利用超音波影像與剪力波彈性影像來偵測分析經放射線照射後之肌肉組織傷害發展

Abstract

背景：放射治療是一種利用高能量的輻射線來殺死腫瘤細胞，達到治療或控制癌症的目的，但同時也會對周邊的正常組織器官造成傷害。患者常在回醫院進行術後追蹤時，本體感覺及運動上並無感到不適或影響生活作息，但於影像上已可看出明顯的肌肉纖維化趨勢。 目的：本研究主要的目的是利用超音波影像與剪力波彈性超音波來分析經過放射線治療後大鼠肌肉組織的變化，瞭解肌肉組織傷害發展。 材料與方法：將12隻實驗大鼠分成三組，分別於一後腿照射8Gy、16Gy及32Gy放射線，另一腿則無照射。利用超音波影像搭配設計的影像分析程式來分析影像目標區域的纖維肌肉比，以及利用彈性超音波量測剪力波波速(shear-wave velocity, Vs)以推測肌肉軟硬程度，最後將肌肉組織取下進行組織染色切片，觀察微觀肌肉組織狀況。 結果：放射線32Gy組別的老鼠，其肌肉組織於照射後5~6個月，超音波影像上發現與正常肌肉組織相比明顯較為模糊，16Gy組別則有一隻老鼠於放射線照射後7~8個月有相同情形；32Gy組別的老鼠肌肉組織於照射後5~6個月，在超音波影像分析上發現纖維比例有增高的情形；放射線所造成的肌肉組織損傷無法由彈性超音波剪力波波速的改變來獲得；切片結果顯示照射16Gy及32Gy放射線會造成肌肉組織的傷害。 結論：放射線對於肌肉組織的傷害確實能在超音波影像上顯現出來，而老鼠肌肉組織受放射線傷害須達到相當高的劑量(本研究:32Gy)才能於超音波影像上顯現出來，且於纖維比例分析上有升高的情形。彈性超音波則須經過更進一步的長期追蹤才能得知是否能偵測到肌肉組織傷害的變化。

Background: Radiation therapy uses high energy radiation to kill cancer cells to achieve the purpose of cancer treatment. Although radiation therapy can kill cancer cells effectively, it also damages the surrounding normal tissues or organs. The fibrosis of the damaged soft tissue may occur months or years later after treatment. A clear trend of muscle fibrosis can be seen on ultrasound imaging when the patients return for follow up without feeling discomfort or affecting their lifestyle. Purpose: The purpose of this study is to use ultrasound image analysis and shear-wave elastography to follow up the development of damaged muscle tissues after radiotherapy. Materials and methods: Experimental rats were divided into three groups : irradiated 8Gy, 16Gy and 32Gy dose on one hind respectively, and the other hind without irradiation. Ultrasound imaging with designed image analysis system was used to analyze the fiber ratio on the region of interest and ultrasound shear-wave elastography was used to measure the shear-wave velocity (Vs) for the elasticity of muscle tissue. Histological sections were taken from the center of the muscles and stained with either H&E or Masson’s trichrome. Results: Five to six months later after irradiation, ultrasound images of the muscle tissues in the 32Gy group became more obscure as compared with normal muscle tissues. Seven to eight months later after irradiation, ultrasound images of one rat in the 16Gy group became more obscure and the fiber ratio increased. The results showed that ultrasound shear-wave elastography could not discriminate the difference between normal and damaged muscle tissues from the changes of the shear-wave velocity. Radiation-induced muscle tissue injury could be observed in histological sections for the 16Gy and 32Gy groups. Conclusion: Ultrasound imaging could detect the damaged muscle tissues of rats induced by hige-dose radiation and the fiber ratio obtained from the image analysis system increased. Ultrasound shear-wave elastography could not discriminate the difference between normal and damaged muscle tissues from the changes of shear-wave velocity.