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Wyatt JJ, Petrides G, Pearson RA, McCallum HM, Maxwell RJ. Impact of attenuation correction of radiotherapy hardware for positron emission tomography-magnetic resonance in ano-rectal radiotherapy patients. J Appl Clin Med Phys 2024; 25:e14193. [PMID: 37922377 PMCID: PMC10962489 DOI: 10.1002/acm2.14193] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 10/02/2023] [Accepted: 10/11/2023] [Indexed: 11/05/2023] Open
Abstract
BACKGROUND Positron Emission Tomography-Magnetic Resonance (PET-MR) scanners could improve ano-rectal radiotherapy planning through improved Gross Tumour Volume (GTV) delineation and enabling dose painting strategies using metabolic measurements. This requires accurate quantitative PET images acquired in the radiotherapy treatment position. PURPOSE This study aimed to evaluate the impact on GTV delineation and metabolic parameter measurement of using novel Attenuation Correction (AC) maps that included the radiotherapy flat couch, coil bridge and anterior coil to see if they were necessary. METHODS Seventeen ano-rectal radiotherapy patients received a18 F $\mathrm{^{18}F}$ -FluoroDeoxyGlucose PET-MR scan in the radiotherapy position. PET images were reconstructed without (CTAC std $\mathrm{CTAC_{std}}$ ) and with (CTAC cba $\mathrm{CTAC_{cba}}$ ) the radiotherapy hardware included. Both AC maps used the same Computed Tomography image for patient AC. Semi-manual and threshold GTVs were delineated on both PET images, the volumes compared and the Dice coefficient calculated. Metabolic parameters: Standardized Uptake ValuesSUV max $\mathrm{SUV_{max}}$ ,SUV mean $\mathrm{SUV_{mean}}$ and Total Lesion Glycolysis (TLG) were compared using paired t-tests with a Bonferroni corrected significance level ofp = 0.05 / 8 = 0.006 $p = 0.05/8 = 0.006$ . RESULTS Differences in semi-manual GTV volumes betweenCTAC cba $\mathrm{CTAC_{cba}}$ andCTAC std $\mathrm{CTAC_{std}}$ were approaching statistical significance (difference- 15.9 % ± 1.6 % $-15.9\%\pm 1.6\%$ ,p = 0.007 $p = 0.007$ ), with larger differences in low FDG-avid tumours (SUV mean < 8.5 g mL - 1 $\mathrm{SUV_{mean}} < 8.5\;\mathrm{g\: mL^{-1}}$ ). TheCTAC cba $\mathrm{CTAC_{cba}}$ andCTAC std $\mathrm{CTAC_{std}}$ GTVs were concordant with Dice coefficients0.89 ± 0.01 $0.89 \pm 0.01$ (manual) and0.98 ± 0.00 $0.98 \pm 0.00$ (threshold). Metabolic parameters were significantly different, withSUV max $\mathrm{SUV_{max}}$ ,SUV mean $\mathrm{SUV_{mean}}$ and TLG differences of- 11.5 % ± 0.3 % $-11.5\%\ \pm 0.3\%$ (p < 0.001 $p < 0.001$ ),- 11.6 % ± 0.3 % $-11.6\% \pm 0.3\%$ (p < 0.001 $p < 0.001$ ) and- 13.7 % ± 0.6 % $-13.7\%\ \pm 0.6\%$ (p = 0.003 $p = 0.003$ ) respectively. The TLG difference resulted in 1/8 rectal cancer patients changing prognosis group, based on literature TLG cut-offs, when usingCTAC cba $\mathrm{CTAC_{cba}}$ rather thanCTAC std $\mathrm{CTAC_{std}}$ . CONCLUSIONS This study suggests that using AC maps with the radiotherapy hardware included is feasible for patient imaging. The impact on tumour delineation was mixed and needs to be evaluated in larger cohorts. However using AC of the radiotherapy hardware is important for situations where accurate metabolic measurements are required, such as dose painting and treatment prognostication.
