Electrical impedance myography and quantitative ultrasound in Duchenne muscular d

描述（由申请人提供）：杜氏肌营养不良症（DMD）是儿童中最常见的神经肌肉疾病之一，影响约3500名活产男性，产生进行性肌肉无力，使受影响的个体在大约12岁时被轮椅束缚，在生命的第三个十年发生死亡。在过去的20年里，人们对疾病发病机制的了解取得了巨大进展，并开发了许多新的潜在治疗策略，从外显子跳跃方法到干细胞疗法。这种疾病治疗选择范围的扩大也大大增加了对改进方法的需求，以加快对II期和III期临床试验中有希望的药物的评估。目前使用的生物标志物，如6分钟步行测试，对变化相对不敏感，需要临床试验招募大量受试者，同时仍然能够检测出通常过于乐观的治疗效果。电阻抗肌图（EIM）和定量超声（QUS）是两种高度创新、易于应用、基于办公室、无痛的方法，它们在作为疾病进展的新颖、敏感标记物方面提供了巨大的希望。在EIM中，微弱的高频电流通过表面电极施加，并测量随之而来的表面电压模式的变化。在QUS中，使用标准设备获得的超声图像被提炼成可用于量化疾病严重程度的数值数据。这可以通过使用模体进行校准的后处理图像分析或通过减少原始背散射声学数据来完成。在这项工作中，我们将分别研究EIM和QUS，以评估它们在DMD试验中的潜在应用。具体来说，我们将对35名正常受试者和35名5至12岁的DMD男孩进行为期两年的研究。在具体目标1中，我们将立即和在几天的时间内建立这两种技术的可重复性。在特异性目标2中，我们将通过比较两年内EIM和QUS的进展率来评估其随时间变化的临床意义。在Specific Aim 3中，我们将评估这两种方法在极短时间内（1 - 2个月）检测疾病进展的能力，以及该进展速度预测长期功能变化的能力。作为我们计划的探索性分析的一部分，我们还将评估将EIM和QUS数据集融合为单一复合生物标志物的方法，以及随着时间的推移，EIM数据中收缩引起的变化的潜在价值。随着这项工作的成功完成，我们将为在DMD II期临床试验中使用一种或两种技术作为首选生物标志物奠定基础。

DESCRIPTION (provided by applicant): Duchenne muscular dystrophy (DMD) is one of the most common neuromuscular diseases of children affecting approximately 1 in 3500 live male births, producing progressive muscle weakness and leaving affected individuals wheelchair bound by approximately 12 years of age with death occurring by the third decade of life. Over the past 20 years great inroads have been made into understanding the basic mechanisms underlying disease pathogenesis and many new potential therapeutic strategies have been developed, ranging from exon-skipping methodologies to stem cell therapies. This expanding range of disease treatment options has also greatly increased the need for improved methods to speed the assessment of promising drugs in Phase II and Phase III clinical trials. The current biomarkers that are employed, such as the 6-minute walk test, are relatively insensitive to change and require clinical trials to enroll large numbers of subjects while still being powered to detect an often overly optimistic treatment effect. Two highly innovative, easily applied, office-based, painless methodologies that offer great promise in serving as novel, sensitive markers of disease progression, are electrical impedance myography (EIM) and quantitative ultrasound (QUS). In EIM, a weak, high-frequency electrical current is applied via surface electrodes and alterations in the consequent surface voltage pattern are measured. In QUS, ultrasound images obtained using standard devices are distilled down to numerical data that can be used to quantify disease severity. This can be accomplished either via post-processing image analysis with use of a phantom for calibration or via a reduction of the raw backscattered acoustic data. In this proposed work, we will study both EIM and QUS independently to assess their potential use in DMD trials. Specifically we will do this by studying a group of 35 normal subjects and 35 boys with DMD aged 5 to 12 years followed for a 2-year period of time. In Specific Aim 1, we will establish the repeatability of both techniques both immediately and over several days time. In Specific Aim 2, we will assess the clinical significance of alterations in both EIM and QUS over time by comparing their rate of progression to that seen with functional measures out to two years. In Specific Aim 3, we will assess the ability of both measures to detect disease progression over very short periods of time-1 to 2 months-and how well that rate of progression predicts long-term functional change. As part of our planned exploratory analyses, we will also assess approaches for fusing EIM and QUS data sets into single composite biomarkers and the potential value of following contraction-induced alterations in the EIM data over time. With the successful completion of this work, we will have set the stage for the use of one or both of these techniques as the preferred biomarkers in Phase II clinical trials in DMD.