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Dassanayake PSB, Prajapati R, Gelman N, Thompson RT, Prato FS, Goldhawk DE. Monocyte MRI Relaxation Rates Are Regulated by Extracellular Iron and Hepcidin. Int J Mol Sci 2023; 24:ijms24044036. [PMID: 36835448 PMCID: PMC9962677 DOI: 10.3390/ijms24044036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 02/19/2023] Open
Abstract
Many chronic inflammatory conditions are mediated by an increase in the number of monocytes in peripheral circulation, differentiation of monocytes to macrophages, and different macrophage subpopulations during pro- and anti-inflammatory stages of tissue injury. When hepcidin secretion is stimulated during inflammation, the iron export protein ferroportin is targeted for degradation on a limited number of cell types, including monocytes and macrophages. Such changes in monocyte iron metabolism raise the possibility of non-invasively tracking the activity of these immune cells using magnetic resonance imaging (MRI). We hypothesized that hepcidin-mediated changes in monocyte iron regulation influence both cellular iron content and MRI relaxation rates. In response to varying conditions of extracellular iron supplementation, ferroportin protein levels in human THP-1 monocytes decreased two- to eightfold, consistent with paracrine/autocrine regulation of iron export. Following hepcidin treatment, ferroportin protein levels further decreased two- to fourfold. This was accompanied by an approximately twofold increase in total transverse relaxation rate, R2*, compared to non-supplemented cells. A positive correlation between total cellular iron content and R2* improved from moderate to strong in the presence of hepcidin. These findings suggest that hepcidin-mediated changes detected in monocytes using MRI could be valuable for in vivo cell tracking of inflammatory responses.
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Affiliation(s)
- Praveen S. B. Dassanayake
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada
- Medical Biophysics, Western University, London, ON N6A 5C1, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, ON N6A 5C1, Canada
| | - Rahil Prajapati
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada
| | - Neil Gelman
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada
- Medical Biophysics, Western University, London, ON N6A 5C1, Canada
| | - R. Terry Thompson
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada
- Medical Biophysics, Western University, London, ON N6A 5C1, Canada
| | - Frank S. Prato
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada
- Medical Biophysics, Western University, London, ON N6A 5C1, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, ON N6A 5C1, Canada
| | - Donna E. Goldhawk
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada
- Medical Biophysics, Western University, London, ON N6A 5C1, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, ON N6A 5C1, Canada
- Correspondence:
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Mouawad M, Lailey O, Poulsen P, O'Neil M, Brackstone M, Lock M, Yaremko B, Shmuilovich O, Kornecki A, Ben Nachum I, Muscedere G, Lynn K, Karnas S, Prato FS, Thompson RT, Gaede S. Intrafraction motion monitoring to determine PTV margins in early stage breast cancer patients receiving neoadjuvant partial breast SABR. Radiother Oncol 2021; 158:276-284. [PMID: 33636230 DOI: 10.1016/j.radonc.2021.02.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 02/10/2021] [Accepted: 02/13/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND AND PURPOSE To quantify intra-fraction tumor motion using imageguidance and implanted fiducial markers to determine if a 5 mm planning-target-volume (PTV) margin is sufficient for early stage breast cancer patients receiving neoadjuvant stereotactic ablative radiotherapy (SABR). MATERIALS AND METHODS A HydroMark© (Mammotome) fiducial was implanted at the time of biopsy adjacent to the tumor. Sixty-one patients with 62 tumours were treated prone using a 5 mm PTV margin. Motion was quantified using two methods (separate patient groups): 1) difference in 3D fiducial position pre- and post-treatment cone-beam CTs (CBCTs) in 18 patients receiving 21 Gy/1fraction (fx); 2) acquiring 2D triggered-kVimages to quantify 3D intra-fraction motion using a 2D-to-3D estimation method for 44 tumours receiving 21 Gy/1fx (n = 22) or 30 Gy/3fx (n = 22). For 2), motion was quantified by calculating the magnitude of intra-fraction positional deviation from the pretreatment CBCT. PTV margins were derived using van Herkian analysis. RESULTS The average ± standard deviation magnitude of motion across patients was 1.3 ± 1.15 mm Left/Right (L/R), 1.0 ± 0.9 mm Inferiorly/Superiorly (I/S), and 1.8 ± 1.5 mm Anteriorly/Posteriorly (A/P). 85/105 (81%) treatment fractions had dominant anterior motion. 6/62patients (9.7%) had mean intra-fraction motion during any fraction > 5 mm in any direction, with 4 in the anterior direction. Estimated PTV margins for single and three-fx patients in the L/R, I/S, and A/P directions were 6.0x4.1x5.9 mm and 4.5x2.9x4.3 mm, respectively. CONCLUSION Our results suggest that a 5 mm PTV margin is sufficient for the I/S and A/P directions if a lateral kV image is acquired immediately before treatment. For the L/R direction, either further immobilization or a larger margin is required.
