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Ebrahimi S, Lundström E, Batasin SJ, Hedlund E, Stålberg K, Ehman EC, Sheth VR, Iranpour N, Loubrie S, Schlein A, Rakow-Penner R. Application of PET/MRI in Gynecologic Malignancies. Cancers (Basel) 2024; 16:1478. [PMID: 38672560 PMCID: PMC11048306 DOI: 10.3390/cancers16081478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 03/23/2024] [Accepted: 03/27/2024] [Indexed: 04/28/2024] Open
Abstract
The diagnosis, treatment, and management of gynecologic malignancies benefit from both positron emission tomography/computed tomography (PET/CT) and MRI. PET/CT provides important information on the local extent of disease as well as diffuse metastatic involvement. MRI offers soft tissue delineation and loco-regional disease involvement. The combination of these two technologies is key in diagnosis, treatment planning, and evaluating treatment response in gynecological malignancies. This review aims to assess the performance of PET/MRI in gynecologic cancer patients and outlines the technical challenges and clinical advantages of PET/MR systems when specifically applied to gynecologic malignancies.
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Affiliation(s)
- Sheida Ebrahimi
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA
| | - Elin Lundström
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA
- Department of Surgical Sciences, Radiology, Uppsala University, 751 85 Uppsala, Sweden
- Center for Medical Imaging, Uppsala University Hospital, 751 85 Uppsala, Sweden
| | - Summer J. Batasin
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA
| | - Elisabeth Hedlund
- Department of Surgical Sciences, Radiology, Uppsala University, 751 85 Uppsala, Sweden
| | - Karin Stålberg
- Department of Women’s and Children’s Health, Uppsala University, 751 85 Uppsala, Sweden
| | - Eric C. Ehman
- Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA
| | - Vipul R. Sheth
- Department of Radiology, Stanford University, Palo Alto, CA 94305, USA; (V.R.S.)
| | - Negaur Iranpour
- Department of Radiology, Stanford University, Palo Alto, CA 94305, USA; (V.R.S.)
| | - Stephane Loubrie
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA
| | - Alexandra Schlein
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA
| | - Rebecca Rakow-Penner
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA
- Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA
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2
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Yan Q, Yan X, Yang X, Li S, Song J. The use of PET/MRI in radiotherapy. Insights Imaging 2024; 15:63. [PMID: 38411742 PMCID: PMC10899128 DOI: 10.1186/s13244-024-01627-6] [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: 09/19/2023] [Accepted: 01/21/2024] [Indexed: 02/28/2024] Open
Abstract
Positron emission tomography/magnetic resonance imaging (PET/MRI) is a hybrid imaging technique that quantitatively combines the metabolic and functional data from positron emission tomography (PET) with anatomical and physiological information from MRI. As PET/MRI technology has advanced, its applications in cancer care have expanded. Recent studies have demonstrated that PET/MRI provides unique advantages in the field of radiotherapy and has become invaluable in guiding precision radiotherapy techniques. This review discusses the rationale and clinical evidence supporting the use of PET/MRI for radiation positioning, target delineation, efficacy evaluation, and patient surveillance.Critical relevance statement This article critically assesses the transformative role of PET/MRI in advancing precision radiotherapy, providing essential insights into improved radiation positioning, target delineation, efficacy evaluation, and patient surveillance in clinical radiology practice.Key points• The emergence of PET/MRI will be a key bridge for precise radiotherapy.• PET/MRI has unique advantages in the whole process of radiotherapy.• New tracers and nanoparticle probes will broaden the use of PET/MRI in radiation.• PET/MRI will be utilized more frequently for radiotherapy.
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Affiliation(s)
- Qi Yan
- Cancer Center, Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences Tongji Shanxi Hospital, Taiyuan, China
| | - Xia Yan
- Cancer Center, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Third Hospital of Shanxi Medical University, Taiyuan, China
- Shanxi Provincial Key Laboratory for Translational Nuclear Medicine and Precision Protection, Taiyuan, China
| | - Xin Yang
- Cancer Center, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, Third Hospital of Shanxi Medical University, Taiyuan, China
| | - Sijin Li
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, Shanxi Medical University, Taiyuan, China.
| | - Jianbo Song
- Cancer Center, Third Hospital of Shanxi Medical University, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences Tongji Shanxi Hospital, Taiyuan, China.
- Shanxi Provincial Key Laboratory for Translational Nuclear Medicine and Precision Protection, Taiyuan, China.
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Krokos G, MacKewn J, Dunn J, Marsden P. A review of PET attenuation correction methods for PET-MR. EJNMMI Phys 2023; 10:52. [PMID: 37695384 PMCID: PMC10495310 DOI: 10.1186/s40658-023-00569-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 08/07/2023] [Indexed: 09/12/2023] Open
Abstract
Despite being thirteen years since the installation of the first PET-MR system, the scanners constitute a very small proportion of the total hybrid PET systems installed. This is in stark contrast to the rapid expansion of the PET-CT scanner, which quickly established its importance in patient diagnosis within a similar timeframe. One of the main hurdles is the development of an accurate, reproducible and easy-to-use method for attenuation correction. Quantitative discrepancies in PET images between the manufacturer-provided MR methods and the more established CT- or transmission-based attenuation correction methods have led the scientific community in a continuous effort to develop a robust and accurate alternative. These can be divided into four broad categories: (i) MR-based, (ii) emission-based, (iii) atlas-based and the (iv) machine learning-based attenuation correction, which is rapidly gaining momentum. The first is based on segmenting the MR images in various tissues and allocating a predefined attenuation coefficient for each tissue. Emission-based attenuation correction methods aim in utilising the PET emission data by simultaneously reconstructing the radioactivity distribution and the attenuation image. Atlas-based attenuation correction methods aim to predict a CT or transmission image given an MR image of a new patient, by using databases containing CT or transmission images from the general population. Finally, in machine learning methods, a model that could predict the required image given the acquired MR or non-attenuation-corrected PET image is developed by exploiting the underlying features of the images. Deep learning methods are the dominant approach in this category. Compared to the more traditional machine learning, which uses structured data for building a model, deep learning makes direct use of the acquired images to identify underlying features. This up-to-date review goes through the literature of attenuation correction approaches in PET-MR after categorising them. The various approaches in each category are described and discussed. After exploring each category separately, a general overview is given of the current status and potential future approaches along with a comparison of the four outlined categories.
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Affiliation(s)
- Georgios Krokos
- School of Biomedical Engineering and Imaging Sciences, The PET Centre at St Thomas' Hospital London, King's College London, 1st Floor Lambeth Wing, Westminster Bridge Road, London, SE1 7EH, UK.
