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Baldassi B, Poladyan H, Shahi A, Maa-Hacquoil H, Rapley M, Komarov B, Stiles J, Freitas V, Waterston M, Aseyev O, Reznik A, Bubon O. Image quality evaluation for a clinical organ-targeted PET camera. Front Oncol 2024; 14:1268991. [PMID: 38590664 PMCID: PMC10999605 DOI: 10.3389/fonc.2024.1268991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 03/12/2024] [Indexed: 04/10/2024] Open
Abstract
Introduction A newly developed clinical organ-targeted Positron Emission Tomography (PET) system (also known as Radialis PET) is tested with a set of standardized and custom tests previously used to evaluate the performance of Positron Emission Mammography (PEM) systems. Methods Imaging characteristics impacting standardized uptake value (SUV) and detectability of small lesions, namely spatial resolution, linearity, uniformity, and recovery coefficients, are evaluated. Results In-plane spatial resolution was measured as 2.3 mm ± 0.1 mm, spatial accuracy was 0.1 mm, and uniformity measured with flood field and NEMA NU-4 phantom was 11.7% and 8.3% respectively. Selected clinical images are provided as reference to the imaging capabilities under different clinical conditions such as reduced activity of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG) and time-delayed acquisitions. SUV measurements were performed for selected clinical acquisitions to demonstrate a capability for quantitative image assessment of different types of cancer including for invasive lobular carcinoma with comparatively low metabolic activity. Quantitative imaging performance assessment with phantoms demonstrates improved contrast recovery and spill-over ratio for this PET technology when compared to other commercial organ-dedicated PET systems with similar spatial resolution. Recovery coefficients were measured to be 0.21 for the 1 mm hot rod and up to 0.89 for the 5 mm hot rod of NEMA NU-4 Image Quality phantom. Discussion Demonstrated ability to accurately reconstruct activity in tumors as small as 5 mm suggests that the Radialis PET technology may be well suited for emerging clinical applications such as image guided assessment of response to neoadjuvant systemic treatment (NST) in lesions smaller than 2 cm. Also, our results suggest that, while spatial resolution greatly influences the partial volume effect which degrades contrast recovery, optimized count rate performance and image reconstruction workflow may improve recovery coefficients for systems with comparable spatial resolution. We emphasize that recovery coefficient should be considered as a primary performance metric when a PET system is used for accurate lesion size or radiotracer uptake assessments.
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Affiliation(s)
- Brandon Baldassi
- Department of Physics, Lakehead University, Thunder Bay, ON, Canada
| | | | - Anirudh Shahi
- Department of Physics, Lakehead University, Thunder Bay, ON, Canada
| | | | - Madeline Rapley
- Department of Physics, Lakehead University, Thunder Bay, ON, Canada
| | | | - Justin Stiles
- Department of Physics, Lakehead University, Thunder Bay, ON, Canada
| | - Vivianne Freitas
- Department of Medical Imaging, University Health Network, Sinai Health System, Women’s College Hospital, Toronto, ON, Canada
- Department of Medical Imaging, University of Toronto, Toronto, ON, Canada
| | | | - Olexiy Aseyev
- Department of Medical Oncology, Thunder Bay Regional Health Sciences Center, Thunder Bay, ON, Canada
| | - Alla Reznik
- Department of Physics, Lakehead University, Thunder Bay, ON, Canada
- Radialis Inc., Thunder Bay, ON, Canada
| | - Oleksandr Bubon
- Department of Physics, Lakehead University, Thunder Bay, ON, Canada
- Radialis Inc., Thunder Bay, ON, Canada
- Thunder Bay Regional Health Research Institute, Thunder Bay, ON, Canada
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Cox CPW, Brabander T, Vegt E, de Lussanet de la Sablonière QG, Graven LH, Verburg FA, Segbers M. Reduction of [ 68Ga]Ga-DOTA-TATE injected activity for digital PET/MR in comparison with analogue PET/CT. EJNMMI Phys 2024; 11:27. [PMID: 38488989 DOI: 10.1186/s40658-024-00629-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/06/2024] [Indexed: 03/17/2024] Open
Abstract
BACKGROUND New digital detectors and block-sequential regularized expectation maximization (BSREM) reconstruction algorithm improve positron emission tomography (PET)/magnetic resonance (MR) image quality. The impact on image quality may differ from analogue PET/computed tomography (CT) protocol. The aim of this study is to determine the potential reduction of injected [68Ga]Ga-DOTA-TATE activity for digital PET/MR with BSREM reconstruction while maintaining at least equal image quality compared to the current analogue PET/CT protocol. METHODS NEMA IQ phantom data and 25 patients scheduled for a diagnostic PET/MR were included. According to our current protocol, 1.5 MBq [68Ga]Ga-DOTA-TATE per kilogram (kg) was injected. After 60 min, scans were acquired with 3 (≤ 70 kg) or 4 (> 70 kg) minutes per bedposition. PET/MR scans were reconstructed using BSREM and factors β 150, 300, 450 and 600. List mode data with reduced counts were reconstructed to simulate scans with 17%, 33%, 50% and 67% activity reduction. Image quality was measured quantitatively for PET/CT and PET/MR phantom and patient data. Experienced nuclear medicine physicians performed visual image quality scoring and lesion counting in the PET/MR patient data. RESULTS Phantom analysis resulted in a possible injected activity reduction of 50% with factor β = 600. Quantitative analysis of patient images revealed a possible injected activity reduction of 67% with factor β = 600. Both with equal or improved image quality as compared to PET/CT. However, based on visual scoring a maximum activity reduction of 33% with factor β = 450 was acceptable, which was further limited by lesion detectability analysis to an injected activity reduction of 17% with factor β = 450. CONCLUSION A digital [68Ga]Ga-DOTA-TATE PET/MR together with BSREM using factor β = 450 result in 17% injected activity reduction with quantitative values at least similar to analogue PET/CT, without compromising on PET/MR visual image quality and lesion detectability.
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Affiliation(s)
- Christina P W Cox
- Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands.
| | - Tessa Brabander
- Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
| | - Erik Vegt
- Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
| | - Quido G de Lussanet de la Sablonière
- Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
| | - Laura H Graven
- Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
| | - Frederik A Verburg
- Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
| | - Marcel Segbers
- Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Postbus 2040, 3000 CA, Rotterdam, The Netherlands
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Wang D, Jiang C, He J, Teng Y, Qin H, Liu J, Yang X. M 3S-Net: multi-modality multi-branch multi-self-attention network with structure-promoting loss for low-dose PET/CT enhancement. Phys Med Biol 2024; 69:025001. [PMID: 38086073 DOI: 10.1088/1361-6560/ad14c5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 12/12/2023] [Indexed: 01/05/2024]
Abstract
Objective.PET (Positron Emission Tomography) inherently involves radiotracer injections and long scanning time, which raises concerns about the risk of radiation exposure and patient comfort. Reductions in radiotracer dosage and acquisition time can lower the potential risk and improve patient comfort, respectively, but both will also reduce photon counts and hence degrade the image quality. Therefore, it is of interest to improve the quality of low-dose PET images.Approach.A supervised multi-modality deep learning model, named M3S-Net, was proposed to generate standard-dose PET images (60 s per bed position) from low-dose ones (10 s per bed position) and the corresponding CT images. Specifically, we designed a multi-branch convolutional neural network with multi-self-attention mechanisms, which first extracted features from PET and CT images in two separate branches and then fused the features to generate the final generated PET images. Moreover, a novel multi-modality structure-promoting term was proposed in the loss function to learn the anatomical information contained in CT images.Main results.We conducted extensive numerical experiments on real clinical data collected from local hospitals. Compared with state-of-the-art methods, the proposed M3S-Net not only achieved higher objective metrics and better generated tumors, but also performed better in preserving edges and suppressing noise and artifacts.Significance.The experimental results of quantitative metrics and qualitative displays demonstrate that the proposed M3S-Net can generate high-quality PET images from low-dose ones, which are competable to standard-dose PET images. This is valuable in reducing PET acquisition time and has potential applications in dynamic PET imaging.
