1
|
Gandhi DB, Higano NS, Hahn AD, Gunatilaka CC, Torres LA, Fain SB, Woods JC, Bates AJ. Comparison of weighting algorithms to mitigate respiratory motion in free-breathing neonatal pulmonary radial UTE-MRI. Biomed Phys Eng Express 2024; 10:10.1088/2057-1976/ad3cdd. [PMID: 38599190 PMCID: PMC11182662 DOI: 10.1088/2057-1976/ad3cdd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 04/10/2024] [Indexed: 04/12/2024]
Abstract
Background. Thoracoabdominal MRI is limited by respiratory motion, especially in populations who cannot perform breath-holds. One approach for reducing motion blurring in radially-acquired MRI is respiratory gating. Straightforward 'hard-gating' uses only data from a specified respiratory window and suffers from reduced SNR. Proposed 'soft-gating' reconstructions may improve scan efficiency but reduce motion correction by incorporating data with nonzero weight acquired outside the specified window. However, previous studies report conflicting benefits, and importantly the choice of soft-gated weighting algorithm and effect on image quality has not previously been explored. The purpose of this study is to map how variable soft-gated weighting functions and parameters affect signal and motion blurring in respiratory-gated reconstructions of radial lung MRI, using neonates as a model population.Methods. Ten neonatal inpatients with respiratory abnormalities were imaged using a 1.5 T neonatal-sized scanner and 3D radial ultrashort echo-time (UTE) sequence. Images were reconstructed using ungated, hard-gated, and several soft-gating weighting algorithms (exponential, sigmoid, inverse, and linear weighting decay outside the period of interest), with %Nprojrepresenting the relative amount of data included. The apparent SNR (aSNR) and motion blurring (measured by the maximum derivative of image intensity at the diaphragm, MDD) were compared between reconstructions.Results. Soft-gating functions produced higher aSNR and lower MDD than hard-gated images using equivalent %Nproj, as expected. aSNR was not identical between different gating schemes for given %Nproj. While aSNR was approximately linear with %Nprojfor each algorithm, MDD performance diverged between functions as %Nprojdecreased. Algorithm performance was relatively consistent between subjects, except in images with high noise.Conclusion. The algorithm selection for soft-gating has a notable effect on image quality of respiratory-gated MRI; the timing of included data across the respiratory phase, and not simply the amount of data, plays an important role in aSNR. The specific soft-gating function and parameters should be considered for a given imaging application's requirements of signal and sharpness.
Collapse
Affiliation(s)
- Deep B Gandhi
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States of America
| | - Nara S Higano
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Andrew D Hahn
- Department of Medical Physics, University of Wisconsin, Madison, WI, United States of America
| | - Chamindu C Gunatilaka
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States of America
| | - Luis A Torres
- Department of Medical Physics, University of Wisconsin, Madison, WI, United States of America
| | - Sean B Fain
- Department of Medical Physics, University of Wisconsin, Madison, WI, United States of America
- Department of Radiology, University of Iowa, Iowa City, IA, United States of America
| | - Jason C Woods
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Alister J Bates
- Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| |
Collapse
|
2
|
Chen S, Fraum TJ, Eldeniz C, Mhlanga J, Gan W, Vahle T, Krishnamurthy UB, Faul D, Gach HM, Binkley MM, Kamilov US, Laforest R, An H. MR-assisted PET respiratory motion correction using deep-learning based short-scan motion fields. Magn Reson Med 2022; 88:676-690. [PMID: 35344592 PMCID: PMC11459372 DOI: 10.1002/mrm.29233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 02/03/2022] [Accepted: 02/23/2022] [Indexed: 11/11/2022]
Abstract
PURPOSE We evaluated the impact of PET respiratory motion correction (MoCo) in a phantom and patients. Moreover, we proposed and examined a PET MoCo approach using motion vector fields (MVFs) from a deep-learning reconstructed short MRI scan. METHODS The evaluation of PET MoCo was performed in a respiratory motion phantom study with varying lesion sizes and tumor to background ratios (TBRs) using a static scan as the ground truth. MRI-based MVFs were derived from either 2000 spokes (MoCo2000 , 5-6 min acquisition time) using a Fourier transform reconstruction or 200 spokes (MoCoP2P200 , 30-40 s acquisition time) using a deep-learning Phase2Phase (P2P) reconstruction and then incorporated into PET MoCo reconstruction. For six patients with hepatic lesions, the performance of PET MoCo was evaluated using quantitative metrics (SUVmax , SUVpeak , SUVmean , lesion volume) and a blinded radiological review on lesion conspicuity. RESULTS MRI-assisted PET MoCo methods provided similar results to static scans across most lesions with varying TBRs in the phantom. Both MoCo2000 and MoCoP2P200 PET images had significantly higher SUVmax , SUVpeak , SUVmean and significantly lower lesion volume than non-motion-corrected (non-MoCo) PET images. There was no statistical difference between MoCo2000 and MoCoP2P200 PET images for SUVmax , SUVpeak , SUVmean or lesion volume. Both radiological reviewers found that MoCo2000 and MoCoP2P200 PET significantly improved lesion conspicuity. CONCLUSION An MRI-assisted PET MoCo method was evaluated using the ground truth in a phantom study. In patients with hepatic lesions, PET MoCo images improved quantitative and qualitative metrics based on only 30-40 s of MRI motion modeling data.
