Maximum likelihood activity and attenuation estimation using both emission and transmission data with application to utilization of Lu‐176 background radiation in TOF PET

Li, Cheng; Ma, Tianyu; Zhang, Xuezhu; Peng, Qiyu; Liu, Yaqiang; Qi, Jinyi

doi:10.1002/mp.13989

Cited by 8 publications

(18 citation statements)

References 33 publications

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“…One of our future work will investigate the effect of X-ray CT image quality on kernel MLAA and material decomposition and how improved methods may conquer the problems. It is also possible to combine X-ray CT projection data and PET emission data to pursue joint MLAA/CT reconstruction from simultaneous emission-transmission scans, in a way similar to (while still different from) earlier and new effort on a related problem (e.g., [16,45]).…”

Section: Discussionmentioning

confidence: 99%

“…A seminal theoretical work later proved that TOF data determine µ up to a constant [8,9]. Since then, the MLAA method has received a wide range of interests (e.g., [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]). It is worth noting that previous attention of MLAA reconstruction was focused on PET attenuation correction.…”

Section: Joint Reconstruction Of Gct Image From Pet Datamentioning

confidence: 99%

“…Theoretical analysis and practical studies have demonstrated that the gamma-ray attenuation image at 511 keV can be jointly estimated with the reconstruction of PET activity image from time-of-flight PET emission data, for example, using the maximum likelihood activity and attenuation (MLAA) reconstruction algorithm [9,35]. Previous attention on this topic has been given to achieve transmission-less PET imaging by excluding the X-ray CT component (e.g., [11][12][13][14][15][16]). Existing studies were also primarily aimed to improve the aspect of attenuation correction for PET activity image reconstruction for PET/CT (e.g., [17][18][19][20]) or PET/MR (e.g., [21][22][23][24][25][26]).…”

Section: Introductionmentioning

confidence: 99%

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PET-enabled Dual-energy CT: A Proof-of-Concept Simulation Study

Wang

2018

2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC)

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Standard dual-energy computed tomography (CT) uses two different X-ray energies to obtain energy-dependent tissue attenuation information to allow quantitative material decomposition. The combined use of dual-energy CT and positron emission tomography (PET) may provide a more comprehensive characterization of disease states in cancer and other diseases. However, the integration of dual-energy CT with PET is not trivial, either requiring costly hardware upgrade or increasing radiation dose. This paper proposes a dual-energy CT imaging method that is enabled by the already-available PET data on PET/CT. Instead of using a second X-ray CT scan with a different energy, this method exploits time-of-flight PET image reconstruction via the maximum likelihood attenuation and activity (MLAA) algorithm to obtain a 511 keV gamma-ray attenuation image from PET emission data. The high-energy gamma-ray CT image is then combined with the low-energy X-ray CT of PET/CT to provide a pair of dual-energy CT images. A major challenge with the standard MLAA reconstruction is the high noise present in the reconstructed 511 keV attenuation map, which would not compromise the PET activity reconstruction too much but may significantly affect the performance of the gamma-ray CT for material decomposition. To overcome the problem, we further propose a kernel MLAA algorithm to exploit the prior information from the available X-ray CT image. We conducted a computer simulation to test the concept and algorithm for the task of material decomposition. The simulation results demonstrate that this PET-enabled dual-energy CT method is promising for quantitative material decomposition. The proposed method can be readily implemented on time-of-flight PET/CT scanners to enable simultaneous PET and dual-energy CT imaging.

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Section: Discussionmentioning

confidence: 99%

Section: Joint Reconstruction Of Gct Image From Pet Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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PET-enabled Dual-energy CT: A Proof-of-Concept Simulation Study

Wang

2018

2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC)

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“…where ∀i : (10) and č(n) i,emis and č(n) i,tran are curvature terms for emission data and transmission data, respectively, defined in (34).…”

Section: Image Reconstructionmentioning

confidence: 99%

“…To our knowledge, this is the first study where lutetium-based AC is implemented in totalbody PET reconstruction using large acceptance angles and the first time that it is used with ultralow-dose PET scans, where using MLAA-like algorithms becomes challenging due to the low-count nature of the PET emission data. Use of regularized MLTR algorithm for reconstructing the PET µ-maps only employing the lutetium transmission data is compared to reconstructions with MLAA using both TOF PET data and lutetium transmission data (MLAA-TX), which has been recently proposed by Cheng et al (34) and tested with a short-AFOV scanner for a regular-dose PET scan. With the .…”

Section: Introductionmentioning

confidence: 99%

Lutetium background radiation in total-body PET—A simulation study on opportunities and challenges in PET attenuation correction

Omidvari

Leung

et al. 2022

Front. Nucl. Med.