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Affiliation(s)
- Dong Wang
- School of Mathematics/S.T.Yau Center of Southeast University, Southeast University, 210096, People's Republic of China
- Nanjing Center of Applied Mathematics, Nanjing, 211135, People's Republic of China
| | - Chong Jiang
- Department of Nuclear Medicine, West China Hospital of Sichuan University, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Jian He
- Department of Nuclear Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, People's Republic of China
| | - Yue Teng
- Department of Nuclear Medicine, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, People's Republic of China
| | - Hourong Qin
- Department of Mathematics, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Jijun Liu
- School of Mathematics/S.T.Yau Center of Southeast University, Southeast University, 210096, People's Republic of China
- Nanjing Center of Applied Mathematics, Nanjing, 211135, People's Republic of China
| | - Xiaoping Yang
- Department of Mathematics, Nanjing University, Nanjing, 210093, People's Republic of China
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Kalaitzidis P, Gustafsson J, Hindorf C, Ljungberg M. Monte Carlo investigation of PET [ 68Ga]Ga-DOTA-TOC activity-administration protocols for consistent image quality. Heliyon 2023; 9:e19504. [PMID: 37681181 PMCID: PMC10480678 DOI: 10.1016/j.heliyon.2023.e19504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 08/24/2023] [Accepted: 08/24/2023] [Indexed: 09/09/2023] Open
Abstract
One example of a PET exam that suffers from noise problems is [68Ga]Ga-DOTA-TOC, where patients are generally administered between 100 and 200 MBq [68Ga]Ga-DOTA-TOC, irrespective of size. However, a fixed activity can result in low signal-to-noise ratios (SNRs) in larger patients. This study aimed to evaluate the impact on image quality with respect to injected activity and patient habitus through Monte Carlo (MC) simulation. Eight anthropomorphic computer phantoms with body mass indices (BMIs) between 19 kg/m2 and 38 kg/m2 and tumours distributed in the liver were simulated using the MC software Gate v8.2 with an activity distribution defined according to [68Ga]Ga-DOTA-TOC standardised uptake values. Three activity-administration protocols were simulated: (i) with a fixed activity of 100 MBq, (ii) with the activity scaled by 2 MBq/kg, and (iii) with the activity scaled by a body size-dependent power-function based on the SNR obtained with (ii). BMI, weight, body surface area, and abdominal circumference were evaluated body size parameters. Images were reconstructed with the CASToR software and evaluated for background SNR and lesion contrast-to-noise ratio (CNR). Large SNR variabilities were obtained with protocols (i) and (ii), while (iii) generated good consistency. Several tumours failed to reach a CNR of 5 for large phantoms with protocol (i), but the CNR was generally improved by (ii) and (iii). An activity scaled by patient habitus generate better image quality consistency, which increases the likelihood that patients receive a similar standard of care.
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Affiliation(s)
| | | | - Cecilia Hindorf
- Medical Radiation Physics, Lund, Lund University, Lund, Sweden
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Solna, Stockholm, Sweden
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Besanjideh M, Shamloo A, Hannani SK. Evaluating the reliability of tumour spheroid-on-chip models for replicating intratumoural drug delivery: considering the role of microfluidic parameters. J Drug Target 2023; 31:179-193. [PMID: 36036226 DOI: 10.1080/1061186x.2022.2119478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Several tumour spheroid-on-chip models have already been proposed in the literature to conduct high throughput drug screening assays. The microfluidic configurations in these models generally depend on the strategies adopted for spheroid formation and entrapment. However, it is not clear how successful they are to mimic in vivo transport mechanisms. In this study, drug transport in different tumour spheroid-on-chip models is numerically investigated under static and dynamic conditions using porous media theory. Moreover, the treatment of a solid tumour at the initial stage of development is modelled using bolus injection and continuous infusion methods. Then, the results of tumour spheroid-on-chip, including drug concentration, cell viability, as well as pressure and fluid shear stress distributions, are compared with those of the solid tumour, assuming identical transport properties in all models. Finally, a new configuration of the microfluidic device along with the optimal drug concentrations is proposed, which can well imitate a given in vivo situation.
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Affiliation(s)
- Mohsen Besanjideh
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.,Stem Cell and Regenerative Medicine Institute, Sharif University of Technology, Tehran, Iran
| | - Amir Shamloo
- Stem Cell and Regenerative Medicine Institute, Sharif University of Technology, Tehran, Iran
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Kersting D, Jentzen W, Jeromin D, Mavroeidi IA, Conti M, Büther F, Herrmann K, Rischpler C, Hamacher R, Fendler WP, Seifert R, Costa PF. Lesion Quantification Accuracy of Digital 90Y PET Imaging in the Context of Dosimetry in Systemic Fibroblast Activation Protein Inhibitor Radionuclide Therapy. J Nucl Med 2023; 64:329-336. [PMID: 35981898 PMCID: PMC9902858 DOI: 10.2967/jnumed.122.264338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 08/13/2022] [Accepted: 08/13/2022] [Indexed: 02/04/2023] Open
Abstract
Therapy with 90Y-labeled fibroblast activation protein inhibitors (90Y-FAPIs) was recently introduced as a novel treatment concept for patients with solid tumors. Lesion and organ-at-risk dosimetry is part of assessing treatment efficacy and safety and requires reliable quantification of tissue uptake. As 90Y quantification is limited by the low internal positron-electron pair conversion rate, the increased effective sensitivity of digital silicon photomultiplier-based PET/CT systems might increase quantification accuracy and, consequently, allow for dosimetry in 90Y-FAPI therapy. The aim of this study was to explore the conditions for reliable lesion image quantification in 90Y-FAPI radionuclide therapy using a digital PET/CT system. Methods: Two tumor phantoms were filled with 90Y solution using different sphere activity concentrations and a constant signal-to-background ratio of 40. The minimum detectable activity concentration was determined, and its dependence on acquisition time (15 vs. 30 min per bed position) and smoothing levels (all-pass vs. 5-mm gaussian filter) was investigated. Quantification accuracy was evaluated at various activity concentrations to estimate the minimum quantifiable activity concentration using contour-based and oversized volume-of-interest-based quantification approaches. A ±20% deviation range between image-derived and true activity concentrations was regarded as acceptable. Tumor dosimetry for 3 patients treated with 90Y-FAPI is presented to project the phantom results to clinical scenarios. Results: For a lesion size of 40 mm and a clinical acquisition time of 15 min, both minimum detectable and minimum quantifiable activity concentrations were 0.12 MBq/mL. For lesion sizes of greater than or equal to 30 mm, accurate quantification was feasible for detectable lesions. Only for the smallest 10-mm sphere, the minimum detectable and minimum quantifiable activity concentrations differ substantially (0.43 vs. 1.97 MBq/mL). No notable differences between the 2 quantification approaches were observed. For the investigated tumors, absorbed dose estimates with reliable accuracy were achievable. Conclusion: For lesion sizes and activity concentrations that are expected to be observed in patients treated with 90Y-FAPI, quantification with reasonable accuracy is possible. Further dosimetry studies are needed to thoroughly investigate the efficacy and safety of 90Y-FAPI therapy.