Collapse
Affiliation(s)
- Sihao Chen
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Tyler J. Fraum
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Cihat Eldeniz
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Joyce Mhlanga
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Weijie Gan
- Department of Computer Science & Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | | | | | - David Faul
- Siemens Medical Solutions USA, Inc., Malvern, PA, USA
| | - H. Michael Gach
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - Michael M. Binkley
- Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Ulugbek S. Kamilov
- Department of Computer Science & Engineering, Washington University in St. Louis, St. Louis, MO, USA
- Department of Electrical & Systems Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Richard Laforest
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Hongyu An
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Electrical & Systems Engineering, Washington University in St. Louis, St. Louis, MO, USA
| |
Collapse
|
3
|
Lamare F, Bousse A, Thielemans K, Liu C, Merlin T, Fayad H, Visvikis D. PET respiratory motion correction: quo vadis? Phys Med Biol 2021; 67. [PMID: 34915465 DOI: 10.1088/1361-6560/ac43fc] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 12/16/2021] [Indexed: 11/12/2022]
Abstract
Positron emission tomography (PET) respiratory motion correction has been a subject of great interest for the last twenty years, prompted mainly by the development of multimodality imaging devices such as PET/computed tomography (CT) and PET/magnetic resonance imaging (MRI). PET respiratory motion correction involves a number of steps including acquisition synchronization, motion estimation and finally motion correction. The synchronization steps include the use of different external device systems or data driven approaches which have been gaining ground over the last few years. Patient specific or generic motion models using the respiratory synchronized datasets can be subsequently derived and used for correction either in the image space or within the image reconstruction process. Similar overall approaches can be considered and have been proposed for both PET/CT and PET/MRI devices. Certain variations in the case of PET/MRI include the use of MRI specific sequences for the registration of respiratory motion information. The proposed review includes a comprehensive coverage of all these areas of development in field of PET respiratory motion for different multimodality imaging devices and approaches in terms of synchronization, estimation and subsequent motion correction. Finally, a section on perspectives including the potential clinical usage of these approaches is included.
Collapse
Affiliation(s)
- Frederic Lamare
- Nuclear Medicine Department, University Hospital Centre Bordeaux Hospital Group South, ., Bordeaux, Nouvelle-Aquitaine, 33604, FRANCE
| | - Alexandre Bousse
- LaTIM, INSERM UMR1101, Université de Bretagne Occidentale, ., Brest, Bretagne, 29285, FRANCE
| | - Kris Thielemans
- University College London Institute of Nuclear Medicine, UCL Hospital, Tower 5, 235 Euston Road, London, NW1 2BU, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Chi Liu
- Department of Diagnostic Radiology, Yale University School of Medicine Department of Radiology and Biomedical Imaging, PO Box 208048, 801 Howard Avenue, New Haven, Connecticut, 06520-8042, UNITED STATES
| | - Thibaut Merlin
- LaTIM, INSERM UMR1101, Universite de Bretagne Occidentale, ., Brest, Bretagne, 29285, FRANCE
| | - Hadi Fayad
- Weill Cornell Medicine - Qatar, ., Doha, ., QATAR
| | - Dimitris Visvikis
- LaTIM, UMR1101, Universite de Bretagne Occidentale, INSERM, Brest, Bretagne, 29285, FRANCE
| |
Collapse
|
4
|
Buzan MT, Wetscherek A, Rank CM, Kreuter M, Heussel CP, Kachelrieß M, Dinkel J. Delayed contrast dynamics as marker of regional impairment in pulmonary fibrosis using 5D MRI - a pilot study. Br J Radiol 2020; 93:20190121. [PMID: 32584606 DOI: 10.1259/bjr.20190121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
OBJECTIVE To analyse delayed contrast dynamics of fibrotic lesions in interstitial lung disease (ILD) using five dimensional (5D) MRI and to correlate contrast dynamics with disease severity. METHODS 20 patients (mean age: 71 years; M:F, 13:7), with chronic fibrosing ILD: n = 12 idiopathic pulmonary fibrosis (IPF) and n = 8 non-IPF, underwent thin-section multislice CT as part of the standard diagnostic workup and additionally MRI of the lung. 2 min after contrast injection, a radial gradient echo sequence with golden-angle spacing was acquired during 5 min of free-breathing, followed by 5D image reconstruction. Disease was categorized as severe or non-severe according to CT morphological regional severity. For each patient, 10 lesions were analysed. RESULTS IPF lesions showed later peak enhancement compared to non-IPF (severe: p = 0.01, non-severe: p = 0.003). Severe lesions showed later peak enhancement compared to non-severe lesions, in non-IPF (p = 0.04), but not in IPF (p = 0.35). There was a tendency towards higher accumulation and washout rates in IPF compared to non-IPF in non-severe disease. Severe lesions had lower washout rate than non-severe ones in both IPF (p = 0.003) and non-IPF (p = 0.005). Continuous contrast agent accumulation, without washout, was found only in IPF lesions. CONCLUSIONS Contrast agent dynamics are influenced by type and severity of pulmonary fibrosis, which might enable a more thorough characterisation of disease burden. The regional impairment is of particular interest in the context of antifibrotic treatments and was characterised using a non-invasive, non-irradiating, free-breathing method. ADVANCES IN KNOWLEDGE Delayed contrast enhancement patterns allow the assessment of regional lung impairment which could represent different disease stages or phenotypes in ILD.