| | - Jane MacKewn
- School of Biomedical Engineering and Imaging Sciences, The PET Centre at St Thomas' Hospital London, King's College London, 1st Floor Lambeth Wing, Westminster Bridge Road, London, SE1 7EH, UK
| | - Joel Dunn
- School of Biomedical Engineering and Imaging Sciences, The PET Centre at St Thomas' Hospital London, King's College London, 1st Floor Lambeth Wing, Westminster Bridge Road, London, SE1 7EH, UK
| | - Paul Marsden
- School of Biomedical Engineering and Imaging Sciences, The PET Centre at St Thomas' Hospital London, King's College London, 1st Floor Lambeth Wing, Westminster Bridge Road, London, SE1 7EH, UK
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4
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Lindemann ME, Gratz M, Blumhagen JO, Jakoby B, Quick HH. MR-based truncation correction using an advanced HUGE method to improve attenuation correction in PET/MR imaging of obese patients. Med Phys 2022; 49:865-877. [PMID: 35014697 DOI: 10.1002/mp.15446] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 12/08/2021] [Accepted: 12/18/2021] [Indexed: 10/19/2022] Open
Abstract
PURPOSE Truncation artifacts in the periphery of the magnetic resonance (MR) field-of-view (FOV) and thus, in the MR-based attenuation correction (AC) map, may hamper accurate positron emission tomography (PET) quantification in whole-body PET/MR, which is especially problematic in patients with obesity with overall large body dimensions. Therefore, an advanced truncation correction (TC) method to extend the conventional MR FOV is needed. METHODS The extent of MR-based AC-map truncations in obese patients was determined in a data set including n = 10 patients that underwent whole-body PET/MR exams. Patient inclusion criteria were defined as BMI > 30 kg/m2 and body weight > 100 kg. Truncations in PET/MR patients with obesity were quantified comparing the MR-based AC-map volume to segmented non-AC PET data, serving as the reference body volume without truncations to demonstrate the need of improved TC. The new method implemented in this study, termed "advanced HUGE", was modified and extended from the original HUGE method by Blumhagen et al. in order to provide improved TC across the entire axial MR FOV and to unlock new clinical applications of PET/MR. Advanced HUGE was then systematically tested in PET/MR NEMA phantom measurements. Relative differences between computed tomography (CT) AC PET data of the phantom setup (reference) and MR-based Dixon AC, respectively Dixon + advanced HUGE AC, were calculated. The applicability of the method for advanced TC was then demonstrated in first MR-based measurements in healthy volunteers. RESULTS It was found that the MR-based AC maps of obese patients often reveal truncations in anterior-posterior direction. Especially the abdominal region could benefit from improved TC, where maximal relative differences in the AC-map volume up to -17 % were calculated. Applying advanced HUGE to improve the MR-based AC in PET/MR, PET quantification errors in the large-volume phantom setup could be considerably reduced from average -18.6 % (Dixon AC) to 4.6 % compared to the CT AC reference. Volunteer measurements demonstrate that formerly missing AC-map volume in the Dixon-VIBE AC-map could be added due to advanced HUGE in anterior-posterior direction and thus, potentially improves AC in PET/MR. CONCLUSIONS The advanced HUGE method for truncation correction considerably reduces truncations in anterior-posterior direction demonstrated in phantom measurements and healthy volunteers and thus, further improves MR-based AC in PET/MR imaging. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Maike E Lindemann
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Marcel Gratz
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, Germany.,Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
| | | | | | - Harald H Quick
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, Germany.,Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
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5
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Abstract
A decade of PET/MRI clinical imaging has passed and many of the pitfalls are similar to those on earlier studies. However, techniques to overcome them have emerged and continue to develop. Although clinically significant lung nodules are demonstrable, smaller nodules may be detected using ultrashort/zero echo-time (TE) lung MRI. Fast reconstruction ultrashort TE sequences have also been used to achieve high-resolution lung MRI even with free-breathing. The introduction and improvement of time-of-flight scanners and increasing the axial length of the PET detector arrays have more than doubled the sensitivity of the PET part of the system. MRI for attenuation correction has provided many potential pitfalls, including misclassification of tissue classes based on MRI information for attenuation correction. Although the use of short echo times have helped to address these pitfalls, one of the most exciting developments has been the use of deep learning algorithms and computational neural networks to rapidly provide soft tissue, fat, bone and air information for the attenuation correction as a supplement to the attenuation correction information from fat-water imaging. Challenges with motion correction, particularly respiratory and cardiac remain but are being addressed with respiratory monitors and using PET data. In order to address truncation artefacts, the system manufacturers have developed methods to extend the MR field-of-view for the purpose of the attenuation and scatter corrections. General pitfalls like stitching of body sections for individual studies, optimum delivery of images for viewing and reporting, and resource implications for the sheer volume of data generated remain Methods to overcome these pitfalls serve as a strong foundation for the future of PET/MRI. Advances in the underlying technology with significant evolution in hard-ware and software and the exiting developments in use of deep learning algorithms and computational neural networks will drive the next decade of PET/MRI imaging.
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Affiliation(s)
- Asim Afaq
- University of Iowa Carver College of Medicine, Iowa City; Institute of Nuclear Medicine, UCL/ UCLH London, UK
| | | | | | - Simon Wan
- Institute of Nuclear Medicine, UCL/ UCLH London, UK
| | - Thomas A Hope
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA
| | - Patrick Veit Haibach
- Toronto Joint Dept. Medical Imaging, University Health Network, Sinai Health System, Women's College University of Toronto, Canada
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6
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Abstract
Attenuation correction has been one of the main methodological challenges in the integrated positron emission tomography and magnetic resonance imaging (PET/MRI) field. As standard transmission or computed tomography approaches are not available in integrated PET/MRI scanners, MR-based attenuation correction approaches had to be developed. Aspects that have to be considered for implementing accurate methods include the need to account for attenuation in bone tissue, normal and pathological lung and the MR hardware present in the PET field-of-view, to reduce the impact of subject motion, to minimize truncation and susceptibility artifacts, and to address issues related to the data acquisition and processing both on the PET and MRI sides. The standard MR-based attenuation correction techniques implemented by the PET/MRI equipment manufacturers and their impact on clinical and research PET data interpretation and quantification are first discussed. Next, the more advanced methods, including the latest generation deep learning-based approaches that have been proposed for further minimizing the attenuation correction related bias are described. Finally, a future perspective focused on the needed developments in the field is given.
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Affiliation(s)
- Ciprian Catana
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States of America
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7
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Arabi H, Zaidi H. Truncation compensation and metallic dental implant artefact reduction in PET/MRI attenuation correction using deep learning-based object completion. ACTA ACUST UNITED AC 2020; 65:195002. [DOI: 10.1088/1361-6560/abb02c] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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8
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Aizaz M, Moonen RPM, van der Pol JAJ, Prieto C, Botnar RM, Kooi ME. PET/MRI of atherosclerosis. Cardiovasc Diagn Ther 2020; 10:1120-1139. [PMID: 32968664 DOI: 10.21037/cdt.2020.02.09] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myocardial infarction and stroke are the most prevalent global causes of death. Each year 15 million people worldwide die due to myocardial infarction or stroke. Rupture of a vulnerable atherosclerotic plaque is the main underlying cause of stroke and myocardial infarction. Key features of a vulnerable plaque are inflammation, a large lipid-rich necrotic core (LRNC) with a thin or ruptured overlying fibrous cap, and intraplaque hemorrhage (IPH). Noninvasive imaging of these features could have a role in risk stratification of myocardial infarction and stroke and can potentially be utilized for treatment guidance and monitoring. The recent development of hybrid PET/MRI combining the superior soft tissue contrast of MRI with the opportunity to visualize specific plaque features using various radioactive tracers, paves the way for comprehensive plaque imaging. In this review, the use of hybrid PET/MRI for atherosclerotic plaque imaging in carotid and coronary arteries is discussed. The pros and cons of different hybrid PET/MRI systems are reviewed. The challenges in the development of PET/MRI and potential solutions are described. An overview of PET and MRI acquisition techniques for imaging of atherosclerosis including motion correction is provided, followed by a summary of vessel wall imaging PET/MRI studies in patients with carotid and coronary artery disease. Finally, the future of imaging of atherosclerosis with PET/MRI is discussed.
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Affiliation(s)
- Mueez Aizaz
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.,CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Rik P M Moonen
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.,CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Jochem A J van der Pol
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Claudia Prieto
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.,Escuela de Ingenieria, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - René M Botnar
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.,Escuela de Ingenieria, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - M Eline Kooi
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.,CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
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9
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Grafe H, Lindemann ME, Ruhlmann V, Oehmigen M, Hirmas N, Umutlu L, Herrmann K, Quick HH. Evaluation of improved attenuation correction in whole-body PET/MR on patients with bone metastasis using various radiotracers. Eur J Nucl Med Mol Imaging 2020; 47:2269-2279. [PMID: 32125487 PMCID: PMC7396397 DOI: 10.1007/s00259-020-04738-6] [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: 10/07/2019] [Accepted: 02/20/2020] [Indexed: 01/18/2023]
Abstract
Purpose This study evaluates the quantitative effect of improved MR-based attenuation correction (AC), including bone segmentation and the HUGE method for truncation correction in PET/MR whole-body hybrid imaging specifically of oncologic patients with bone metastasis and using various radiotracers. Methods Twenty-three patients that underwent altogether 28 whole-body PET/MR examinations with findings of bone metastasis were included in this study. Different radiotracers (18F-FDG, 68Ga-PSMA, 68Ga-DOTATOC, 124I–MIBG) were injected according to appropriate clinical indications. Each of the 28 whole-body PET datasets was reconstructed three times using AC with (1) standard four-compartment μ-maps (background air, lung, muscle, and soft tissue), (2) five-compartment μ-maps (adding bone), and (3) six-compartment μ-maps (adding bone and HUGE truncation correction). The SUVmax of each detected bone lesion was measured in each reconstruction to evaluate the quantitative impact of improved MR-based AC. Relative difference images between four- and six-compartment μ-maps were calculated. MR-based HUGE truncation correction was compared with the PET-based MLAA truncation correction method in all patients. Results Overall, 69 bone lesions were detected and evaluated. The mean increase in relative difference over all 69 lesions in SUVmax was 5.4 ± 6.4% when comparing the improved six-compartment AC with the standard four-compartment AC. Maximal relative difference of 28.4% was measured in one lesion. Truncation correction with HUGE worked robust and resulted in realistic body contouring in all 28 exams and for all 4 different radiotracers. Truncation correction with MLAA revealed overestimations of arm tissue volume in all PET/MR exams with 18F-FDG radiotracer and failed in all other exams with radiotracers 68Ga-PSMA, 68Ga-DOTATOC, and 124I- MIBG due to limitations in body contour detection. Conclusion Improved MR-based AC, including bone segmentation and HUGE truncation correction in whole-body PET/MR on patients with bone lesions and using various radiotracers, is important to ensure best possible diagnostic image quality and accurate PET quantification. The HUGE method for truncation correction based on MR worked robust and results in realistic body contouring, independent of the radiotracers used.
