Presentation Seated vs. supine: optimum measurement pose for brain-dedicated PET

Iwao, Yuma  ,  Tashima, Hideaki  ,  Yoshida, Eiji  ,  Wakizaka, Hidekatsu  ,  Nishikido, Fumihiko  ,  Yamashita, Taichi  ,  Yamaya, Taiga

In some recently developed brain-dedicated PET systems, a seated position is selected for the patient. The PET scanners with the seated measurement style have a merit of allowing system downsizing. However, the effect of the seated position for head motion suppression compared with the conventional supine position is not clear. Although motion correction methods have been developed, they are not in practical use at a routine level. Even when using the motion correction method, it is desirable to make the head motion as small as possible. In this study, we developed a contactless head motion tracking system, and we conducted a volunteer study of the head motion tracking to assess the optimum measurement position for the brain PET. We developed the tracking system using the Microsoft Kinect sensor as a range sensor. As a result of the accuracy evaluation, translation accuracy of about 1 mm and rotation accuracy of less than 1 deg were achieved. In the volunteer study, we measured the head motion of volunteers with supine, normal sitting, and reclining. Additionally, we measured these positions with and without head fixation. As a result, the normal sitting position without head fixation had the largest head motion, and the reclining position had smaller motion than the supine position. The head fixation was effective for motion suppression in all cases. The lowest head motion was achieved with the reclining and supine positions (average displacement in 60 s was about 0.5 mm). In order to assess the effect of the head motion, we added the motion information obtained with the volunteer study to brain phantom data measured with our helmet-chin PET prototype. In the case of the reclining with head fixation, we could obtain reconstruction images of equal quality to the case without motion even though we did not apply any motion correction. We concluded that the reclining position had a high head motion suppression effect equal to or better than that of the supine position.( M-15-058)

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