Collapse
Affiliation(s)
- Maria Ta Buzan
- Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at Heidelberg University Hospital, Heidelberg, Germany.,Department of Pneumology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania.,Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany.,Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom
| | - Andreas Wetscherek
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom
| | - Christopher M Rank
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Michael Kreuter
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany.,Center for Rare and Interstitial Lung Diseases, Pneumology and respiratory critical care medicine, Thoraxklinik, Heidelberg University Hospital, Heidelberg, Germany
| | - Claus Peter Heussel
- Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at Heidelberg University Hospital, Heidelberg, Germany.,Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany.,Center for Rare and Interstitial Lung Diseases, Pneumology and respiratory critical care medicine, Thoraxklinik, Heidelberg University Hospital, Heidelberg, Germany
| | - Marc Kachelrieß
- Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Julien Dinkel
- Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at Heidelberg University Hospital, Heidelberg, Germany.,Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Munich, Germany.,Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research (DZL), Munich, Germany
| |
Collapse
|
5
|
Gratz M, Ruhlmann V, Umutlu L, Fenchel M, Hong I, Quick HH. Impact of respiratory motion correction on lesion visibility and quantification in thoracic PET/MR imaging. PLoS One 2020; 15:e0233209. [PMID: 32497135 PMCID: PMC7272064 DOI: 10.1371/journal.pone.0233209] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 04/30/2020] [Indexed: 01/04/2023] Open
Abstract
The impact of a method for MR-based respiratory motion correction of PET data on lesion visibility and quantification in patients with oncologic findings in the lung was evaluated. Twenty patients with one or more lesions in the lung were included. Hybrid imaging was performed on an integrated PET/MR system using 18F-FDG as radiotracer. The standard thoracic imaging protocol was extended by a free-breathing self-gated acquisition of MR data for motion modelling. PET data was acquired simultaneously in list-mode for 5-10 mins. One experienced radiologist and one experienced nuclear medicine specialist evaluated and compared the post-processed data in consensus regarding lesion visibility (scores 1-4, 4 being best), image noise levels (scores 1-3, 3 being lowest noise), SUVmean and SUVmax. Motion-corrected (MoCo) images were additionally compared with gated images. Non-motion-corrected free-breathing data served as standard of reference in this study. Motion correction generally improved lesion visibility (3.19 ± 0.63) and noise ratings (2.95 ± 0.22) compared to uncorrected (2.81 ± 0.66 and 2.95 ± 0.22, respectively) or gated PET data (2.47 ± 0.93 and 1.30 ± 0.47, respectively). Furthermore, SUVs (mean and max) were compared for all methods to estimate their respective impact on the quantification. Deviations of SUVmax were smallest between the uncorrected and the MoCo lesion data (average increase of 9.1% of MoCo SUVs), while SUVmean agreed best for gated and MoCo reconstructions (MoCo SUVs increased by 1.2%). The studied method for MR-based respiratory motion correction of PET data combines increased lesion sharpness and improved lesion activity quantification with high signal-to-noise ratio in a clinical setting. In particular, the detection of small lesions in moving organs such as the lung and liver may thus be facilitated. These advantages justify the extension of the PET/MR imaging protocol by 5-10 minutes for motion correction.
Collapse
Affiliation(s)
- Marcel Gratz
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg Essen, Essen, Germany
- High Field and Hybrid MR Imaging, University of Duisburg-Essen, Essen, 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
| | | | - Inki Hong
- Siemens Medical Solutions Inc, Knoxville, Tennessee, United States of America
| | - Harald H. Quick
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg Essen, Essen, Germany
- High Field and Hybrid MR Imaging, University of Duisburg-Essen, Essen, Germany
| |
Collapse
|
6
|
Zhu X, Chan M, Lustig M, Johnson KM, Larson PEZ. Iterative motion-compensation reconstruction ultra-short TE (iMoCo UTE) for high-resolution free-breathing pulmonary MRI. Magn Reson Med 2019; 83:1208-1221. [PMID: 31565817 DOI: 10.1002/mrm.27998] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/19/2019] [Accepted: 08/26/2019] [Indexed: 12/24/2022]
Abstract
PURPOSE To develop a high-scanning efficiency, motion-corrected imaging strategy for free-breathing pulmonary MRI by combining an iterative motion-compensation reconstruction with a ultrashort echo time (UTE) acquisition called iMoCo UTE. METHODS An optimized golden-angle ordering radial UTE sequence was used to continuously acquire data for 5 minutes. All readouts were grouped to different respiratory motion states based on self-navigator signals, and then motion-resolved data was reconstructed by XD golden-angle radial sparse parallel reconstruction. One state from the motion-resolved images was selected as a reference, and then motion fields from the other states to the reference were derived via nonrigid registration. Finally, all motion-resolved data and motion fields were reconstructed by using an iterative motion-compensation (MoCo) reconstruction with a total generalized variation sparse constraint. RESULTS The iMoCo UTE strategy was evaluated in volunteers and nonsedated pediatric patient (4-6 years old) studies. Images reconstructed with iMoCo UTE provided sharper anatomical lung structures and higher apparent SNR and contrast-to-noise ratio compared to using other motion-correction strategies, such as soft-gating, motion-resolved reconstruction, and nonrigid MoCo. iMoCo UTE also showed promising results in an infant study. CONCLUSION The proposed iMoCo UTE combines self-navigation, motion modeling, and a compressed sensing reconstruction to increase scan efficiency and SNR and to reduce respiratory motion in lung MRI. This proposed strategy shows improvements in free-breathing lung MRI scans, especially in very challenging application situations such as pediatric MRI studies.