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Affiliation(s)
- Hong Grafe
- Department of Nuclear Medicine, University Hospital Essen, University Duisburg-Essen, Hufelandstr. 55, 45147, Essen, Germany.
| | - Maike E Lindemann
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Hufelandstr. 55, 45147, Essen, Germany
| | - Verena Ruhlmann
- Department of Nuclear Medicine, University Hospital Essen, University Duisburg-Essen, Hufelandstr. 55, 45147, Essen, Germany
| | - Mark Oehmigen
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Hufelandstr. 55, 45147, Essen, Germany
| | - Nader Hirmas
- Department of Nuclear Medicine, University Hospital Essen, University Duisburg-Essen, Hufelandstr. 55, 45147, Essen, Germany
| | - Lale Umutlu
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University Duisburg-Essen, Hufelandstr. 55, 45147, Essen, Germany
| | - Ken Herrmann
- Department of Nuclear Medicine, University Hospital Essen, University Duisburg-Essen, Hufelandstr. 55, 45147, Essen, Germany
| | - Harald H Quick
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Hufelandstr. 55, 45147, Essen, Germany.,Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Zollverein, 45141, Essen, Germany
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10
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Rischpler C, Siebermair J, Kessler L, Quick HH, Umutlu L, Rassaf T, Antoch G, Herrmann K, Nensa F. Cardiac PET/MRI: Current Clinical Status and Future Perspectives. Semin Nucl Med 2020; 50:260-269. [PMID: 32284112 DOI: 10.1053/j.semnuclmed.2020.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Combined PET/MRI has now been in clinical routine for almost 10 years. Since then, it has not only had to face validation, comparison and research questions, it has also been increasingly used in clinical routine. A number of cardiovascular applications have become established here, whereby viability imaging and assessment of inflammatory and infiltrative processes in the heart are to be emphasized. However, further interesting applications are expected in the near future. This review summarizes the most important clinical applications on the one hand and mentions interesting areas of application in research on the other.
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Affiliation(s)
- Christoph Rischpler
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
| | - Johannes Siebermair
- Department of Cardiology and Vascular Medicine, University Hospital Essen, West German Heart and Vascular Center, University of Duisburg-Essen, Essen, Germany
| | - Lukas Kessler
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Harald H Quick
- High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany; Erwin L Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
| | - Lale Umutlu
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Tienush Rassaf
- Department of Cardiology and Vascular Medicine, University Hospital Essen, West German Heart and Vascular Center, University of Duisburg-Essen, Essen, Germany
| | - Gerald Antoch
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Düsseldorf, Düsseldorf, Germany
| | - Ken Herrmann
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Felix Nensa
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
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11
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Lindemann ME, Guberina N, Wetter A, Fendler WP, Jakoby B, Quick HH. Improving 68Ga-PSMA PET/MRI of the Prostate with Unrenormalized Absolute Scatter Correction. J Nucl Med 2019; 60:1642-1648. [DOI: 10.2967/jnumed.118.224139] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 03/18/2019] [Indexed: 12/18/2022] Open
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12
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Lindemann ME, Nensa F, Quick HH. Impact of improved attenuation correction on 18F-FDG PET/MR hybrid imaging of the heart. PLoS One 2019; 14:e0214095. [PMID: 30908507 PMCID: PMC6433217 DOI: 10.1371/journal.pone.0214095] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 03/06/2019] [Indexed: 01/16/2023] Open
Abstract
PURPOSE The aim of this study was to evaluate and quantify the effect of improved attenuation correction (AC) including bone segmentation and truncation correction on 18F-Fluordesoxyglucose cardiac positron emission tomography/magnetic resonance (PET/MR) imaging. METHODS PET data of 32 cardiac PET/MR datasets were reconstructed with three different AC-maps (1. Dixon-VIBE only, 2. HUGE truncation correction and bone segmentation, 3. MLAA). The Dixon-VIBE AC-maps served as reference of reconstructed PET data. 17-segment short-axis polar plots of the left ventricle were analyzed regarding the impact of each of the three AC methods on PET quantification in cardiac PET/MR imaging. Non-AC PET images were segmented to specify the amount of truncation in the Dixon-VIBE AC-map serving as a reference. All AC-maps were evaluated for artifacts. RESULTS Using HUGE + bone AC results in a homogeneous gain of ca. 6% and for MLAA 8% of PET signal distribution across the myocardium of the left ventricle over all patients compared to Dixon-VIBE AC only. Maximal relative differences up to 18% were observed in segment 17 (apex). The body volume truncation of -12.7 ± 7.1% compared to the segmented non-AC PET images using the Dixon-VIBE AC method was reduced to -1.9 ± 3.9% using HUGE and 7.8 ± 8.3% using MLAA. In each patient, a systematic overestimation in AC-map volume was observed when applying MLAA. Quantitative impact of artifacts showed regional differences up to 6% within single segments of the myocardium. CONCLUSIONS Improved AC including bone segmentation and truncation correction in cardiac PET/MR imaging is important to ensure best possible diagnostic quality and PET quantification. The results exhibited an overestimation of AC-map volume using MLAA, while HUGE resulted in a more realistic body contouring. Incorporation of bone segmentation into the Dixon-VIBE AC-map resulted in homogeneous gain in PET signal distribution across the myocardium. The majority of observed AC-map artifacts did not significantly affect the quantitative assessment of the myocardium.
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Affiliation(s)
- Maike E. Lindemann
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Felix Nensa
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Harald H. Quick
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, Germany
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
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13
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Rischpler C, Nekolla SG, Heusch G, Umutlu L, Rassaf T, Heusch P, Herrmann K, Nensa F. Cardiac PET/MRI-an update. Eur J Hybrid Imaging 2019; 3:2. [PMID: 34191143 PMCID: PMC8212244 DOI: 10.1186/s41824-018-0050-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 12/17/2018] [Indexed: 12/21/2022] Open
Abstract
It is now about 8 years since the first whole-body integrated PET/MRI has been installed. First, reports on technical characteristics and system performance were published. Early after, reports on the first use of PET/MRI in oncological patients were released. Interestingly, the first article on the application in cardiology was a review article, which was published before the first original article was put out. Since then, researchers have gained a lot experience with the PET/MRI in various cardiovascular diseases and an increasing number on auspicious indications is appearing. In this review article, we give an overview on technical updates within these last years with potential impact on cardiac imaging and summarize those scenarios where PET/MRI plays a pivotal role in cardiovascular medicine.
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Affiliation(s)
- C Rischpler
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
| | - S G Nekolla
- Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, 81675, Munich, Germany.,DZHK (Deutsches Zentrum für Herz-Kreislauf-Forschung e.V.) partner site Munich Heart alliance, Munich, Germany
| | - G Heusch
- Institute for Pathophysiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - L Umutlu
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - T Rassaf
- Department of Cardiology and Vascular Medicine, University Hospital Essen, West German Heart and Vascular Center, University of Duisburg-Essen, Essen, Germany
| | - P Heusch
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Düsseldorf, Düsseldorf, Germany
| | - K Herrmann
- Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - F Nensa
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
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Nensa F, Bamberg F, Rischpler C, Menezes L, Poeppel TD, la Fougère C, Beitzke D, Rasul S, Loewe C, Nikolaou K, Bucerius J, Kjaer A, Gutberlet M, Prakken NH, Vliegenthart R, Slart RHJA, Nekolla SG, Lassen ML, Pichler BJ, Schlosser T, Jacquier A, Quick HH, Schäfers M, Hacker M. Hybrid cardiac imaging using PET/MRI: a joint position statement by the European Society of Cardiovascular Radiology (ESCR) and the European Association of Nuclear Medicine (EANM). Eur Radiol 2018; 28:4086-4101. [PMID: 29717368 PMCID: PMC6132726 DOI: 10.1007/s00330-017-5008-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/01/2017] [Accepted: 07/27/2017] [Indexed: 12/19/2022]
Abstract
Positron emission tomography (PET) and magnetic resonance imaging (MRI) have both been used for decades in cardiovascular imaging. Since 2010, hybrid PET/MRI using sequential and integrated scanner platforms has been available, with hybrid cardiac PET/MR imaging protocols increasingly incorporated into clinical workflows. Given the range of complementary information provided by each method, the use of hybrid PET/MRI may be justified and beneficial in particular clinical settings for the evaluation of different disease entities. In the present joint position statement, we critically review the role and value of integrated PET/MRI in cardiovascular imaging, provide a technical overview of cardiac PET/MRI and practical advice related to the cardiac PET/MRI workflow, identify cardiovascular applications that can potentially benefit from hybrid PET/MRI, and describe the needs for future development and research. In order to encourage its wide dissemination, this article is freely accessible on the European Radiology and European Journal of Hybrid Imaging web sites. KEY POINTS • Studies and case-reports indicate that PET/MRI is a feasible and robust technology. • Promising fields of application include a variety of cardiac conditions. • Larger studies are required to demonstrate its incremental and cost-effective value. • The translation of novel radiopharmaceuticals and MR-sequences will provide exciting new opportunities.
