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Accelerated Simultaneous T 2 and T 2* Mapping of Multiple Sclerosis Lesions Using Compressed Sensing Reconstruction of Radial RARE-EPI MRI. Tomography 2023; 9:299-314. [PMID: 36828376 PMCID: PMC9960840 DOI: 10.3390/tomography9010024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/26/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
(1) Background: Radial RARE-EPI MRI facilitates simultaneous T2 and T2* mapping (2in1-RARE-EPI). With modest undersampling (R = 2), the speed gain of 2in1-RARE-EPI relative to Multi-Spin-Echo and Multi-Gradient-Recalled-Echo references is limited. Further reduction in scan time is crucial for clinical studies investigating T2 and T2* as imaging biomarkers. We demonstrate the feasibility of further acceleration, utilizing compressed sensing (CS) reconstruction of highly undersampled 2in1-RARE-EPI. (2) Methods: Two-fold radially-undersampled 2in1-RARE-EPI data from phantoms, healthy volunteers (n = 3), and multiple sclerosis patients (n = 4) were used as references, and undersampled (Rextra = 1-12, effective undersampling Reff = 2-24). For each echo time, images were reconstructed using CS-reconstruction. For T2 (RARE module) and T2* mapping (EPI module), a linear least-square fit was applied to the images. T2 and T2* from CS-reconstruction of undersampled data were benchmarked against values from CS-reconstruction of the reference data. (3) Results: We demonstrate accelerated simultaneous T2 and T2* mapping using undersampled 2in1-RARE-EPI with CS-reconstruction is feasible. For Rextra = 6 (TA = 01:39 min), the overall MAPE was ≤8% (T2*) and ≤4% (T2); for Rextra = 12 (TA = 01:06 min), the overall MAPE was <13% (T2*) and <5% (T2). (4) Conclusion: Substantial reductions in scan time are achievable for simultaneous T2 and T2* mapping of the brain using highly undersampled 2in1-RARE-EPI with CS-reconstruction.
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Ilbey S, Jungmann PM, Fischer J, Jung M, Bock M, Özen AC. Single point imaging with radial acquisition and compressed sensing. Magn Reson Med 2022; 87:2685-2696. [PMID: 35037292 DOI: 10.1002/mrm.29156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/26/2021] [Accepted: 12/23/2021] [Indexed: 12/22/2022]
Abstract
PURPOSE To accelerate the Pointwise Encoding Time Reduction with Radial Acquisition (PETRA) sequence using compressed sensing while preserving the image quality for high-resolution MRI of tissue with ultra-short T 2 ∗ values. METHODS Compressed sensing was introduced in the PETRA sequence (csPETRA) to accelerate the time-consuming single point acquisition of the k-space center data. Random undersampling was applied to achieve acceleration factors up to Acc = 32. Phantom and in vivo images of the knee joint of six volunteers were measured at 3T using csPETRA sequence with Acc = 4, 8, 12, 16, 24, and 32. Images were compared against fully sampled PETRA data (Acc = 1) for structural similarity and normalized-mean-square-error. Qualitative and semi-quantitative analyses were performed to assess the effect of the acceleration on image artifacts, image quality, and delineation of anatomical structures at the knee. RESULTS Even at high acceleration factors of Acc = 16 no aliasing artifacts were observed, and the anatomical details were preserved compared with the fully sampled data. The normalized-mean-square-error was less than 1% for Acc = 16, in which single point imaging acquisition time was reduced from 165 to 10 s, reducing the total scan time from 7.8 to 5.2 min. Semi-quantitative analyses suggest that Acc = 16 yields comparable diagnostic quality as the fully sampled data for knee imaging at a scan time of 5.2 min. CONCLUSION csPETRA allows for ultra-short T 2 ∗ imaging of the knee joint in clinically acceptable scan times while maintaining the image quality of original non-accelerated PETRA sequence.
