Erstellung eines digitalen dreidimensionalen Volumenmodelles des menschlichen Hirnstammes nach dem stereotaktischen Wahrscheinlichkeitsatlanten von AFSHAR, WATKINS und YAP

In 1978 Afshar, Watkins and Yap published a stereotaxic probability atlas of the human brainstem containing 52 horizontal slices, cut in a distance of 1 mm, covering the caudal mesencephalon, the pons and the medulla oblongata. Contour-drawings of 42 anatomical structures represent the 70 percent percentile of 30 examined specimen. All histologically measured structures including their reference marks were carefully digitized. According to spatial interpolation along the cranio-caudal axis an isotropic three dimensional volume contour model with a resolution of 0.2 mm per voxel was developed. In a 3D MRI navigation system Prototyp the digital representation of the atlas can be integrated in FLASH (fast low angle shot) 3D MRI scans by superimposition. Corresponding MRI series of six healthy volunteers differing in thickness of slices SL, zoom factor X and MRI pixel size were selected and the digital atlas was examplarily applied. By interactive establishment of the reference co-ordinate system in the respective MRI series an initial transformation matrix was defined. Using global rigid transforms (translation, rotation and scaling) the initial transformation matrix could interactively be refined, by doing so only the atlas was transformed not the MRI data. In addition to this exemplary superimposition of six MRI series a systematical adaptation of the atlas to a larger random sample of MRI data should be performed. So a detailed statistical evaluation and judgement of the quality of application of the digital stereotaxic brainstem atlas by Afshar, Watkins and Yap can be made possible