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Affiliation(s)
- David Kersting
- Department of Nuclear Medicine, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany; .,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany
| | - Walter Jentzen
- Department of Nuclear Medicine, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany;,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany
| | - Daniel Jeromin
- Department of Nuclear Medicine, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany;,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany
| | - Ilektra-Antonia Mavroeidi
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany;,Department of Medical Oncology, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Maurizio Conti
- Siemens Medical Solutions USA, Inc., Knoxville, Tennessee; and
| | - Florian Büther
- Department of Nuclear Medicine, University Hospital Muenster, University of Muenster, Muenster, Germany
| | - Ken Herrmann
- Department of Nuclear Medicine, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany;,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany
| | - Christoph Rischpler
- Department of Nuclear Medicine, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany;,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany
| | - Rainer Hamacher
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany;,Department of Medical Oncology, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Wolfgang P. Fendler
- Department of Nuclear Medicine, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany;,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany
| | - Robert Seifert
- Department of Nuclear Medicine, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany;,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany;,Department of Nuclear Medicine, University Hospital Muenster, University of Muenster, Muenster, Germany
| | - Pedro Fragoso Costa
- Department of Nuclear Medicine, West German Cancer Center (WTZ), University Hospital Essen, University of Duisburg-Essen, Essen, Germany;,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Essen, Germany
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Sang Z, Kuang Z, Wang X, Ren N, Wu S, Niu M, Cong L, Liu Z, Hu Z, Sun T, Liang D, Liu X, Zheng H, Li Y, Yang Y. Mutual interferences between SIAT aPET insert and a 3 T uMR 790 MRI scanner. Phys Med Biol 2023; 68. [PMID: 36549011 DOI: 10.1088/1361-6560/acae17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 12/22/2022] [Indexed: 12/24/2022]
Abstract
Objective.Dual-modality small animal PET/MR imaging provides temporally correlated information on two biochemical processes of a living object. An magnetic resonance imaging (MRI)-compatible small animal PET insert named Shenzhen Institutes of Advanced Technology (SIAT) aPET was developed by using dual-ended readout depth encoding detectors to simultaneously achieve a uniform high spatial resolution and high sensitivity at the SIAT. In this work, the mutual interferences between SIAT aPET and the 3 T uMR 790 MRI scanner of United Imaging was quantitatively evaluated.Approach.To minimize the mutual interferences, only the PET detectors and the readout electronics were placed inside the MRI scanner, the major signal processing electronic was placed in the corner of the MRI room and the auxiliary unit was placed in the MRI technical room. A dedicated mouse radio fRequency (RF) coil with a transmitter and receiver was developed for the PET insert. The effects of PET scanner on theB0andB1field of the MRI scanner and the quality of the MRI images were measured. The effects of MRI imaging on the performance of both the PET detectors and scanner were also measured.Main results.The electronic and mechanical components of the PET insert affected the homogeneity of theB0field. The PET insert had no effect on the homogeneity ofB1produced by the dedicated mouse coil but slightly reduced the strength ofB1. The mean and standard deviation of the RF noise map were increased by 2.2% and 11.6%, respectively, while the PET insert was placed in the MRI scanner and powered on. Eddy current was produced while the PET insert was placed in the MRI scanner, and it was further increased while the PET insert was powered on. Despite the above-mentioned interferences from the PET insert, the MR images of a uniform cylindrical water phantom showed that the changes in the signal-to-noise ratio (SNR) and homogeneity as the PET insert was placed in the MRI scanner were acceptable regardless of whether the PET insert was powered off or powered on. The maximum reduction of SNR was less than 11%, and the maximum reduction of homogeneity was less than 2.5% while the PET insert was placed inside the MRI scanner and powered on for five commonly used MRI sequences. MRI using gradient echo (GRE), spin echo (SE) and fast spin echo (FSE) sequences had negligible effects on the flood histograms and energy resolution of the PET detectors, as well as the spatial resolution and sensitivity of the PET scanner.Significance.The mutual interference between the SIAT aPET and the 3 T uMR 790 MRI scanner are acceptable. Simultaneous PET/MRI imaging of small animals can be performed with the two scanners.
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Affiliation(s)
- Ziru Sang
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Zhonghua Kuang
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Xiaohui Wang
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Ning Ren
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - San Wu
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Ming Niu
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Longhan Cong
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Zheng Liu
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Zhanli Hu
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Tao Sun
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Dong Liang
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Xin Liu
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Hairong Zheng
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Ye Li
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
| | - Yongfeng Yang
- Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, People's Republic of China
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Rausch I, Mannheim JG, Kupferschläger J, la Fougère C, Schmidt FP. Image quality assessment along the one metre axial field-of-view of the total-body Biograph Vision Quadra PET/CT system for 18F-FDG. EJNMMI Phys 2022; 9:87. [PMID: 36513949 PMCID: PMC9747988 DOI: 10.1186/s40658-022-00516-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 12/02/2022] [Indexed: 12/15/2022] Open
Abstract
AIM Recently, total-body PET/CT systems with an extended axial field-of-view (aFOV) became commercially available which allow acquiring physiologic information of multiple organs simultaneously. However, the nominal aFOV may clinically not be used effectively due to the inherently reduced sensitivity at the distal ends of the aFOV. The aim of this study was to assess the extent of the useful aFOV of the Biograph Vision Quadra PET/CT system. METHODS A NEMA image quality (IQ) phantom mimicking a standard [18F]FDG examination was used. Image contrast and noise were assessed across the 106 cm aFOV of the Biograph Vision Quadra PET/CT system (Siemens Healthineers). Phantom acquisitions were performed at different axial positions. PET data were rebinned to simulate different acquisition times for a standard injected activity and reconstructed using different filter settings to evaluate the noise and images along the axial direction. RESULTS Image noise and contrast were stable within the central 80 cm of the aFOV. Outside this central area, image contrast variability as well as image noise increased. This degradation of IQ was in particular evident for short acquisition times of less than 30 s. At 10 min acquisition time and in the absence of post-reconstruction filtering, the useful aFOV was 100 cm. For a 2 min acquisition time, a useful aFOV with image noise below 15% was only achievable using Gaussian filtering with axial extents of between 83 and 103 cm when going from 2 to 6 mm full-width-half-maximum, respectively. CONCLUSION Image noise increases substantially towards the ends of the aFOV. However, good IQ in compliance with generally accepted benchmarks is achievable for an aFOV of > 90 cm. When accepting higher image noise or using dedicated protocol settings such as stronger filtering a useful aFOV of around 1 m can be achieved for a 2 min acquisition time.
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Affiliation(s)
- Ivo Rausch
- grid.22937.3d0000 0000 9259 8492QIMP Team, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090 Vienna, Austria
| | - Julia G. Mannheim
- grid.10392.390000 0001 2190 1447Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard-Karls University Tuebingen, Tübingen, Germany ,grid.10392.390000 0001 2190 1447Cluster of Excellence iFIT (EXC 2180) “Image Guided and Functionally Instructed Tumor Therapies”, University of Tuebingen, Tübingen, Germany
| | - Jürgen Kupferschläger
- grid.411544.10000 0001 0196 8249Department of Nuclear Medicine and Clinical Molecular Imaging, University Hospital Tuebingen, Otfried-Mueller-Strasse 14, 72076 Tübingen, Germany
| | - Christian la Fougère
- grid.10392.390000 0001 2190 1447Cluster of Excellence iFIT (EXC 2180) “Image Guided and Functionally Instructed Tumor Therapies”, University of Tuebingen, Tübingen, Germany ,grid.411544.10000 0001 0196 8249Department of Nuclear Medicine and Clinical Molecular Imaging, University Hospital Tuebingen, Otfried-Mueller-Strasse 14, 72076 Tübingen, Germany
| | - Fabian P. Schmidt
- grid.10392.390000 0001 2190 1447Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard-Karls University Tuebingen, Tübingen, Germany ,grid.411544.10000 0001 0196 8249Department of Nuclear Medicine and Clinical Molecular Imaging, University Hospital Tuebingen, Otfried-Mueller-Strasse 14, 72076 Tübingen, Germany
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Diagnostic Value of 18 F-FACBC PET/MRI in Brain Metastases. Clin Nucl Med 2022; 47:1030-1039. [PMID: 36241129 PMCID: PMC9653108 DOI: 10.1097/rlu.0000000000004435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE The study aims to evaluate whether combined 18 F-FACBC PET/MRI could provide additional diagnostic information compared with MRI alone in brain metastases. PATIENTS AND METHODS Eighteen patients with newly diagnosed or suspected recurrence of brain metastases received dynamic 18 F-FACBC PET/MRI. Lesion detection was evaluated on PET and MRI scans in 2 groups depending on prior stereotactic radiosurgery (SRS group) or not (no-SRS group). SUVs, time-activity curves, and volumetric analyses of the lesions were performed. RESULTS In the no-SRS group, 29/29 brain lesions were defined as "MRI positive." With PET, 19/29 lesions were detected and had high tumor-to-background ratios (TBRs) (D max MR , ≥7 mm; SUV max , 1.2-8.4; TBR, 3.9-25.9), whereas 10/29 lesions were undetected (D max MR , ≤8 mm; SUV max , 0.3-1.2; TBR, 1.0-2.7). In the SRS group, 4/6 lesions were defined as "MRI positive," whereas 2/6 lesions were defined as "MRI negative" indicative of radiation necrosis. All 6 lesions were detected with PET (D max MR , ≥15 mm; SUV max , 1.4-4.2; TBR, 3.6-12.6). PET volumes correlated and were comparable in size with contrast-enhanced MRI volumes but were only partially congruent (mean DSC, 0.66). All time-activity curves had an early peak, followed by a plateau or a decreasing slope. CONCLUSIONS 18 F-FACBC PET demonstrated uptake in brain metastases from cancer of different origins (lung, gastrointestinal tract, breast, thyroid, and malignant melanoma). However, 18 F-FACBC PET/MRI did not improve detection of brain metastases compared with MRI but might detect tumor tissue beyond contrast enhancement on MRI. 18 F-FACBC PET should be further evaluated in recurrent brain metastases.
