根據世界衛生組織報告全球人口老化問題越趨嚴重，並預計60歲以上人口比例將在2015年至2050年間翻倍從12%增長至22%，因此需要增加對於老年疾病的關注。肌少症(Sarcopenia)被定義為一種以非正常速度肌肉衰減的現象，雖然好發於年老病患但年齡並非此症狀發生的唯一因素。目前篩檢肌少症的方法多為對病患進行一系統的體能評估，而要更精準的確診檢驗則需要較昂貴的檢測儀器如雙能量X光吸光式測定儀(DXA)，因此我們希望透過這個研究提出以電阻抗成像作為初期篩檢肌少症的工具。電阻抗成像(EIT)是一種非侵入式的成像方法，其利用注入電流至表面電極並量測相應的表面電壓以得到內部的電導系數分佈資訊，由於其成像快速以及輕便的特性使其在臨床上常用於實時肺功能監測。目前市面上主流的電阻抗儀器使用相鄰法(neighbouring method)作為量測方法，透過注入電流至兩兩成對的電極以及量測其電壓得到影像。但近期有文獻指出相鄰法對於邊界的物體導電率改變雖然較好，但對於中心物體的改變則表現較差，因此有作者提出利用解析解得出的trigonometric current作為刺激電流可以得到更好的影像。本研究使用此作者提出的方法嘗試驗證不同的刺激電流對於物體在不同位置的特徵偵測有何不同，並提出各個分佈的最佳刺激電流。

According to the World Health Organization (WHO), the proportion of the global population aged 60 and above is projected to nearly double from 12% to 22% between 2015 and 2050, leading to a corresponding increase in age-related diseases. Sarcopenia, characterized by the abnormal deterioration of muscle function, is one such condition associated with aging, although not exclusively. Presently, the screening process for sarcopenia relies on multiple sets of questionnaires, with confirmation requiring expensive and large-scale equipment like dual-energy X-ray absorptiometry (DXA). Hence, the objective is to explore a more cost-effective and dependable alternative to identify potential sarcopenia patients within the population.
Electrical Impedance Tomography (EIT) is a non-invasive imaging technique capable of detecting changes in conductivity distribution within the body, thereby enabling the tracking of functional and structural alterations in internal organs. However, the conventional method of adjacent current injection and paired measurement has faced challenges due to its limited sensitivity in detecting inhomogeneities within the central region. Consequently, researchers in the field of EIT have proposed an alternative approach known as the adaptive current pattern or the optimal current pattern.
The objective of this study is to investigate the feasibility of applying optimal current pattern in EIT for characterizing morphological changes in muscle distribution. The distinguishability on small conductivity changes of the proposed method and that of the conventional adjacent current pattern are compared. Also, finite element meshes are built using reference of the MRI image to build an anatomical phantom model.
The experimental results show that the optimal current pattern yields the highest distinguishability. From the tank phantom studies, we can confirm that the best current pattern on concentric disc object converge to a sinusoidal pattern, which agrees with the analytical solution. We have also simulated the sarcopenic changes in muscle distribution such as fatty infiltration and muscle atrophy and find that the optimal current pattern does function well in both cases. The proposed optimal current pattern can maximize the sensitivity of impedance changes in individual patients that can be correlated to morphological changes in muscle distribution, improving spatial resolution in the generated images.

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