Suga K, Matsunaga N, Kawakami Y, Furukawa M
Department of Radiology, Yamaguchi University School of Medicine, Ube, Japan.
Ann Nucl Med. 2000 Aug;14(4):271-7. doi: 10.1007/BF02988209.
A phantom study was conducted to evaluate the feasibility of body contour definition with Compton scatter photons from external sources of technetium-99m pertechnetate (Tc-99m) to create a fusion image of CT and SPECT images.
External sources of 1 mCi (37 MBq) Tc-99m were placed on each collimator, and body-contour SPECT images were obtained with an energy window of 100 keV +/- 25% for detecting 90 degrees and 180 degrees Compton scatter photons of Tc-99m from the body surface in water-filled cylindrical and hexagonal phantoms, and in a chest phantom with a Tc-99m-avid simulated lung nodule and multimethod surface markers. In the chest phantom, each transaxial SPECT slices was registered with the corresponding CT slice by using image-matching soft ware. A summation of the registered images yielded a three-dimensional (3-D) fusion image of this phantom.
This method clearly visualized the body contour on all the SPECT slices in all the phantoms except for the complex hexagonal phantom. There was no significant difference between the known and SPECT-measured diameters of the cylindrical phantom. The fit of CT and SPECT images of the chest phantom was achieved with a mean alignment error of 5% in visual inspection, which was improved to 0.2% after correction of the magnification of the SPECT images according to the resultant dimensional differences. The 3-D fusion image of this phantom effectively visualized the anatomic location of the lung nodule and surface markers.
This simple method effectively provided boundary information on the cold phantoms. Although further improvements in the registration technique with CT images are desirable, the body-contour SPECT image obtained by this method has the potential for accurately creating a 3-D fusion image with CT images, and is a feasible way of anticipating the anatomical localization of a target tissue.
进行一项体模研究，以评估利用来自外部高锝酸盐-99m（Tc-99m）源的康普顿散射光子进行身体轮廓定义，从而创建CT与SPECT图像融合图像的可行性。
将1毫居里（37兆贝可）的Tc-99m外部源放置在每个准直器上，在充满水的圆柱形和六边形体模以及带有Tc-99m亲合性模拟肺结节和多方法表面标记的胸部体模中，通过100千电子伏特±25%的能量窗获取身体轮廓SPECT图像，用于检测来自体表的Tc-99m的90度和180度康普顿散射光子。在胸部体模中，通过使用图像匹配软件将每个断层SPECT切片与相应的CT切片进行配准。对配准后的图像进行求和，得到该体模的三维（3-D）融合图像。
除复杂六边形体模外，该方法在所有体模的所有SPECT切片上均清晰显示了身体轮廓。圆柱形体模已知直径与SPECT测量直径之间无显著差异。胸部体模的CT和SPECT图像配准在视觉检查中的平均对准误差为5%，根据所得尺寸差异对SPECT图像的放大倍数进行校正后，该误差改善至0.2%。该体模的3-D融合图像有效地显示了肺结节和表面标记的解剖位置。
这种简单方法有效地提供了冷体模的边界信息。尽管需要进一步改进与CT图像的配准技术，但通过该方法获得的身体轮廓SPECT图像有潜力与CT图像精确创建三维融合图像，并且是预测目标组织解剖定位的一种可行方法。