Collapse
Affiliation(s)
- Xucheng Zhu
- UCSF/UC Berkeley Graduate Program in Bioengineering, University of California, San Francisco, California.,Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Marilynn Chan
- Department of Pediatrics, Division of Pediatric Pulmonology, University of California, San Francisco, California
| | - Michael Lustig
- UCSF/UC Berkeley Graduate Program in Bioengineering, University of California, San Francisco, California.,Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California
| | - Kevin M Johnson
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin.,Department of Radiology, University of Wisconsin, Madison, Wisconsin
| | - Peder E Z Larson
- UCSF/UC Berkeley Graduate Program in Bioengineering, University of California, San Francisco, California.,Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| |
Collapse
|
7
|
Lassen ML, Rasul S, Beitzke D, Stelzmüller ME, Cal-Gonzalez J, Hacker M, Beyer T. Assessment of attenuation correction for myocardial PET imaging using combined PET/MRI. J Nucl Cardiol 2019; 26:1107-1118. [PMID: 29168158 PMCID: PMC6660490 DOI: 10.1007/s12350-017-1118-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 10/18/2017] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To evaluate the frequency of artifacts in MR-based attenuation correction (AC) maps and their impact on the quantitative accuracy of PET-based flow and metabolism measurements in a cohort of consecutive heart failure patients undergoing combined PET/MR imaging. METHODS Myocardial viability studies were performed in 20 patients following a dual-tracer protocol involving the assessment of myocardial perfusion (13N-NH3: 813 ± 86 MBq) and metabolism (18F-FDG: 335 ± 38 MBq). All acquisitions were performed using a fully-integrated PET/MR system, with standard DIXON-attenuation correction (DIXON-AC) mapping for each PET scan. All AC maps were examined for spatial misalignment with the emission data, total lung volume, susceptibility artifacts, and tissue inversion (TI). Misalignment and susceptibility artifacts were corrected using rigid co-registration and retrospective filling of the susceptibility-induced gaps, respectively. The effects of the AC artifacts were evaluated by relative difference measures and perceived changes in clinical interpretations. RESULTS Average respiratory misalignment of (7 ± 4) mm of the PET-emission data and the AC maps was observed in 18 (90%) patients. Substantial changes in the lung volumes of the AC maps were observed in the test-retest analysis (ratio: 1.0 ± 0.2, range: 0.8-1.4). Susceptibility artifacts were observed in 10 (50%) patients, while six (30%) patients had TI artifacts. Average differences of 14 ± 10% were observed for PET images reconstructed with the artifactual AC maps. The combined artifact effects caused false-positive findings in three (15%) patients. CONCLUSION Standard DIXON-AC maps must be examined carefully for artifacts and misalignment effects prior to AC correction of cardiac PET/MRI studies in order to avoid misinterpretation of biased perfusion and metabolism readings from the PET data.
Collapse
Affiliation(s)
- Martin Lyngby Lassen
- QIMP Group, Center for Medical Physics and Biomedical Engineering, General Hospital Vienna, Medical University of Vienna, 1090, Vienna, Austria.
| | - Sazan Rasul
- Division of Nuclear Medicine, Department of Biomedical Engineering and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Dietrich Beitzke
- Division of Cardiovascular and Interventional Radiology, Department of Biomedical Engineering and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | | | - Jacobo Cal-Gonzalez
- QIMP Group, Center for Medical Physics and Biomedical Engineering, General Hospital Vienna, Medical University of Vienna, 1090, Vienna, Austria
| | - Marcus Hacker
- Division of Nuclear Medicine, Department of Biomedical Engineering and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Thomas Beyer
- QIMP Group, Center for Medical Physics and Biomedical Engineering, General Hospital Vienna, Medical University of Vienna, 1090, Vienna, Austria
| |
Collapse
|
8
|
Deng Z, Pang J, Lao Y, Bi X, Wang G, Chen Y, Fenchel M, Tuli R, Li D, Yang W, Fan Z. A post-processing method based on interphase motion correction and averaging to improve image quality of 4D magnetic resonance imaging: a clinical feasibility study. Br J Radiol 2019; 92:20180424. [PMID: 30604622 PMCID: PMC6541178 DOI: 10.1259/bjr.20180424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 10/26/2018] [Accepted: 12/11/2018] [Indexed: 11/05/2022] Open
Abstract
METHODS: Nine patients (seven pancreas, one liver, and one lung) were recruited. 4D-MRI was performed using two prototype k-space sorted techniques, stack-of-stars (SOS) and koosh-ball (KB) acquisitions. Post-processing using MoCoAve was implemented for both methods. Image quality score, apparent SNR (aSNR), sharpness, motion trajectory and standard deviation (σ_GTV) of the gross tumor volumes were compared between original and MoCoAve image sets. RESULTS: All subjects successfully underwent 4D-MRI scans and MoCoAve was performed on all data sets. Significantly higher image quality scores (2.64 ± 0.39 vs 1.18 ± 0.34, p = 0.001) and aSNR (37.6 ± 15.3 vs 18.1 ± 5.7, p = 0.001) was observed in the MoCoAve images when compared to the original images. High correlation in tumor motion trajectories in the superoinferior direction (SI: 0.91 ± 0.08) and weaker in the anteroposterior (AP: 0.51 ± 0.44) and mediolateral (ML: 0.37 ± 0.23) directions, similar image sharpness (0.367 ± 0.068 vs 0.369 ± 0.072, p = 0.805), and minimal average absolute difference (0.47 ± 0.34 mm) of the motion trajectory profiles was found between the two image sets. The σ_GTV in pancreas patients was significantly (p = 0.039) lower in MoCoAve images (1.48 ± 1.35 cm3) than in the original images (2.17 ± 1.31 cm3). CONCLUSION: MoCoAve using interphase motion correction and averaging has shown promise as a post-processing method for improving k-space sorted (SOS and KB) 4D-MRI image quality in thoracic and abdominal cancer patients. ADVANCES IN KNOWLEDGE: The proposed method is an image based post-processing method that could be applied to many k-space sorted 4D-MRI methods for improved image quality and signal-to-noise ratio while preserving image sharpness and respiratory motion fidelity. It is a useful technique for the radiotherapy planning community who are interested in using 4D-MRI but aren't satisfied with their current MR image quality.