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Affiliation(s)
- Felix Nensa
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstrasse 55, 45147, Essen, Germany
| | - Fabian Bamberg
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
| | - Christoph Rischpler
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675, Munich, Germany
| | - Leon Menezes
- UCL Institute of Nuclear Medicine, and NIHR, University College London Hospitals Biomedical Research Centre, 5th Floor Tower, University College London Hospital, 235 Euston Road, London, NW1 2BU, UK
| | - Thorsten D Poeppel
- Klinik für Nuklearmedizin, Universitätsklinikum Essen, Hufelandstraße 55, 45122, Essen, Germany
| | - Christian la Fougère
- Nuklearmedizin und Klinische Molekulare Bildgebung, Otfried-Müller-Straße 14, 72076, Tübingen, Germany
| | - Dietrich Beitzke
- Department of Bioimaging and Image-Guided Therapy, Medical University Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria
| | - Sazan Rasul
- Department of Radiology and Nuclear Medicine, Medical University Vienna, Währinger Gürtel 18-20, Floor 5L, 1090, Vienna, Austria
| | - Christian Loewe
- Department of Bioimaging and Image-Guided Therapy, Medical University Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria
| | - Konstantin Nikolaou
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany
| | - Jan Bucerius
- Maastricht Oncology Centre, Medical University Maastricht, P. Debyelaan 25, 6229 HX, Maastrich, Netherlands
| | - Andreas Kjaer
- Section of Endocrinology Research, University of Copenhagen, Panum Instituttet, Blegdamsvej 3, 2200, 12.3, Copenhagen N, Denmark
| | - Matthias Gutberlet
- Diagnostic and Interventional Radiology, University of Leipzig-Heart Center, Strümpellstrasse 39, 04289, Leipzig, Germany
| | - Niek H Prakken
- University Medical Center Groningen, Department of Radiology, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, Netherlands
| | - Rozemarijn Vliegenthart
- University Medical Center Groningen, Department of Radiology, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, Netherlands
| | - Riemer H J A Slart
- Department of Nuclear Medicine and Molecular, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30.001, 9700 RB, Groningen, Netherlands
| | - Stephan G Nekolla
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675, Munich, Germany
| | - Martin L Lassen
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, AKH-4L Währinger Gürtel 18-20, 1090, Vienna, Austria
| | - Bernd J Pichler
- Abteilung für Präklinische Bildgebung und Radiopharmazie, University of Tübingen, Röntgenweg 13, 72026, Tübingen, Germany
| | - Thomas Schlosser
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstrasse 55, 45147, Essen, Germany
| | - Alexis Jacquier
- Department of Cardiovascular and Thoracic Radiology, Assistance Publique Hopitaux de Marseille; University of Aix-Marseille, 264 rue Saint Pierre, 13385, Marseille, France
| | - Harald H Quick
- High-Field and Hybrid MR Imaging, University Hospital Essen, Hufelandstrasse 55, 45147, Essen, Germany
| | - Michael Schäfers
- Department of Nuclear Medicine and European Institute for Molecular Imaging (EIMI), University of Münster, Albert-Schweitzer-Campus 1, building A1, 48149, Münster, Germany
| | - Marcus Hacker
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Währinger Gürtel 18-20, Floor 5L, 1090, Vienna, Austria
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Nensa F, Bamberg F, Rischpler C, Menezes L, Poeppel TD, Fougère CL, Beitzke D, Rasul S, Loewe C, Nikolaou K, Bucerius J, Kjaer A, Gutberlet M, Prakken NH, Vliegenthart R, Slart RHJA, Nekolla SG, Lassen ML, Pichler BJ, Schlosser T, Jacquier A, Quick HH, Schäfers M, Hacker M. Hybrid cardiac imaging using PET/MRI: a joint position statement by the European Society of Cardiovascular Radiology (ESCR) and the European Association of Nuclear Medicine (EANM). Eur J Hybrid Imaging 2018. [DOI: 10.1186/s41824-018-0032-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Bailey DL, Pichler BJ, Gückel B, Antoch G, Barthel H, Bhujwalla ZM, Biskup S, Biswal S, Bitzer M, Boellaard R, Braren RF, Brendle C, Brindle K, Chiti A, la Fougère C, Gillies R, Goh V, Goyen M, Hacker M, Heukamp L, Knudsen GM, Krackhardt AM, Law I, Morris JC, Nikolaou K, Nuyts J, Ordonez AA, Pantel K, Quick HH, Riklund K, Sabri O, Sattler B, Troost EGC, Zaiss M, Zender L, Beyer T. Combined PET/MRI: Global Warming-Summary Report of the 6th International Workshop on PET/MRI, March 27-29, 2017, Tübingen, Germany. Mol Imaging Biol 2018; 20:4-20. [PMID: 28971346 PMCID: PMC5775351 DOI: 10.1007/s11307-017-1123-5] [Citation(s) in RCA: 36] [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] [Indexed: 12/22/2022]
Abstract
The 6th annual meeting to address key issues in positron emission tomography (PET)/magnetic resonance imaging (MRI) was held again in Tübingen, Germany, from March 27 to 29, 2017. Over three days of invited plenary lectures, round table discussions and dialogue board deliberations, participants critically assessed the current state of PET/MRI, both clinically and as a research tool, and attempted to chart future directions. The meeting addressed the use of PET/MRI and workflows in oncology, neurosciences, infection, inflammation and chronic pain syndromes, as well as deeper discussions about how best to characterise the tumour microenvironment, optimise the complementary information available from PET and MRI, and how advanced data mining and bioinformatics, as well as information from liquid biomarkers (circulating tumour cells and nucleic acids) and pathology, can be integrated to give a more complete characterisation of disease phenotype. Some issues that have dominated previous meetings, such as the accuracy of MR-based attenuation correction (AC) of the PET scan, were finally put to rest as having been adequately addressed for the majority of clinical situations. Likewise, the ability to standardise PET systems for use in multicentre trials was confirmed, thus removing a perceived barrier to larger clinical imaging trials. The meeting openly questioned whether PET/MRI should, in all cases, be used as a whole-body imaging modality or whether in many circumstances it would best be employed to give an in-depth study of previously identified disease in a single organ or region. The meeting concluded that there is still much work to be done in the integration of data from different fields and in developing a common language for all stakeholders involved. In addition, the participants advocated joint training and education for individuals who engage in routine PET/MRI. It was agreed that PET/MRI can enhance our understanding of normal and disrupted biology, and we are in a position to describe the in vivo nature of disease processes, metabolism, evolution of cancer and the monitoring of response to pharmacological interventions and therapies. As such, PET/MRI is a key to advancing medicine and patient care.
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Affiliation(s)
- D L Bailey
- Department of Nuclear Medicine, Royal North Shore Hospital, and Faculty of Health Sciences, University of Sydney, Sydney, Australia
| | - B J Pichler
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard-Karls-Universität, Tübingen, Germany
| | - B Gückel
- Department of Diagnostic and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - G Antoch
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, 40225, Dusseldorf, Germany
| | - H Barthel
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig, Germany
| | - Z M Bhujwalla
- Division of Cancer Imaging Research, Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - S Biskup
- Praxis für Humangenetik Tübingen, Paul-Ehrlich-Str. 23, 72076, Tübingen, Germany
| | - S Biswal
- Molecular Imaging Program at Stanford (MIPS) and Bio-X, Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA
| | - M Bitzer
- Department of Internal Medicine I, Eberhard-Karls University, Tübingen, Germany
| | - R Boellaard
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - R F Braren
- Institute of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - C Brendle
- Diagnostic and Interventional Neuroradiology, Department of Radiology, Eberhard Karls University, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany
| | - K Brindle
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, UK
| | - A Chiti
- Department of Biomedical Sciences, Humanitas University, Milan, Italy
- Department of Nuclear Medicine, Humanitas Research Hospital, Milan, Italy
| | - C la Fougère
- Department of Radiology, Nuclear Medicine and Clinical Molecular Imaging, Eberhard-Karls-Universität, Tübingen, Germany
| | - R Gillies
- Department of Cancer Imaging and Metabolism, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33621, USA
| | - V Goh
- Cancer Imaging, School of Biomedical Engineering & Imaging Sciences, King's College London, London, UK
- Department of Radiology, Guy's & St Thomas' Hospitals London, London, UK
| | - M Goyen
- GE Healthcare GmbH, Beethovenstrasse 239, Solingen, Germany
| | - M Hacker
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | | | - G M Knudsen
- Neurobiology Research Unit, Rigshospitalet and Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - A M Krackhardt
- III. Medical Department, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - I Law
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - J C Morris
- Knight Alzheimer Disease Research Center, Washington University School of Medicine, St Louis, MO, USA
| | - K Nikolaou
- Department of Diagnostic and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - J Nuyts
- Nuclear Medicine & Molecular Imaging, KU Leuven, Leuven, Belgium
| | - A A Ordonez
- Department of Pediatrics, Center for Infection and Inflammation Imaging Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - K Pantel
- Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - H H Quick
- High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany
| | - K Riklund
- Department of Radiation Sciences, Umea University, Umea, Sweden
| | - O Sabri
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig, Germany
| | - B Sattler
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig, Germany
| | - E G C Troost
- OncoRay-National Center for Radiation Research in Oncology, Dresden, Germany
- Institute of Radiooncology-OncoRay, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
- Department of Radiotherapy, University Hospital Carl Gustav Carus and Medical Faculty of Technische Universität Dresden, Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, Dresden, Germany
| | - M Zaiss
- High Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - L Zender
- Department of Internal Medicine VIII, University Hospital Tübingen, Tübingen, Germany
| | - Thomas Beyer
- QIMP Group, Center for Medical Physics and Biomedical Engineering General Hospital Vienna, Medical University Vienna, 4L, Waehringer Guertel 18-20, 1090, Vienna, Austria.