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Affiliation(s)
- Matthew Mouawad
- Medical Biophysics, Western University, London, Canada; London Health Sciences Centre, London, Canada.
| | - Owen Lailey
- London Health Sciences Centre, London, Canada
| | - Per Poulsen
- Danish Center for Particle Therapy and Department of Oncology, Aarhus University Hospital, Denmark.
| | | | - Muriel Brackstone
- Medical Biophysics, Western University, London, Canada; London Health Sciences Centre, London, Canada; Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada.
| | - Michael Lock
- London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada.
| | - Brian Yaremko
- London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada.
| | - Olga Shmuilovich
- Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada.
| | - Anat Kornecki
- Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada.
| | - Ilanit Ben Nachum
- Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada.
| | - Giulio Muscedere
- Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada.
| | - Kalan Lynn
- London Health Sciences Centre, London, Canada; Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada.
| | | | - Frank S Prato
- Medical Biophysics, Western University, London, Canada; Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada.
| | - R Terry Thompson
- Medical Biophysics, Western University, London, Canada; Lawson Health Research Institute, London, Canada.
| | - Stewart Gaede
- Medical Biophysics, Western University, London, Canada; London Health Sciences Centre, London, Canada; Lawson Health Research Institute, London, Canada; Department of Oncology, Western University, London, Canada.
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Poirier SE, Kwan BYM, Jurkiewicz MT, Samargandy L, Iacobelli M, Steven DA, Lam Shin Cheung V, Moran G, Prato FS, Thompson RT, Burneo JG, Anazodo UC, Thiessen JD. An evaluation of the diagnostic equivalence of 18F-FDG-PET between hybrid PET/MRI and PET/CT in drug-resistant epilepsy: A pilot study. Epilepsy Res 2021; 172:106583. [PMID: 33636504 DOI: 10.1016/j.eplepsyres.2021.106583] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 01/27/2021] [Accepted: 02/09/2021] [Indexed: 01/19/2023]
Abstract
OBJECTIVE Hybrid PET/MRI may improve detection of seizure-onset zone (SOZ) in drug-resistant epilepsy (DRE), however, concerns over PET bias from MRI-based attenuation correction (MRAC) have limited clinical adoption of PET/MRI. This study evaluated the diagnostic equivalency and potential clinical value of PET/MRI against PET/CT in DRE. MATERIALS AND METHODS MRI, FDG-PET and CT images (n = 18) were acquired using a hybrid PET/MRI and a CT scanner. To assess diagnostic equivalency, PET was reconstructed using MRAC (RESOLUTE) and CT-based attenuation correction (CTAC) to generate PET/MRI and PET/CT images, respectively. PET/MRI and PET/CT images were compared qualitatively through visual assessment and quantitatively through regional standardized uptake value (SUV) and z-score assessment. Diagnostic accuracy and sensitivity of PET/MRI and PET/CT for SOZ detection were calculated through comparison to reference standards (clinical hypothesis and histopathology, respectively). RESULTS Inter-reader agreement in visual assessment of PET/MRI and PET/CT images was 78 % and 81 %, respectively. PET/MRI and PET/CT were strongly correlated in mean SUV (r = 0.99, p < 0.001) and z-scores (r = 0.92, p < 0.001) across all brain regions. MRAC SUV bias was <5% in most brain regions except the inferior temporal gyrus, temporal pole, and cerebellum. Diagnostic accuracy and sensitivity were similar between PET/MRI and PET/CT (87 % vs. 85 % and 83 % vs. 83 %, respectively). CONCLUSION We demonstrate here that PET/MRI with optimal MRAC can yield similar diagnostic performance as PET/CT. Nevertheless, further exploration of the potential added value of PET/MRI is necessary before clinical adoption of PET/MRI for epilepsy imaging.