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Takahashi Y, Nemoto A, Hosokawa S, Ito H, Oriuchi N. Construction of a Phantom for Image Quality Evaluation in PET/MRI System. ANNALS OF NUCLEAR CARDIOLOGY 2022; 8:103-108. [PMID: 36540182 PMCID: PMC9749749 DOI: 10.17996/anc.22-00152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/22/2022] [Accepted: 05/19/2022] [Indexed: 06/17/2023]
Abstract
Background: There is no phantom for image quality test in magnetic resonance imaging combined with positron emission tomography systems (PET/MRI systems). In MRI, radioactive water phantom containing 2-deoxy-2-[F-18] fluoro-D-glucose (18F-FDG) cannot be used due to the dielectric effect. Even for phantoms filled with MR-available solutions, the source current of the RF coil is strongly disturbed as the diameter of the phantom increases. Stable MR images require proper phantom size and solution selection. Previous reports have not provided these details. Other than that, few existing phantoms evaluate negative signals such as N-13 ammonia (13N-NH3). We created a phantom for PET/MRI system for image quality test. Methods: The phantom for the PET/MRI system was assembled in two portions. One portion is a signal part containing 18F-FDG radioactive water. The other portion is filled with polyvinyl alcohol glue to construct MRI image to generate µ-map. The glue part is allowed to rewrite the table position overlaps with the first layer, and attenuation correction is performed. Signals are set as positive (4 times and twice higher than background radioactivity) and negative (no radioactivity) columns with different sizes (15 mm φ and 7 mm φ). The PET images with X-ray computed tomography-based attenuation correction (CT-AC) and MRI-AC were evaluated by %-contrasts, variation and uniformity. Results: The %-contrasts of the positive shallow signals with PET/magnetic resonance (MR) and PET/CT were 41.8% and 45.4%, respectively. And it of the positive deep signals with PET/MR and PET/CT were 40.7% and 44.9%. On the other hand, the %-contrasts of the negative shallow signals with PET/MR and PET/CT were 62.3% and 65.6%, respectively. And it of the negative deep signals with PET/MR and PET/CT were 60.7% and 63.7%. Moreover, the % Nj index of uniformity was 2.0% on PET/MRI images and 0.34% on PET/CT images. For negative signals that assume a decrease in myocardial blood flow, The image quality of MR-AC was almost the same as that of CT-AC. Consistency between the images after CT-AC and MR-AC correction were confirmed, and in particular, a stable MR-AC µ-map was obtained in the phantom study. Conclusion: The suggested prototype phantom for generating µ-map is reasonable and useful for evaluating PET/MRI image quality, based on the present standard.
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Affiliation(s)
- Yasuyuki Takahashi
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, Hirosaki, Japan
| | - Ayaka Nemoto
- Department of Advanced Clinical Research Center, Fukushima Medical University, Fukushima, Japan
| | - Shota Hosokawa
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, Hirosaki, Japan
| | - Hiroshi Ito
- Department of Advanced Clinical Research Center, Fukushima Medical University, Fukushima, Japan
- Department of Radiology, Fukushima Medical University, Fukushima, Japan
| | - Noboru Oriuchi
- Department of Advanced Clinical Research Center, Fukushima Medical University, Fukushima, Japan
- Department of Nuclear Medicine, Fukushima Medical University, Fukushima, Japan
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Artificial intelligence-based PET image acquisition and reconstruction. Clin Transl Imaging 2022. [DOI: 10.1007/s40336-022-00508-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Withofs N, Kumar R, Alavi A, Hustinx R. Facts and Fictions About [ 18F]FDG versus Other Tracers in Managing Patients with Brain Tumors: It Is Time to Rectify the Ongoing Misconceptions. PET Clin 2022; 17:327-342. [PMID: 35717096 DOI: 10.1016/j.cpet.2022.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
MRI is the first-choice imaging technique for brain tumors. Positron emission tomography can be combined together with multiparametric MRI to increase diagnostic confidence. Radiolabeled amino acids have gained wide clinical acceptance. The reported pooled specificity of [18F]FDG positron emission tomography is high and [18F]FDG might still be the first-choice positron emission tomography tracer in cases of World Health Organization grade 3 to 4 gliomas or [18F]FDG-avid tumors, avoiding the use of more expensive and less available radiolabeled amino acids. The present review discusses the additional value of positron emission tomography with a focus on [18F]FDG and radiolabeled amino acids.
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Affiliation(s)
- Nadia Withofs
- Division of Nuclear Medicine and Oncological Imaging, Department of Medical Physics, CHU of Liege, Quartier Hopital, Avenue de l'hopital, 1, Liege 1 4000, Belgium; GIGA-CRC in vivo imaging, University of Liege, GIGA CHU - B34 Quartier Hôpital Avenue de l'Hôpital,11, 4000 Liège, Belgium.
| | - Rakesh Kumar
- Diagnostic Nuclear Medicine Division, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Abass Alavi
- Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
| | - Roland Hustinx
- Division of Nuclear Medicine and Oncological Imaging, Department of Medical Physics, CHU of Liege, Quartier Hopital, Avenue de l'hopital, 1, Liege 1 4000, Belgium; GIGA-CRC in vivo imaging, University of Liege, GIGA CHU - B34 Quartier Hôpital Avenue de l'Hôpital,11, 4000 Liège, Belgium
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Abstract
Purpose To evaluate the clinical feasibility of high-resolution dedicated breast positron emission tomography (dbPET) with real low-dose 18F-2-fluorodeoxy-d-glucose (18F-FDG) by comparing images acquired with full-dose FDG. Materials and methods Nine women with no history of breast cancer and previously scanned by dbPET injected with a clinical 18F-FDG dose (3 MBq/kg) were enrolled. They were injected with 50% of the clinical 18F-FDG dose and scanned with dbPET for 10 min for each breast 60 and 90 min after injection. To investigate the effect of the scan start time and acquisition time on image quality, list-mode data were divided into 1, 3, 5, and 7 min (and 10 min with 50% FDG injected) from the start of acquisition and reconstructed. The reconstructed images were visually and quantitatively compared for contrast between mammary gland and fat (contrast) and for coefficient of variation (CV) in the mammary gland. Results In visual evaluation, the contrast between the mammary gland and fat acquired at a 50% dose for 7 min was comparable and even better in smoothness than that in the images acquired at a 100% dose. No visual difference between the images with a 50% dose was found with scan start times 60 and 90 min after injection. Quantitative evaluation showed a slightly lower contrast in the image at 60 min after 50% dosing, with no difference between acquisition times. There was no difference in CV between conditions; however, smoothness decreased with shorter acquisition time in all conditions. Conclusions The quality of dbPET images with a 50% FDG dose was high enough for clinical application. Although the optimal scan start time for improved lesion-to-background mammary gland contrast remained unknown in this study, it will be clarified in future studies of breast cancer patients.