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Affiliation(s)
- Jonathan J. Wyatt
- Translational and Clinical Research InstituteNewcastle UniversityNewcastleUK
- Northern Centre for Cancer CareNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastleUK
| | - George Petrides
- Translational and Clinical Research InstituteNewcastle UniversityNewcastleUK
- Nuclear Medicine DepartmentNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastleUK
| | - Rachel A. Pearson
- Translational and Clinical Research InstituteNewcastle UniversityNewcastleUK
- Northern Centre for Cancer CareNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastleUK
| | - Hazel M. McCallum
- Translational and Clinical Research InstituteNewcastle UniversityNewcastleUK
- Northern Centre for Cancer CareNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastleUK
| | - Ross J. Maxwell
- Translational and Clinical Research InstituteNewcastle UniversityNewcastleUK
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Deantonio L, Castronovo F, Paone G, Treglia G, Zilli T. Metabolic Imaging for Radiation Therapy Treatment Planning: The Role of Hybrid PET/MR Imaging. Magn Reson Imaging Clin N Am 2023; 31:637-654. [PMID: 37741647 DOI: 10.1016/j.mric.2023.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/25/2023]
Abstract
The use of hybrid PET/MR imaging for radiotherapy treatment planning has the potential to reduce tumor and organ displacements caused by different scan times and setup changes. Although with mixed results mainly due to single-center studies with small sample size, PET/MR imaging could provide better target delineation, especially by reducing coregistration discrepancies on computed tomography simulation scan and offering better soft tissue contrast. The main limitation to drive stronger conclusions is due to the relatively low availability of hybrid PET/MR imaging systems, mainly limited to large academic centers.
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Affiliation(s)
- Letizia Deantonio
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona 6500, Switzerland; Faculty of Biomedical Sciences, Università della Svizzera italiana, Lugano 6900, Switzerland
| | - Francesco Castronovo
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona 6500, Switzerland
| | - Gaetano Paone
- Faculty of Biomedical Sciences, Università della Svizzera italiana, Lugano 6900, Switzerland; Clinic for Nuclear Medicine and Molecular Imaging, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona 6500, Switzerland
| | - Giorgio Treglia
- Faculty of Biomedical Sciences, Università della Svizzera italiana, Lugano 6900, Switzerland; Clinic for Nuclear Medicine and Molecular Imaging, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona 6500, Switzerland; Faculty of Biology and Medicine, University of Lausanne, Lausanne 1015, Switzerland
| | - Thomas Zilli
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona 6500, Switzerland; Faculty of Biomedical Sciences, Università della Svizzera italiana, Lugano 6900, Switzerland; Faculty of Medicine, University of Geneva, Geneva 1211, Switzerland.
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Koole M, Armstrong I, Krizsan AK, Stromvall A, Visvikis D, Sattler B, Nekolla SG, Dickson J. EANM guidelines for PET-CT and PET-MR routine quality control. Z Med Phys 2023; 33:103-113. [PMID: 36167600 PMCID: PMC10068535 DOI: 10.1016/j.zemedi.2022.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 08/25/2022] [Indexed: 01/29/2023]
Abstract
We present guidelines by the European Association of Nuclear Medicine (EANM) for routine quality control (QC) of PET-CT and PET-MR systems. These guidelines are partially based on the current EANM guidelines for routine quality control of Nuclear Medicine instrumentation but focus more on the inherent multimodal aspect of the current, state-of-the-art PET-CT and PET-MR scanners. We briefly discuss the regulatory context put forward by the International Electrotechnical Commission (IEC) and European Commission (EC) and consider relevant guidelines and recommendations by other societies and professional organizations. As such, a comprehensive overview of recommended quality control procedures is provided to ensure the optimal operational status of a PET system, integrated with either a CT or MR system. In doing so, we also discuss the rationale of the different tests, advice on the frequency of each test and present the relevant MR and CT tests for an integrated system. In addition, we recommend a scheme of preventive actions to avoid QC tests from drifting out of the predefined range of acceptable performance values such that an optimal performance of the PET system is maintained for routine clinical use.
