Germano G, Kavanagh P B, Su H T, Mazzanti M, Kiat H, Hachamovitch R, Van Train K F, Areeda J S, Berman D S
Department of Medical Physics and Imaging, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
J Nucl Med. 1995 Jun;36(6):1107-14.
We developed a completely automatic technique to reorient transaxial images into short-axis (oblique) myocardial perfusion SPECT images.
The algorithm starts by isolating (segmenting) the left ventricle (LV) myocardium using a combination of iterative clusterification and rule-based location/size/shape criteria. The three-dimensional, mid-myocardial LV surface is initially estimated as the locus of the trilinearly interpolated maxima for the count profiles originating from the center of mass of the segmented LV. The final mid-myocardial surface is obtained by iteratively applying this process, incorporating additional constraints of shape and texture and using the nonsegmented, nonthresholded transaxial image to obtain information on hypoperfused areas of the myocardium. It is then fitted to an ellipsoid, of which the major axis is assumed to represent the long axis of the LV, and the three-dimensional image volume is resliced perpendicularly to it.
The algorithm was retrospectively applied to 400 dual-isotope studies (200 rest 201TI, 200 stress 99mTc-sestamibi) from 200 consecutive patients. Segmentation was successful in 394/400 (98.5%) of the patients. The reproducibility of computer-based reorientation was perfect and significantly better than either intraobserver or interobserver reproducibility.
Automatic reorientation offers the potential for consistently faster and more accurate image processing and analysis and is an important step towards totally operator-less management of myocardial perfusion SPECT data.
我们开发了一种完全自动化技术，可将横轴图像重新定位为短轴（斜位）心肌灌注单光子发射计算机断层扫描（SPECT）图像。
该算法首先通过迭代聚类和基于规则的位置/大小/形状标准相结合的方式来分离（分割）左心室（LV）心肌。三维心肌中部LV表面最初被估计为源自分割后LV质心的计数轮廓的三线性插值最大值的轨迹。通过迭代应用此过程，纳入形状和纹理的附加约束，并使用未分割、未阈值化的横轴图像来获取心肌灌注不足区域的信息，从而获得最终的心肌中部表面。然后将其拟合到一个椭球体，假定其长轴代表LV的长轴，并垂直于该长轴对三维图像体积进行重新切片。
该算法被回顾性应用于来自200例连续患者的400项双同位素研究（200例静息201铊，200例负荷99m锝-甲氧基异丁基异腈）。394/400（98.5%）的患者分割成功。基于计算机的重新定位的重现性极佳，且明显优于观察者内或观察者间的重现性。
自动重新定位为持续更快、更准确的图像处理和分析提供了潜力，是朝着心肌灌注SPECT数据完全无需操作员管理迈出的重要一步。
