Author: Dirk Grunwald, Hans Herzog, Hidehiro Iida, N. Jon Shah, Usman Khalid, Manfred Lennartz, Philipp Lohmann, Ceren Memis, Tobias Meurer, Claudia Regio Brambilla, Jürgen Scheins, Lutz Tellmann, Christoph W. Lerche, Martin Wiesmann, Karl Ziemons 👨🔬
Affiliation: FH Aachen University of Applied Sciences, Department of Chemistry and Biotechnology, Clinic for Diagnostic and Interventional Neuroradiology, Uniklinik Aachen,, Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich GmbH,, Central Institute for Engineering, Electronics and Analytics (ZEA-1), Forschungszentrum, Turku PET Center, Institute of Biomedicine, Faculty of Medicine, University of Turku, 🌍
Purpose: Quantitative brain studies with positron emission tomography (PET) often require an arterial input function (AIF), which traditionally requires arterial cannulation. However, this is invasive. An alternative, non-invasive method is to use the image-derived input function (IDIF) derived from the activity concentration in the internal carotid arteries (ICAs) in the images. To achieve an accurate IDIF, validation and optimization of IDIF estimations using phantoms with controlled methodological parameters are required. The goal of this study was to develop: 1) a geometrical phantom with ICA inserts as a reliable baseline for IDIF studies, and 2) an anthropomorphic head phantom with realistic anatomical features to enhance IDIF accuracy and expand validation applications.
Methods: Phantom 1) was based on a combination of a cylindrical quality-control phantom already available in our institute [1] and an additional ICA insert [2]. Phantom 2), based on previous work [3], replicates the human head contour and brain anatomy. Segmentation of grey matter (GM), white matter (WM), and scalp was performed using 3D Slicer v5.4.0, combining manual and semi-automatic threshold methods. ICA structures were extracted from magnetic resonance angiography data and refined using CAD software. The GM, WM, and ICA compartments were designed as fillable hollow compartments.
Results: Both 3D-printed phantoms include watertight compartments capable of holding different radiotracer concentrations and ICA dynamic simulations. The neck structure of the head phantom is extended to facilitate secure attachment to mechanical holders, enabling precise motion simulations during PET/MR studies.
Conclusion: The cylindrical phantom with an ICA insert is currently in the printing phase and the head phantom is in the final development phase (equivalent tissue materials and printing tests). After successfully printing both phantoms, PET/MR acquisitions will be performed for testing and validation. The updated status of this work will be presented during the conference.