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Affiliation(s)
- Michel Koole
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, KU Leuven, Belgium.
| | - Ian Armstrong
- Nuclear Medicine, Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | | | - Anne Stromvall
- Radiation Physics, Department of Radiation Sciences, Umeå universitet, Umeå, Sweden
| | | | - Bernhard Sattler
- Department of Nuclear Medicine, University Medical Centre Leipzig, Leipzig, Germany
| | - Stephan G Nekolla
- Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar der Technischen Universität München, München, Germany
| | - John Dickson
- Institute of Nuclear Medicine, University College London Hospital, London, United Kingdom
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Olin AB, Thomas C, Hansen AE, Rasmussen JH, Krokos G, Urbano TG, Michaelidou A, Jakoby B, Ladefoged CN, Berthelsen AK, Håkansson K, Vogelius IR, Specht L, Barrington SF, Andersen FL, Fischer BM. Robustness and Generalizability of Deep Learning Synthetic Computed Tomography for Positron Emission Tomography/Magnetic Resonance Imaging-Based Radiation Therapy Planning of Patients With Head and Neck Cancer. Adv Radiat Oncol 2021; 6:100762. [PMID: 34585026 PMCID: PMC8452789 DOI: 10.1016/j.adro.2021.100762] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 07/13/2021] [Accepted: 07/19/2021] [Indexed: 11/26/2022] Open
Abstract
Purpose Radiotherapy planning based only on positron emission tomography/magnetic resonance imaging (PET/MRI) lacks computed tomography (CT) information required for dose calculations. In this study, a previously developed deep learning model for creating synthetic CT (sCT) from MRI in patients with head and neck cancer was evaluated in 2 scenarios: (1) using an independent external dataset, and (2) using a local dataset after an update of the model related to scanner software-induced changes to the input MRI. Methods and Materials Six patients from an external site and 17 patients from a local cohort were analyzed separately. Each patient underwent a CT and a PET/MRI with a Dixon MRI sequence over either one (external) or 2 (local) bed positions. For the external cohort, a previously developed deep learning model for deriving sCT from Dixon MRI was directly applied. For the local cohort, we adapted the model for an upgraded MRI acquisition using transfer learning and evaluated it in a leave-one-out process. The sCT mean absolute error for each patient was assessed. Radiotherapy dose plans based on sCT and CT were compared by assessing relevant absorbed dose differences in target volumes and organs at risk. Results The MAEs were 78 ± 13 HU and 76 ± 12 HU for the external and local cohort, respectively. For the external cohort, absorbed dose differences in target volumes were within ± 2.3% and within ± 1% in 95% of the cases. Differences in organs at risk were <2%. Similar results were obtained for the local cohort. Conclusions We have demonstrated a robust performance of a deep learning model for deriving sCT from MRI when applied to an independent external dataset. We updated the model to accommodate a larger axial field of view and software-induced changes to the input MRI. In both scenarios dose calculations based on sCT were similar to those of CT suggesting a robust and reliable method.
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Affiliation(s)
- Anders B Olin
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Christopher Thomas
- Department of Medical Physics, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Adam E Hansen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.,Department of Radiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jacob H Rasmussen
- Department of Otorhinolaryngology, Head & Neck Surgery and Audiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Otorhinolaryngology and Maxillofacial Surgery, Zealand University Hospital, Køge, Denmark
| | - Georgios Krokos
- King's College London and Guy's and St Thomas' PET Centre, School of Biomedical Engineering and Imaging Sciences, King's College London, King's Health Partners, London, United Kingdom
| | - Teresa Guerrero Urbano
- Department of Oncology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Andriana Michaelidou
- Department of Oncology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Björn Jakoby
- Siemens Healthcare GmbH, Erlangen, Germany.,University of Surrey, Guildford, Surrey, United Kingdom
| | - Claes N Ladefoged
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Anne K Berthelsen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Katrin Håkansson
- Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Ivan R Vogelius
- Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Lena Specht
- Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.,Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sally F Barrington
- King's College London and Guy's and St Thomas' PET Centre, School of Biomedical Engineering and Imaging Sciences, King's College London, King's Health Partners, London, United Kingdom
| | - Flemming L Andersen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Barbara M Fischer
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,King's College London and Guy's and St Thomas' PET Centre, School of Biomedical Engineering and Imaging Sciences, King's College London, King's Health Partners, London, United Kingdom
