脊椎側彎之脊椎三維運動幾何之影像量測方法開發與評估

Abstract

人體脊椎是一個複雜的結構，它保護脊髓以及傳遞頭顱與軀幹的重量至骨盆。脊椎側彎是一種常見的脊椎疾病，脊椎側彎不僅影響患者的外觀，同時也會造成中樞及末梢脊椎神經之壓迫，進而導致疼痛及肌肉無力等症狀，甚至壓迫心肺，造成心肺功能障礙。目前，X光攝影是臨床上評估脊椎側彎的主要方式，然而X光攝影無法提供脊椎於三度空間中的方位及運動幾何。而且，X光攝影讓病患暴露於放射線之下，檢測頻率不可過高，無法對疾病進程及治療成效密集監控。另外，近年來，光柵攝影已被廣泛運用於重建背部三維表面形狀，光柵攝影投影多條平行直線在背部表面，藉由平行直線在背部表面之扭曲與幾何數學關係，快速建立背部三維表面形狀。透過特定的脊椎特徵點，該三維背部表面形狀可進一步定義連結棘突的曲線，並用以重建脊椎三維軸線，然而，此方法無法精確測得脊椎軸向旋轉之變化，亦未經實驗評估其效度(validity)。因此，本研究的目的在於開發一非侵入式且無放射線之方法以量測脊椎之三維運動幾何。 本研究以光柵攝影為基礎之影像方法重建背部曲面的模型，同時，以重建之背部表面曲面變化計算棘突的曲線，且利用脊椎側彎患者背部呈現兩側不對稱進一步提升脊椎三維運動幾何量在軸向旋轉的量測精度，同時提供空間中脊椎幾何模型。 本方法具有三維量測、非侵入式、準確量測、後續運算時間較短、免除病患暴露於放射線之下而且能夠提供空間中脊椎的幾何模型。適用於量測人體三維脊椎運動幾何以及臨床的評估。 本研究量測了十二位脊椎側彎之受試者的實驗資料(胸椎T1至腰椎L5)，包括十二組電腦斷層掃描影像，其中兩位受試者同時接受本研究之影像方法，得到其背部曲面以及另外收取的X光影像。電腦斷層掃描可以準確地定義出各節脊椎的相對位置，因此將其作為本研究所使用黃金準則(gold standard)。電腦斷層掃描重建之三維脊椎模型，作為驗證本研究中脊椎重建方法的精度。其中兩組接受本研究的影像方法重建背部曲面，利用計算出的脊椎相對位置與電腦斷層掃描以及X光影像得到的脊椎相對位置比較，藉此驗證本研究中影像方法的精度。 未來，希望能應用我們所開發的方法，量測脊椎側彎患者使其免除過去方法檢測時所會受到的輻射線。同時，希望能夠幫助骨科、復健科、物理治療、職能治療、影像醫學等領域的進步。

Scoliosis has been known as a complex three dimensional spinal deformity and recognized as the most common spinal disorder in adolescents. Abnormal spinal deformity will not only change the physical appearance, but may also cause problems such as central and/or peripheral spinal nerve compression, muscle pain and weakness, and oppression lung that may lead to cardiopulmonary dysfunction. X-ray imaging serves as the ‘gold standard’ for the evaluation of spinal deformities or structural vertebral disorders, this method of assessment does not account for three-dimensional changes in the spine and may expose patients to ionizing radiation which has been shown to increase the risk of developing several types of cancers, including breast and thyroid cancers. Recently, raster stereography has established as an accurate and reliable technique for analyzing the shape of the back and for reconstructing spinal deformities. The method applies a system of parallel light lines projected onto the back surface. From the distortion of the raster lines, the 3D shape of the surface can be reconstructed. However, measurement the change of the spinal axial rotation is not accurate and the validity is not evaluated by experiment. Therefore, the goal of this study is to develop a three-dimensional and non-radiating measurement method for spinal geometrical kinematics based on raster stereography. In our study, we used two cameras and one projector to reconstruct the back surface from the distortion line that projected onto the back surface. The curvature of the back were calculated and provide information to reconstruct the spinous process line. The axial rotation in the spine was calculated from the asymmetric of the back surface. 12 subjects with scoliosis were participated in our study. Each subjects were examined in supine posture in computed tomography photography and two subjects were examined in the method that developed in this study. To evaluate the accuracy of the measurement of spinal geometrical kinematics, the reconstruction of the spine from computed tomography was served as golden standard. In the future, the method we develop will help scoliosis assessment, diagnosis, treatment, and long-term tracking without exposing to high level of radiation dose. Thus, the application of our method is helpful for the progress in the fields of orthopedic, rehabilitation, physical therapy, occupational therapy and medical imaging.