Department of Radiology, The First Affiliated Hospital of Kunming Medical University, Kunming, China.
Department of Physiology, Faculty of Basic Medical Science, Kunming Medical University, Kunming, Yunnan, China.
Exp Gerontol. 2023 Nov;183:112322. doi: 10.1016/j.exger.2023.112322. Epub 2023 Oct 31.
Severe sarcopenia may result in severe disability. Early diagnosis is currently the key to enhancing the treatment of sarcopenia, and there is an urgent need for a highly sensitive and dependable tool to evaluate the course of early sarcopenia in clinical practice. This study aims to investigate longitudinally the early diagnosability of magnetic resonance imaging (MRI)-based fat infiltration and blood flow perfusion technology in sarcopenia progression.
48 Sprague-Dawley rats were randomly assigned into six groups that were based on different periods of dexamethasone (DEX) injection (0, 2, 4, 6, 8, 10 days). Multimodal MRI was scanned to assess muscle mass. Grip strength and swimming exhaustion time of rats were measured to assess muscle strength and function. Immunofluorescence staining for CD31 was employed to assess skeletal muscle capillary formation, and western blot was used to detect vascular endothelial growth factor-A (VEGF-A) and muscle ring finger-1 (MuRF-1) protein expression. Subsequently, we analyzed the correlation between imaging and histopathologic parameters. A receiver operating characteristic (ROC) analysis was conducted to assess the effectiveness of quantitative MRI parameters for discriminating diagnosis in both pre- and post-modeling of DEX-induced sarcopenic rats.
Significant differences were found in PDFF, R2* and T2 values on day 2 of DEX-induction compared to the control group, occurring prior to the MRI-CSA values and limb grip strength on day 6 of induction and swimming exhaustion time on day 8 of induction. There is a strong correlation between MRI-CSA with HE-CSA values (r = 0.67; p < 0.001), oil red O (ORO) area with PDFF (r = 0.67; p < 0.001), microvascular density (MVD) (r = -0.79; p < 0.001) and VEGF-A (r = -0.73; p < 0.001) with R2*, MuRF-1 with MRI-CSA (r = -0.82; p < 0.001). The AUC of PDFF, R2*, and T2 values used for modeling evaluation are 0.81, 0.93, and 0.98, respectively.
Imaging parameters PDFF, R2*, and T2 can be used to sensitively evaluate early pathological changes in sarcopenia. The successful construction of a sarcopenia rat model can be assessed when PDFF exceeds 1.25, R2* exceeds 53.85, and T2 exceeds 33.88.
严重的肌肉减少症可能导致严重残疾。目前，早期诊断是增强肌肉减少症治疗的关键，因此迫切需要一种高度敏感和可靠的工具来评估临床实践中早期肌肉减少症的进程。本研究旨在纵向研究磁共振成像（MRI）为基础的脂肪浸润和血流灌注技术在肌肉减少症进展中的早期诊断能力。
将 48 只 Sprague-Dawley 大鼠随机分为六组，根据不同的地塞米松（DEX）注射时间（0、2、4、6、8、10 天）进行分组。使用多模态 MRI 扫描评估肌肉质量。通过握力和游泳衰竭时间测试评估大鼠的肌肉力量和功能。免疫荧光染色 CD31 用于评估骨骼肌毛细血管形成，Western blot 用于检测血管内皮生长因子 A（VEGF-A）和肌肉环指蛋白-1（MuRF-1）蛋白表达。随后，我们分析了影像学和组织病理学参数之间的相关性。进行了接收器工作特征（ROC）分析，以评估定量 MRI 参数在 DEX 诱导的肌肉减少症大鼠模型建立前后的诊断效果。
DEX 诱导后第 2 天，与对照组相比，PDFF、R2和 T2 值有显著差异，早于 MRI-CSA 值和第 6 天的肢体握力以及第 8 天的游泳衰竭时间。MRI-CSA 与 HE-CSA 值之间存在很强的相关性（r=0.67；p<0.001），油红 O（ORO）面积与 PDFF（r=0.67；p<0.001）、微血管密度（MVD）（r=-0.79；p<0.001）和 VEGF-A（r=-0.73；p<0.001）与 R2、MuRF-1 与 MRI-CSA（r=-0.82；p<0.001）之间存在相关性。PDFF、R2*和 T2 值的 AUC 用于模型评估分别为 0.81、0.93 和 0.98。
PDFF、R2和 T2 等影像学参数可用于敏感评估肌肉减少症的早期病理变化。当 PDFF 超过 1.25、R2超过 53.85 和 T2 超过 33.88 时，可成功评估肌肉减少症大鼠模型的建立。
