title: MR compatibility aspects of a silicon photomultiplier-based PET/RF insert with integrated digitisation.
abstract: The combination of Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) into a single device is being considered a promising tool for molecular imaging as it combines the high sensitivity of PET with the functional and anatomical images of MRI. For highest performance, a scalable, MR compatible detector architecture with a small form factor is needed, targeting at excellent PET signal-to-noise ratios and time-of-flight information. Therefore it is desirable to use silicon photo multipliers and to digitize their signals directly in the detector modules inside the MRI bore. A preclinical PET/RF insert for clinical MRI scanner was built to demonstrate a new architecture and to study the interactions between the two modalities.The disturbance of the MRI's static magnetic field stays below 2 ppm peak-to-peak within a diameter of 56 mm (90 mm using standard automatic volume shimming). MRI SNR is decreased by 14%, RF artefacts (dotted lines) are only visible in sequences with very low SNR. Ghosting artefacts are visible to the eye in about 26% of the EPI images, severe ghosting only in 7.6%. Eddy-current related heating effects during long EPI sequences are noticeable but with low influence of 2% on the coincidences count rate. The time resolution of 2.5 ns, the energy resolution of 29.7% and the volumetric spatial resolution of 1.8 mm(3) in the PET isocentre stay unaffected during MRI operation. Phantom studies show no signs of other artefacts or distortion in both modalities. A living rat was simultaneously imaged after the injection with (18)F-Fluorodeoxyglucose (FDG) proving the in vivo capabilities of the system.
authors.affiliation: Clinical Application Research, Philips Research Europe-Aachen, Pauwelsstrasse 17, D-52074 Aachen, Germany. Department of Physics of Molecular Imaging Systems, Institute of Experimental Molecular Imaging, RWTH Aachen University, Pauwelsstrasse 20, D-52074 Aachen, Germany. Institute of High Frequency Technology, RWTH Aachen University, Melatener Straße 25, D-52074 Aachen, Germany, Pauwelsstrasse 20, D-52074 Aachen, Germany.
authors.forename: Bjoern
authors.initials: B
authors.lastname: Weissler
authors.forename: Pierre
authors.initials: P
authors.lastname: Gebhardt
authors.forename: Christoph W
authors.initials: CW
authors.lastname: Lerche
authors.forename: Jakob
authors.initials: J
authors.lastname: Wehner
authors.forename: Torsten
authors.initials: T
authors.lastname: Solf
authors.forename: Benjamin
authors.initials: B
authors.lastname: Goldschmidt
authors.forename: Jane E
authors.initials: JE
authors.lastname: Mackewn
authors.forename: Paul K
authors.initials: PK
authors.lastname: Marsden
authors.forename: Fabian
authors.initials: F
authors.lastname: Kiessling
authors.forename: Michael
authors.initials: M
authors.lastname: Perkuhn
authors.forename: Dirk
authors.initials: D
authors.lastname: Heberling
authors.forename: Volkmar
authors.initials: V
authors.lastname: Schulz
mesh_terms: D000818:Animals; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D064847:Multimodal Imaging / Q000295:instrumentation / Q000379:methods*; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D051381:Rats; D059629:Signal-To-Noise Ratio; D012825:Silicon / Q000737:chemistry*
chemical_list: D012825:Silicon