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Oehmigen M, Lindemann ME, Gratz M, Kirchner J, Ruhlmann V, Umutlu L, Blumhagen JO, Fenchel M, Quick HH. Impact of improved attenuation correction featuring a bone atlas and truncation correction on PET quantification in whole-body PET/MR. Eur J Nucl Med Mol Imaging 2017; 45:642-653. [PMID: 29119237 DOI: 10.1007/s00259-017-3864-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 10/19/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE Recent studies have shown an excellent correlation between PET/MR and PET/CT hybrid imaging in detecting lesions. However, a systematic underestimation of PET quantification in PET/MR has been observed. This is attributable to two methodological challenges of MR-based attenuation correction (AC): (1) lack of bone information, and (2) truncation of the MR-based AC maps (μmaps) along the patient arms. The aim of this study was to evaluate the impact of improved AC featuring a bone atlas and truncation correction on PET quantification in whole-body PET/MR. METHODS The MR-based Dixon method provides four-compartment μmaps (background air, lungs, fat, soft tissue) which served as a reference for PET/MR AC in this study. A model-based bone atlas provided bone tissue as a fifth compartment, while the HUGE method provided truncation correction. The study population comprised 51 patients with oncological diseases, all of whom underwent a whole-body PET/MR examination. Each whole-body PET dataset was reconstructed four times using standard four-compartment μmaps, five-compartment μmaps, four-compartment μmaps + HUGE, and five-compartment μmaps + HUGE. The SUVmax for each lesion was measured to assess the impact of each μmap on PET quantification. RESULTS All four μmaps in each patient provided robust results for reconstruction of the AC PET data. Overall, SUVmax was quantified in 99 tumours and lesions. Compared to the reference four-compartment μmap, the mean SUVmax of all 99 lesions increased by 1.4 ± 2.5% when bone was added, by 2.1 ± 3.5% when HUGE was added, and by 4.4 ± 5.7% when bone + HUGE was added. Larger quantification bias of up to 35% was found for single lesions when bone and truncation correction were added to the μmaps, depending on their individual location in the body. CONCLUSION The novel AC method, featuring a bone model and truncation correction, improved PET quantification in whole-body PET/MR imaging. Short reconstruction times, straightforward reconstruction workflow, and robust AC quality justify further routine clinical application of this method.
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Affiliation(s)
- Mark Oehmigen
- High Field and Hybrid MR Imaging, University Hospital Essen, Hufelandstr. 55, 45147, Essen, Germany.
| | - Maike E Lindemann
- High Field and Hybrid MR Imaging, University Hospital Essen, Hufelandstr. 55, 45147, Essen, Germany
| | - Marcel Gratz
- High Field and Hybrid MR Imaging, University Hospital Essen, Hufelandstr. 55, 45147, Essen, Germany.,Erwin L. Hahn Institute for MR Imaging, University Duisburg-Essen, Essen, Germany
| | - Julian Kirchner
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Dusseldorf, Germany
| | - Verena Ruhlmann
- Department of Nuclear Medicine, University Hospital Essen, Essen, Germany
| | - Lale Umutlu
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
| | | | | | - Harald H Quick
- High Field and Hybrid MR Imaging, University Hospital Essen, Hufelandstr. 55, 45147, Essen, Germany.,Erwin L. Hahn Institute for MR Imaging, University Duisburg-Essen, Essen, Germany
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Hybrid Positron Emission Tomography/Magnetic Resonance Imaging: Challenges, Methods, and State of the Art of Hardware Component Attenuation Correction. Invest Radiol 2017; 51:624-34. [PMID: 27175550 DOI: 10.1097/rli.0000000000000289] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Attenuation correction (AC) is an essential step in the positron emission tomography (PET) data reconstruction process to provide accurate and quantitative PET images. The introduction of PET/magnetic resonance (MR) hybrid systems has raised new challenges but also possibilities regarding PET AC. While in PET/computed tomography (CT) imaging, CT images can be converted to attenuation maps, MR images in PET/MR do not provide a direct relation to attenuation. For the AC of patient tissues, new methods have been suggested, for example, based on image segmentation, atlas registration, or ultrashort echo time MR sequences. Another challenge in PET/MR hybrid imaging is AC of hardware components that are placed in the PET/MR field of view, such as the patient table or various radiofrequency (RF) coils covering the body of the patient for MR signal detection. Hardware components can be categorized into 4 different groups: (1) patient table, (2) RF receiver coils, (3) radiation therapy equipment, and (4) PET and MR imaging phantoms. For rigid and stationary objects, such as the patient table and some RF coils like the head/neck coil, predefined CT-based attenuation maps stored on the system can be used for automatic AC. Flexible RF coils are not included into the AC process till now because they can vary in position as well as in shape and are not accurately detectable with the PET/MR system.This work summarizes challenges, established methods, new concepts, and the state of art in hardware component AC in the context of PET/MR hybrid imaging. The work also gives an overview of PET/MR hardware devices, their attenuation properties, and their effect on PET quantification.
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Nekolla SG, van Marwick S, Schachoff S, Kunze KP, Rischpler C. Cardiovascular PET/MRI: Technical Considerations and Outlook. CURRENT CARDIOVASCULAR IMAGING REPORTS 2017. [DOI: 10.1007/s12410-017-9435-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Heußer T, Mann P, Rank CM, Schäfer M, Dimitrakopoulou-Strauss A, Schlemmer HP, Hadaschik BA, Kopka K, Bachert P, Kachelrieß M, Freitag MT. Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI. PLoS One 2017; 12:e0183329. [PMID: 28817656 PMCID: PMC5560715 DOI: 10.1371/journal.pone.0183329] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/02/2017] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVES Combined positron emission tomography (PET) and magnetic resonance imaging (MRI) targeting the prostate-specific membrane antigen (PSMA) with a 68Ga-labelled PSMA-analog (68Ga-PSMA-11) is discussed as a promising diagnostic method for patients with suspicion or history of prostate cancer. One potential drawback of this method are severe photopenic (halo-) artifacts surrounding the bladder and the kidneys in the scatter-corrected PET images, which have been reported to occur frequently in clinical practice. The goal of this work was to investigate the occurrence and impact of these artifacts and, secondly, to evaluate variants of the standard scatter correction method with regard to halo-artifact suppression. METHODS Experiments using a dedicated pelvis phantom were conducted to investigate whether the halo-artifact is modality-, tracer-, and/or concentration-dependent. Furthermore, 31 patients with history of prostate cancer were selected from an ongoing 68Ga-PSMA-11-PET/MRI study. For each patient, PET raw data were reconstructed employing six different variants of PET scatter correction: absolute scatter scaling, relative scatter scaling, and relative scatter scaling combined with prompt gamma correction, each of which was combined with a maximum scatter fraction (MaxSF) of MaxSF = 75% or MaxSF = 40%. Evaluation of the reconstructed images with regard to halo-artifact suppression was performed both quantitatively using statistical analysis and qualitatively by two independent readers. RESULTS The phantom experiments did not reveal any modality-dependency (PET/MRI vs. PET/CT) or tracer-dependency (68Ga vs. 18F-FDG). Patient- and phantom-based data indicated that halo-artifacts derive from high organ-to-background activity ratios (OBR) between bladder/kidneys and surrounding soft tissue, with a positive correlation between OBR and halo size. Comparing different variants of scatter correction, reducing the maximum scatter fraction from the default value MaxSF = 75% to MaxSF = 40% was found to efficiently suppress halo-artifacts in both phantom and patient data. In 1 of 31 patients, reducing the maximum scatter fraction provided new PET-based information changing the patient's diagnosis. CONCLUSION Halo-artifacts are particularly observed for 68Ga-PSMA-11-PET/MRI due to 1) the biodistribution of the PSMA-11-tracer resulting in large OBRs for bladder and kidneys and 2) inaccurate scatter correction methods currently used in clinical routine, which tend to overestimate the scatter contribution. If not compensated for, 68Ga-PSMA-11 uptake pathologies may be masked by halo-artifacts leading to false-negative diagnoses. Reducing the maximum scatter fraction was found to efficiently suppress halo-artifacts.