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Wyatt JJ, Howell E, Lohezic M, McCallum HM, Maxwell RJ. Evaluating the image quality of combined positron emission tomography-magnetic resonance images acquired in the pelvic radiotherapy position. Phys Med Biol 2021; 66:035018. [PMID: 33242847 DOI: 10.1088/1361-6560/abce1c] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Positron emission tomography-magnetic resonance (PET-MR) scanners could improve radiotherapy planning through combining PET and MR functional imaging. This depends on acquiring high quality and quantitatively accurate images in the radiotherapy position. This study evaluated PET-MR image quality using a flat couch and coil bridge for pelvic radiotherapy. MR and PET image quality phantoms were imaged in three setups: phantom on the PET-MR couch with anterior coil on top (diagnostic), phantom on a flat couch with coil on top (couch), and phantom on the flat couch with coil on a coil bridge (radiotherapy). PET images were also acquired in each setup without the anterior coil. PET attenuation correction of the flat couch and coil bridge were generated using kilovoltage computed tomography (CT) images and of the anterior coil using megavoltage CT images. MR image quality was substantially affected, with MR signal to noise ratio (SNR) relative to the diagnostic setup of 89% ± 2% (mean ± standard error of the mean, couch) and 54% ± 1% (radiotherapy), likely due to the increased distance between the patient and receive coils. The reduction impacted the low-contrast detectability score: 23 ± 1 (diagnostic), 19.7 ± 0.3 (couch) and 15 ± 1 (radiotherapy). All other MR metrics agreed within one standard error. PET quantitative accuracy was also affected, with measured activity with anterior coil being different to diagnostic without anterior coil by -16.7% ± 0.2% (couch) and -17.7 ± 0.1% (radiotherapy), without attenuation correction modification. Including the couch and coil bridge attenuation correction reduced this difference to -7.5% ± 0.1%, and including the anterior coil reduced this to -2.7% ± 0.1%. This was better than the diagnostic setup with anterior coil (difference -8.3% ± 0.2%). This translated into greater PET SNR performance for the fully corrected radiotherapy setup compared to diagnostic with coil. However contrast recovery was unchanged by the modified attenuation correction, with the diagnostic setup remaining ∼2% better. Quantitative PET in the radiotherapy setup is possible if appropriate attenuation correction is used. Pelvic radiotherapy PET-MR imaging protocols will need to consider the impact on PET-MR image quality.
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Affiliation(s)
- Jonathan J Wyatt
- Centre for In Vivo Imaging, Newcastle University, United Kingdom. Centre for Cancer, Newcastle University, United Kingdom. Northern Centre for Cancer Care, Newcastle upon Tyne Hospitals, United Kingdom
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Branderhorst W, Steensma BR, Beijst C, Huijing ER, Alborahal C, Versteeg E, Weissler B, Schug D, Gebhardt P, Gross-Weege N, Mueller F, Krueger K, Dey T, Radermacher H, Lips O, Lagendijk J, Schulz V, de Jong HWAM, Klomp DWJ. Evaluation of the radiofrequency performance of a wide-bore 1.5 T positron emission tomography/magnetic resonance imaging body coil for radiotherapy planning. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2020; 17:13-19. [PMID: 33898772 PMCID: PMC8057958 DOI: 10.1016/j.phro.2020.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 11/17/2020] [Accepted: 12/09/2020] [Indexed: 11/13/2022]
Abstract
Background and purpose The restricted bore diameter of current simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) systems can be an impediment to achieving similar patient positioning during PET/MRI planning and radiotherapy. Our goal was to evaluate the B1 transmit (B1+) uniformity, B1+ efficiency, and specific absorption rate (SAR) of a novel radiofrequency (RF) body coil design, in which RF shielded PET detectors were integrated with the specific aim of enabling a wide-bore PET/MRI system. Materials and methods We designed and constructed a wide-bore PET/MRI RF body coil to be integrated with a clinical MRI system. To increase its inner bore diameter, the PET detectors were positioned between the conductors and the RF shield of the RF body coil. Simulations and experiments with phantoms and human volunteers were performed to compare the B1+ uniformity, B1+ efficiency, and SAR between our design and the clinical body coil. Results In the simulations, our design achieved nearly the same B1+ field uniformity as the clinical body coil and an almost identical SAR distribution. The uniformity findings were confirmed by the physical experiments. The B1+ efficiency was 38% lower compared to the clinical body coil. Conclusions To achieve wide-bore PET/MRI, it is possible to integrate shielding for PET detectors between the body coil conductors and the RF shield without compromising MRI performance. Reduced B1+ efficiency may be compensated by adding a second RF amplifier. This finding may facilitate the application of simultaneous whole-body PET/MRI in radiotherapy planning.