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Affiliation(s)
- Stefan E Poirier
- Lawson Imaging, Lawson Health Research Institute, London, ON, Canada; Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
| | - Benjamin Y M Kwan
- Department of Diagnostic Radiology, Queen's University, Kingston, ON, Canada
| | - Michael T Jurkiewicz
- Department of Medical Imaging, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Lina Samargandy
- Department of Medical Imaging, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Maryssa Iacobelli
- Lawson Imaging, Lawson Health Research Institute, London, ON, Canada
| | - David A Steven
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada; Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Victor Lam Shin Cheung
- Department of Medical Imaging, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | | | - Frank S Prato
- Lawson Imaging, Lawson Health Research Institute, London, ON, Canada; Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada; Department of Medical Imaging, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - R Terry Thompson
- Lawson Imaging, Lawson Health Research Institute, London, ON, Canada; Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada; Department of Medical Imaging, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Jorge G Burneo
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada; Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Udunna C Anazodo
- Lawson Imaging, Lawson Health Research Institute, London, ON, Canada; Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada; Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada; Research Centre for Studies in Aging, McGill University, Montréal, QC, Canada.
| | - Jonathan D Thiessen
- Lawson Imaging, Lawson Health Research Institute, London, ON, Canada; Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada; Department of Medical Imaging, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
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Farag A, Thompson RT, Thiessen JD, Biernaski H, Prato FS, Théberge J. Evaluation of 511 keV photon attenuation by a novel 32-channel phased array prospectively designed for cardiovascular hybrid PET/MRI imaging. Eur J Hybrid Imaging 2020; 4:7. [PMID: 32626841 PMCID: PMC7324084 DOI: 10.1186/s41824-020-00076-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 04/29/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Simultaneous cardiovascular imaging with positron emission tomography (PET) and magnetic resonance imaging (MRI) requires tools such as radio frequency (RF) phased arrays to achieve high temporal and spatial resolution in the MRI, as well as accurate quantification of PET. Today, high-density phased arrays (> 16 channels) used for cardiovascular PET/MRI are not designed to achieve low PET attenuation, and correcting the PET attenuation they cause requires off-line reconstruction, extra time and resources. PURPOSE Motivated by previous work assessing the MRI performance of a novel prospectively designed 32-channel phased array, this study assessed the PET image quality with this array in place. Guided by NEMA standards, PET performance was measured using global PET counts, regional background variation (BV), contrast recovery (CR) and contrast-to-noise ratio (CNR) for both the novel array and standard arrays (mMR 12-channel and MRI 32-channel). Nonattenuation-corrected (NAC) data from all arrays (and each part of the array) were processed and compared to no-array, and relative percentage difference (RPD) of the global means was estimated and reported for each part of the arrays. Attenuation correction (AC) of PET images (water in the phantom) using two approaches, MR-based AC map (MRAC) and dual-energy CT-based map (DCTAC), was performed, and RPD compared for each part of the arrays. Percent mean attenuation within regions of interests of the phantom images from each array were compared using a two-way analysis of variance (ANOVA). RESULTS The NAC data of the anterior part of the novel array recorded the least PET attenuation (≤ 2%); while the full novel array (anterior and posterior together) AC data, produced by MRAC and DCTAC approaches, recorded attenuation of 1.5 ± 2.9% and 0.0 ± 2.5%, respectively. The novel array PET count loss was significantly lower (p = 0.001) than those caused by the standard arrays. CONCLUSIONS Results of this novel 32-channel cardiac array PET performance evaluation, together with its previously reported MRI performance assessment, suggest the novel array to be a strong alternative to the standard arrays currently used for cardiovascular hybrid PET/MRI imaging. It enables accurate PET quantification and high-temporal and spatial resolution for MR imaging.
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Affiliation(s)
- Adam Farag
- Imaging Division, Lawson Health Research Institute, London, Ontario Canada
- Department of Medical Biophysics, Western University, London, Ontario Canada
| | - R. Terry Thompson
- Imaging Division, Lawson Health Research Institute, London, Ontario Canada
- Department of Medical Biophysics, Western University, London, Ontario Canada
| | - Jonathan D. Thiessen
- Imaging Division, Lawson Health Research Institute, London, Ontario Canada