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Affiliation(s)
- Thorsten Heußer
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Philipp Mann
- Applied Medical Radiation Physics, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Christopher M. Rank
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martin Schäfer
- Divison of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | | | | | - Klaus Kopka
- Divison of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Peter Bachert
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Marc Kachelrieß
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martin T. Freitag
- Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
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Lindemann ME, Oehmigen M, Blumhagen JO, Gratz M, Quick HH. MR-based truncation and attenuation correction in integrated PET/MR hybrid imaging using HUGE with continuous table motion. Med Phys 2017; 44:4559-4572. [DOI: 10.1002/mp.12449] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 05/08/2017] [Accepted: 06/27/2017] [Indexed: 01/19/2023] Open
Affiliation(s)
- Maike E. Lindemann
- High Field and Hybrid MR Imaging; University Hospital Essen; University Duisburg-Essen; Essen Germany
| | - Mark Oehmigen
- High Field and Hybrid MR Imaging; University Hospital Essen; University Duisburg-Essen; Essen Germany
| | | | - Marcel Gratz
- High Field and Hybrid MR Imaging; University Hospital Essen; University Duisburg-Essen; Essen Germany
- Erwin L. Hahn Institute for Magnetic Resonance Imaging; University Duisburg-Essen; Essen Germany
| | - Harald H. Quick
- High Field and Hybrid MR Imaging; University Hospital Essen; University Duisburg-Essen; Essen Germany
- Erwin L. Hahn Institute for Magnetic Resonance Imaging; University Duisburg-Essen; Essen Germany
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Effects of arm truncation on the appearance of the halo artifact in 68Ga-PSMA-11 (HBED-CC) PET/MRI. Eur J Nucl Med Mol Imaging 2017; 44:1636-1646. [PMID: 28508120 DOI: 10.1007/s00259-017-3718-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 04/27/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE PSMA ligand imaging with hybrid PET/MRI scanners could be an integral part of the clinical routine in the future. However, the first study about this novel method revealed a severe photopenic artifact ("halo artifact") around the urinary bladder causing significantly reduced tumor visibility. The aim of this evaluation was to analyze the role of arm truncation on the appearance of the halo artifact in 68Ga-PSMA-11 PET/MRI hypothesizing that this influences the appearance. METHODS Twenty-seven consecutive patients were subjected to 68Ga-PSMA-11 PET/CT (1 h p.i.) followed by PET/MRI (3 h p.i.). PET/MRI was first started with scans of the abdomen to pelvis with arms positioned up above the head. Immediately thereafter, additional scans from the pelvis to abdomen were conducted with arms positioned down beside the trunk. All investigations were first analyzed separately and then compared with respect to tumor detection and tumor uptake (SUV) as well as the presence and intensity of the halo artifact. The Wilcoxon signed rank test was used to determine statistical differences including Bonferroni correction. RESULTS The halo was significantly reduced if the arms were elevated. Lesions inside the halo artifact (n = 16) demonstrated significantly increased SUVmean (p = 0.0007) and SUVmax (p = 0.0024) with arms positioned up. The halo appearance and intensity was not dependent on the total activity and activity concentration of the urinary bladder. CONCLUSION Positioning the arms down was shown to be significantly associated with the appearance of the halo artifact in PET/MRI. Positioning the arms up above the head can significantly reduce the halo artifact, thereby detecting more tumor lesions.
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Systems, Physics, and Instrumentation of PET/MRI for Cardiovascular Studies. CURRENT CARDIOVASCULAR IMAGING REPORTS 2017. [DOI: 10.1007/s12410-017-9414-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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25
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Rausch I, Quick HH, Cal-Gonzalez J, Sattler B, Boellaard R, Beyer T. Technical and instrumentational foundations of PET/MRI. Eur J Radiol 2017; 94:A3-A13. [PMID: 28431784 DOI: 10.1016/j.ejrad.2017.04.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 04/07/2017] [Indexed: 12/23/2022]
Abstract
This paper highlights the origins of combined positron emission tomography (PET) and magnetic resonance imaging (MRI) whole-body systems that were first introduced for applications in humans in 2010. This text first covers basic aspects of each imaging modality before describing the technical and methodological challenges of combining PET and MRI within a single system. After several years of development, combined and even fully-integrated PET/MRI systems have become available and made their way into the clinic. This multi-modality imaging system lends itself to the advanced exploration of diseases to support personalized medicine in a long run. To that extent, this paper provides an introduction to PET/MRI methodology and important technical solutions.
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Affiliation(s)
- Ivo Rausch
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria.
| | - Harald H Quick
- High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany; Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany
| | - Jacobo Cal-Gonzalez
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria
| | - Bernhard Sattler
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig, Germany
| | - Ronald Boellaard
- Department of Nuclear Medicine and Molecular Imaging, Academisch Ziekenhuis Groningen, Groningen, The Netherlands
| | - Thomas Beyer
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria
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Weavers PT, Tao S, Trzasko JD, Shu Y, Tryggestad EJ, Gunter JL, McGee KP, Litwiller DV, Hwang KP, Bernstein MA. Image-based gradient non-linearity characterization to determine higher-order spherical harmonic coefficients for improved spatial position accuracy in magnetic resonance imaging. Magn Reson Imaging 2016; 38:54-62. [PMID: 28034637 DOI: 10.1016/j.mri.2016.12.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 12/22/2016] [Accepted: 12/22/2016] [Indexed: 11/30/2022]
Abstract
PURPOSE Spatial position accuracy in magnetic resonance imaging (MRI) is an important concern for a variety of applications, including radiation therapy planning, surgical planning, and longitudinal studies of morphologic changes to study neurodegenerative diseases. Spatial accuracy is strongly influenced by gradient linearity. This work presents a method for characterizing the gradient non-linearity fields on a per-system basis, and using this information to provide improved and higher-order (9th vs. 5th) spherical harmonic coefficients for better spatial accuracy in MRI. METHODS A large fiducial phantom containing 5229 water-filled spheres in a grid pattern is scanned with the MR system, and the positions all the fiducials are measured and compared to the corresponding ground truth fiducial positions as reported from a computed tomography (CT) scan of the object. Systematic errors from off-resonance (i.e., B0) effects are minimized with the use of increased receiver bandwidth (±125kHz) and two acquisitions with reversed readout gradient polarity. The spherical harmonic coefficients are estimated using an iterative process, and can be subsequently used to correct for gradient non-linearity. Test-retest stability was assessed with five repeated measurements on a single scanner, and cross-scanner variation on four different, identically-configured 3T wide-bore systems. RESULTS A decrease in the root-mean-square error (RMSE) over a 50cm diameter spherical volume from 1.80mm to 0.77mm is reported here in the case of replacing the vendor's standard 5th order spherical harmonic coefficients with custom fitted 9th order coefficients, and from 1.5mm to 1mm by extending custom fitted 5th order correction to the 9th order. Minimum RMSE varied between scanners, but was stable with repeated measurements in the same scanner. CONCLUSIONS The results suggest that the proposed methods may be used on a per-system basis to more accurately calibrate MR gradient non-linearity coefficients when compared to vendor standard corrections.
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Affiliation(s)
- Paul T Weavers
- Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States
| | - Shengzhen Tao
- Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States; Mayo Graduate School, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States
| | - Joshua D Trzasko
- Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States
| | - Yunhong Shu
- Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States
| | - Erik J Tryggestad
- Radiation Oncology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States
| | - Jeffrey L Gunter
- Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States
| | - Kiaran P McGee
- Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States
| | | | - Ken-Pin Hwang
- MD Anderson Cancer Center, 1515 Holcomb Blvd, Houston, TX 77030, United States
| | - Matt A Bernstein
- Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States.
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Mehranian A, Arabi H, Zaidi H. Vision 20/20: Magnetic resonance imaging-guided attenuation correction in PET/MRI: Challenges, solutions, and opportunities. Med Phys 2016; 43:1130-55. [PMID: 26936700 DOI: 10.1118/1.4941014] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Attenuation correction is an essential component of the long chain of data correction techniques required to achieve the full potential of quantitative positron emission tomography (PET) imaging. The development of combined PET/magnetic resonance imaging (MRI) systems mandated the widespread interest in developing novel strategies for deriving accurate attenuation maps with the aim to improve the quantitative accuracy of these emerging hybrid imaging systems. The attenuation map in PET/MRI should ideally be derived from anatomical MR images; however, MRI intensities reflect proton density and relaxation time properties of biological tissues rather than their electron density and photon attenuation properties. Therefore, in contrast to PET/computed tomography, there is a lack of standardized global mapping between the intensities of MRI signal and linear attenuation coefficients at 511 keV. Moreover, in standard MRI sequences, bones and lung tissues do not produce measurable signals owing to their low proton density and short transverse relaxation times. MR images are also inevitably subject to artifacts that degrade their quality, thus compromising their applicability for the task of attenuation correction in PET/MRI. MRI-guided attenuation correction strategies can be classified in three broad categories: (i) segmentation-based approaches, (ii) atlas-registration and machine learning methods, and (iii) emission/transmission-based approaches. This paper summarizes past and current state-of-the-art developments and latest advances in PET/MRI attenuation correction. The advantages and drawbacks of each approach for addressing the challenges of MR-based attenuation correction are comprehensively described. The opportunities brought by both MRI and PET imaging modalities for deriving accurate attenuation maps and improving PET quantification will be elaborated. Future prospects and potential clinical applications of these techniques and their integration in commercial systems will also be discussed.