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Image reconstruction using small-voxel size improves small lesion detection for positron emission tomography. Radiol Oncol 2022; 56:142-149. [PMID: 35417108 PMCID: PMC9122293 DOI: 10.2478/raon-2022-0015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 02/16/2022] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND PET/CT imaging is widely used in oncology and provides both metabolic and anatomic information. Because of the relatively poor spatial resolution of PET, the detection of small lesions is limited. The low spatial resolution introduces the partial-volume effect (PVE) which negatively affects images both qualitatively and quantitatively. The aim of the study was to investigate the effect of small-voxel (2 mm in-line pixel size) vs. standard-voxel (4 mm in-line pixel size) reconstruction on lesion detection and image quality in a range of activity ratios. MATERIALS AND METHODS The National Electrical Manufacturers Association (NEMA) body phantom and the Micro Hollow-Sphere phantom spheres were filled with a solution of [18F]fluorodeoxyglucose ([18F]FDG) in sphere-to-background ratios of 2:1, 3:1, 4:1 and 8:1. In all images reconstructed with 2 mm and 4 mm in-line pixel size the visual lesion delineation, contrast recovery coefficient (CRC) and contrast-to-noise ratio (CNR) were evaluated. RESULTS For smaller (≤ 13 mm) phantom spheres, significantly higher CRC and CNR using small-voxel reconstructions were found, also improving visual lesion delineation. CRC did not differ significantly for larger (≥ 17 mm) spheres using 2 mm and 4 mm in-line pixel size, but CNR was significantly lower; however, lower CNR did not affect visual lesion delineation. CONCLUSIONS Small-voxel reconstruction consistently improves precise small lesion delineation, lesion contrast and image quality.
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Alqahtani MM, Willowson KP, Constable C, Fulton R, Kench PL. Optimization of
99m
Tc whole‐body SPECT/CT image quality: A phantom study. J Appl Clin Med Phys 2022; 23:e13528. [PMID: 35049129 PMCID: PMC8992937 DOI: 10.1002/acm2.13528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 12/13/2021] [Accepted: 12/17/2021] [Indexed: 11/10/2022] Open
Affiliation(s)
- Mansour M. Alqahtani
- Faculty of Medicine and Health University of Sydney Sydney Australia
- Department of Radiological sciences College of Applied Medical Science Najran University Najran Saudi Arabia
| | - Kathy P. Willowson
- Department of Nuclear Medicine Royal North Shore Hospital Sydney Australia
- Institute of Medical Physics Faculty of Science The University of Sydney Sydney Australia
| | - Chris Constable
- Faculty of Medicine and Health University of Sydney Sydney Australia
- HERMES Medical Solutions, Strandbergsgatan 16 Stockholm Sweden
| | - Roger Fulton
- Faculty of Medicine and Health University of Sydney Sydney Australia
- Department of Medical Physics Westmead Hospital Sydney Australia
| | - Peter L. Kench
- Faculty of Medicine and Health University of Sydney Sydney Australia
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Ichikawa H. [[Nuclear Medicine] 4. Phantom Studies in Oncology]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2022; 78:637-645. [PMID: 35718453 DOI: 10.6009/jjrt.2022-2038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Affiliation(s)
- Hajime Ichikawa
- Department of Radiology, Toyohashi Municipal Hospital
- Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University
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Nadig V, Herrmann K, Mottaghy FM, Schulz V. Hybrid total-body pet scanners-current status and future perspectives. Eur J Nucl Med Mol Imaging 2022; 49:445-459. [PMID: 34647154 PMCID: PMC8803785 DOI: 10.1007/s00259-021-05536-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 08/20/2021] [Indexed: 12/18/2022]
Abstract
Purpose Since the 1990s, PET has been successfully combined with MR or CT systems. In the past years, especially PET systems have seen a trend towards an enlarged axial field of view (FOV), up to a factor of ten. Methods Conducting a thorough literature research, we summarize the status quo of contemporary total-body (TB) PET/CT scanners and give an outlook on possible future developments. Results Currently, three human TB PET/CT systems have been developed: The PennPET Explorer, the uExplorer, and the Biograph Vision Quadra realize aFOVs between 1 and 2 m and show a tremendous increase in system sensitivity related to their longer gantries. Conclusion The increased system sensitivity paves the way for short-term, low-dose, and dynamic TB imaging as well as new examination methods in almost all areas of imaging.
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Affiliation(s)
- Vanessa Nadig
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Ken Herrmann
- Department of Nuclear Medicine, University of Duisburg-Essen, Duisburg, Germany
- German Cancer Consortium (DKTK) - University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Felix M Mottaghy
- Department of Nuclear Medicine, University Hospital Aachen, RWTH Aachen University, Aachen, Germany
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.
- Physics Institute III B, RWTH Aachen University, Aachen, Germany.
- Fraunhofer Institute for Digital Medicine MEVIS, Aachen, Germany.
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Lu S, Zhang P, Li C, Sun J, Liu W, Zhang P. A NIM PET/CT phantom for evaluating the PET image quality of micro-lesions and the performance parameters of CT. BMC Med Imaging 2021; 21:165. [PMID: 34749660 PMCID: PMC8576981 DOI: 10.1186/s12880-021-00683-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 10/07/2021] [Indexed: 11/10/2022] Open
Abstract
Background The commonly used NEMA IEC Body phantom has a number of defects, hindering its application for detecting micro-lesions and measuring the performance parameters of computed tomography (CT). This study aimed to propose a PET/CT phantom designed by National Institute of Metrology (NIM), China, which is capable of simultaneously testing the performance of PET and CT systems, and to evaluate the quality of imaging. Methods The phantom developed in the present study, the NIM PET/CT phantom, is composed of a PET imaging module and a CT imaging module, and these modules are connected together through bolts, which can simultaneously measure the imaging performance of PET and CT systems. Hot spheres were filled with 4:1 sphere-to-background activity concentration using 18F-fluorodeoxyglucose (18F-FDG), and cold spheres were filled with non-radioactive water. We compared the results of imaging obtained from the NIM PET/CT phantom and the NEMA IEC Body phantom to assess their diagnostic efficacy. In order to evaluate the generalization ability of the NIM PET/CT phantom, three different PET/CT systems were used to scan on the same scanning protocol. To evaluate the effects of image reconstruction algorithms on image quality assessment, ordered subset expectation maximization (OSEM), OSEM-point-spread function (PSF), OSEM-TOF, and OSEM-PSF-TOF algorithms were employed. Results The imaging quality of the NIM PET/CT phantom and the NEMA IEC Body phantom was relatively consistent. The NIM PET/CT phantom could detect 7 mm spheres without influencing the imaging quality. It was found that PSF reconstruction exhibited to reduce the speed of convergence, the contrast and background variability of spheres (13–28 mm) were significantly improved after two iterations. In addition to improve the image contrast and background variability, TOF could markedly improve the overall image quality and instrument detection limit. TOF-PSF could noticeably reduce noise level, enhance imaging details, and improve quality of imaging. Conclusions The results showed that in comparison with the NEMA IEC Body phantom, the NIM PET/CT phantom outperformed in evaluating the PET image quality of micro-lesions and the performance parameters of CT.
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Affiliation(s)
- Shujie Lu
- Center for Medical Metrology, National Institute of Metrology, Beijing, China
| | - Peng Zhang
- Center for Medical Metrology, National Institute of Metrology, Beijing, China
| | - Chengwei Li
- Center for Medical Metrology, National Institute of Metrology, Beijing, China
| | - Jie Sun
- Center for Medical Metrology, National Institute of Metrology, Beijing, China
| | - Wenli Liu
- Center for Medical Metrology, National Institute of Metrology, Beijing, China
| | - Pu Zhang
- Center for Medical Metrology, National Institute of Metrology, Beijing, China.
