高能聚焦超音波的技術提供了一種非侵入式熱治療手術的方法。磁共振影像導引技術能夠即時量測待測組織溫度的變化，透過使用氫原子共振頻率轉移(PRF- shift)的方法來達到磁共振溫度造影。磁轉移效應的改變也被使用在監控組織燒灼程度的依據，藉由設計的雙迴訊梯度脈衝序列可以同時觀察溫度的變化以及生物磁轉移效應的改變。本研究中提出了一種實驗方式，藉由仿照實際臨床手術的熱治療方式，以一個點接著一個點的燒灼方式應用於離體豬肉的實驗，希望可以同時觀察受燒灼組織的物理性變化。我們將以連續時間的方式來同時觀察溫度和生物性磁轉移效應的改變，並藉此得知此實驗方式的治療效益。結果顯示︰即使物理性的溫度升高現象在加熱之後就逐漸消失，組織受加熱後所產生的生物性磁轉移效應改變仍會存留著。除此之外，我們還提出了一個新的判斷方法，使用相關性分析來對於某些區域中不同程度的組織傷害同時與生物性磁轉移效應來做對照比較，藉由使用這個相關性分析的方法，可以多一個判斷組織變異的參考依據。由本研究的結果顯示，利用磁共振影像去導引高能聚焦超音波的熱治療實驗，以一個連續時間同時觀察組織因受熱而產生變異的情況，將有機會提升未來高能聚焦超音波臨床手術治療的準確性及可行性。

High intensity focused ultrasound (HIFU) provided tissue destruction or tumor ablation in a non-invasive way, which is one of the promising thermotherapy techniques. Combined with the MRI techniques, MR-guided focused ultrasound (MRgFUS) generally utilizes the PRF-shift thermometry to monitor the temperature in the targeted tissue in real time. To further improve the monitoring of the treatment process, Peng et al. have shown that magnetization-transfer (MT) gradient-echo sequence is a practical tool to simultaneously monitor the temperature change and MT contrast during HIFU energy transmission. In this study, we improved the previous experiment with a movable HIFU transducer mimicking the procedure of the MRgFUS thermotherapy and presented a new analysis approach similar to the correlation method detecting the “activation” regions in functional MRI (fMRI) studies by multi-spot heating experiment, the efficiency of the MT/temperature measurement mapping was demonstrated in consecutive time. We can notice that the temperature rose after heating and fell gradually after turning off HIFU power, whereas the MT effect retained after heating. In addition, the MTR mapping was compatible to the widely used PRF-thermometry, which was to detect the tissue damage. In addition, this method that can monitor temperature changes as well as the level of MT change opens a potentially useful window to observe the tissue coagulation due to the HIFU power transmission in real-time.

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