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Affiliation(s)
- Woutjan Branderhorst
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bart R Steensma
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Casper Beijst
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Erik R Huijing
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Cezar Alborahal
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Edwin Versteeg
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bjoern Weissler
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - David Schug
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Pierre Gebhardt
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Nicolas Gross-Weege
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Florian Mueller
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Karl Krueger
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Thomas Dey
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Harald Radermacher
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | | | - Jan Lagendijk
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Volkmar Schulz
- Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany
| | - Hugo W A M de Jong
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Dennis W J Klomp
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
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Feasibility of Multiparametric Positron Emission Tomography/Magnetic Resonance Imaging as a One-Stop Shop for Radiation Therapy Planning for Patients with Head and Neck Cancer. Int J Radiat Oncol Biol Phys 2020; 108:1329-1338. [DOI: 10.1016/j.ijrobp.2020.07.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/03/2020] [Accepted: 07/10/2020] [Indexed: 11/23/2022]
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Deller TW, Mathew NK, Hurley SA, Bobb CM, McMillan AB. PET Image Quality Improvement for Simultaneous PET/MRI with a Lightweight MRI Surface Coil. Radiology 2020; 298:166-172. [PMID: 33141004 DOI: 10.1148/radiol.2020200967] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Background During simultaneous PET/MRI, flexible MRI surface coils that lay on the patient are often omitted from PET attenuation correction processing, leading to quantification bias in PET images. Purpose To identify potential PET image quality improvement by using a recently developed lightweight MRI coil technology for the anterior array (AA) surface coil in both a phantom and in vivo study. Materials and Methods A phantom study and a prospective in vivo study were performed with a PET/CT scanner under three conditions: (a) no MRI surface coil (standard of reference), (b) traditional AA coil, and (c) lightweight AA coil. AA coils were not used in attenuation correction processing to emulate clinical PET/MRI. For the phantom study, PET images were reconstructed with and without time of flight (TOF) to assess quantification accuracy and uniformity. The in vivo study consisted of 10 participants (mean age, 66 years ± 10 [standard deviation]; six men) referred for a PET/CT oncologic examination who had undergone imaging between October 2019 and February 2020. Assessment of image quantification bias (defined as the standard error of the mean values) was conducted by comparing mean liver region of interest standardized uptake values with the no-coil standard of reference. A Wilcoxon signed-rank test was used to establish significance. Results For TOF and non-TOF, respectively, the phantom study revealed a mean PET quantification bias of -9.0% and -8.6% with the traditional AA coil and a mean PET quantification bias of -4.3% and -4.0% with the lightweight AA coil. The coefficients of variation reduced from 4.3% and 6.2% with the traditional AA coil to 2.1% and 2.7% with the lightweight AA coil, which demonstrated a homogeneity benefit from the lightweight coil that was greater with, versus without, TOF reconstruction. For the in vivo study, the mean liver standardized uptake value error was -5.9% with the traditional AA coil (P = .002 vs no coil) and -2.4% with the lightweight AA coil (P = .004 vs no coil). Conclusion The lightweight anterior array coil reduced PET image quantification bias by more than 50% compared with the traditional coil. Using the lightweight coil and performing time of flight-based reconstruction each reduced the variation of error. © RSNA, 2020 Online supplemental material is available for this article.
