Dedicated PET/MRI Research Systems based on the Hyperion III Detector Platform

The clinical research community demands a variety of dedicated PET and PET/MRI scanners, each tailored to the different needs and research questions. The Hyperion III PET detector platform was thus designed as a flexible and scalable common detector platform from which the desired devices can be constructed. In first projects, different PET/MRI research prototype systems were built: A brain insert for a Siemens 7T MRI Scanner (FZ Juelich), a dedicated breast insert with two simultaneously working PET rings (Hypmed consortium), An MR-Linac radiotherapy planning device (UMU Utrecht, Philips, Futura). The brain PET insert employs 24-mm height, 2-mm pitch, 3-layer DOI crystal arrays. With a total amount of crystals of 196 080, it offers a large FOV of 282 mm × 250 and high sensitivity. The breast PET insert consists of two complete PET rings for the female breasts (1.3-mm crystal pitch, 3-layer DOI crystal arrays). Comparing measurements demonstrate the advantage in spatial resolution over a standard clinical whole-body PET/MRI scanner. The radiotherapy planning PET/MRI scanner is a whole-body installation, that employs a similar split gradient coil with a 20 cm gap for the MRI as the Elekta Unity MR-Linac radiotherapy device. With the with PET ring installed in that gap, a full 70 cm wide-bore system was built, and MRI compatibility was approved by the MRI vendors engineers. The successful scanner implementations demonstrate the flexibility of the Hyperion III detector platform. Currently, more dedicated scanners are built, and the versatility of the platform will be enhanced by adding analog SiPM/ASIC combinations to the portfolio.