Abstract
Objective:The aim of the present study was to compare the performance of positron emission tomography (PET) component of PET/computed tomography (CT) with new emerging PET/magnetic resonance (MR) of the same vendor.Methods:According to National Electrical Manufacturers Association NU2-07, five separate experimental tests were performed to evaluate the performance of PET scanner of General Electric GE company; SIGNATM model PET/MR and GE Discovery 710 model PET/CT. The main investigated aspects were spatial resolution, sensitivity, scatter fraction, count rate performance, image quality, count loss and random events correction accuracy.Results:The findings of this study demonstrated superior sensitivity (~ 4 folds) of PET scanner in PET/MR compared to PET/CT system. Image quality test exhibited higher contrast in PET/MR (~ 9%) compared with PET/CT. The scatter fraction of PET/MR was 43.4% at noise equivalent count rate (NECR) peak of 218 kcps and the corresponding activity concentration was 17.7 kBq/cc. Whereas the scatter fraction of PET/CT was found as 39.2% at NECR peak of 72 kcps and activity concentration of 24.3 kBq/cc. The percentage error of the random event correction accuracy was 3.4% and 3.1% in PET/MR and PET/CT, respectively.Conclusion:It was concluded that PET/MR system is about 4 times more sensitive than PET/CT, and the contrast of hot lesions in PET/MR was ~ 9% higher than PET/CT. These outcomes also emphasize the possibility to achieve excellent clinical PET images with low administered dose and/or a short acquisition time in PET/MR.
Highlights
Positron emission tomography/magnetic resonance (PET/ MR) has been increasingly considered the cutting edge technology in nuclear medicine
While these for the positron emission tomography (PET)/computed tomography (CT) were designed as: axial field of view (FOV) 15.7 cm, crystal size 4.7×6.3×25 mm, LYSO scintillator, trans-axial FOV 70 cm and metallic photon multiplier tubes (PMTs). the varied technical aspects of PET scanner in both PET/MR and PET/CT might arise the difference on the performance
The measured spatial resolution of PET/MR and PET/CT were shown in a pattern of full width at half maximum (FWHM) and full width at tenth maximum (FWTM) on transverse and axial dimensions
Summary
Positron emission tomography/magnetic resonance (PET/ MR) has been increasingly considered the cutting edge technology in nuclear medicine. The merger of two different scanner technologies, PET and magnetic resonance imaging (MRI), presented more advanced and reliable means of cancer diagnosis. PET/ computed tomography (CT) combination has been used in oncological investigations with long-standing experience and knowledge. Such premium changes in PET scanner design rendered PET/MR technology more versatile and promising evidenced by the enhanced tissue contrast and absence of radiation hazards (1). The conventionally used metallic photon multiplier tubes (PMTs) in PET/CT are not applicable for PET/MR configuration. The providers might start to replace the classical PMTs by SiPM in the new generations of PET/CT devices (4)
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