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Affiliation(s)
- Serhat Ilbey
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Pia M Jungmann
- Department of Diagnostic and Interventional Radiology, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Department of Radiology, Cantonal Hospital Grisons, Chur, Switzerland
| | - Johannes Fischer
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Matthias Jung
- Department of Diagnostic and Interventional Radiology, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Bock
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ali Caglar Özen
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Haber-Pohlmeier S, Caterina D, Blümich B, Pohlmeier A. Magnetic Resonance Imaging of Water Content and Flow Processes in Natural Soils by Pulse Sequences with Ultrashort Detection. Molecules 2021; 26:molecules26175130. [PMID: 34500563 PMCID: PMC8433766 DOI: 10.3390/molecules26175130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/16/2021] [Accepted: 08/17/2021] [Indexed: 11/17/2022] Open
Abstract
Magnetic resonance imaging is a valuable tool for three-dimensional mapping of soil water processes due to its sensitivity to the substance of interest: water. Since conventional gradient- or spin-echo based pulse sequences do not detect rapidly relaxing fractions of water in natural porous media with transverse relaxation times in the millisecond range, pulse sequences with ultrafast detection open a way out. In this work, we compare a spin-echo multislice pulse sequence with ultrashort (UTE) and zero-TE (ZTE) sequences for their suitability to map water content and its changes in 3D in natural soil materials. Longitudinal and transverse relaxation times were found in the ranges around 80 ms and 1 to 50 ms, respectively, so that the spin echo sequence misses larger fractions of water. In contrast, ZTE and UTE could detect all water, if the excitation and detection bandwidths were set sufficiently broad. More precisely, with ZTE we could map water contents down to 0.1 cm3/cm3. Finally, we employed ZTE to monitor the development of film flow in a natural soil core with high temporal resolution. This opens the route for further quantitative imaging of soil water processes.
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Affiliation(s)
- Sabina Haber-Pohlmeier
- Institute for Modelling Hydraulic and Environmental Systems, University of Stuttgart, Pfaffenwaldring 61, D-70569 Stuttgart, Germany;
| | - David Caterina
- Institute for Bio- and Geosciences Agrosphere (IBG-3), Research Center Jülich, D-52425 Jülich, Germany;
- Département UEE, Faculté des Sciences Appliquées, Université de Liège, B-4000 Liège, Belgium
| | - Bernhard Blümich
- Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringer Weg 2, D-52074 Aachen, Germany;
| | - Andreas Pohlmeier
- Institute for Bio- and Geosciences Agrosphere (IBG-3), Research Center Jülich, D-52425 Jülich, Germany;
- Correspondence:
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Marriott A, Bowen C, Rioux J, Brewer K. Simultaneous quantification of SPIO and gadolinium contrast agents using MR fingerprinting. Magn Reson Imaging 2021; 79:121-129. [PMID: 33774098 DOI: 10.1016/j.mri.2021.03.017] [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: 10/23/2020] [Revised: 03/22/2021] [Accepted: 03/22/2021] [Indexed: 11/16/2022]
Abstract
PURPOSE Develop a magnetic resonance fingerprinting (MRF) methodology with R2∗ quantification, intended for use with simultaneous contrast agent concentration mapping, particularly gadolinium (Gd) and iron labelled CD8+ T cells. METHODS Variable-density spiral SSFP MRF was used, modified to allow variable TE, and with an exp.(-TE·R2∗) dictionary modulation. In vitro phantoms containing SPIO labelled cells and/or gadolinium were used to validate parameter maps, probe undersampling capacity, and verify dual quantification capabilities. A C57BL/6 mouse was imaged using MRF to demonstrate acceptable in vivo resolution and signal at 8× undersampling necessary for a 25-min scan. RESULTS Strong agreement was found between conventional and MRF-derived values for R1, R2, and R2∗. Expanded MRF allowed quantification of iron-loaded CD8+ T cells. Results were robust to 8× undersampling and enabled recreation of relaxation profiles for both a Gd agent and iron labelled cells simultaneously. In vivo data demonstrated sufficient SNR in undersampled data for parameter mapping to visualise key features. CONCLUSION MRF can be expanded to include R1, R2, and R2∗ mapping required for simultaneous quantification of gadolinium and SPIO in vitro, allowing for potential implementation of a variety of future in vivo studies using dual MR contrast agents, including molecular imaging of labelled cells.