Collapse
Affiliation(s)
- Zixin Deng
- Department of Biomedical Sciences, Biomedical Imaging Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | | | - Yi Lao
- Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Xiaoming Bi
- MR R&D, Siemens Healthineers, Los Angeles, CA, USA
| | - Guan Wang
- Department of Biomedical Sciences, Biomedical Imaging Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Yuhua Chen
- Department of Biomedical Sciences, Biomedical Imaging Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | | | - Richard Tuli
- Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | | | | | | |
Collapse
|
9
|
Smith DS, Sengupta S, Smith SA, Brian Welch E. Trajectory optimized NUFFT: Faster non-Cartesian MRI reconstruction through prior knowledge and parallel architectures. Magn Reson Med 2018; 81:2064-2071. [PMID: 30329181 PMCID: PMC6347498 DOI: 10.1002/mrm.27497] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/02/2018] [Accepted: 07/31/2018] [Indexed: 11/17/2022]
Abstract
Purpose The non‐uniform fast Fourier transform (NUFFT) involves interpolation of non‐uniformly sampled Fourier data onto a Cartesian grid, an interpolation that is slowed by complex, non‐local data access patterns. A faster NUFFT would increase the clinical relevance of the plethora of advanced non‐Cartesian acquisition methods. Methods Here we customize the NUFFT procedure for a radial trajectory and GPU architecture to eliminate the bottlenecks encountered when allowing for arbitrary trajectories and hardware. We call the result TRON, for TRajectory Optimized NUFFT. We benchmark the speed and accuracy TRON on a Shepp‐Logan phantom and on whole‐body continuous golden‐angle radial MRI. Results TRON was 6–30× faster than the closest competitor, depending on test data set, and was the most accurate code tested. Conclusions Specialization of the NUFFT algorithm for a particular trajectory yielded significant speed gains. TRON can be easily extended to other trajectories, such as spiral and PROPELLER. TRON can be downloaded at http://github.com/davidssmith/TRON.
Collapse
Affiliation(s)
- David S Smith
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Saikat Sengupta
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Seth A Smith
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - E Brian Welch
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| |
Collapse
|
10
|
Yang J, Liu J, Wiesinger F, Menini A, Zhu X, Hope TA, Seo Y, Larson PEZ. Developing an efficient phase-matched attenuation correction method for quiescent period PET in abdominal PET/MRI. Phys Med Biol 2018; 63:185002. [PMID: 30106008 DOI: 10.1088/1361-6560/aada26] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Respiratory motion causes misalignments between positron emission tomography (PET) and magnetic resonance (MR)-derived attenuation maps (µ-maps) in addition to artifacts on both PET and MR images in simultaneous PET/MRI for organs such as liver that can experience motion of several centimeters. To address this problem, we developed an efficient MR-based attenuation correction (MRAC) method to generate phase-matched µ-maps for quiescent period PET (PETQ) in abdominal PET/MRI. MRAC data was acquired with CIRcular Cartesian UnderSampling (CIRCUS) sampling during 100 s in free-breathing as an accelerated data acquisition strategy for phase-matched MRAC (MRACPM-CIRCUS). For comparison, MRAC data with raster (Default) k-space sampling was also acquired during 100 s in free-breathing (MRACPM-Default), and used to evaluate MRACPM-CIRCUS as well as un-matched MRAC (MRACUM) that was un-gated. We purposefully oversampled the MRACPM data to ensure we had enough information to capture all respiratory phases to make this comparison as robust as possible. The proposed MRACPM-CIRCUS was evaluated in 17 patients with 68Ga-DOTA-TOC PET/MRI exams, suspected of having neuroendocrine tumors or liver metastases. Effects of CIRCUS sampling for accelerating a data acquisition were evaluated by simulating the data acquisition time retrospectively in increments of 5 s. Effects of MRACPM-CIRCUS on PETQ were evaluated using uptake differences in the liver lesions (n = 35), compared to PETQ with MRACPM-Default and MRACUM. A Wilcoxon signed-rank test was performed to compare lesion uptakes between the MRAC methods. MRACPM-CIRCUS showed higher image quality compared to MRACPM-Default for the same acquisition times, demonstrating that a data acquisition time of 30 s was reasonable to achieve phase-matched µ-maps. Lesion update differences between MRACPM-CIRCUS (30 s) versus MRACPM-Default (reference, 100 s) were 0.1% ± 1.4% (range of -2.7% to 3.2%) and not significant (P > .05); while, the differences between MRACUM versus MRACPM-Default were 0.6% ± 11.4% with a large variation (range of -37% to 20%) and significant (P < .05). In conclusion, we demonstrated that a data acquisition of 30 s achieved phase-matched µ-maps when using specialized CIRCUS data sampling and phase-matched µ-maps improved PETQ quantification significantly.
