Nagashima Masaki, Abe Hitoshi, Amaya Kenji, Matsumoto Hideo, Yanaihara Hisashi, Nishiwaki Yuji, Toyama Yoshiaki, Matsumoto Morio
Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
Acta Radiol. 2012 Nov 1;53(9):1059-65. doi: 10.1258/ar.2012.120039. Epub 2012 Sep 19.
Quantification of intervertebral disc degeneration based on intensity of the nucleus pulposus in magnetic resonance imaging (MRI) often uses the mean intensity of the region of interest (ROI) within the nucleus pulposus. However, the location and size of ROI have varied in different reports, and none of the reported methods can be considered fully objective.
To develop a more objective method of establishing ROIs for quantitative evaluation of signal intensity in the nucleus pulposus using T2-weighted MRI.
A 1.5-T scanner was used to obtain T2-weighted mid-sagittal images. A total of 288 intervertebral discs from 48 patients (25 men, 23 women) were analyzed. Mean age was 47.4 years (range, 17-69 years). All discs were classified into five grades according to Pfirrmann et al. Discs in grades I and II were defined as bright discs, and discs in grades IV and V were defined as dark discs. Eight candidate methods of ROI determination were devised. The method offering the highest degree of discrimination between bright and dark discs was investigated among these eight methods.
The method with the greatest degree of discrimination was as follows. The quadrangle formed by anterior and posterior edges of the upper and lower end plates in contact with the intervertebral disc to be measured was defined as the intervertebral area. A shape similar to the intervertebral area but with one-quarter the area was drawn. The geometrical center of the shape was matched to the center of intensity, and this shape was then used as the ROI. Satisfactory validity and reproducibility were obtained using this method.
The present method offers adequate discrimination and could be useful for longitudinal tracking of intervertebral disc degeneration with sufficient reproducibility.
基于磁共振成像（MRI）中髓核强度对椎间盘退变进行量化时，通常使用髓核内感兴趣区域（ROI）的平均强度。然而，不同报告中ROI的位置和大小各不相同，且所报道的方法均不能被认为是完全客观的。
开发一种更客观的方法来建立ROI，以便使用T2加权MRI定量评估髓核信号强度。
使用1.5-T扫描仪获取T2加权正中矢状面图像。对48例患者（25例男性，23例女性）的288个椎间盘进行分析。平均年龄为47.4岁（范围17 - 69岁）。所有椎间盘根据Pfirrmann等人的方法分为五个等级。I级和II级椎间盘被定义为亮椎间盘，IV级和V级椎间盘被定义为暗椎间盘。设计了八种确定ROI的候选方法。在这八种方法中研究了对亮暗椎间盘区分度最高的方法。
区分度最高的方法如下。将与待测椎间盘接触的上下终板前后边缘形成的四边形定义为椎间盘区域。绘制一个与椎间盘区域形状相似但面积为其四分之一的形状。将该形状的几何中心与强度中心匹配，然后将此形状用作ROI。使用该方法获得了令人满意的有效性和可重复性。
本方法具有足够的区分度，可用于椎间盘退变的纵向跟踪，且具有足够的可重复性。
