Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.
Ann Nucl Med. 2022 Oct;36(10):904-912. doi: 10.1007/s12149-022-01774-0. Epub 2022 Jul 19.
Head motions during brain PET scan cause degradation of brain images, but head fixation or external-maker attachment become burdensome on patients. Therefore, we have developed a motion correction method that uses a 3D face-shape model generated by a range-sensing camera (Kinect) and by CT images. We have successfully corrected the PET images of a moving mannequin-head phantom containing radioactivity. Here, we conducted a volunteer study to verify the effectiveness of our method for clinical data.
Eight healthy men volunteers aged 22-45 years underwent a 10-min head-fixed PET scan as a standard of truth in this study, which was started 45 min after F-fluorodeoxyglucose (285 ± 23 MBq) injection, and followed by a 15-min head-moving PET scan with the developed Kinect based motion-tracking system. First, selecting a motion-less period of the head-moving PET scan provided a reference PET image. Second, CT images separately obtained on the same day were registered to the reference PET image, and create a 3D face-shape model, then, to which Kinect-based 3D face-shape model matched. This matching parameter was used for spatial calibration between the Kinect and the PET system. This calibration parameter and the motion-tracking of the 3D face shape by Kinect comprised our motion correction method. The head-moving PET with motion correction was compared with the head-fixed PET images visually and by standard uptake value ratios (SUVRs) in the seven volume-of-interest regions. To confirm the spatial calibration accuracy, a test-retest experiment was performed by repeating the head-moving PET with motion correction twice where the volunteer's pose and the sensor's position were different.
No difference was identified visually and statistically in SUVRs between the head-moving PET images with motion correction and the head-fixed PET images. One of the small nuclei, the inferior colliculus, was identified in the head-fixed PET images and in the head-moving PET images with motion correction, but not in those without motion correction. In the test-retest experiment, the SUVRs were well correlated (determinant coefficient, r = 0.995).
Our motion correction method provided good accuracy for the volunteer data which suggested it is useable in clinical settings.
脑部正电子发射断层扫描（PET）过程中的头部运动会导致脑图像质量下降，但头部固定或外部标记物的附着会给患者带来负担。因此，我们开发了一种使用由距离感测相机（Kinect）和 CT 图像生成的 3D 面部形状模型的运动校正方法。我们已经成功校正了含有放射性的运动人体模型头部 PET 图像。在此，我们进行了一项志愿者研究，以验证我们的方法在临床数据中的有效性。
在这项研究中，8 名 22-45 岁的健康男性志愿者接受了 10 分钟的头部固定 PET 扫描，作为标准参考，该扫描在注射 F-氟脱氧葡萄糖后 45 分钟开始，随后使用我们开发的基于 Kinect 的运动跟踪系统进行了 15 分钟的头部运动 PET 扫描。首先，选择头部运动 PET 扫描中的无运动时段作为参考 PET 图像。其次，当天分别获得的 CT 图像被注册到参考 PET 图像上，并创建一个 3D 面部形状模型，然后将其与基于 Kinect 的 3D 面部形状模型匹配。该匹配参数用于 Kinect 和 PET 系统之间的空间校准。该校准参数和 Kinect 对 3D 面部形状的运动跟踪构成了我们的运动校正方法。通过标准摄取值比（SUVr）比较校正后的头部运动 PET 与 7 个感兴趣区域的头部固定 PET 图像。为了确认空间校准精度，通过改变志愿者姿势和传感器位置，重复两次头部运动 PET 扫描并进行运动校正，进行了测试-重测实验。
校正后的头部运动 PET 与头部固定 PET 图像在 SUVr 上没有明显差异。在头部固定 PET 图像和校正后的头部运动 PET 图像中可以识别出一个小核，即下丘，但在未校正的头部运动 PET 图像中则无法识别。在测试-重测实验中，SUVr 相关性良好（决定系数 r=0.995）。
我们的运动校正方法为志愿者数据提供了良好的准确性，这表明它可以在临床环境中使用。
