Improvements in PET Image Quality in Time of Flight (TOF) Simultaneous PET/MRI
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An integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) scanner with time of flight (TOF) technology is now available for clinical use. The aim of this study is to evaluate the potential of TOF PET in PET/MRI to reduce artifacts in PET images when compared to non-TOF PET/MRI, TOF PET/X-ray computed tomography (CT), and non-TOF PET/CT.
All patients underwent a single 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) injection, followed first by PET/CT, and subsequently by PET/MRI. PET/CT exams were requested as standard-of-care for oncological indications. Using the PET acquisitions datasets, 4 series of images (TOF PET/CT, non-TOF PET/CT, TOF PET/MRI, and non-TOF PET/MRI) were reconstructed. These image series were visually evaluated for: (1) dental metal artifacts, (2) breathing artifacts, and (3) pelvic artifacts due to scatter correction errors from high bladder [18F]FDG concentration. PET image quality was assessed by a 3-point scale (1—clinically significant artifact, 2—non clinically significant artifact, and 3—no artifact).
Twenty-five patients (mean ± SD age: 56 ± 13 years old; female: 10, male: 15) were enrolled. TOF PET/MRI, non-TOF PET/MRI, TOF PET/CT, and non-TOF PET/CT scores 2.8, 2.5, 2.4, and 2.3, respectively for the presence of dental artifacts, 2.8, 2.5, 2.2, and 1.9, respectively, for the presence of breathing artifacts, and 2.7, 1.7, 2.0, and 1.3, respectively, for the presence of pelvic artifacts TOF PET/MRI images showed the highest image quality scores among the 4 datasets of PET images.
The superior timing resolution and resulting TOF capability of the new PET/MRI scanner improved PET image quality in this cohort by reducing artifacts compared to non-TOF PET/MRI, TOF PET/CT, and non-TOF PET/CT.
Key wordsPET/MRI PET/CT Time of flight Artifact Image quality
We thank Floris Jansen, PhD (GE Healthcare) for valuable technical suggestions and Mehdi Khalighi, PhD (GE Healthcare) for technical support. We also thank Praven Gulaka, PhD, our research coordinators, the radiochemistry staff, and the nuclear medicine technologists. Special thanks to all the patients who agreed to participate in the study and their families.
Compliance with Ethical standards
The authors thank GE Healthcare for supporting the study.
Conflict of Interest
The authors declare that they have no conflict of interest.
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