睡眠呼吸障礙是指病患在睡眠中上呼吸道發生反覆的塌陷，而造成上呼吸道部分或全部阻塞，輕微者可能出現打鼾的症狀，影響同床者之睡眠品質；嚴重者會造成上呼吸道完全封閉，呼吸道氣體進出暫停，導致暫時性缺氧並影響睡眠品質。許多研究也發現舌根的變化對於睡眠呼吸障礙扮演著一個重要的角色，而目前臨床診斷上還會使用一些醫療儀器來記錄呼吸道的變化，例如：磁振造影和電腦斷層影像。然而，上述輔助診斷方式幾乎都必須在病患於清醒中完成診斷，為了克服這些問題，本研究為開發一套穿戴式超音波影像裝置用來即時與長時間監測舌根的動態變化。
此系統裝置包含一個3 MHz客製化超音波陣列式換能器、超音波激發/接收電路、高速類比數位轉換模組、與FPGA模組。透過可程式化邏輯閘陣列去控制系統脈衝重複週期訊號與主要頻率。此裝置具有非侵入式、即時成像、可攜帶式與非游離輻射等優點，能在最不干擾自然睡眠及睡眠姿勢的狀況下檢查，並有助提供專科醫師對於診斷睡眠呼吸障礙病患的新資訊。
在人體測量中更進一步驗證系統的可行性，從結果方面可以藉由此系統明顯地看出舌根的動態變化，並有效的將此超音波裝置與睡眠多項生理檢查分別記錄患者於自然睡眠下舌根後區上呼吸道形態學與相關生理訊號的變化，協助睡眠與耳鼻喉科醫生判斷睡眠呼吸障礙患者上呼吸道的阻塞部分與塌陷程度。

Obstructive sleep apnea (OSA), a breathing disorder characterized by repetitive collapse of the pharyngeal airway during sleep, can cause intermittent hypoxemia and frequent arousal. Many studies have demonstrated that the deformation of tongue base plays an important role in OSA. Currently, several medical imaging modalities have been used to record the airway changes, such as cine MRI and ultrafast CT. However, most of them are difficult to be used widely in clinical diagnosis for continuous recording the deformation of tongue in real-time, particularly during sleeping. In order to overcome these problems, a wearable ultrasonic device was developed for real-time monitor of the dynamic change of the tongue base in this study.
The device includes a custom-designed 3-MHz ultrasonic array transducer, an ultrasound pulser/receiver, high speed analog-to-digital converter, and a FPGA board. The ultrasound pulse repetition frequency and pulse center frequency are controlled by the programmable FPGA board. Since this device exhibits non-invasive, real time imaging, portable, and non-ionizing radiation, it can be used to detect the airway situation during natural sleeping with various postures. This new information will help physicians to diagnose the symptoms.
The anthropometric measurement was carried out for verifying the system performance. Results demonstrated that the dynamic variation of tongue base can be clearly distinguished by using this wearable system. It has the potential to be incorporated into polysomnography and to provide information about retroglossal airway behavior during natural sleep. Furthermore, it is very important in devising, applying and determining the effectiveness of tailor-made treatment modalities.

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