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The current generation of total-body positron emission tomography (PET) scanners offer significant sensitivity increase with an extended axial imaging extent. With the large volume of lutetium-based scintillation crystals that are used as detector elements in these scanners, there is an increased flux of background radiation originating from 176Lu decay in the crystals and higher sensitivity for detecting it. Combined with the ability of scanning the entire body in a single bed position, this allows more effective utilization of the lutetium background as a transmission source for estimating 511 keV attenuation coefficients. In this study, utilization of the lutetium background radiation for attenuation correction in total-body PET was studied using Monte Carlo simulations of a 3D whole-body XCAT phantom in the uEXPLORER PET scanner, with particular focus on ultralow-dose PET scans that are now made possible with these scanners. Effects of an increased acceptance angle, reduced scan durations, and Compton scattering on PET quantification were studied. Furthermore, quantification accuracy of lutetium-based attenuation correction was compared for a 20-min scan of the whole body on the uEXPLORER, a one-meter-long, and a conventional 24-cm-long scanner. Quantification and lesion contrast were minimally affected in both long axial field-of-view scanners and in a whole-body 20-min scan, the mean bias in all analyzed organs of interest were within a ±10% range compared to ground-truth activity maps. Quantification was affected in certain organs, when scan duration was reduced to 5 min or a reduced acceptance angle of 17° was used. Analysis of the Compton scattered events suggests that implementing a scatter correction method for the transmission data will be required, and increasing the energy threshold from 250 keV to 290 keV can reduce the computational costs and data rates, with negligible effects on PET quantification. Finally, the current results can serve as groundwork for transferring lutetium-based attenuation correction into research and clinical practice.

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PET-enabled dual-energy CT: image reconstruction and a proof-of-concept computer simulation study

Wang

2020

Phys. Med. Biol.

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Standard dual-energy computed tomography (CT) uses two different x-ray energies to obtain energy-dependent tissue attenuation information to allow quantitative material decomposition. The combined use of dual-energy CT and positron emission tomography (PET) may provide a more comprehensive characterization of disease states in cancer and other diseases. However, the integration of dual-energy CT with PET is not trivial, either requiring costly hardware upgrades or increasing radiation exposure. This paper proposes a different dual-energy CT imaging method that is enabled by PET. Instead of using a second x-ray CT scan with a different energy, this method exploits time-of-flight PET image reconstruction via the maximum likelihood attenuation and activity (MLAA) algorithm to obtain a 511 keV gamma-ray attenuation image from PET emission data. The high-energy gamma-ray attenuation image is then combined with the low-energy x-ray CT of PET/CT to provide a pair of dual-energy CT images. A major challenge with the standard MLAA reconstruction is the high noise present in the reconstructed 511 keV attenuation map, which would not compromise the PET activity reconstruction too much but may significantly affect the performance of the gamma-ray attenuation image for material decomposition. To overcome the problem, we further propose a kernel MLAA algorithm to exploit the prior information from the available x-ray CT image. We conducted a computer simulation to test the concept and algorithm for the task of material decomposition. The simulation results demonstrate that this PET-enabled dual-energy CT method is promising for quantitative material decomposition. The proposed method can be readily implemented on time-of-flight PET/CT scanners to enable simultaneous PET and dual-energy CT imaging.

show abstract

Maximum likelihood activity and attenuation estimation using both emission and transmission data with application to utilization of Lu‐176 background radiation in TOF PET

Cited by 8 publications

References 33 publications

PET-enabled Dual-energy CT: A Proof-of-Concept Simulation Study

PET-enabled Dual-energy CT: A Proof-of-Concept Simulation Study

Lutetium background radiation in total-body PET—A simulation study on opportunities and challenges in PET attenuation correction

PET-enabled dual-energy CT: image reconstruction and a proof-of-concept computer simulation study

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