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Affiliation(s)
- Timothy W Deller
- From the Departments of PET/MR Engineering (T.W.D.) and Clinical Development (C.M.B.), GE Healthcare, 3200 N Grandview Blvd, Waukesha, WI 53188; and Department of Radiology, University of Wisconsin-Madison, Wisconsin Institutes for Medical Research, Madison, Wis (N.K.M., S.A.H., A.B.M.)
| | - Nicholas K Mathew
- From the Departments of PET/MR Engineering (T.W.D.) and Clinical Development (C.M.B.), GE Healthcare, 3200 N Grandview Blvd, Waukesha, WI 53188; and Department of Radiology, University of Wisconsin-Madison, Wisconsin Institutes for Medical Research, Madison, Wis (N.K.M., S.A.H., A.B.M.)
| | - Samuel A Hurley
- From the Departments of PET/MR Engineering (T.W.D.) and Clinical Development (C.M.B.), GE Healthcare, 3200 N Grandview Blvd, Waukesha, WI 53188; and Department of Radiology, University of Wisconsin-Madison, Wisconsin Institutes for Medical Research, Madison, Wis (N.K.M., S.A.H., A.B.M.)
| | - Chad M Bobb
- From the Departments of PET/MR Engineering (T.W.D.) and Clinical Development (C.M.B.), GE Healthcare, 3200 N Grandview Blvd, Waukesha, WI 53188; and Department of Radiology, University of Wisconsin-Madison, Wisconsin Institutes for Medical Research, Madison, Wis (N.K.M., S.A.H., A.B.M.)
| | - Alan B McMillan
- From the Departments of PET/MR Engineering (T.W.D.) and Clinical Development (C.M.B.), GE Healthcare, 3200 N Grandview Blvd, Waukesha, WI 53188; and Department of Radiology, University of Wisconsin-Madison, Wisconsin Institutes for Medical Research, Madison, Wis (N.K.M., S.A.H., A.B.M.)
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Créhange G, Soussan M, Gensanne D, Decazes P, Thariat J, Thureau S. Interest of positron-emission tomography and magnetic resonance imaging for radiotherapy planning and control. Cancer Radiother 2020; 24:398-402. [PMID: 32247688 DOI: 10.1016/j.canrad.2020.02.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 02/07/2020] [Indexed: 12/24/2022]
Abstract
Computed tomography (CT) in the treatment position is currently indispensable for planning radiation therapy. Other imaging modalities, such as magnetic resonance imaging (MRI) and positron emission-tomography (PET), can be used to improve the definition of the tumour and/or healthy tissue but also to provide functional data of the target volume. Accurate image registration is essential for treatment planning, so MRI and PET scans should be registered at the planning CT scan. Hybrid PET/MRI scans with a hard plane can be used but pose the problem of the absence of CT scans. Finally, techniques for moving the patient on a rigid air-cushioned table allow PET/CT/MRI scans to be performed in the treatment position while limiting the patient's movements exist. At the same time, the advent of MRI-linear accelerator systems allows to redefine image-guided radiotherapy and to propose treatments with daily recalculation of the dose. The place of PET during treatment remains more confidential and currently only in research and prototype status. The same development of imaging during radiotherapy is underway in proton therapy.
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Affiliation(s)
- G Créhange
- Département de radiothérapie oncologique, institut Curie, 26, rue d'Ulm, 75005 Paris, France
| | - M Soussan
- Service de médecine nucléaire, hôpital Avicenne, AP-HP, hôpitaux universitaires, 125, rue de Stalingrad, 93000 Bobigny, France
| | - D Gensanne
- Département de radiothérapie et de physique médicale, centre Henri-Becquerel, 1, rue d'Amiens, 76038 Rouen, France; Quantif-Litis EA4108, université de Rouen Normandie, rue d'Amiens, 76000 Rouen, France
| | - P Decazes
- Quantif-Litis EA4108, université de Rouen Normandie, rue d'Amiens, 76000 Rouen, France; Département d'imagerie-médecine nucléaire, centre Henri-Becquerel, 1, rue d'Amiens, 76038 Rouen, France
| | - J Thariat
- Département d'onco-radiothérapie, centre François-Baclesse, 3, avenue General-Harris, 14000 Caen, France; Association Advance Resource Centre for Hadrontherapy in Europe (Archade), 3, avenue General-Harris, 14000 Caen, France; Université de Caen Normandie (Unicaen), 3, avenue General-Harris, 14000 Caen, France; Laboratoire de physique corpusculaire, Institut national de physique nucléaire et de physique des particules (IN2P3), 6, boulevard Maréchal-Juin, 14000 Caen, France
| | - S Thureau
- Département de radiothérapie et de physique médicale, centre Henri-Becquerel, 1, rue d'Amiens, 76038 Rouen, France; Quantif-Litis EA4108, université de Rouen Normandie, rue d'Amiens, 76000 Rouen, France; Département d'imagerie-médecine nucléaire, centre Henri-Becquerel, 1, rue d'Amiens, 76038 Rouen, France; Laboratoire de physique corpusculaire, Institut national de physique nucléaire et de physique des particules (IN2P3), 6, boulevard Maréchal-Juin, 14000 Caen, France.