- Department of Medical Biophysics, Western University, London, Ontario Canada
- Department of Medical Imaging, Western University, London, Ontario Canada
| | - Heather Biernaski
- Imaging Division, Lawson Health Research Institute, London, Ontario Canada
| | - Frank S. Prato
- Imaging Division, Lawson Health Research Institute, London, Ontario Canada
- Department of Medical Biophysics, Western University, London, Ontario Canada
- Department of Medical Imaging, Western University, London, Ontario Canada
- Diagnostic Imaging, St. Joseph’s Health Care, London, Ontario Canada
| | - Jean Théberge
- Imaging Division, Lawson Health Research Institute, London, Ontario Canada
- Department of Medical Biophysics, Western University, London, Ontario Canada
- Department of Medical Imaging, Western University, London, Ontario Canada
- Diagnostic Imaging, St. Joseph’s Health Care, London, Ontario Canada
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Mouawad M, Biernaski H, Brackstone M, Lock M, Yaremko B, Shmuilovich O, Kornecki A, Ben Nachum I, Muscedere G, Lynn K, Prato FS, Thompson RT, Gaede S, Gelman N. DCE-MRI assessment of response to neoadjuvant SABR in early stage breast cancer: Comparisons of single versus three fraction schemes and two different imaging time delays post-SABR. Clin Transl Radiat Oncol 2020; 21:25-31. [PMID: 32021911 PMCID: PMC6993055 DOI: 10.1016/j.ctro.2019.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 12/22/2019] [Indexed: 12/25/2022] Open
Abstract
PURPOSE To determine the effect of dose fractionation and time delay post-neoadjuvant stereotactic ablative radiotherapy (SABR) on dynamic contrast-enhanced (DCE)-MRI parameters in early stage breast cancer patients. MATERIALS AND METHODS DCE-MRI was acquired in 17 patients pre- and post-SABR. Five patients were imaged 6-7 days post-21 Gy/1fraction (group 1), six 16-19 days post-21 Gy/1fraction (group 2), and six 16-18 days post-30 Gy/3 fractions every other day (group 3). DCE-MRI scans were performed using half the clinical dose of contrast agent. Changes in the surrounding tissue were quantified using a signal-enhancement threshold metric that characterizes changes in signal-enhancement volume (SEV). Tumour response was quantified using Ktrans and ve (Tofts model) pre- and post-SABR. Significance was assessed using a Wilcoxin signed-rank test. RESULTS All group 1 and 4/6 group 2 patients' SEV increased post-SABR. All group 3 patients' SEV decreased. The mean Ktrans increased for group 1 by 76% (p = 0.043) while group 2 and 3 decreased 15% (p = 0.028) and 34% (p = 0.028), respectively. For ve, there was no significant change in Group 1 (p = 0.35). Groups 2 showed an increase of 24% (p = 0.043), and Group 3 trended toward an increase (23%, p = 0.08). CONCLUSION Kinetic parameters measured 2.5 weeks post-SABR in both single fraction and three fraction groups were indicative of response but only the single fraction protocol led to enhancement in the surrounding tissue. Our results also suggest that DCE-MRI one-week post-SABR may be too early for response assessment, at least for single fraction SABR, whereas 2.5 weeks appears sufficiently long to minimize confounding acute effects.
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Affiliation(s)
- Matthew Mouawad
- Medical Biophysics, Western University, London, Ontario, Canada
| | | | - Muriel Brackstone
- Medical Biophysics, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- London Health Sciences Centre, London, Ontario, Canada
- St. Joseph’s Health Care, London, Ontario, Canada
| | - Michael Lock
- London Health Sciences Centre, London, Ontario, Canada
- Department of Oncology, Western University, London, Ontario, Canada
| | - Brian Yaremko
- London Health Sciences Centre, London, Ontario, Canada
- Department of Oncology, Western University, London, Ontario, Canada
| | - Olga Shmuilovich
- Lawson Health Research Institute, London, Ontario, Canada
- St. Joseph’s Health Care, London, Ontario, Canada
- Department of Medical Imaging, Western University, London, Ontario, Canada
| | - Anat Kornecki
- Lawson Health Research Institute, London, Ontario, Canada
- St. Joseph’s Health Care, London, Ontario, Canada
- Department of Medical Imaging, Western University, London, Ontario, Canada
| | - Ilanit Ben Nachum
- Lawson Health Research Institute, London, Ontario, Canada
- St. Joseph’s Health Care, London, Ontario, Canada
- Department of Medical Imaging, Western University, London, Ontario, Canada
| | - Giulio Muscedere
- Lawson Health Research Institute, London, Ontario, Canada
- St. Joseph’s Health Care, London, Ontario, Canada
- Department of Medical Imaging, Western University, London, Ontario, Canada
| | - Kalan Lynn
- Lawson Health Research Institute, London, Ontario, Canada
- London Health Sciences Centre, London, Ontario, Canada
- St. Joseph’s Health Care, London, Ontario, Canada
| | - Frank S. Prato
- Medical Biophysics, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- St. Joseph’s Health Care, London, Ontario, Canada
- Department of Medical Imaging, Western University, London, Ontario, Canada
| | - R. Terry Thompson
- Medical Biophysics, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
| | - Stewart Gaede
