Benefit of Time-of-Flight in PET: Experimental and Clinical Results
TLDR
ToF leads to a better contrast-versus-noise trade-off than non-TOF but one that is difficult to quantify in terms of a simple sensitivity gain improvement.Abstract:
Significant improvements have made it possible to add the technology of time-of-flight (TOF) to improve PET, particularly for oncology applications. The goals of this work were to investigate the benefits of TOF in experimental phantoms and to determine how these benefits translate into improved performance for patient imaging. Methods: In this study we used a fully 3-dimensional scanner with the scintillator lutetium-yttrium oxyorthosilicate and a system timing resolution of ;600 ps. The data are acquired in list-mode and reconstructed with a maximum-likelihood expectation maximization algorithm; the system model includes the TOF kernel and corrections for attenuation, detector normalization, randoms, and scatter. The scatter correction is an extension of the model-based singlescatter simulation to include the time domain. Phantom measurements to study the benefit of TOF include 27-cm- and 35-cm-diameter distributions with spheres ranging in size from 10to37mm.ToassessthebenefitofTOFPETforclinicalimaging, patient studies are quantitatively analyzed. Results: The lesion phantom studies demonstrate the improved contrast of the smallest spheres with TOF compared with non-TOF and also confirm the faster convergence of contrast with TOF. These gains are evident from visual inspection of the images as well as a quantitative evaluation of contrast recovery of the spheres and noise in the background. The gains with TOF are higher for larger objects. These results correlate with patient studies in which lesions are seen more clearly and with higher uptake at comparable noise for TOF than with non-TOF. Conclusion: TOF leads to a better contrast-versus-noise trade-off than non-TOF but one that is difficult to quantify in terms of a simple sensitivity gain improvement: A single gain factor for TOF improvement does not include the increased rate of convergence with TOF nor does it consider that TOF may converge to a different contrast than non-TOF. The experimental phantom results agree with those of prior simulations and help explain the improved image quality with TOF for patient oncology studies.read more
Citations
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Journal ArticleDOI
Physical and clinical performance of the mCT time-of-flight PET/CT scanner
Bjoern Jakoby,Bjoern Jakoby,Bjoern Jakoby,Y. Bercier,Maurizio Conti,Michael E. Casey,Bernard Bendriem,David W. Townsend,David W. Townsend +8 more
TL;DR: The physical and clinical PET performance of the first Biograph mCT TOF PET/CT scanner (Siemens Medical Solutions USA, Inc.) in comparison with its predecessor, the Biograph TruePoint TrueV, is characterized and improvements with TOF are defined.
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PET/MRI: Paving the Way for the Next Generation of Clinical Multimodality Imaging Applications
TL;DR: Multimodality imaging and, more specifically, the combination of PET and CT has matured into an important diagnostic tool and requires not only significant modifications of the PET detector to make it compact and insensitive to magnetic fields but also a major redesign of the MRI hardware.
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Design and performance evaluation of a whole-body Ingenuity TF PET-MRI system
Habib Zaidi,Navdeep Ojha,Michael A. Morich,Jerome J. Griesmer,Zhiqiang Hu,Piotr Maniawski,Osman Ratib,David Izquierdo-Garcia,Zahi A. Fayad,Ling Shao +9 more
TL;DR: The results were comparable to PET-CT systems demonstrating that the effect of design modifications required on the PET system to remove the harmful effect of the magnetic field on the PMTs was negligible, and it is conceived that advantages of hybrid PET-MRI will become more evident in the near future.
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Physical performance of the new hybrid PET∕CT Discovery-690.
Valentino Bettinardi,Luca Presotto,E. Rapisarda,Maria Picchio,Luigi Gianolli,Maria Carla Gilardi +5 more
TL;DR: The Discovery-690 shows very good PET physical performance for all the standard NEMA NU-2-2007 measurements and the new reconstruction algorithms available for PET data (TOF and PSF) allow further improvements of the D-690 image quality performance both qualitatively and quantitatively.
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Focus on time-of-flight PET: the benefits of improved time resolution.
TL;DR: A set of performance advantages is presented which include better image quality, shorter scan times, lower dose, higher spatial resolution, lower sensitivity to inconsistent data, and the opportunity for new architectures with missing angles.
References
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Journal Article
Performance of Philips Gemini TF PET/CT Scanner with Special Consideration for Its Time-of-Flight Imaging Capabilities
Suleman Surti,Austin Kuhn,Matthew E. Werner,Amy E. Perkins,Jeffrey A. Kolthammer,Joel S. Karp +5 more
TL;DR: The Gemini TF whole-body scanner represents the first commercially available fully 3-dimensional PET scanner that achieves time-of-flight capability as well as conventional imaging capabilities.
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List-mode likelihood: EM algorithm and image quality estimation demonstrated on 2-D PET
TL;DR: This paper formulates a corresponding expectation-maximization (EM) algorithm, as well as a method for estimating noise properties at the ML estimate, for an idealized two-dimensional positron emission tomography [2-D PET] detector.
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Time of flight in PET revisited
TL;DR: In this paper, the authors analyzed the performance enhancements made possible by improved timing as a function of the coincidence time resolution, and showed that PET scanners based on LSO have the potential for significantly better coincidence timing resolution than the 6 ns FWHM typically achieved with BGO.
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Time-of-Flight Positron Emission Tomography: Status Relative to Conventional PET
TL;DR: At present, due to lack of availability of small and highly efficient, crystal-phototube detectors, TOFPET does not have the high spatial resolution capabilities of non-TOFPET.