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Affiliation(s)
- Anna Marriott
- Biomedical Translational Imaging Centre (BIOTIC), Halifax, NS, Canada; Dalhousie University, Halifax, NS, Canada
| | - Chris Bowen
- Biomedical Translational Imaging Centre (BIOTIC), Halifax, NS, Canada; Dalhousie University, Halifax, NS, Canada
| | - James Rioux
- Biomedical Translational Imaging Centre (BIOTIC), Halifax, NS, Canada; Dalhousie University, Halifax, NS, Canada
| | - Kimberly Brewer
- Biomedical Translational Imaging Centre (BIOTIC), Halifax, NS, Canada; Dalhousie University, Halifax, NS, Canada.
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Tremblay ML, O’Brien-Moran Z, Rioux JA, Nuschke A, Davis C, Kast WM, Weir G, Stanford M, Brewer KD. Quantitative MRI cell tracking of immune cell recruitment to tumors and draining lymph nodes in response to anti-PD-1 and a DPX-based immunotherapy. Oncoimmunology 2020; 9:1851539. [PMID: 33299663 PMCID: PMC7714509 DOI: 10.1080/2162402x.2020.1851539] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/11/2020] [Accepted: 11/11/2020] [Indexed: 11/01/2022] Open
Abstract
DPX is a unique T cell activating formulation that generates robust immune responses (both clinically and preclinically) which can be tailored to various cancers via the use of tumor-specific antigens and adjuvants. While DPX-based immunotherapies may act complementary with checkpoint inhibitors, combination therapy is not always easily predictable based on individual therapeutic responses. Optimizing these combinations can be improved by understanding the mechanism of action underlying the individual therapies. Magnetic Resonance Imaging (MRI) allows tracking of cells labeled with superparamagnetic iron oxide (SPIO), which can yield valuable information about the localization of crucial immune cell subsets. In this work, we evaluated the use of a multi-echo, single point MRI pulse sequence, TurboSPI, for tracking and quantifying cytotoxic T lymphocytes (CTLs) and myeloid lineage cells (MLCs). In a subcutaneous cervical cancer model (C3) we compared untreated mice to mice treated with either a single therapy (anti-PD-1 or DPX-R9F) or a combination of both therapies. We were able to detect, using TurboSPI, significant increases in CTL recruitment dynamics in response to combination therapy. We also observed differences in MLC recruitment to therapy-draining (DPX-R9F) lymph nodes in response to treatment with DPX-R9F (alone or in combination with anti-PD-1). We demonstrated that the therapies presented herein induced time-varying changes in cell recruitment. This work establishes that these quantitative molecular MRI techniques can be expanded to study a number of cancer and immunotherapy combinations to improve our understanding of longitudinal immunological changes and mechanisms of action.
