title: NEMA NU 2-2012 performance studies for the SiPM-based ToF-PET component of the GE SIGNA PET/MR system.
abstract: OBJECTIVE
  The GE SIGNA PET/MR is a new whole body integrated time-of-flight (ToF)-PET/MR scanner from GE Healthcare. The system is capable of simultaneous PET and MR image acquisition with sub-400 ps coincidence time resolution. Simultaneous PET/MR holds great potential as a method of interrogating molecular, functional, and anatomical parameters in clinical disease in one study. Despite the complementary imaging capabilities of PET and MRI, their respective hardware tends to be incompatible due to mutual interference. In this work, the GE SIGNA PET/MR is evaluated in terms of PET performance and the potential effects of interference from MRI operation.
  
  
  METHODS
  The NEMA NU 2-2012 protocol was followed to measure PET performance parameters including spatial resolution, noise equivalent count rate, sensitivity, accuracy, and image quality. Each of these tests was performed both with the MR subsystem idle and with continuous MR pulsing for the duration of the PET data acquisition. Most measurements were repeated at three separate test sites where the system is installed.
  
  
  RESULTS
  The scanner has achieved an average of 4.4, 4.1, and 5.3 mm full width at half maximum radial, tangential, and axial spatial resolutions, respectively, at 1 cm from the transaxial FOV center. The peak noise equivalent count rate (NECR) of 218 kcps and a scatter fraction of 43.6% are reached at an activity concentration of 17.8 kBq/ml. Sensitivity at the center position is 23.3 cps/kBq. The maximum relative slice count rate error below peak NECR was 3.3%, and the residual error from attenuation and scatter corrections was 3.6%. Continuous MR pulsing had either no effect or a minor effect on each measurement.
  
  
  CONCLUSIONS
  Performance measurements of the ToF-PET whole body GE SIGNA PET/MR system indicate that it is a promising new simultaneous imaging platform.
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California 94305-5128 and Department of Radiology, Stanford University, Stanford, California 94305-5128.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Grant
authors.affiliation: GE Healthcare, Waukesha, Wisconsin 53188-1678.
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Deller
authors.affiliation: GE Healthcare, Applied Science Lab, Menlo Park, California 94025-3493.
authors.forename: Mohammad Mehdi
authors.initials: MM
authors.lastname: Khalighi
authors.affiliation: GE Healthcare, Waukesha, Wisconsin 53188-1678.
authors.forename: Sri Harsha
authors.initials: SH
authors.lastname: Maramraju
authors.affiliation: GE Healthcare and University Hospital of Zurich, Zurich 8006, Switzerland.
authors.forename: Gaspar
authors.initials: G
authors.lastname: Delso
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California 94305-5128; Department of Radiology, Stanford University, Stanford, California 94305-5128; Department of Electrical Engineering, Stanford University, Stanford, California 94305-5128; and Department of Physics, Stanford University, Stanford, California 94305-5128.
authors.forename: Craig S
authors.initials: CS
authors.lastname: Levin
mesh_terms: D004867:Equipment Design; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D064847:Multimodal Imaging / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000379:methods; D019275:Radiopharmaceuticals; D012542:Scattering, Radiation; D013696:Temperature; D013997:Time Factors; D051598:Whole Body Imaging / Q000295:instrumentation* / Q000379:methods
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18