- Medical Biophysics, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- London Health Sciences Centre, London, Ontario, Canada
- Department of Oncology, Western University, London, Ontario, Canada
| | - Neil Gelman
- Medical Biophysics, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Imaging, Western University, London, Ontario, Canada
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Farag A, Thompson RT, Thiessen JD, Butler J, Prato FS, Théberge J. Assessment of a novel 32-channel phased array for cardiovascular hybrid PET/MRI imaging: MRI performance. Eur J Hybrid Imaging 2019; 3:13. [PMID: 33283144 PMCID: PMC7717874 DOI: 10.1186/s41824-019-0061-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/01/2019] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Cardiovascular imaging using hybrid positron emission tomography (PET) and magnetic resonance imaging (MRI) requires a radio frequency phased array resonator capable of high acceleration factors in order to achieve the shortest breath-holds while maintaining optimal MRI signal-to-noise ratio (SNR) and minimum PET photon attenuation. To our knowledge, the only two arrays used today for hybrid PET/MRI cardiovascular imaging are either incapable of achieving high acceleration or affect the PET photon count greatly. PURPOSE This study is focused on the evaluation of the MRI performance of a novel third-party prototype 32-channel phased array designed for simultaneous PET/MRI cardiovascular imaging. The study compares the quality parameters of MRI parallel imaging, such as g-factor, noise correlation coefficients, and SNR, to the conventional arrays (mMR 12-channel and MRI-only 32-channel) currently used with hybrid PET/MRI systems. The quality parameters of parallel imaging were estimated for multiple acceleration factors on a phantom and three healthy volunteers. Using a Germanium-68 (Ge-68) phantom, preliminary measurements of PET photon attenuation caused by the novel array were briefly compared to the photon counts produced from no-array measurements. RESULTS The global mean of the g-factor and SNRg produced by the novel 32-channel PET/MRI array were better than those produced by the MRI-only 32-channel array by 5% or more. The novel array has resulted in MRI SNR improvements of > 30% at all acceleration factors, in comparison to the mMR12-channel array. Preliminary evaluation of PET transparency showed less than 5% photon attenuation caused by both anterior and posterior parts of the novel array. CONCLUSIONS The MRI performance of the novel PET/MRI 32-channel array qualifies it to be a viable alternative to the conventional arrays for cardiovascular hybrid PET/MRI. A detailed evaluation of the novel array's PET performance remains to be conducted, but cursory assessment promises significantly reduced attenuation.
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Affiliation(s)
- Adam Farag
- Lawson Health Research Institute, Imaging Division, 268 Grosvenor St., Rm E5-118, PO Box 5777, STN B, London, ON N6A 4V2 Canada
- Department of Medical Biophysics, Western University, London, ON Canada
| | - R. Terry Thompson
- Lawson Health Research Institute, Imaging Division, 268 Grosvenor St., Rm E5-118, PO Box 5777, STN B, London, ON N6A 4V2 Canada
- Department of Medical Biophysics, Western University, London, ON Canada
| | - Jonathan D. Thiessen
- Lawson Health Research Institute, Imaging Division, 268 Grosvenor St., Rm E5-118, PO Box 5777, STN B, London, ON N6A 4V2 Canada
- Department of Medical Biophysics, Western University, London, ON Canada
- Department of Medical Imaging, Western University, London, ON Canada
| | - John Butler
- Lawson Health Research Institute, Imaging Division, 268 Grosvenor St., Rm E5-118, PO Box 5777, STN B, London, ON N6A 4V2 Canada
| | - Frank S. Prato
- Lawson Health Research Institute, Imaging Division, 268 Grosvenor St., Rm E5-118, PO Box 5777, STN B, London, ON N6A 4V2 Canada
- Department of Medical Biophysics, Western University, London, ON Canada
- Department of Medical Imaging, Western University, London, ON Canada
- St. Joseph’s Health Care, Diagnostic Imaging, London, ON Canada
| | - Jean Théberge
- Lawson Health Research Institute, Imaging Division, 268 Grosvenor St., Rm E5-118, PO Box 5777, STN B, London, ON N6A 4V2 Canada
- Department of Medical Biophysics, Western University, London, ON Canada
- Department of Medical Imaging, Western University, London, ON Canada
- St. Joseph’s Health Care, Diagnostic Imaging, London, ON Canada
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7
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Liu L, Alizadeh K, Donnelly SC, Dassanayake P, Hou TT, McGirr R, Thompson RT, Prato FS, Gelman N, Hoffman L, Goldhawk DE. MagA expression attenuates iron export activity in undifferentiated multipotent P19 cells. PLoS One 2019; 14:e0217842. [PMID: 31170273 PMCID: PMC6553743 DOI: 10.1371/journal.pone.0217842] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 05/20/2019] [Indexed: 12/21/2022] Open
Abstract
