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Introduction: Recently, a mouse model was developed showing spontaneous plaque rupture leading to stroke (ApoE−/−Fbn1C1039G+/− mouse). However, a longitudinal follow-up of these mice was hampered by the lack of an accurate in vivo method to visualize the cerebral vasculature. Methods: In this feasibility study, a female ApoE−/−Fbn1C1039G+/− and an ApoE−/− (control) mouse (stable plaques) were fed a western-type diet for up to 20 weeks. At week 10, 15 and 20 after the start of the diet CT-scans were performed before and after injection of a gold-nanoparticle contrast agent (Aurovist®, Nanoprobes, New York, USA). Image reconstruction was based on the iterative maximum-likelihood polychromatic algorithm, to reconstruct high quality images at 50-μm. Post- and pre- contrast injection images were co-registered and subtracted, using 3Dslicer, resulting in angiographic images. These images were segmented by executing a Frangi vesselness filtering, an isosurface extraction and a geodesic evolution step in VMTK. Results: It was feasible to obtain a 3D-visualisation of the mouse cerebral vasculature (see figures for the ApoE−/−Fbn1C1039G+/−mouse) up to vessels of 0.15 mm diameter. Interestingly, at week 15 and 20 contrast agent from previous injections was still present in plaques (presumably taken up by macrophages), allowing us to determine plaque position and progression over time. More severe stenosis was observed in the ApoE−/−Fbn1C1039G+/−mouse compared to the control mouse. Conclusions: The described in vivo method enabled us to generate detailed 3D reconstructions of the mouse cerebral vasculature, including presence of atherosclerotic plaques. Future work will include numerical models of the blood flow.

The majority of current whole-body PET scanners are based on pixelated scintillator arrays with a transverse pixel size of 4 mm. However, recent studies have shown that decreasing the pixel size to 2 mm can significantly improve image spatial resolution. In this study, the performance of Digital Photon Counter (DPC) from Philips Digital Photon Counting (PDPC) was evaluated to determine their potential for high-resolution whole-body time of flight (TOF) PET scanners. Two detector configurations were evaluated. First, the DPC3200-44-22 DPC array was coupled to a LYSO block of 15  ×  15 2  ×  2 × 22 mm3 pixels through a 1 mm thick light guide. Due to light sharing among the dies neighbour logic of the DPC was used. In a second setup the same DPC was coupled directly to a scalable 4  ×  4 LYSO matrix of 1.9  ×  1.9  ×  22 mm3 crystals with a dedicated reflector arrangement allowing for controlled light sharing patterns inside the matrix. With the first approach an average energy resolution of 14.5% and an average CRT of 376 ps were achieved. For the second configuration an average energy resolution of 11% and an average CRT of 295 ps were achieved. Our studies show that the DPC is a suitable photosensor for a high-resolution TOF-PET detector. The dedicated reflector arrangement allows one to achieve better performances than the light guide approach. The count loss, caused by dark counts, is overcome by fitting the matrix size to the size of DPC single die. [ABSTRACT FROM AUTHOR]