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Affiliation(s)
- Abolfazl Mehranian
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva CH-1211, Switzerland
| | - Hossein Arabi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva CH-1211, Switzerland
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva CH-1211, Switzerland; Geneva Neuroscience Centre, University of Geneva, Geneva CH-1205, Switzerland; and Department of Nuclear Medicine and Molecular Imaging, University of Groningen, Groningen 9700 RB, Netherlands
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Tao S, Trzasko JD, Shu Y, Huston J, Johnson KM, Weavers PT, Gray EM, Bernstein MA. NonCartesian MR image reconstruction with integrated gradient nonlinearity correction. Med Phys 2016; 42:7190-201. [PMID: 26632073 DOI: 10.1118/1.4936098] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To derive a noniterative gridding-type reconstruction framework for nonCartesian magnetic resonance imaging (MRI) that prospectively accounts for gradient nonlinearity (GNL)-induced image geometrical distortion during MR image reconstruction, as opposed to the standard, image-domain based GNL correction that is applied after reconstruction; to demonstrate that such framework is able to reduce the image blurring introduced by the conventional GNL correction, while still offering effective correction of GNL-induced geometrical distortion and compatibility with off-resonance correction. METHODS After introducing the nonCartesian MRI signal model that explicitly accounts for the effects of GNL and off-resonance, a noniterative gridding-type reconstruction framework with integrated GNL correction based on the type-III nonuniform fast Fourier transform (NUFFT) is derived. A novel type-III NUFFT implementation is then proposed as a numerically efficient solution to the proposed framework. The incorporation of simultaneous B0 off-resonance correction to the proposed framework is then discussed. Several phantom and in vivo data acquired via various 2D and 3D nonCartesian acquisitions, including 2D Archimedean spiral, 3D shells with integrated radial and spiral, and 3D radial sampling, are used to compare the results of the proposed and the standard GNL correction methods. RESULTS Various phantom and in vivo data demonstrate that both the proposed and the standard GNL correction methods are able to correct the coarse-scale geometric distortion and blurring induced by GNL and off-resonance. However, the standard GNL correction method also introduces blurring effects to corrected images, causing blurring of resolution inserts in the phantom images and loss of small vessel clarity in the angiography examples. On the other hand, the results after the proposed GNL correction show better depiction of resolution inserts and higher clarity of small vessel. CONCLUSIONS The proposed GNL-integrated nonCartesian reconstruction method can mitigate the resolution loss that occurs during standard image-domain GNL correction, while still providing effective correction of coarse-scale geometric distortion and blurring induced by GNL and off-resonance.
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Affiliation(s)
- Shengzhen Tao
- Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 and Mayo Graduate School, Mayo Clinic, Rochester, Minnesota 55905
| | - Joshua D Trzasko
- Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905
| | - Yunhong Shu
- Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905
| | - John Huston
- Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905
| | - Kevin M Johnson
- Department of Medical Physics, The University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Paul T Weavers
- Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905
| | - Erin M Gray
- Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905
| | - Matt A Bernstein
- Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905
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Abstract
Whole-body PET/MR hybrid imaging combines excellent soft tissue contrast and various functional imaging parameters provided by MR with high sensitivity and quantification of radiotracer uptake provided by PET. Although clinical evaluation now is under way, PET/MR demands for new technologies and innovative solutions, currently subject to interdisciplinary research. Attenuation correction (AC) of human soft tissues and of hardware components has to be MR based to maintain quantification of PET imaging as CT attenuation information is missing. MR-based AC is inherently associated with the following challenges: patient tissues are segmented into only few tissue classes, providing discrete attenuation coefficients; bone is substituted as soft tissue in MR-based AC; the limited field of view in MRI leads to truncations in body imaging and, consequently, in MR-based AC; and correct segmentation of lung tissue may be hampered by breathing artifacts. Use of time of flight during PET image acquisition and reconstruction, however, may improve the accuracy of AC. This article provides a status of current image acquisition options in PET/MR hybrid imaging.
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Affiliation(s)
- Ronald Boellaard
- Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands
| | - Harald H Quick
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany; High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany.
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30
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Bailey DL, Antoch G, Bartenstein P, Barthel H, Beer AJ, Bisdas S, Bluemke DA, Boellaard R, Claussen CD, Franzius C, Hacker M, Hricak H, la Fougère C, Gückel B, Nekolla SG, Pichler BJ, Purz S, Quick HH, Sabri O, Sattler B, Schäfer J, Schmidt H, van den Hoff J, Voss S, Weber W, Wehrl HF, Beyer T. Combined PET/MR: The Real Work Has Just Started. Summary Report of the Third International Workshop on PET/MR Imaging; February 17-21, 2014, Tübingen, Germany. Mol Imaging Biol 2016; 17:297-312. [PMID: 25672749 PMCID: PMC4422837 DOI: 10.1007/s11307-014-0818-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
This paper summarises the proceedings and discussions at the third annual workshop held in Tübingen, Germany, dedicated to the advancement of the technical, scientific and clinical applications of combined PET/MRI systems in humans. Two days of basic scientific and technical instructions with "hands-on" tutorials were followed by 3 days of invited presentations from active researchers in this and associated fields augmented by round-table discussions and dialogue boards with specific themes. These included the use of PET/MRI in paediatric oncology and in adult neurology, oncology and cardiology, the development of multi-parametric analyses, and efforts to standardise PET/MRI examinations to allow pooling of data for evaluating the technology. A poll taken on the final day demonstrated that over 50 % of those present felt that while PET/MRI technology underwent an inevitable slump after its much-anticipated initial launch, it was now entering a period of slow, progressive development, with new key applications emerging. In particular, researchers are focusing on exploiting the complementary nature of the physiological (PET) and biochemical (MRI/MRS) data within the morphological framework (MRI) that these devices can provide. Much of the discussion was summed up on the final day when one speaker commented on the state of PET/MRI: "the real work has just started".
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Affiliation(s)
- D L Bailey
- Department of Nuclear Medicine, Royal North Shore Hospital, and Faculty of Health Sciences, University of Sydney, Sydney, Australia
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Rausch I, Rust P, DiFranco MD, Lassen M, Stadlbauer A, Mayerhoefer ME, Hartenbach M, Hacker M, Beyer T. Reproducibility of MRI Dixon-Based Attenuation Correction in Combined PET/MR with Applications for Lean Body Mass Estimation. J Nucl Med 2016; 57:1096-101. [DOI: 10.2967/jnumed.115.168294] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 02/08/2016] [Indexed: 01/09/2023] Open
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Izquierdo-Garcia D, Catana C. MR Imaging-Guided Attenuation Correction of PET Data in PET/MR Imaging. PET Clin 2016; 11:129-49. [PMID: 26952727 DOI: 10.1016/j.cpet.2015.10.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Attenuation correction (AC) is one of the most important challenges in the recently introduced combined PET/magnetic resonance (MR) scanners. PET/MR AC (MR-AC) approaches aim to develop methods that allow accurate estimation of the linear attenuation coefficients of the tissues and other components located in the PET field of view. MR-AC methods can be divided into 3 categories: segmentation, atlas, and PET based. This review provides a comprehensive list of the state-of-the-art MR-AC approaches and their pros and cons. The main sources of artifacts are presented. Finally, this review discusses the current status of MR-AC approaches for clinical applications.
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Affiliation(s)
- David Izquierdo-Garcia
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown 02129, MA, USA.
| | - Ciprian Catana
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown 02129, MA, USA
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Beyer T, Lassen ML, Boellaard R, Delso G, Yaqub M, Sattler B, Quick HH. Investigating the state-of-the-art in whole-body MR-based attenuation correction: an intra-individual, inter-system, inventory study on three clinical PET/MR systems. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2016; 29:75-87. [PMID: 26739263 DOI: 10.1007/s10334-015-0505-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/21/2015] [Accepted: 10/23/2015] [Indexed: 01/19/2023]
Abstract
OBJECTIVE We assess inter- and intra-subject variability of magnetic resonance (MR)-based attenuation maps (MRμMaps) of human subjects for state-of-the-art positron emission tomography (PET)/MR imaging systems. MATERIALS AND METHODS Four healthy male subjects underwent repeated MR imaging with a Siemens Biograph mMR, Philips Ingenuity TF and GE SIGNA PET/MR system using product-specific MR sequences and image processing algorithms for generating MRμMaps. Total lung volumes and mean attenuation values in nine thoracic reference regions were calculated. Linear regression was used for comparing lung volumes on MRμMaps. Intra- and inter-system variability was investigated using a mixed effects model. RESULTS Intra-system variability was seen for the lung volume of some subjects, (p = 0.29). Mean attenuation values across subjects were significantly different (p < 0.001) due to different segmentations of the trachea. Differences in the attenuation values caused noticeable intra-individual and inter-system differences that translated into a subsequent bias of the corrected PET activity values, as verified by independent simulations. CONCLUSION Significant differences of MRμMaps generated for the same subjects but different PET/MR systems resulted in differences in attenuation correction factors, particularly in the thorax. These differences currently limit the quantitative use of PET/MR in multi-center imaging studies.