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Affiliation(s)
- Marie-Laurence Tremblay
- Biomedical Translational Imaging Centre (BIOTIC, IWK Health Centre, Halifax, NS, Canada
- Dalhousie University, Halifax, NS, Canada
- IMV Inc, Halifax, NS, Canada
| | - Zoe O’Brien-Moran
- Biomedical Translational Imaging Centre (BIOTIC, IWK Health Centre, Halifax, NS, Canada
- Department of Physics, Dalhousie University, Halifax, NS, Canada
| | - James A. Rioux
- Biomedical Translational Imaging Centre (BIOTIC, IWK Health Centre, Halifax, NS, Canada
- Department of Physics, Dalhousie University, Halifax, NS, Canada
- Department of Diagnostic Radiology, Dalhousie University, Halifax, NS, Canada
| | - Andrea Nuschke
- Biomedical Translational Imaging Centre (BIOTIC, IWK Health Centre, Halifax, NS, Canada
| | - Christa Davis
- Biomedical Translational Imaging Centre (BIOTIC, IWK Health Centre, Halifax, NS, Canada
| | - W. Martin Kast
- Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | | | - Marianne Stanford
- Dalhousie University, Halifax, NS, Canada
- IMV Inc, Halifax, NS, Canada
| | - Kimberly D. Brewer
- Biomedical Translational Imaging Centre (BIOTIC, IWK Health Centre, Halifax, NS, Canada
- Dalhousie University, Halifax, NS, Canada
- Department of Physics, Dalhousie University, Halifax, NS, Canada
- Department of Diagnostic Radiology, Dalhousie University, Halifax, NS, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
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O'Brien-Moran Z, Bowen CV, Rioux JA, Brewer KD. Cell density quantification with TurboSPI: R 2* mapping with compensation for off-resonance fat modulation. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2019; 33:469-481. [PMID: 31872356 DOI: 10.1007/s10334-019-00817-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/10/2019] [Accepted: 12/12/2019] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Tracking the migration of superparamagnetic iron oxide (SPIO)-labeled immune cells in vivo is valuable for understanding the immunogenic response to cancer and therapies. Quantitative cell tracking using TurboSPI-based R2* mapping is a promising development to improve accuracy in longitudinal studies on immune recruitment. However, off-resonance fat signal isochromats lead to modulations in the signal time-course that can be erroneously fit as R2* signal decay, overestimating the density of labeled cells, while excluding voxels with fat-typical modulations results in underestimation of cell density in voxels with mixed content. Approaches capable of accurate R2* estimation in the presence of fat are needed. METHODS We propose a dual-decay (separate R2f* and R2w* for fat and water) Dixon-based signal model that accounts for the presence of fat in a voxel to provide better estimates of SPIO-induced dephasing. This model was tested in silico, in phantoms with varying quantities of fat and SPIO-labeled cells, and in 5 mice injected with SPIO-labeled CD8+ T cells. RESULTS In silico single voxel simulations illustrate how the proposed dual-decay model provides stable R2w* estimates that are invariant to fat content. The proposed model outperforms previous methods when applied to in vitro samples of SPIO-labeled cells and oil prepared with oil content ≥ 15%. Preliminary in vivo results show that, compared to previous methods, the dual-decay model improves the balance of R2* mapping in fat-dense areas, which will yield more reliable analysis in future cell tracking studies. DISCUSSION The proposed model is a promising tool for quantitative TurboSPI R2* cell tracking, with further refinements offering the possibility of better specificity and sensitivity.
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Affiliation(s)
- Zoe O'Brien-Moran
- Biomedical Translational Imaging Centre, IWK Health Centre and Nova Scotia Health Authority, Halifax, NS, Canada.,Dalhousie University, Halifax, NS, Canada
| | - Chris Van Bowen
- Biomedical Translational Imaging Centre, IWK Health Centre and Nova Scotia Health Authority, Halifax, NS, Canada.,Dalhousie University, Halifax, NS, Canada
| | - James Allen Rioux
- Biomedical Translational Imaging Centre, IWK Health Centre and Nova Scotia Health Authority, Halifax, NS, Canada.,Dalhousie University, Halifax, NS, Canada
| | - Kimberly Dawn Brewer
- Biomedical Translational Imaging Centre, IWK Health Centre and Nova Scotia Health Authority, Halifax, NS, Canada. .,Dalhousie University, Halifax, NS, Canada.
