驗證及應用創新動態核磁共振影像技術量測活體膝關節三維運動

Abstract

精確量測膝關節於功能性動作時的關節運動將有助於對膝關節功能之了解與許多臨床醫療與研究之應用。雖然許多量測技術已被提出且用來量測膝關節運動，至今能夠以非侵入式的方法精準量測三維、動態膝關節運動的方法仍然有限。在臨床上，基於皮膚表面反光標記之動作捕捉方法被大量應用在評估人體肢段在空間中的運動行為，然而位於皮膚表面的反光標記與骨頭之間的相對移動卻會造成誤差，進而影響計算結果。 近年來，許多利用放射影像的對位方法被開發出來，藉由直接觀察骨頭在空間中的方位來計算膝關節的運動，克服了皮膚移動誤差所帶來的問題，但受試者須接受輻射劑量，對受試者還是有一定的風險，限制此方法在臨床上的應用。 核磁共振影像提供了一個非侵入式、無輻射的技術來觀測膝關節的運動行為，現今，二維或是三維的核磁共振影像已大量地被用在準靜態狀態下的膝關節測量，然而，動態狀態下的核磁共振影像測量技術由於拍攝空間、影像在時空間的解析度等諸多限制，仍然有需多待發展的空間。本實驗室已成功開發出單切面MRI 對位技術[1]，並進一步地發展出以雙平面動態核磁共振影像為基礎之創新的雙切面對位技術[2]。 本研究希望藉由膝關節試體來驗證，在不同速度條件下此創新雙切面對位技術之精確度，並將此量測方法應用在膝關節於不同功能性動作（膝關節彎曲伸直）情況下的運動學量測，希望本研究所得到之數據，能夠幫助了解膝關節複雜的運動模式，以及提供醫學在治療與復健上更精確的診斷依據。

Accurate quantification of the three-dimensional (3-D) kinematics of the knee is essential for studying its normal function and diagnosing pathology. Although, there are many techniques have been developed for measuring knee kinematics, the methods for non-invasively measuring three-dimensional and dynamic knee motion are still limited. Skin marker-based methods have been widely used in clinical gait analysis and sports biomechanics to reconstruct quantitatively the 3-D kinematics of human body segments. However, movements between the skin markers and the underlying bones (i.e., soft tissue artifacts) during activities are inevitable and have been shown to affect the measurement outcome of joint kinematics. Recently, many radiographic techniques based on the registration of 3-D bone models and 2-D dynamic fluoroscopic images have been developed to acquire kinematic data of the bones for a variety of human joints without the distraction of the soft tissues artifacts. However, such techniques are subject to a risk of radiation overdose, limiting their widespread clinical application. Magnetic resonance imaging (MRI) provides an opportunity to measure non-invasively and free of ionizing radiation the kinematics of the knee. MRI has been used predominately for static 2D or 3D measurements of the knee alignment at discrete positions. However, limited scan space and low temporal resolution of the MR scanner let those techniques affront to many limitations. In our lab, a slice-to-volume (SVR) registration method was proposed for measuring dynamic joint positions using real-time MRI with single-slice. We also proposed a new registration method in conjunction with dual-slices real-time MRI for measuring 3-D kinematics of the knee. The purpose of this study was to validate dual-slices SVR methods in different speed condition and apply this novel method to in vivo kinematics study such as the effects of different functional movement and acting different force and moment on the knee. With the results of this study, it will provide a kinematics analysis methods and data of complicated knee motion. It may be used in rehabilitation programs for better treatment outcome in future clinical applications.