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Affiliation(s)
- Thomas Beyer
- Center for Medical Physics and Biomedical Engineering, General Hospital Vienna, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090, Vienna, Austria.
| | - Martin L Lassen
- Center for Medical Physics and Biomedical Engineering, General Hospital Vienna, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090, Vienna, Austria
| | - Ronald Boellaard
- Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands. .,Department of Nuclear Medicine and Molecular Imaging, University Medical Centre Groningen, Groningen, The Netherlands.
| | - Gaspar Delso
- Department of Medical Imaging, University Hospital of Zurich, Zurich, Switzerland.,GE Healthcare, Waukesha, WI, USA
| | - Maqsood Yaqub
- Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands
| | - Bernhard Sattler
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig, Germany
| | - Harald H Quick
- Institute of Medical Physics, University of Erlangen-Nürnberg, Erlangen, Germany.,High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
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Bailey DL, Pichler BJ, Gückel B, Barthel H, Beer AJ, Bremerich J, Czernin J, Drzezga A, Franzius C, Goh V, Hartenbach M, Iida H, Kjaer A, la Fougère C, Ladefoged CN, Law I, Nikolaou K, Quick HH, Sabri O, Schäfer J, Schäfers M, Wehrl HF, Beyer T. Combined PET/MRI: Multi-modality Multi-parametric Imaging Is Here: Summary Report of the 4th International Workshop on PET/MR Imaging; February 23-27, 2015, Tübingen, Germany. Mol Imaging Biol 2015; 17:595-608. [PMID: 26286794 DOI: 10.1007/s11307-015-0886-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This paper summarises key themes and discussions from the 4th international workshop dedicated to the advancement of the technical, scientific and clinical applications of combined positron emission tomography (PET)/magnetic resonance imaging (MRI) systems that was held in Tübingen, Germany, from February 23 to 27, 2015. Specifically, we summarise the three days of invited presentations from active researchers in this and associated fields augmented by round table discussions and dialogue boards with specific topics. These include the use of PET/MRI in cardiovascular disease, paediatrics, oncology, neurology and multi-parametric imaging, the latter of which was suggested as a key promoting factor for the wider adoption of integrated PET/MRI. Discussions throughout the workshop and a poll taken on the final day demonstrated that attendees felt more strongly that PET/MRI has further advanced in both technical versatility and acceptance by clinical and research-driven users from the status quo of last year. Still, with only minimal evidence of progress made in exploiting the true complementary nature of the PET and MRI-based information, PET/MRI is still yet to achieve its potential. In that regard, the conclusion of last year's meeting "the real work has just started" still holds true.
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Affiliation(s)
- D L Bailey
- Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia
- Faculty of Health Sciences, University of Sydney, Sydney, Australia
| | - B J Pichler
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, Tübingen, Germany
| | - B Gückel
- Department of Interventional and Diagnostic Radiology, Eberhard Karls University, Tübingen, Germany
| | - H Barthel
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany
| | - A J Beer
- Department of Nuclear Medicine, Ulm University, Ulm, Germany
| | - J Bremerich
- Cardiothoracic Section, Department of Radiology and Nuclear Medicine, University of Basel Hospital, Basel, Switzerland
| | - J Czernin
- Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, USA
| | - A Drzezga
- Department of Nuclear Medicine, University Hospital Cologne, Cologne, Germany
| | - C Franzius
- Centre of Morphological and Molecular Diagnostics (ZeMoDi), MR- and PET/MRI; Centre of Nuclear Medicine and PET/CT, Bremen, Germany
| | - V Goh
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK
- Department of Radiology, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - M Hartenbach
- Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - H Iida
- Department of Investigative Radiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - A Kjaer
- Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Rigshospitalet and University of Copenhagen, Copenhagen, Denmark
| | - C la Fougère
- Department of Nuclear Medicine and Molecular Imaging, Eberhard Karls University Tübingen, Tübingen, Germany
| | - C N Ladefoged
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - I Law
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - K Nikolaou
- Department of Interventional and Diagnostic Radiology, Eberhard Karls University, Tübingen, Germany
| | - H H Quick
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany
- High Field and Hybrid MR-Imaging, University Hospital Essen, Essen, Germany
| | - O Sabri
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany
| | - J Schäfer
- Department of Interventional and Diagnostic Radiology, Eberhard Karls University, Tübingen, Germany
| | - M Schäfers
- Department of Nuclear Medicine, University Hospital Münster, Münster, Germany
| | - H F Wehrl
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, Tübingen, Germany
| | - T Beyer
- Center for Medical Physics and Biomedical Engineering, General Hospital Vienna, Medical University Vienna, 4L, Waehringer Guertel 18-20, 1090, Vienna, Austria.
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Boellaard R, Rausch I, Beyer T, Delso G, Yaqub M, Quick HH, Sattler B. Quality control for quantitative multicenter whole-body PET/MR studies: A NEMA image quality phantom study with three current PET/MR systems. Med Phys 2015; 42:5961-9. [DOI: 10.1118/1.4930962] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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36
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Paulus DH, Quick HH, Geppert C, Fenchel M, Zhan Y, Hermosillo G, Faul D, Boada F, Friedman KP, Koesters T. Whole-Body PET/MR Imaging: Quantitative Evaluation of a Novel Model-Based MR Attenuation Correction Method Including Bone. J Nucl Med 2015; 56:1061-6. [PMID: 26025957 DOI: 10.2967/jnumed.115.156000] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/18/2015] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED In routine whole-body PET/MR hybrid imaging, attenuation correction (AC) is usually performed by segmentation methods based on a Dixon MR sequence providing up to 4 different tissue classes. Because of the lack of bone information with the Dixon-based MR sequence, bone is currently considered as soft tissue. Thus, the aim of this study was to evaluate a novel model-based AC method that considers bone in whole-body PET/MR imaging. METHODS The new method ("Model") is based on a regular 4-compartment segmentation from a Dixon sequence ("Dixon"). Bone information is added using a model-based bone segmentation algorithm, which includes a set of prealigned MR image and bone mask pairs for each major body bone individually. Model was quantitatively evaluated on 20 patients who underwent whole-body PET/MR imaging. As a standard of reference, CT-based μ-maps were generated for each patient individually by nonrigid registration to the MR images based on PET/CT data. This step allowed for a quantitative comparison of all μ-maps based on a single PET emission raw dataset of the PET/MR system. Volumes of interest were drawn on normal tissue, soft-tissue lesions, and bone lesions; standardized uptake values were quantitatively compared. RESULTS In soft-tissue regions with background uptake, the average bias of SUVs in background volumes of interest was 2.4% ± 2.5% and 2.7% ± 2.7% for Dixon and Model, respectively, compared with CT-based AC. For bony tissue, the -25.5% ± 7.9% underestimation observed with Dixon was reduced to -4.9% ± 6.7% with Model. In bone lesions, the average underestimation was -7.4% ± 5.3% and -2.9% ± 5.8% for Dixon and Model, respectively. For soft-tissue lesions, the biases were 5.1% ± 5.1% for Dixon and 5.2% ± 5.2% for Model. CONCLUSION The novel MR-based AC method for whole-body PET/MR imaging, combining Dixon-based soft-tissue segmentation and model-based bone estimation, improves PET quantification in whole-body hybrid PET/MR imaging, especially in bony tissue and nearby soft tissue.
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Affiliation(s)
- Daniel H Paulus
- Institute of Medical Physics, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Harald H Quick
- Institute of Medical Physics, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Erlangen, Germany Erwin L. Hahn Institute for MR Imaging, University Duisburg-Essen, Essen, Germany High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| | | | | | | | | | - David Faul
- Siemens AG Healthcare, New York, New York
| | - Fernando Boada
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York; and Center for Advanced Imaging Innovation and Research (CAI2R), New York, New York
| | - Kent P Friedman
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York; and
| | - Thomas Koesters
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York; and Center for Advanced Imaging Innovation and Research (CAI2R), New York, New York
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Martinez-Rios C, Muzic RF, DiFilippo FP, Hu L, Rubbert C, Herrmann KA. Artifacts and diagnostic pitfalls in positron emission tomography-magnetic resonance imaging. Semin Roentgenol 2014; 49:255-70. [PMID: 25497910 DOI: 10.1053/j.ro.2014.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
| | - Raymond F Muzic
- Department of Radiology, Case Western Reserve University, Cleveland, OH; Case Center for Imaging Research, Case Western Reserve University, Cleveland, OH
| | - Frank P DiFilippo
- Department of Nuclear Medicine, Cleveland Clinic, Imaging Institute, Cleveland, OH
| | | | - Christian Rubbert
- Institute of Diagnostic and Interventional Radiology, University Hospitals, Düsseldorf, Germany
| | - Karin A Herrmann
- Department of Radiology, Case Western Reserve University, Cleveland, OH; Department of Radiology, University Hospitals Case Medical Center, Cleveland, OH.
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Paulus DH, Thorwath D, Schmidt H, Quick HH. Towards integration of PET/MR hybrid imaging into radiation therapy treatment planning. Med Phys 2014; 41:072505. [DOI: 10.1118/1.4881317] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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