Magnetic resonance imaging (MRI) is a non-invasive imaging modality used in longitudinal cell tracking. Previous studies suggest that MagA, a putative iron transport protein from magnetotactic bacteria, is a useful gene-based magnetic resonance contrast agent. Hemagglutinin-tagged MagA was stably expressed in undifferentiated embryonic mouse teratocarcinoma, multipotent P19 cells to provide a suitable model for tracking these cells during differentiation. Western blot and immunocytochemistry confirmed the expression and membrane localization of MagA in P19 cells. Surprisingly, elemental iron analysis using inductively-coupled plasma mass spectrometry revealed significant iron uptake in both parental and MagA-expressing P19 cells, cultured in the presence of iron-supplemented medium. Withdrawal of this extracellular iron supplement revealed unexpected iron export activity in P19 cells, which MagA expression attenuated. The influence of iron supplementation on parental and MagA-expressing cells was not reflected by longitudinal relaxation rates. Measurement of transverse relaxation rates (R2* and R2) reflected changes in total cellular iron content but did not clearly distinguish MagA-expressing cells from the parental cell type, despite significant differences in the uptake and retention of total cellular iron. Unlike other cell types, the reversible component R2′ (R2* ‒ R2) provided only a moderately strong correlation to amount of cellular iron, normalized to amount of protein. This is the first report to characterize MagA expression in a previously unrecognized iron exporting cell type. The interplay between contrast gene expression and systemic iron metabolism substantiates the potential for diverting cellular iron toward the formation of a novel iron compartment, however rudimentary when using a single magnetotactic bacterial gene expression system like magA. Since relatively few mammalian cells export iron, the P19 cell line provides a tractable model of ferroportin activity, suitable for magnetic resonance analysis of key iron-handling activities and their influence on gene-based MRI contrast.
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Affiliation(s)
- Linshan Liu
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
- Medical Biophysics, Western University, London, Ontario, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Ontario, Canada
| | - Kobra Alizadeh
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
- Medical Biophysics, Western University, London, Ontario, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Ontario, Canada
| | - Sarah C. Donnelly
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Ontario, Canada
- Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Praveen Dassanayake
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
- Medical Biophysics, Western University, London, Ontario, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Ontario, Canada
| | - Tian Tian Hou
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
| | - Rebecca McGirr
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
| | - R. Terry Thompson
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
- Medical Biophysics, Western University, London, Ontario, Canada
- Medical Imaging, Western University, London, Ontario, Canada
- Physics and Astronomy, Western University, London, Ontario, Canada
| | - Frank S. Prato
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
- Medical Biophysics, Western University, London, Ontario, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Ontario, Canada
- Medical Imaging, Western University, London, Ontario, Canada
- Physics and Astronomy, Western University, London, Ontario, Canada
| | - Neil Gelman
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
- Medical Biophysics, Western University, London, Ontario, Canada
- Medical Imaging, Western University, London, Ontario, Canada
| | - Lisa Hoffman
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
- Medical Biophysics, Western University, London, Ontario, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Ontario, Canada
- Anatomy and Cell Biology, Western University, London, Ontario, Canada
| | - Donna E. Goldhawk
- Imaging, Lawson Health Research Institute, London, Ontario, Canada
- Medical Biophysics, Western University, London, Ontario, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Ontario, Canada
- * E-mail:
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8
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Atkinson HF, Birmingham TB, Moyer RF, Yacoub D, Kanko LE, Bryant DM, Thiessen JD, Thompson RT. MRI T2 and T1ρ relaxation in patients at risk for knee osteoarthritis: a systematic review and meta-analysis. BMC Musculoskelet Disord 2019; 20:182. [PMID: 31039785 PMCID: PMC6492327 DOI: 10.1186/s12891-019-2547-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/28/2019] [Indexed: 12/19/2022] Open
Abstract