Collapse
Affiliation(s)
- Jaewon Yang
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, United States of America. UCSF Physics Research Laboratory, 185 Berry Street, Suite 350, San Francisco, CA 94143-0946, United States of America. Author to whom any correspondence should be addressed
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Deng Z, Yang W, Pang J, Bi X, Tuli R, Li D, Fan Z. Improved vessel-tissue contrast and image quality in 3D radial sampling-based 4D-MRI. J Appl Clin Med Phys 2017; 18:250-257. [PMID: 28980395 PMCID: PMC5689937 DOI: 10.1002/acm2.12194] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/21/2017] [Accepted: 08/27/2017] [Indexed: 12/26/2022] Open
Abstract
Purpose In radiation treatment planning for thoracic and abdominal tumors, 4D‐MRI has shown promise in respiratory motion characterization with improved soft‐tissue contrast compared to clinical standard, 4D computed tomography (4D‐CT). This study aimed to further improve vessel–tissue contrast and overall image quality in 3D radial sampling‐based 4D‐MRI using a slab‐selective (SS) excitation approach. Methods The technique was implemented in a 3D radial sampling with self‐gating‐based k‐space sorting sequence. The SS excitation approach was compared to a non‐selective (NS) approach in six cancer patients and two healthy volunteers at 3T. Improvements in vessel–tissue contrast ratio (CR) and vessel signal‐to‐noise ratio (SNR) were analyzed in five of the eight subjects. Image quality was visually assessed in all subjects on a 4‐point scale (0: poor; 3: excellent). Tumor (patients) and pancreas (healthy) motion trajectories were compared between the two imaging approaches. Results Compared with NS‐4D‐MRI, SS‐4D‐MRI significantly improved the overall vessel–tissue CR (2.60 ± 3.97 vs. 1.03 ± 1.44, P < 0.05), SNR (63.33 ± 38.45 vs. 35.74 ± 28.59, P < 0.05), and image quality score (2.6 ± 0.5 vs. 1.4 ± 0.5, P = 0.02). Motion trajectories from the two approaches exhibited strong correlation in the superior–inferior (0.96 ± 0.06), but weaker in the anterior–posterior (0.78 ± 0.24) and medial–lateral directions (0.46 ± 0.44). Conclusions The proposed 4D‐MRI with slab‐selectively excited 3D radial sampling allows for improved blood SNR, vessel–tissue CR, and image quality.
Collapse
Affiliation(s)
- Zixin Deng
- Department of Biomedical Sciences, Biomedical Imaging Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA.,Department of Bioengineering, University of California, Los Angeles, CA, USA
| | - Wensha Yang
- Department of Biomedical Sciences, Biomedical Imaging Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA.,Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Jianing Pang
- Department of Biomedical Sciences, Biomedical Imaging Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA.,MR R&D, Siemens Healthineers, Chicago, IL, USA
| | - Xiaoming Bi
- MR R&D, Siemens Healthineers, Los Angeles, CA, USA
| | - Richard Tuli
- Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Debiao Li
- Department of Biomedical Sciences, Biomedical Imaging Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA.,Department of Bioengineering, University of California, Los Angeles, CA, USA.,Department of Medicine, University of California, Los Angeles, CA, USA
| | - Zhaoyang Fan
- Department of Biomedical Sciences, Biomedical Imaging Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA.,Department of Medicine, University of California, Los Angeles, CA, USA
| |
Collapse
|
12
|
Robson PM, Dey D, Newby DE, Berman D, Li D, Fayad ZA, Dweck MR. MR/PET Imaging of the Cardiovascular System. JACC Cardiovasc Imaging 2017; 10:1165-1179. [PMID: 28982570 PMCID: PMC6415529 DOI: 10.1016/j.jcmg.2017.07.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/26/2017] [Accepted: 07/27/2017] [Indexed: 12/11/2022]
Abstract
Cardiovascular imaging has largely focused on identifying structural, functional, and metabolic changes in the heart. The ability to reliably assess disease activity would have major potential clinical advantages, including the identification of early disease, differentiating active from stable conditions, and monitoring disease progression or response to therapy. Positron emission tomography (PET) imaging now allows such assessments of disease activity to be acquired in the heart, whereas magnetic resonance (MR) scanning provides detailed anatomic imaging and tissue characterization. Hybrid MR/PET scanners therefore combine the strengths of 2 already powerful imaging modalities. Simultaneous acquisition of the 2 scans also provides added benefits, including improved scanning efficiency, motion correction, and partial volume correction. Radiation exposure is lower than with hybrid PET/computed tomography scanning, which might be particularly beneficial in younger patients who may need repeated scans. The present review discusses the expanding clinical literature investigating MR/PET imaging, highlights its advantages and limitations, and explores future potential applications.
Collapse
Affiliation(s)
- Philip M Robson
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Damini Dey
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | - David E Newby
- British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, United Kingdom
| | - Daniel Berman
- Departments of Imaging and Medicine, Cedars-Sinai Medical Center, Los Angeles, California
| | - Debiao Li
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | - Zahi A Fayad
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Marc R Dweck
- British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, United Kingdom.
| |
Collapse
|
13
|
Boada FE, Koesters T, Block KT, Chandarana H. Improved Detection of Small Pulmonary Nodules Through Simultaneous MR/PET Imaging. Magn Reson Imaging Clin N Am 2017; 25:273-279. [PMID: 28390528 DOI: 10.1016/j.mric.2016.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Magnetic resonance (MR)/PET scanners provide an imaging platform that enables simultaneous acquisition of MR and PET data in perfect spatial and temporal registration. This feature allows improving image quality for the MR and PET images obtained during the course of an examination. In this work the authors demonstrate the use of prospective MR-based motion tracking information for removing motion blur in MR/PET images of small pulmonary nodules. The theoretical basis for the algorithms is presented alongside clinical examples of its use.
