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T1rho MRI in Brain Aging, Lumbar Disc Degeneration, and Liver Fibrosis: Clinical and Experimental Studies.

机译：T1rho MRI在脑衰老，腰椎间盘退变和肝纤维化中的应用：临床和实验研究。

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摘要

T1rho relaxation is spin-lattice relaxation in the rotating frame. It determines the decay of the transverse magnetization in the presence of a spin-lock radiofrequency pulse, which applied along the transverse magnetization. T1rho MRI is sensitive to low frequency motional processes, so it can be used to investigate the interaction between water molecules and their macromolecular environment. T1rho imaging is suggested to have the potential to identify early biochemical changes in tissues.;Aging and chronic hypertension are two major risk factors for common neurodegenerative disease. However, whether normal brain aging and chronic spontaneous hypertensive are associated with brain T1rho values changes were not reported. We longitudinally measured the T1rho value in rat brain of Sprague-Dawley (SD) rats from 5-month to 15-month, and spontaneous hypertensive rats (SHR) with Wistar Kyoto (WKY) rats from 6-month to 12-month. The T1rho values in three brain regions of thalamus, hippocampus, and cortices increased with aging process, and were significantly higher in SHR than WKY rats.;For intervertebral disc, the correlation between T1rho and degenerative grade has been reported. However, whether and how T1rho specifically offer better evaluation of disc degeneration compared with T2 was not studied previously. T1rho and T2 value of nucleus pulposus (NP) and annulus fibrosus (AF) was compared with reference to the five-level and eight-level semi-quantitative disc degeneration grading systems. For NP, T1rho and T2 decreased quadratically with disc degeneration grades and had no significant trend difference (P=0.40). In NP, T1rho and T2 decrease in a similar pattern following disc degeneration. For AF, T1rho and T2 decreased linearly and the slopes of T2 were significantly flatter than those of T1rho (P<0.001). Therefore, the T1rho is better suited for evaluating AF in degenerated disc than T2.;Liver fibrosis, a common feature of almost all causes of chronic liver disease, involves macromolecules accumulated within the extracellular matrix. Male Sprague-Dawley rats received intraperitoneal injection of 2 ml/kg CCl4 twice weekly for up to 6 weeks. Then CCl4 was withdrawn for recovery. The liver T1rho values increased slightly on day 2, then increased further and were highest at week 6 post CCl4 insults, and decreased upon the withdrawal of the CCl4 insult. This study demonstrated that T1rho MRI is a valuable imaging biomarker for liver injury and fibrosis induced by CCl4. Liver T1rho value was only mildly affected by edema and acute inflammation when there was no apparent fibrosis.;To translate liver T1rho MRI to clinical application, the technical feasibility of T1rho MRI in human liver was explored and the normal range of T1rho values in healthy volunteers was determined. We found it is feasible to obtain consistent liver T1rho measurement for healthy human liver with six spin-lock time (SLT) points of 1, 10, 20, 30, 40, and 50ms; the mean liver T1rho value of the healthy subjects was 42.5ms, with a range of 38.8-46.5ms. Adopting 3-SLT points of 1, 20, and 50ms for T1rho measurement could provide reliable measurement and reduce the scanning time, while 2-SLT points of 1 and 50ms do not provide reliable measurement.
机译：T1rho弛豫是旋转框架中的自旋晶格弛豫。它在存在自旋锁定射频脉冲的情况下确定横向磁化强度的衰减，该脉冲沿横向磁化强度施加。 T1rho MRI对低频运动过程敏感，因此可用于研究水分子与其大分子环境之间的相互作用。提示T1rho成像具有识别组织中早期生化变化的潜力。衰老和慢性高血压是常见神经退行性疾病的两个主要危险因素。但是，尚无正常脑衰老和慢性自发性高血压是否与脑T1rho值变化有关。我们纵向测量了Sprague-Dawley（SD）大鼠从5个月到15个月的脑内T1rho值，以及Wistar Kyoto（WKY）大鼠从6个月到12个月的自发性高血压大鼠（SHR）。丘脑，海马和皮层三个大脑区域的T1rho值随衰老过程而增加，并且在SHR中明显高于WKY大鼠。对于椎间盘，已有报道T1rho与退化程度之间的相关性。但是，与T2相比，T1rho是否以及如何专门提供更好的椎间盘退变评估尚未被研究。参照五级和八级半定量椎间盘退变分级系统比较髓核（NP）和纤维环（AF）的T1rho和T2值。对于NP，T1rho和T2与椎间盘退变程度呈二次下降趋势，且无明显趋势差异（P = 0.40）。在NP中，椎间盘退变后，T1rho和T2以相似的方式下降。对于AF，T1rho和T2线性下降，并且T2的斜率比T1rho的斜率显着平坦（P <0.001）。因此，T1rho比T2更适合评估变性椎间盘的房颤。肝纤维化是几乎所有慢性肝病原因的共同特征，涉及大分子积聚在细胞外基质中。雄性Sprague-Dawley大鼠每周两次腹膜内注射2 ml / kg CCl4，长达6周。然后取出CCl 4进行回收。肝T1rho值在第2天略有上升，然后进一步上升，并在CCl4损伤后第6周达到最高，而在CCl4损伤停止后下降。这项研究表明，T1rho MRI是CCl4诱导的肝损伤和纤维化的有价值的成像生物标记。在没有明显纤维化的情况下，肝脏T1rho值仅受水肿和急性炎症的轻微影响。；为了将肝脏T1rho MRI转化为临床应用，探讨了T1rho MRI在人肝中的技术可行性，并研究了健康志愿者中T1rho值的正常范围被确定。我们发现，通过六个自旋锁定时间（SLT）点分别为1、10、20、30、40和50ms，可以对健康的人类肝脏获得一致的肝脏T1rho测量值；健康受试者的平均肝脏T1rho值为42.5ms，范围为38.8-46.5ms。为T1rho测量采用1、20和50ms的3-SLT点可以提供可靠的测量并减少扫描时间，而1和50ms的2-SLT点不能提供可靠的测量。

著录项

  • 作者

    Zhao, Feng.;

  • 作者单位

    The Chinese University of Hong Kong (Hong Kong).;

  • 授予单位 The Chinese University of Hong Kong (Hong Kong).;
  • 学科 Health Sciences Radiology.;Health Sciences Oncology.;Health Sciences General.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 171 p.
  • 总页数 171
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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