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Węglarz WP, Krzyżak A, Machowski G, Stefaniuk M. ZTE MRI in high magnetic field as a time effective 3D imaging technique for monitoring water ingress in porous rocks at sub-millimetre resolution. Magn Reson Imaging 2018; 47:54-59. [DOI: 10.1016/j.mri.2017.11.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 11/16/2017] [Accepted: 11/21/2017] [Indexed: 10/18/2022]
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Speidel T, Paul J, Wundrak S, Rasche V. Quasi-Random Single-Point Imaging Using Low-Discrepancy $k$ -Space Sampling. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:473-479. [PMID: 28991736 DOI: 10.1109/tmi.2017.2760919] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Magnetic resonance imaging of short relaxation time spin systems has been a widely discussed topic with serious clinical applications and led to the emergence of fast imaging ultra-short echo-time sequences. Nevertheless, these sequences suffer from image blurring, due to the related sampling point spread function and are highly prone to imaging artefacts arising from, e.g., chemical shifts or magnetic susceptibilities. In this paper, we present a concept of spherical quasi-random single-point imaging. The approach is highly accelerateable, due to intrinsic undersampling properties and capable of strong metal artefact suppression. Imaging acceleration is achieved by sampling of quasi-random points in -space, based on a low-discrepancy sequence, and a combination with non-linear optimization reconstruction techniques [compressed sensing (CS)]. The presented low-discrepancy trajectory shows ideal noise like undersampling properties for the combination with CS, leading to denoised images with excellent metal artefact reduction. Using eightfold undersampling, acquisition time of a few minutes can be achieved for volume acquisitions.
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Tremblay ML, Davis C, Bowen CV, Stanley O, Parsons C, Weir G, Karkada M, Stanford MM, Brewer KD. Using MRI cell tracking to monitor immune cell recruitment in response to a peptide-based cancer vaccine. Magn Reson Med 2017; 80:304-316. [PMID: 29193231 DOI: 10.1002/mrm.27018] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/26/2017] [Accepted: 10/28/2017] [Indexed: 12/18/2022]
Abstract
PURPOSE MRI cell tracking can be used to monitor immune cells involved in the immunotherapy response, providing insight into the mechanism of action, temporal progression of tumor growth, and individual potency of therapies. To evaluate whether MRI could be used to track immune cell populations in response to immunotherapy, CD8+ cytotoxic T cells, CD4+ CD25+ FoxP3+ regulatory T cells, and myeloid-derived suppressor cells were labeled with superparamagnetic iron oxide particles. METHODS Superparamagnetic iron oxide-labeled cells were injected into mice (one cell type/mouse) implanted with a human papillomavirus-based cervical cancer model. Half of these mice were also vaccinated with DepoVaxTM (ImmunoVaccine, Inc., Halifax, Nova Scotia, Canada), a lipid-based vaccine platform that was developed to enhance the potency of peptide-based vaccines. RESULTS MRI visualization of CD8+ cytotoxic T cells, regulatory T cells, and myeloid-derived suppressor cells was apparent 24 h post-injection, with hypointensities due to iron-labeled cells clearing approximately 72 h post-injection. Vaccination resulted in increased recruitment of CD8+ cytotoxic T cells, and decreased recruitment of myeloid-derived suppressor cells and regulatory T cells to the tumor. We also found that myeloid-derived suppressor cell and regulatory T cell recruitment were positively correlated with final tumor volume. CONCLUSION This type of analysis can be used to noninvasively study changes in immune cell recruitment in individual mice over time, potentially allowing improved application and combination of immunotherapies. Magn Reson Med 80:304-316, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
| | - Christa Davis
- Biomedical Translational Imaging Centre (BIOTIC), Halifax, Nova Scotia, Canada
| | - Chris V Bowen
- Biomedical Translational Imaging Centre (BIOTIC), Halifax, Nova Scotia, Canada.,Department of Diagnostic Radiology, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Olivia Stanley
- Biomedical Translational Imaging Centre (BIOTIC), Halifax, Nova Scotia, Canada
| | - Cathryn Parsons
- Biomedical Translational Imaging Centre (BIOTIC), Halifax, Nova Scotia, Canada
| | | | - Mohan Karkada
- Wyss Institute at Harvard Medical School, Boston, Massachusetts, USA
| | - Marianne M Stanford
- Immunovaccine Inc., Halifax, Nova Scotia, Canada.,Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kimberly D Brewer
- Biomedical Translational Imaging Centre (BIOTIC), Halifax, Nova Scotia, Canada.,Department of Diagnostic Radiology, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada.,School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
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