Background Magnetic resonance imaging (MRI) T2 and T1ρ relaxation are increasingly being proposed as imaging biomarkers potentially capable of detecting biochemical changes in articular cartilage before structural changes are evident. We aimed to: 1) summarize MRI methods of published studies investigating T2 and T1ρ relaxation time in participants at risk for but without radiographic knee OA; and 2) compare T2 and T1ρ relaxation between participants at-risk for knee OA and healthy controls. Methods We conducted a systematic review of studies reporting T2 and T1ρ relaxation data that included both participants at risk for knee OA and healthy controls. Participant characteristics, MRI methodology, and T1ρ and T2 relaxation data were extracted. Standardized mean differences (SMDs) were calculated within each study. Pooled effect sizes were then calculated for six commonly segmented knee compartments. Results 55 articles met eligibility criteria. There was considerable variability between scanners, coils, software, scanning protocols, pulse sequences, and post-processing. Moderate risk of bias due to lack of blinding was common. Pooled effect sizes indicated participants at risk for knee OA had lengthened T2 relaxation time in all compartments (SMDs from 0.33 to 0.74; p < 0.01) and lengthened T1ρ relaxation time in the femoral compartments (SMD from 0.35 to 0.40; p < 0.001). Conclusions T2 and T1ρ relaxation distinguish participants at risk for knee OA from healthy controls. Greater standardization of MRI methods is both warranted and required for progress towards biomarker validation. Electronic supplementary material The online version of this article (10.1186/s12891-019-2547-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hayden F Atkinson
- School of Physical Therapy, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada.,Wolf Orthopaedic Biomechanics Laboratory, Fowler Kennedy Sport Medicine Clinic, University of Western Ontario, London, Ontario, Canada.,Bone and Joint Institute, University of Western Ontario, London, Ontario, Canada
| | - Trevor B Birmingham
- School of Physical Therapy, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada. .,Wolf Orthopaedic Biomechanics Laboratory, Fowler Kennedy Sport Medicine Clinic, University of Western Ontario, London, Ontario, Canada. .,Bone and Joint Institute, University of Western Ontario, London, Ontario, Canada. .,Musculoskeletal Rehabilitation, Elborn College, University of Western Ontario, London, Ontario, N6G 1H1, Canada.
| | - Rebecca F Moyer
- Bone and Joint Institute, University of Western Ontario, London, Ontario, Canada.,School of Physiotherapy, Faculty of Health, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Daniel Yacoub
- Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
| | - Lauren E Kanko
- School of Physical Therapy, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada.,Wolf Orthopaedic Biomechanics Laboratory, Fowler Kennedy Sport Medicine Clinic, University of Western Ontario, London, Ontario, Canada.,Bone and Joint Institute, University of Western Ontario, London, Ontario, Canada
| | - Dianne M Bryant
- School of Physical Therapy, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada.,Wolf Orthopaedic Biomechanics Laboratory, Fowler Kennedy Sport Medicine Clinic, University of Western Ontario, London, Ontario, Canada.,Bone and Joint Institute, University of Western Ontario, London, Ontario, Canada
| | - Jonathan D Thiessen
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.,Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
| | - R Terry Thompson
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.,Imaging Program, Lawson Health Research Institute, London, Ontario, Canada
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9
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Patrick JC, Terry Thompson R, So A, Butler J, Faul D, Stodilka RZ, Yartsev S, Prato FS, Gaede S. Technical Note: Comparison of megavoltage, dual-energy, and single-energy CT-based μ-maps for a four-channel breast coil in PET/MRI. Med Phys 2017. [PMID: 28622420 DOI: 10.1002/mp.12407] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE The purpose of this study was to describe and evaluate methods for calculating a megavoltage computed tomography (MVCT)-derived MR hardware attenuation map (μ-map) and dual-energy CT (DECT) for 511 keV photons. METHODS Phantom measurements were acquired on a whole-body hybrid PET/MRI system, using a four-channel receive-only MR radiofrequency (RF) breast coil. Two acquisitions were performed: with the phantoms positioned in the four-channel RF breast coil, and without the breast coil. PET attenuation from the breast coil was corrected using three different CT-derived hardware μ-maps: (a) Single-energy CT (SECT), (b) DECT, and (c) MVCT. Each attenuation-corrected (AC) PET volume was evaluated and compared with the acquisition performed without the breast coil. RESULTS The breast coil attenuated PET photons by 10% overall. Threshold values were applied to the SECT μ-map to reduce the effects of metal artifacts, but overcorrection occurred in more highly attenuated regions. The DECT-derived virtual monochromatic image reduced beam-hardening artifacts, but other metal artifacts remained. Despite the remaining metal artifacts in the DECT image, it led to an improvement in the more attenuated regions. The MVCT images appear to be free from metal artifacts leading to an artifact-free μ-map and a further improvement AC-PET images. CONCLUSIONS Our MVCT-based approach for creating μ-maps for MR RF coils greatly reduces artifacts produced by metal in a SECT approach. This eliminates the need for other artifact reduction methods, including the application of a threshold of narrow beam attenuation coefficients, or disassembling hardware to remove high-Z components before imaging with a kilovoltage source.
