Acoustic System for Diagnosis of Pneumonia and Pneumothorax using Transfer Function Analysis

项目总结/摘要 每年，肺炎是全世界100多万人的死因，其中大多数人死亡 发生在没有先进医疗基础设施的地区。当前临床黄金 检测肺炎的标准是胸部X光检查，虽然对诊断有效，但通常无法获得， 患者在资源有限的情况下，由于高昂的经济成本。对于这些人来说，身体 检查提供了一种可获得的，方便的，低成本的选择-因此，所有的医生都接受过培训， 进行身体检查。叩诊的身体检查技术是通过敲击特定区域来进行的 并评估所产生的声音是否对应于健康或患病的组织。 不幸的是，医生技术的差异导致不一致的结果和解雇的打击 方法时，X射线机可用。我们设备的目标是量化这些发现， 观察者间的错误，并利用叩诊的诊断能力，提供一个低成本，定量的物理 用于诊断胸腔通路受限患者群体中的肺炎的检查工具 放射线照相术。我们已经开发出一种原型设备，可以为胸部提供声学刺激;声音是 使用电子听诊器从背部记录，并且该记录用于估计胸部 腔的声学传递函数。传递函数表征了系统响应的强度， 不同的频率，可以用来区分不同的系统。我们的具体目标集中在 开发了一种方法来研究由于结构变化对声学传递函数的影响， 目的1），并探讨这种方法对气胸的普遍适用性 特别是其他肺部病变（目的2）。在目标1中，我们假设 在肺炎的肺叶中的渗出物（流体）将导致更高频率的更好的声音传输 与健康的肺相比。首先，我们将使用与人类肺部组织密度相似的海绵作为成像 幻影，以提高我们的设备的信噪比和简化数据分析。第二，我们将执行 我们在病人身上的实验比较了他们健康的一侧肺和患大叶性肺炎的一侧肺。最后， 我们将开发一种分类器，可以考虑年龄和性别等其他变量， 提高我们测试的性能，并根据声学结果返回肺炎的严重程度评分。为宗旨 2，我们的假设是胸膜腔中空气的积聚会减少声音的传播，特别是 在更高的频率。我们将首先进行一个实验与一个充满空气的腔（胃）相比，固体 组织（膝盖），以确定空气积聚对传递函数的影响。接下来，与目标1一样，我们将 对患者进行测试，将气胸侧与健康侧进行比较。最后我们将 开发分类器以提供气胸的严重程度评分。我们预计， 这些研究将为肺炎和气胸的声学诊断的可行性提供新的见解。

PROJECT SUMMARY/ABSTRACT Every year pneumonia is the cause of death for over a million people worldwide, with most of these deaths occurring in areas that do not have access to advanced medical infrastructure. The current clinical gold standard for detecting pneumonia is a chest x-ray, which, while effective for diagnosis, is often unavailable to patients in resource limited settings due to inhibitive financial costs. For these populations, physical examinations provide an accessible, convenient, and low-cost alternative---thus, all doctors are trained to perform the physical exam. The physical exam technique of percussion is performed by tapping specific areas of the back and assessing whether the resulting sound corresponds to healthy or diseased tissue. Unfortunately, differences in physician technique lead to inconsistent findings and dismissal of the percussion method when x-ray machines are available. The goal of our device is to quantify these findings to eliminate interobserver error and harness the diagnostic power of percussion to provide a low-cost, quantitative physical examination tool for the diagnosis of pneumonia in patient populations with limited access to chest radiography. We have developed a prototype device that provides acoustic stimulation to the chest; sound is recorded from the back using an electronic stethoscope and this recording is used to estimate the chest cavity's acoustic transfer function. The transfer function characterizes the strength of response of a system to different frequencies and can be used to distinguish between different systems. Our specific aims focus on developing a method to study the effects on the acoustic transfer function due to structural changes in the lungs during pneumonia (Aim 1) and to explore the generalizability of this approach to pneumothorax specifically as well as other lung pathologies (Aim 2). In Aim 1, we hypothesize that the accumulation of exudate (fluid) in a lobe of the lungs in pneumonia will lead to better sound transmission of higher frequencies compared to healthy lung. First, we will use a sponge with similar density to human lung tissue as an imaging phantom to improve our device's signal-to-noise ratio and streamline data analysis. Second, we will perform our experiments in patients comparing the healthy side of their lungs to the side with lobar pneumonia. Finally, we will develop a classifier that can take additional variables such as age and gender into consideration to improve performance of our test and return a severity score of pneumonia based on acoustic findings. For Aim 2, our hypothesis is that the accumulation of air in pleural spaces will reduce transmission of sound, especially at higher frequencies. We will first perform an experiment with an air-filled cavity (stomach) compared to solid tissue (knee) to determine the effect of air accumulation on the transfer function. Next, as in Aim 1, we will perform tests on patients comparing the side with the pneumothorax to the healthy side. Finally, we will develop a classifier to provide a severity score of pneumothorax. We anticipate that the findings from our studies will provide novel insight into the feasibility of acoustic diagnosis of pneumonia and pneumothorax.