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Manafi-Farid R, Ranjbar S, Jamshidi Araghi Z, Pilz J, Schweighofer-Zwink G, Pirich C, Beheshti M. Molecular Imaging in Primary Staging of Prostate Cancer Patients: Current Aspects and Future Trends. Cancers (Basel) 2021; 13:5360. [PMID: 34771523 PMCID: PMC8582501 DOI: 10.3390/cancers13215360] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/17/2021] [Accepted: 10/19/2021] [Indexed: 12/19/2022] Open
Abstract
Accurate primary staging is the cornerstone in all malignancies. Different morphological imaging modalities are employed in the evaluation of prostate cancer (PCa). Regardless of all developments in imaging, invasive histopathologic evaluation is still the standard method for the detection and staging of the primary PCa. Magnetic resonance imaging (MRI) and computed tomography (CT) play crucial roles; however, functional imaging provides additional valuable information, and it is gaining ever-growing acceptance in the management of PCa. Targeted imaging with different radiotracers has remarkably evolved in the past two decades. [111In]In-capromab pendetide scintigraphy was a new approach in the management of PCa. Afterwards, positron emission tomography (PET) tracers such as [11C/18F]choline and [11C]acetate were developed. Nevertheless, none found a role in the primary staging. By introduction of the highly sensitive small molecule prostate-specific membrane antigen (PSMA) PET/CT, as well as recent developments in MRI and hybrid PET/MRI systems, non-invasive staging of PCa is being contemplated. Several studies investigated the role of these sophisticated modalities in the primary staging of PCa, showing promising results. Here, we recapitulate the role of targeted functional imaging. We briefly mention the most popular radiotracers, their diagnostic accuracy in the primary staging of PCa, and impact on patient management.
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Affiliation(s)
- Reyhaneh Manafi-Farid
- Research Center for Nuclear Medicine, Tehran University of Medical Sciences, Tehran 1411713135, Iran;
| | - Shaghayegh Ranjbar
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Zahra Jamshidi Araghi
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Julia Pilz
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Gregor Schweighofer-Zwink
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Christian Pirich
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
| | - Mohsen Beheshti
- Department of Nuclear Medicine, Division of Molecular Imaging and Theranostics, University Hospital Salzburg, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; (S.R.); (Z.J.A.); (J.P.); (G.S.-Z.); (C.P.)
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Kersting D, Jentzen W, Fragoso Costa P, Sraieb M, Sandach P, Umutlu L, Conti M, Zarrad F, Rischpler C, Fendler WP, Herrmann K, Weber M. Silicon-photomultiplier-based PET/CT reduces the minimum detectable activity of iodine-124. Sci Rep 2021; 11:17477. [PMID: 34471170 PMCID: PMC8410931 DOI: 10.1038/s41598-021-95719-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/29/2021] [Indexed: 02/03/2023] Open
Abstract
The radioiodine isotope pair 124I/131I is used in a theranostic approach for patient-specific treatment of differentiated thyroid cancer. Lesion detectability is notably higher for 124I PET (positron emission tomography) than for 131I gamma camera imaging but can be limited for small and low uptake lesions. The recently introduced silicon-photomultiplier-based (SiPM-based) PET/CT (computed tomography) systems outperform previous-generation systems in detector sensitivity, coincidence time resolution, and spatial resolution. Hence, SiPM-based PET/CT shows an improved detectability, particularly for small lesions. In this study, we compare the size-dependant minimum detectable 124I activity (MDA) between the SiPM-based Biograph Vision and the previous-generation Biograph mCT PET/CT systems and we attempt to predict the response to 131I radioiodine therapy of lesions additionally identified on the SiPM-based system. A tumour phantom mimicking challenging conditions (derived from published patient data) was used; i.e., 6 small spheres (diameter of 3.7-9.7 mm), 9 low activity concentrations (0.25-25 kBq/mL), and a very low signal-to-background ratio (20:1). List-mode emission data (single-bed position) were divided into frames of 4, 8, 16, and 30 min. Images were reconstructed with ordinary Poisson ordered-subsets expectation maximization (OSEM), additional time-of-flight (OSEM-TOF) or TOF and point spread function modelling (OSEM-TOF+PSF). The signal-to-noise ratio and the MDA were determined. Absorbed dose estimations were performed to assess possible treatment response to high-activity 131I radioiodine therapy. The signal-to-noise ratio and the MDA were improved from the mCT to the Vision, from OSEM to OSEM-TOF and from OSEM-TOF to OSEM-TOF+PSF reconstructed images, and from shorter to longer emission times. The overall mean MDA ratio of the Vision to the mCT was 0.52 ± 0.18. The absorbed dose estimations indicate that lesions ≥ 6.5 mm with expected response to radioiodine therapy would be detectable on both systems at 4-min emission time. Additional smaller lesions of therapeutic relevance could be detected when using a SiPM-based PET system at clinically reasonable emission times. This study demonstrates that additional lesions with predicted response to 131I radioiodine therapy can be detected. Further clinical evaluation is warranted to evaluate if negative 124I PET scans on a SiPM-based system can be sufficient to preclude patients from blind radioiodine therapy.
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Affiliation(s)
- David Kersting
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany.
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany.
| | - Walter Jentzen
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
| | - Pedro Fragoso Costa
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
| | - Miriam Sraieb
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
| | - Patrick Sandach
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
| | - Lale Umutlu
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
| | | | - Fadi Zarrad
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
| | - Christoph Rischpler
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
| | - Wolfgang Peter Fendler
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
| | - Ken Herrmann
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
| | - Manuel Weber
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany
- German Cancer Consortium (DKTK, Partner Site Essen), Essen, Germany
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Krokos G, Pike LC, Cook GJR, Marsden PK. Standardisation of conventional and advanced iterative reconstruction methods for Gallium-68 multi-centre PET-CT trials. EJNMMI Phys 2021; 8:52. [PMID: 34273020 PMCID: PMC8286213 DOI: 10.1186/s40658-021-00400-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 07/05/2021] [Indexed: 11/16/2022] Open
Abstract
PURPOSE To assess the applicability of the Fluorine-18 performance specifications defined by EANM Research Ltd (EARL), in Gallium-68 multi-centre PET-CT trials using conventional (ordered subset expectation maximisation, OSEM) and advanced iterative reconstructions which include the systems' point spread function (PSF) and a Bayesian penalised likelihood algorithm (BPL) commercially known as Q.CLEAR. The possibility of standardising the two advanced reconstruction methods was examined. METHODS The NEMA image quality phantom was filled with Gallium-68 and scanned on a GE PET-CT system. PSF and BPL with varying post-reconstruction Gaussian filter width (2-6.4 mm) and penalisation factor (200-1200), respectively, were applied. The average peak-to-valley ratio from six profiles across each sphere was estimated to inspect any edge artefacts. Image noise was assessed using background variability and image roughness. Six GE and Siemens PET-CT scanners provided Gallium-68 images of the NEMA phantom using both conventional and advanced reconstructions from which the maximum, mean and peak recoveries were drawn. Fourteen patients underwent 68Ga-PSMA PET-CT imaging. BPL (200-1200) reconstructions of the data were compared against PSF smoothed with a 6.4-mm Gaussian filter. RESULTS A Gaussian filter width of approximately 6 mm for PSF and a penalisation factor of 800 for BPL were needed to suppress the edge artefacts. In addition, those reconstructions provided the closest agreement between the two advanced iterative reconstructions and low noise levels with the background variability and the image roughness being lower than 7.5% and 11.5%, respectively. The recoveries for all methods generally performed at the lower limits of the EARL specifications, especially for the 13- and 10-mm spheres for which up to 27% (conventional) and 41% (advanced reconstructions) lower limits are suggested. The lesion standardised uptake values from the clinical data were significantly different between BPL and PSF smoothed with a Gaussian filter of 6.4 mm wide for all penalisation factors except for 800 and 1000. CONCLUSION It is possible to standardise the advanced reconstruction methods with the reconstruction parameters being also sufficient for minimising the edge artefacts and noise in the images. For both conventional and advanced reconstructions, Gallium-68 specific recovery coefficient limits were required, especially for the smallest phantom spheres.