Collapse
Affiliation(s)
- Fernando E Boada
- Department of Radiology, Center for Advanced Imaging Innovation and Research, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA.
| | - Thomas Koesters
- Department of Radiology, Center for Advanced Imaging Innovation and Research, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA
| | - Kai Tobias Block
- Department of Radiology, Center for Advanced Imaging Innovation and Research, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA
| | - Hersh Chandarana
- Department of Radiology, Center for Advanced Imaging Innovation and Research, New York University Langone Medical Center, 660 First Avenue, New York, NY 10016, USA
| |
Collapse
|
14
|
Dutta J, Huang C, Li Q, El Fakhri G. Pulmonary imaging using respiratory motion compensated simultaneous PET/MR. Med Phys 2016; 42:4227-40. [PMID: 26133621 DOI: 10.1118/1.4921616] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Pulmonary positron emission tomography (PET) imaging is confounded by blurring artifacts caused by respiratory motion. These artifacts degrade both image quality and quantitative accuracy. In this paper, the authors present a complete data acquisition and processing framework for respiratory motion compensated image reconstruction (MCIR) using simultaneous whole body PET/magnetic resonance (MR) and validate it through simulation and clinical patient studies. METHODS The authors have developed an MCIR framework based on maximum a posteriori or MAP estimation. For fast acquisition of high quality 4D MR images, the authors developed a novel Golden-angle RAdial Navigated Gradient Echo (GRANGE) pulse sequence and used it in conjunction with sparsity-enforcing k-t FOCUSS reconstruction. The authors use a 1D slice-projection navigator signal encapsulated within this pulse sequence along with a histogram-based gate assignment technique to retrospectively sort the MR and PET data into individual gates. The authors compute deformation fields for each gate via nonrigid registration. The deformation fields are incorporated into the PET data model as well as utilized for generating dynamic attenuation maps. The framework was validated using simulation studies on the 4D XCAT phantom and three clinical patient studies that were performed on the Biograph mMR, a simultaneous whole body PET/MR scanner. RESULTS The authors compared MCIR (MC) results with ungated (UG) and one-gate (OG) reconstruction results. The XCAT study revealed contrast-to-noise ratio (CNR) improvements for MC relative to UG in the range of 21%-107% for 14 mm diameter lung lesions and 39%-120% for 10 mm diameter lung lesions. A strategy for regularization parameter selection was proposed, validated using XCAT simulations, and applied to the clinical studies. The authors' results show that the MC image yields 19%-190% increase in the CNR of high-intensity features of interest affected by respiratory motion relative to UG and a 6%-51% increase relative to OG. CONCLUSIONS Standalone MR is not the traditional choice for lung scans due to the low proton density, high magnetic susceptibility, and low T2 (∗) relaxation time in the lungs. By developing and validating this PET/MR pulmonary imaging framework, the authors show that simultaneous PET/MR, unique in its capability of combining structural information from MR with functional information from PET, shows promise in pulmonary imaging.
Collapse
Affiliation(s)
- Joyita Dutta
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Chuan Huang
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114; Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115; and Departments of Radiology and Psychiatry, Stony Brook Medicine, Stony Brook, New York 11794
| | - Quanzheng Li
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Georges El Fakhri
- Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115
| |
Collapse
|
15
|
Abstract
Subject motion is unavoidable in clinical and research imaging studies. Breathing is the most important source of motion in whole-body PET and MRI studies, affecting not only thoracic organs but also those in the upper and even lower abdomen. The motion related to the pumping action of the heart is obviously relevant in high-resolution cardiac studies. These two sources of motion are periodic and predictable, at least to a first approximation, which means certain techniques can be used to control the motion (eg, by acquiring the data when the organ of interest is relatively at rest). Additionally, nonperiodic and unpredictable motion can also occur during the scan. One obvious limitation of methods relying on external devices (eg, respiratory bellows or the electrocardiogram signal to monitor the respiratory or cardiac cycle, respectively) to trigger or gate the data acquisition is that the complex motion of internal organs cannot be fully characterized. However, detailed information can be obtained using either the PET or MRI data (or both) allowing the more complete characterization of the motion field so that a motion model can be built. Such a model and the information derived from simple external devices can be used to minimize the effects of motion on the collected data. In the ideal case, all the events recorded during the PET scan would be used to generate a motion-free or corrected PET image. The detailed motion field can be used for this purpose by applying it to the PET data before, during, or after the image reconstruction. Integrating all these methods for motion control, characterization, and correction into a workflow that can be used for routine clinical studies is challenging but could potentially be extremely valuable given the improvement in image quality and reduction of motion-related image artifacts.
