Abstract
Time-of-flight (TOF) PET was initially introduced in the early days of PET. The TOF PET scanners developed in the 1980s had limited sensitivity and spatial resolution, were operated in 2-dimensional mode with septa, and used analytic image reconstruction methods. The current generation of TOF PET scanners has the highest sensitivity and spatial resolution ever achieved in commercial whole-body PET, is operated in fully-3-dimensional mode, and uses iterative reconstruction with full system modeling. Previously, it was shown that TOF provides a gain in image signal-to-noise ratio that is proportional to the square root of the object size divided by the system timing resolution. With oncologic studies being the primary application of PET, more recent work has shown that in modern TOF PET scanners there is an improved tradeoff between lesion contrast, image noise, and total imaging time, leading to a combination of improved lesion detectability, reduced scan time or injected dose, and more accurate and precise lesion uptake measurement. Because the benefit of TOF PET is also higher for heavier patients, clinical performance is more uniform over all patient sizes.
Footnotes
Published online Dec. 18, 2014.
Learning Objectives: On successful completion of this activity, participants should be able to (1) understand the differences between the current generation of time-of-flight (TOF) PET scanners and the earlier generation produced in the 1980s; (2) understand that TOF information leads to bigger gains in image quality for larger patients; and (3) understand that gains in TOF image quality are task-specific but that, overall, TOF information leads to better lesion detection and uptake measurement for oncologic tasks.
Financial Disclosure: This work was supported by National Institutes of Health grants R01-CA113941 and R01-EB009056. The author of this article has indicated no other relevant relationships that could be perceived as a real or apparent conflict of interest.
CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, SAM, and other credit types, participants can access this activity through the SNMMI website (http://www.snmmilearningcenter.org) through January 2018.
- © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.
Jump to section
- Article
- Abstract
- HISTORICAL BACKGROUND
- PAST ESTIMATES OF TOF GAIN
- NEW GENERATION OF TOF PET SCANNERS
- GAIN IN IMAGE SNR FROM FULLY-3D TOF PET
- BENEFIT OF MODERN TOF PET SCANNERS IN CLINICALLY RELEVANT IMAGING TASKS
- OTHER BENEFITS OF TOF INFORMATION IN PET IMAGING STUDIES
- FUTURE APPLICATIONS IN LOW-COUNT IMAGING SCENARIOS
- SUMMARY
- Footnotes
- REFERENCES
- Figures & Data
- Info & Metrics
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