A Digital Preclinical PET/MRI Insert and Initial Results

Bjoern Weissler, Pierre Gebhardt, Peter Duppenbecker, Jakob Wehner, David Schug, Christoph Lerche, Benjamin Goldschmidt, Andre Salomon, Iris Verel, Edwin Heijman, Michael Perkuhn, Dirk Heberling, Rene Botnar, Fabian Kiessling, Volkmar Schulz

Research output: Contribution to journalArticlepeer-review

97 Citations (Scopus)
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Abstract

Combining Positron Emission Tomography (PET) with Magnetic Resonance Imaging (MRI) results in a promising hybrid molecular imaging modality as it unifies the high sensitivity of PET for molecular and cellular processes with the functional and anatomical information from MRI. Digital Silicon Photomultipliers (dSiPMs) are the digital evolution in scintillation light detector technology and promise high PET SNR. DSiPMs from Philips Digital Photon Counting (PDPC) were used to develop a preclinical PET/RF gantry with 1-mm scintillation crystal pitch as an insert for clinical MRI scanners. With three exchangeable RF coils, the hybrid field of view has a maximum size of 160 mm × 96.6 mm (transaxial × axial). 0.1 ppm volume-root-mean-square B0-homogeneity is kept within a spherical diameter of 96 mm (automatic volume shimming). Depending on the coil, MRI SNR is decreased by 13% or 5% by the PET system. PET count rates, energy resolution of 12.6% FWHM, and spatial resolution of 0.73 mm3 (isometric volume resolution at isocenter) are not affected by applied MRI sequences. PET time resolution of 565 ps (FWHM) degraded by 6 ps during an EPI sequence. Timing-optimized settings yielded 260 ps time resolution. PET and MR images of a hot-rod phantom show no visible differences when the other modality was in operation and both resolve 0.8-mm rods. Versatility of the insert is shown by successfully combining multi-nuclei MRI (1H/19F) with simultaneously measured PET (18F-FDG). A longitudinal study of a tumor-bearing mouse verifies the operability, stability, and in-vivo capabilities of the system.Cardiac- and respiratory-gated PET/MRI motion-capturing (CINE) images of the mouse heart demonstrate the advantage of simultaneous acquisition for temporal and spatial image registration.

Original languageEnglish
Pages (from-to)2258-2270
Number of pages13
JournalIeee Transactions on Medical Imaging
Volume34
Issue number11
Early online date29 Apr 2015
DOIs
Publication statusPublished - 1 Nov 2015

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