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Affiliation(s)
- Georgios Krokos
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
| | - Lucy C Pike
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | - Gary J R Cook
- Department of Cancer Imaging, School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | - Paul K Marsden
- Department of Biomedical Engineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
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Automatic quantification package (Hone Graph) for phantom-based image quality assessment in bone SPECT: computerized automatic classification of detectability. Ann Nucl Med 2021; 35:937-946. [PMID: 34028702 DOI: 10.1007/s12149-021-01631-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 05/12/2021] [Indexed: 01/12/2023]
Abstract
OBJECTIVE We previously developed a custom-design thoracic bone scintigraphy-specific phantom ("SIM2 bone phantom") to assess image quality in bone single-photon emission computed tomography (SPECT). We aimed to develop an automatic assessment system for imaging technology in bone SPECT and demonstrate the validity of this system. METHODS Four spherical lesions of 13-, 17-, 22-, and 28-mm diameters in the vertebrae of SIM2 bone phantom simulating the thorax were filled with radioactivity (target-to-background ratio: 4). Dynamic SPECT acquisitions were performed for 15 min; reconstructions were performed using ordered subset expectation maximization at 3-15-min timepoints. Consequently, 216 lesions (54 SPECT images) were obtained: 120 and 96 lesions were used for software development and validation, respectively. The developed software used statistical parametric mapping to rigidly register and automatically calculate quantitative indexes (contrast-to-noise ratio, % coefficient of variance, % detectability equivalence volume, recovery coefficient, target-to-normal bone ratio, and full width at half maximum). A detectability score (DS) was used to define the four observation types (4, excellent; 3, adequate; 2, average; 1, poor) to score hot spherical lesions. The gold standard for DSs was independently classified by three experienced board-certified nuclear medicine technologists using the four observation types; thereafter, a consensus regarding the gold standard for DSs was reached. Using 120 lesions for development, decision tree analysis was performed to determine DS based on the quantitative indexes. We verified the validation of the quantitative indexes and their threshold values for automatic classification using 96 lesions for validation. RESULTS The trends in the automatically calculated quantitative indices were consistent. Decision tree analysis produced four terminal groups; two quantitative indexes (% detectability equivalence volume and contrast-to-noise ratio) were used to classify DS. The automatically classified DSs exhibited an almost perfect agreement with the gold standard. The percentage agreement and kappa coefficient were 91.7% and 0.93, respectively, in 96 lesions for validation. CONCLUSIONS The developed software automatically classified the detectability of hot lesions in the SIM2 bone phantom using the automatically calculated quantitative indexes, suggesting that this software could provide a means to automatically perform detectability analysis after data input that is excellent in reproducibility and accuracy.
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Satoh Y, Imai M, Hirata K, Asakawa Y, Ikegawa C, Onishi H. Optimal relaxation parameters of dynamic row-action maximum likelihood algorithm and post-smoothing filter for image reconstruction of dedicated breast PET. Ann Nucl Med 2021; 35:608-616. [PMID: 33772738 DOI: 10.1007/s12149-021-01604-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/07/2021] [Indexed: 11/26/2022]
Abstract
OBJECTIVE This study aimed to determine the optimal β value of the relaxation control parameter and the post-smoothing filter in the list-mode dynamic row-action maximum likelihood algorithm (LM-DRAMA) to detect early stage breast cancer with high-resolution dedicated breast positron emission tomography (dbPET) in phantom and clinical studies. METHODS A breast phantom containing four spheres (5, 7.5, 10, and 16 mm in diameter) was filled with 18F-fluorodeoxyglucose solution (sphere-to-background ratio, 8:1) and scanned on a dbPET scanner. The images were reconstructed using LM-DRAMA with different β values (5, 20, or 100) and Gaussian post-filters (0, 0.78, 1.17, 1.56, 1.95, or 2.34 mm). Other conditions were according to those routinely used (1 iteration and 128 subsets including attenuation and scatter correction). Image quality was evaluated visually and by computing the coefficient of variation of the background (CVBG), detectability index (DI), and contrast recovery coefficient. Parameters optimized in these phantom studies were applied to 25 clinical data sets. Variabilities for different reconstruction methods in visual scores, the maximum standardized uptake value of breast cancer, and the tumor-to-background uptake ratio were estimated. RESULTS The reconstruction images of the phantom with higher β values and smaller post-filters yielded higher visual scores for detectability and DI and lower smoothness and CVBG scores. Based on the phantom study, the β values and post-filter were optimized for clinical dbPET images except for β5 and 2.34 mm post-filter. Applying the other reconstructions to clinical studies showed that β100 provided higher quantitative parameter values. The detectability of lesions was similar for β100 and β20 and decreased with larger post-filters. The lesion detection rate was similar for β100 and β20 and decreased with larger post-filter. CONCLUSION The relaxation coefficient factor β20 and a 0.78- or 1.17-mm post-filter were optimal for dbPET image reconstruction with balanced spatial resolution and noise. However, they should be selected according to the impact on the dbPET image and the purpose of the examination.
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Affiliation(s)
- Yoko Satoh
- Yamanashi PET Imaging Clinic, Shimokato, Chuo City, Yamanashi, 3046-2, Japan.
- Department of Radiology, University of Yamanashi, Chuo City, Yamanashi, Japan.
| | - Masamichi Imai
- Yamanashi PET Imaging Clinic, Shimokato, Chuo City, Yamanashi, 3046-2, Japan
| | - Kenji Hirata
- Department of Diagnostic Imaging, Hokkaido University School of Medicine, Sapporo, Hokkaido, Japan
| | - Yuzo Asakawa
- Yamanashi PET Imaging Clinic, Shimokato, Chuo City, Yamanashi, 3046-2, Japan
| | - Chihiro Ikegawa
- Yamanashi PET Imaging Clinic, Shimokato, Chuo City, Yamanashi, 3046-2, Japan
| | - Hiroshi Onishi
- Department of Radiology, University of Yamanashi, Chuo City, Yamanashi, Japan
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Mannheim JG, Cheng JCK, Vafai N, Shahinfard E, English C, McKenzie J, Zhang J, Barlow L, Sossi V. Cross-validation study between the HRRT and the PET component of the SIGNA PET/MRI system with focus on neuroimaging. EJNMMI Phys 2021; 8:20. [PMID: 33635449 PMCID: PMC7910400 DOI: 10.1186/s40658-020-00349-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 12/16/2020] [Indexed: 01/20/2023] Open
Abstract
Background The Siemens high-resolution research tomograph (HRRT - a dedicated brain PET scanner) is to this day one of the highest resolution PET scanners; thus, it can serve as useful benchmark when evaluating performance of newer scanners. Here, we report results from a cross-validation study between the HRRT and the whole-body GE SIGNA PET/MR focusing on brain imaging. Phantom data were acquired to determine recovery coefficients (RCs), % background variability (%BG), and image voxel noise (%). Cross-validation studies were performed with six healthy volunteers using [11C]DTBZ, [11C]raclopride, and [18F]FDG. Line profiles, regional time-activity curves, regional non-displaceable binding potentials (BPND) for [11C]DTBZ and [11C]raclopride scans, and radioactivity ratios for [18F]FDG scans were calculated and compared between the HRRT and the SIGNA PET/MR. Results Phantom data showed that the PET/MR images reconstructed with an ordered subset expectation maximization (OSEM) algorithm with time-of-flight (TOF) and TOF + point spread function (PSF) + filter revealed similar RCs for the hot spheres compared to those obtained on the HRRT reconstructed with an ordinary Poisson-OSEM algorithm with PSF and PSF + filter. The PET/MR TOF + PSF reconstruction revealed the highest RCs for all hot spheres. Image voxel noise of the PET/MR system was significantly lower. Line profiles revealed excellent spatial agreement between the two systems. BPND values revealed variability of less than 10% for the [11C]DTBZ scans and 19% for [11C]raclopride (based on one subject only). Mean [18F]FDG ratios to pons showed less than 12% differences. Conclusions These results demonstrated comparable performances of the two systems in terms of RCs with lower voxel-level noise (%) present in the PET/MR system. Comparison of in vivo human data confirmed the comparability of the two systems. The whole-body GE SIGNA PET/MR system is well suited for high-resolution brain imaging as no significant performance degradation was found compared to that of the reference standard HRRT.