Collapse
Affiliation(s)
- Ciprian Catana
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA.
| |
Collapse
|
16
|
Hope TA, Verdin EF, Bergsland EK, Ohliger MA, Corvera CU, Nakakura EK. Correcting for respiratory motion in liver PET/MRI: preliminary evaluation of the utility of bellows and navigated hepatobiliary phase imaging. EJNMMI Phys 2015; 2:21. [PMID: 26501822 PMCID: PMC4573645 DOI: 10.1186/s40658-015-0125-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/11/2015] [Indexed: 12/21/2022] Open
Abstract
Background The purpose of this study was to evaluate the utility of bellows-based respiratory compensation and navigated hepatobiliary phase imaging to correct for respiratory motion in the setting of dedicated liver PET/MRI. Methods Institutional review board approval and informed consent were obtained. Six patients with metastatic neuroendocrine tumor were imaged using Ga-68 DOTA-TOC PET/MRI. Whole body imaging and a dedicated 15-min liver PET acquisition was performed, in addition to navigated and breath-held hepatobiliary phase (HBP) MRI. Liver PET data was reconstructed three ways: the entire data set (liver PET), gated using respiratory bellows (RC-liver PET), and a non-gated data set reconstructed using the same amount of data used in the RC-liver PET (shortened liver PET). Liver lesions were evaluated using SUVmax, SUVpeak, SUVmean, and Volisocontour. Additionally, the displacement of each lesion between the RC-liver PET images and the navigated and breath-held HBP images was calculated. Results Respiratory compensation resulted in a 43 % increase in SUVs compared to ungated data (liver vs RC-liver PET SUVmax 26.0 vs 37.3, p < 0.001) and a 25 % increase compared to a non-gated reconstruction using the same amount of data (RC-liver vs shortened liver PET SUVmax 26.0 vs 32.6, p < 0.001). Lesion displacement was minimized using navigated HBP MRI (1.3 ± 1.0 mm) compared to breath-held HBP MRI (23.3 ± 1.0 mm). Conclusions Respiratory bellows can provide accurate respiratory compensation when imaging liver lesions using PET/MRI, and results in increased SUVs due to a combination of increased image noise and reduced respiratory blurring. Additionally, navigated HBP MRI accurately aligns with respiratory compensated PET data.
Collapse
Affiliation(s)
- Thomas A Hope
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA. .,Department of Radiology, San Francisco VA Medical Center, San Francisco, CA, USA.
| | - Emily F Verdin
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Emily K Bergsland
- Division of Hematology/Oncology, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Michael A Ohliger
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA.,Department of Radiology, San Francisco General Hospital, San Francisco, CA, USA
| | - Carlos U Corvera
- Division of Surgical Oncology, Department of Surgery, University of California, San Francisco, San Francisco, CA, USA
| | - Eric K Nakakura
- Division of Surgical Oncology, Department of Surgery, University of California, San Francisco, San Francisco, CA, USA
| |
Collapse
|
17
|
Grimm R, Fürst S, Souvatzoglou M, Forman C, Hutter J, Dregely I, Ziegler SI, Kiefer B, Hornegger J, Block KT, Nekolla SG. Self-gated MRI motion modeling for respiratory motion compensation in integrated PET/MRI. Med Image Anal 2015; 19:110-20. [PMID: 25461331 DOI: 10.1016/j.media.2014.08.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 08/27/2014] [Accepted: 08/30/2014] [Indexed: 11/25/2022]
|
18
|
Ramalho M, AlObaidy M, Catalano OA, Guimaraes AR, Salvatore M, Semelka RC. MR-PET of the body: Early experience and insights. Eur J Radiol Open 2014; 1:28-39. [PMID: 26937425 PMCID: PMC4750620 DOI: 10.1016/j.ejro.2014.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 09/01/2014] [Indexed: 12/19/2022] Open
Abstract
MR-PET is a novel imaging modality that combines anatomic and metabolic data acquisition, allowing for simultaneous depiction of morphological and functional abnormalities with an excellent soft tissue contrast and good spatial resolution; as well as accurate temporal and spatial image fusion; while substantially reducing radiation dose when compared with PET-CT. In this review, we will discuss MR-PET basic principles and technical challenges and limitations, explore some practical considerations, and cover the main clinical applications, while shedding some light on some of the future trends regarding this new imaging technique.
Collapse
Affiliation(s)
- Miguel Ramalho
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mamdoh AlObaidy
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Onofrio A Catalano
- Department of Radiology, SDN-IRCCS and University of Naples "Parthenope", Naples, Italy
| | | | - Marco Salvatore
- Department of Radiology, University of Naples "Federico II", Naples, Italy
| | - Richard C Semelka
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| |
Collapse
|
19
|
Fieseler M, Kösters T, Glielmi C, Boada F, Faul D, Fenchel M, Grimm R, Jiang X, Schäfers KP. Motion estimation in PET-MRI based on dual registration: preliminary results for human data. EJNMMI Phys 2014; 1:A39. [PMID: 26501626 PMCID: PMC4545218 DOI: 10.1186/2197-7364-1-s1-a39] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
- Michael Fieseler
- European Institute for Molecular Imaging, University of Münster, Münster, Germany.,Department of Computer Science, University of Münster, Münster, Germany
| | - Thomas Kösters
- Center for Advanced Imaging Innovation and Research, NYU Langone Medical Center, New York, USA
| | | | - Fernando Boada
- Center for Advanced Imaging Innovation and Research, NYU Langone Medical Center, New York, USA
| | - David Faul
- Siemens Medical Solutions USA, New York, USA
| | | | - Robert Grimm
- Pattern Recognition Lab, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Xiaoyi Jiang
- European Institute for Molecular Imaging, University of Münster, Münster, Germany.,Department of Computer Science, University of Münster, Münster, Germany
| | - Klaus P Schäfers
- European Institute for Molecular Imaging, University of Münster, Münster, Germany
| |
Collapse
|