Automatic recognition of vertebral landmarks in fluoroscopic sequences for analysis of intervertebral kinematics
Automatic recognition of vertebral landmarks in fluoroscopic sequences for analysis of intervertebral kinematics
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DOI：
10.1007/bf02345268
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发表时间：
2006
影响因子：
3.2
通讯作者：
P. Bifulco;M. Cesarelli;R. Allen;M. Sansone;M. Bracale
中科院分区：
文献类型：
--
作者：
P. Bifulco;M. Cesarelli;R. Allen;M. Sansone;M. Bracale
椎间运动学与脊柱节段的功能密切相关。在体内直接测量椎间运动学是非常有问题的。使用荧光镜设备可以在患者自发运动期间以可接受的低X射线剂量提供对腰道的连续筛查。运动学分析旨在限于平面运动。根据图像序列的每帧上的椎骨界标计算运动学参数。通常手动选择标志，尽管这是主观的、执行起来繁琐的，并且被认为是计算的运动学参数中的误差的主要贡献者之一。这项工作的目的是提出一种创新的方法，自动识别整个荧光透视图像序列的椎骨标志，提供一个客观和更精确的量化椎间运动学。识别过程是基于通过互相关指数比较两个相邻帧中的椎骨特征，尽管腰椎透视图像的信噪比低，但该互相关指数也是鲁棒的。为了提供这种方法的定量评估，使用了由万向节连接的两个腰椎组成的校准模型。对运动学测量的可靠性和精度进行了研究。对于椎间旋转中心的定位，误差为毫米量级，对于椎间角度，误差为十分之一度。误差分析表明，该方法提高了椎间运动学计算的准确性，并有可能自动选择解剖标志。
Intervertebral kinematics closely relates to the functionality of the spinal segments. Direct measurement of the intervertebral kinematics in vivo is very problematic. The use of a fluoroscopic device can provide continuous screening of the lumbar tract during patient spontaneous motion, with an acceptable, low X-ray dose. The kinematic analysis is intended to be limited to planar motion. Kinematic parameters are computed from vertebral landmarks on each frame of the image sequence. Landmarks are normally selected manually in spite of the fact that this is subjective, tedious to perform and regarded as one of the major contributors to errors in the computed kinematic parameters. The aim of this work is to present an innovative method for the automatic recognition of vertebral landmarks throughout a fluoroscopic image sequence to provide an objective and more precise quantification of intervertebral kinematics. The recognition procedure is based upon comparing vertebral features in two adjacent frames by means of a cross-correlation index, which is also robust despite the low signal-to-noise ratio of the lumbar fluoroscopic images. To provide a quantitative assessment of this method a calibration model was used which consisted of two lumbar vertebrae linked by a universal joint. The reliability and accuracy of the kinematic measurements have been investigated. The errors are of the order of a millimetre for the localisation of the intervertebral centre of rotation and tenths of a degree for the intervertebral angle. Error analysis suggests that this method improves the accuracy of the intervertebral kinematic calculations and has the potential to automate the selection of anatomical landmarks.