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Affiliation(s)
- Julia G Mannheim
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada. .,Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard-Karls University Tuebingen, Tuebingen, Germany. .,Cluster of Excellence iFIT (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", University of Tuebingen, Tuebingen, Germany.
| | - Ju-Chieh Kevin Cheng
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.,Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nasim Vafai
- Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Elham Shahinfard
- Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Carolyn English
- Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jessamyn McKenzie
- Djavad Mowafaghian Centre for Brain Health, Pacific Parkinson's Research Centre, University of British Columbia & Vancouver Coastal Health, Vancouver, British Columbia, Canada
| | - Jing Zhang
- Global MR Applications & Workflow, GE Healthcare Canada, Vancouver, British Columbia, Canada
| | - Laura Barlow
- UBC MRI Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Vesna Sossi
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
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Wyatt JJ, Howell E, Lohezic M, McCallum HM, Maxwell RJ. Evaluating the image quality of combined positron emission tomography-magnetic resonance images acquired in the pelvic radiotherapy position. Phys Med Biol 2021; 66:035018. [PMID: 33242847 DOI: 10.1088/1361-6560/abce1c] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Positron emission tomography-magnetic resonance (PET-MR) scanners could improve radiotherapy planning through combining PET and MR functional imaging. This depends on acquiring high quality and quantitatively accurate images in the radiotherapy position. This study evaluated PET-MR image quality using a flat couch and coil bridge for pelvic radiotherapy. MR and PET image quality phantoms were imaged in three setups: phantom on the PET-MR couch with anterior coil on top (diagnostic), phantom on a flat couch with coil on top (couch), and phantom on the flat couch with coil on a coil bridge (radiotherapy). PET images were also acquired in each setup without the anterior coil. PET attenuation correction of the flat couch and coil bridge were generated using kilovoltage computed tomography (CT) images and of the anterior coil using megavoltage CT images. MR image quality was substantially affected, with MR signal to noise ratio (SNR) relative to the diagnostic setup of 89% ± 2% (mean ± standard error of the mean, couch) and 54% ± 1% (radiotherapy), likely due to the increased distance between the patient and receive coils. The reduction impacted the low-contrast detectability score: 23 ± 1 (diagnostic), 19.7 ± 0.3 (couch) and 15 ± 1 (radiotherapy). All other MR metrics agreed within one standard error. PET quantitative accuracy was also affected, with measured activity with anterior coil being different to diagnostic without anterior coil by -16.7% ± 0.2% (couch) and -17.7 ± 0.1% (radiotherapy), without attenuation correction modification. Including the couch and coil bridge attenuation correction reduced this difference to -7.5% ± 0.1%, and including the anterior coil reduced this to -2.7% ± 0.1%. This was better than the diagnostic setup with anterior coil (difference -8.3% ± 0.2%). This translated into greater PET SNR performance for the fully corrected radiotherapy setup compared to diagnostic with coil. However contrast recovery was unchanged by the modified attenuation correction, with the diagnostic setup remaining ∼2% better. Quantitative PET in the radiotherapy setup is possible if appropriate attenuation correction is used. Pelvic radiotherapy PET-MR imaging protocols will need to consider the impact on PET-MR image quality.
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Affiliation(s)
- Jonathan J Wyatt
- Centre for In Vivo Imaging, Newcastle University, United Kingdom. Centre for Cancer, Newcastle University, United Kingdom. Northern Centre for Cancer Care, Newcastle upon Tyne Hospitals, United Kingdom
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Satoh Y, Motosugi U, Imai M, Omiya Y, Onishi H. Evaluation of image quality at the detector's edge of dedicated breast positron emission tomography. EJNMMI Phys 2021; 8:5. [PMID: 33462645 PMCID: PMC7813900 DOI: 10.1186/s40658-020-00351-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 12/22/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Using phantoms and clinical studies in prone hanging breast imaging, we assessed the image quality of a commercially available dedicated breast PET (dbPET) at the detector's edge, where mammary glands near the chest wall are located. These are compared to supine PET/CT breast images of the same clinical subjects. METHODS A breast phantom with four spheres (16-, 10-, 7.5-, and 5-mm diameter) was filled with 18F-fluorodeoxyglucose solution (sphere-to-background activity concentration ratio, 8:1). The spheres occupied five different positions from the top edge to the centre of the detector and were scanned for 5 min in each position. Reconstructed images were visually evaluated, and the contrast-to-noise ratio (CNR), contrast recovery coefficient (CRC) for all spheres, and coefficient of variation of the background (CVB) were calculated. Subsequently, clinical images obtained with standard supine PET/CT and prone dbPET were retrospectively analysed. Tumour-to-background ratios (TBRs) between breast cancer near the chest wall (close to the detector's edge; peripheral group) and at other locations (non-peripheral group) were compared. The TBR of each lesion was compared between dbPET and PET/CT. RESULTS Closer to the detector's edge, the CNR and CRC of all spheres decreased while the CVB increased in the phantom study. The disadvantages of this placement were visually confirmed. Regarding clinical images, TBR of dbPET was significantly higher than that of PET/CT in both the peripheral (12.38 ± 6.41 vs 6.73 ± 3.5, p = 0.0006) and non-peripheral (12.44 ± 5.94 vs 7.71 ± 7.1, p = 0.0183) groups. There was no significant difference in TBR of dbPET between the peripheral and non-peripheral groups. CONCLUSION The phantom study revealed poorer image quality at < 2-cm distance from the detector's edge than at other more central parts. In clinical studies, however, the visibility of breast lesions with dbPET was the same regardless of the lesion position, and it was higher than that in PET/CT. dbPET has a great potential for detecting breast lesions near the chest wall if they are at least 2 cm from the edge of the FOV, even in young women with small breasts.
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Affiliation(s)
- Yoko Satoh
- Yamanashi PET Imaging Clinic, Shimokato 3046-2, Chuo City, Yamanashi Prefecture, 409-3821, Japan. .,Department of Radiology, University of Yamanashi, Chuo City, Yamanashi Prefecture, Japan.
| | - Utaroh Motosugi
- Department of Radiology, Kofu-kyoritsu Hospital, Kofu City, Yamanashi Prefecture, Japan
| | - Masamichi Imai
- Yamanashi PET Imaging Clinic, Shimokato 3046-2, Chuo City, Yamanashi Prefecture, 409-3821, Japan
| | - Yoshie Omiya
- Department of Radiology, University of Yamanashi, Chuo City, Yamanashi Prefecture, Japan
| | - Hiroshi Onishi
- Department of Radiology, University of Yamanashi, Chuo City, Yamanashi Prefecture, Japan
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Sudarshan VP, Egan GF, Chen Z, Awate SP. Joint PET-MRI image reconstruction using a patch-based joint-dictionary prior. Med Image Anal 2020; 62:101669. [DOI: 10.1016/j.media.2020.101669] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 02/20/2020] [Accepted: 02/21/2020] [Indexed: 12/18/2022]
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García-Pérez P, España S. Simultaneous emission and attenuation reconstruction in time-of-flight PET using a reference object. EJNMMI Phys 2020; 7:3. [PMID: 31932984 PMCID: PMC6957598 DOI: 10.1186/s40658-020-0272-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 01/07/2020] [Indexed: 12/20/2022] Open
Abstract
Background Simultaneous reconstruction of emission and attenuation images in time-of-flight (TOF) positron emission tomography (PET) does not provide a unique solution. In this study, we propose to solve this limitation by including additional information given by a reference object with known attenuation placed outside the patient. Different configurations of the reference object were studied including geometry, material composition, and activity, and an optimal configuration was defined. In addition, this configuration was tested for different timing resolutions and noise levels. Results The proposed strategy was tested in 2D simulations obtained by forward projection of available PET/CT data and noise was included using Monte Carlo techniques. Obtained results suggest that the optimal configuration corresponds to a water cylinder inserted in the patient table and filled with activity. In that case, mean differences between reconstructed and true images were below 10%. However, better results can be obtained by increasing the activity of the reference object. Conclusion This study shows promising results that might allow to obtain an accurate attenuation map from pure TOF-PET data without prior knowledge obtained from CT, MRI, or transmission scans.
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Affiliation(s)
- Pablo García-Pérez
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, IdISSC, Ciudad Universitaria, 28040, Madrid, Spain
| | - Samuel España
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, IdISSC, Ciudad Universitaria, 28040, Madrid, Spain. .,Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain.
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