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Adjeiwaah M, Garpebring A, Nyholm T. Sensitivity analysis of different quality assurance methods for magnetic resonance imaging in radiotherapy. Phys Imaging Radiat Oncol 2020; 13:21-27. [PMID: 33458303 PMCID: PMC7807625 DOI: 10.1016/j.phro.2020.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 02/27/2020] [Accepted: 03/02/2020] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE There are currently no standard quality assurance (QA) methods for magnetic resonance imaging (MRI) in radiotherapy (RT). This work was aimed at evaluating the ability of two QA protocols to detect common events that affect quality of MR images under RT settings. MATERIALS AND METHODS The American College of Radiology (ACR) MRI QA phantom was repeatedly scanned using a flexible coil and action limits for key image quality parameters were derived. Using an exploratory survey, issues that reduce MR image quality were identified. The most commonly occurring events were introduced as provocations to produce MR images with degraded quality. From these images, detection sensitivities of the ACR MRI QA protocol and a commercial geometric accuracy phantom were determined. RESULTS Machine-specific action limits for key image quality parameters set at mean ± 3 σ were comparable with the ACR acceptable values. For the geometric accuracy phantom, provocations from uncorrected gradient nonlinearity effects and a piece of metal in the bore of the scanner resulted in worst distortions of 22.2 mm and 3.4 mm, respectively. The ACR phantom was sensitive to uncorrected signal variations, electric interference and a piece of metal in the bore of the scanner but could not adequately detect individual coil element failures. CONCLUSIONS The ACR MRI QA phantom combined with the large field-of-view commercial geometric accuracy phantom were generally sensitive in identifying some common MR image quality issues. The two protocols when combined may provide a tool to monitor the performance of MRI systems in the radiotherapy environment.
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Affiliation(s)
- Mary Adjeiwaah
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | | | - Tufve Nyholm
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
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Paganelli C, Whelan B, Peroni M, Summers P, Fast M, van de Lindt T, McClelland J, Eiben B, Keall P, Lomax T, Riboldi M, Baroni G. MRI-guidance for motion management in external beam radiotherapy: current status and future challenges. Phys Med Biol 2018; 63:22TR03. [PMID: 30457121 DOI: 10.1088/1361-6560/aaebcf] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
High precision conformal radiotherapy requires sophisticated imaging techniques to aid in target localisation for planning and treatment, particularly when organ motion due to respiration is involved. X-ray based imaging is a well-established standard for radiotherapy treatments. Over the last few years, the ability of magnetic resonance imaging (MRI) to provide radiation-free images with high-resolution and superb soft tissue contrast has highlighted the potential of this imaging modality for radiotherapy treatment planning and motion management. In addition, these advantageous properties motivated several recent developments towards combined MRI radiation therapy treatment units, enabling in-room MRI-guidance and treatment adaptation. The aim of this review is to provide an overview of the state-of-the-art in MRI-based image guidance for organ motion management in external beam radiotherapy. Methodological aspects of MRI for organ motion management are reviewed and their application in treatment planning, in-room guidance and adaptive radiotherapy described. Finally, a roadmap for an optimal use of MRI-guidance is highlighted and future challenges are discussed.
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Affiliation(s)
- C Paganelli
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy. Author to whom any correspondence should be addressed. www.cartcas.polimi.it
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