
出版信息
J Magn Reson Imaging. 2020 Feb;51(2):563-570. doi: 10.1002/jmri.26844. Epub 2019 Jun 22.
BACKGROUND
Creatine chemical exchange saturation transfer (CrCEST) imaging is expected to be a novel evaluation method of muscular energy metabolism.
PURPOSE
To develop CrCEST imaging of mouse skeletal muscle and to validate this technique by measuring changes in Cr concentration of ischemic hindlimbs.
STUDY TYPE
Prospective.
ANIMAL MODEL
C57BL/6 mice (n = 6), mild hindlimb ischemic mice (n = 6), and severe hindlimb ischemic mice (n = 6).
FIELD STRENGTH/SEQUENCE: Magnetic resonance angiography (MRA), CrCEST imaging, and phosphorus magnetic resonance spectroscopy ( P MRS) obtained at 11.7T.
ASSESSMENT
MRA and P MRS were performed to confirm the presence of ischemia following the compression by rubber tourniquet. CrCEST imaging was performed and magnetization transfer ratio asymmetry (MTR ), which reflects Cr concentration, and was calculated in severe ischemia models, mild ischemia models, and control mice. Follow-up CrCEST imaging was performed after the release of ischemia in the mild ischemia models.
STATISTICAL TESTS
Mean ± SD, one-way analysis of variance (ANOVA) with Tukey's HSD test, unpaired or paired t-test.
RESULTS
MRA revealed the loss of blood flow of the femoral artery in the ischemic hindlimb. P MRS revealed different degrees of PCr decrease in severe and mild ischemic hindlimb (n = 3 per group, normal hindlimb: 1.0 ± 0, mild ischemic hindlimb: 0.77 ± 0.13, severe ischemic hindlimb: 0 ± 0). CrCEST imaging inversely revealed a significant stepwise increase in the MTR ratio of ischemic hindlimbs compared with controls (control, mild ischemia, and severe ischemia; 0.99 ± 0.04, 1.36 ± 0.08, and 1.59 ± 0.23, respectively, P < 0.0001). In addition, follow-up CrCEST imaging after the release of ischemia revealed normalization of the MTR ratios (recovered hindlimb: 1.01 ± 0.05).
DATA CONCLUSION
We demonstrated an increase in the MTR of ischemic hindlimbs, along with a decrease of PCr. We demonstrated the normalization of MTR after the release of ischemia and developed CrCEST imaging of mouse skeletal muscle.
LEVEL OF EVIDENCE
2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:563-570.
背景
肌酸化学交换饱和转移（CrCEST）成像有望成为一种评估肌肉能量代谢的新方法。
目的
开发小鼠骨骼肌的CrCEST成像，并通过测量缺血后肢肌酸浓度的变化来验证该技术。
研究类型
前瞻性研究。
动物模型
C57BL/6小鼠（n = 6）、轻度后肢缺血小鼠（n = 6）和重度后肢缺血小鼠（n = 6）。
场强/序列：在11.7T下进行磁共振血管造影（MRA）、CrCEST成像和磷磁共振波谱（P MRS）。
评估
通过MRA和P MRS确认橡胶止血带压迫后缺血的存在。在重度缺血模型、轻度缺血模型和对照小鼠中进行CrCEST成像，并计算反映肌酸浓度的磁化转移率不对称性（MTR）。在轻度缺血模型中缺血解除后进行随访CrCEST成像。
统计检验
均值±标准差、采用Tukey's HSD检验的单因素方差分析（ANOVA）、非配对或配对t检验。
结果
MRA显示缺血后肢股动脉血流消失。P MRS显示重度和轻度缺血后肢磷酸肌酸（PCr）有不同程度降低（每组n = 3，正常后肢：1.0±0，轻度缺血后肢：0.77±0.13，重度缺血后肢：0±0）。CrCEST成像则显示，与对照组相比，缺血后肢的MTR比值呈显著逐步升高（对照组、轻度缺血组和重度缺血组分别为0.99±0.04、1.36±0.08和1.59±0.23，P < 0.0001）。此外，缺血解除后的随访CrCEST成像显示MTR比值恢复正常（恢复后肢：1.01±0.05）。
数据结论
我们证明了缺血后肢MTR升高，同时PCr降低。我们证明了缺血解除后MTR恢复正常，并开发了小鼠骨骼肌的CrCEST成像。
证据水平
2 技术效能：2期 《磁共振成像杂志》2020年；51:563 - 570。
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