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Affiliation(s)
- John C Patrick
- London Regional Cancer Program, Physics and Engineering Dept., London, ON, Canada.,Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, Western University, London, ON, Canada
| | - R Terry Thompson
- Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, Western University, London, ON, Canada
| | - Aaron So
- Lawson Health Research Institute, London, ON, Canada.,Imaging Laboratories, Robarts Research Institute, London, ON, Canada
| | - John Butler
- Lawson Health Research Institute, London, ON, Canada
| | | | - Robert Z Stodilka
- Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, Western University, London, ON, Canada
| | - Slav Yartsev
- London Regional Cancer Program, Physics and Engineering Dept., London, ON, Canada.,Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, Western University, London, ON, Canada
| | - Frank S Prato
- Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, Western University, London, ON, Canada
| | - Stewart Gaede
- London Regional Cancer Program, Physics and Engineering Dept., London, ON, Canada.,Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, Western University, London, ON, Canada
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10
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Mouawad M, Biernaski H, Brackstone M, Klassen M, Lock M, Prato FS, Thompson RT, Gaede S, Gelman N. Sci-Fri AM: MRI and Diagnostic Imaging - 03: The influence of sampling percentage in deformable registration on kinetic model analysis results in DCE-MRI of the breast. Med Phys 2016. [DOI: 10.1118/1.4961834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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11
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Lee CY, Thompson RT, Prato FS, Goldhawk DE, Gelman N. Investigating the Relationship between Transverse Relaxation Rate (R2) and Interecho Time in MagA-Expressing, Iron-Labeled Cells. Mol Imaging 2015; 14:551-60. [PMID: 26637544 DOI: 10.2310/7290.2015.00027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Reporter gene-based labeling of cells with iron is an emerging method of providing magnetic resonance imaging contrast for long-term cell tracking and monitoring cellular activities. This report investigates 9.4 T nuclear magnetic resonance properties of mammalian cells overexpressing MagA, a putative iron transport protein from magnetotactic bacteria. MagA-expressing MDA-MB-435 cells were cultured in the presence and absence of iron supplementation and compared to the untransfected control. The relationship between the transverse relaxation rate (R2) and interecho time was investigated using the Carr-Purcell-Meiboom-Gill sequence. This relationship was analyzed using a model based on water diffusion in weak magnetic field inhomogeneities (Jensen-Chandra model) as well as a fast-exchange model (Luz-Meiboom model). Increases in R2 with increasing interecho time were larger in the iron-supplemented, MagA-expressing cells compared to other cells. The dependence of R2 on interecho time in these iron-supplemented, MagA-expressing cells was better represented by the Jensen-Chandra model compared to the Luz-Meiboom model, whereas the Luz-Meiboom model performed better for the remaining cell types. Our findings provide an estimate of the distance scale of microscopic magnetic field variations in MagA-expressing cells, which is thought to be related to the size of iron-containing vesicles.
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12
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Prato FS, Butler J, Sykes J, Keenliside L, Blackwood KJ, Thompson RT, White JA, Mikami Y, Thiessen JD, Wisenberg G. Can the Inflammatory Response Be Evaluated Using 18F-FDG Within Zones of Microvascular Obstruction After Myocardial Infarction? J Nucl Med 2015; 56:299-304. [DOI: 10.2967/jnumed.114.147835] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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13
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Anazodo UC, Thiessen JD, Ssali T, Mandel J, Günther M, Butler J, Pavlosky W, Prato FS, Thompson RT, St Lawrence KS. Feasibility of simultaneous whole-brain imaging on an integrated PET-MRI system using an enhanced 2-point Dixon attenuation correction method. Front Neurosci 2015; 8:434. [PMID: 25601825 PMCID: PMC4283546 DOI: 10.3389/fnins.2014.00434] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 12/10/2014] [Indexed: 02/05/2023] Open
Abstract
PURPOSE To evaluate a potential approach for improved attenuation correction (AC) of PET in simultaneous PET and MRI brain imaging, a straightforward approach that adds bone information missing on Dixon AC was explored. METHODS Bone information derived from individual T1-weighted MRI data using segmentation tools in SPM8, were added to the standard Dixon AC map. Percent relative difference between PET reconstructed with Dixon+bone and with Dixon AC maps were compared across brain regions of 13 oncology patients. The clinical potential of the improved Dixon AC was investigated by comparing relative perfusion (rCBF) measured with arterial spin labeling to relative glucose uptake (rPETdxbone) measured simultaneously with (18)F-flurodexoyglucose in several regions across the brain. RESULTS A gradual increase in PET signal from center to the edge of the brain was observed in PET reconstructed with Dixon+bone. A 5-20% reduction in regional PET signals were observed in data corrected with standard Dixon AC maps. These regional underestimations of PET were either reduced or removed when Dixon+bone AC was applied. The mean relative correlation coefficient between rCBF and rPETdxbone was r = 0.53 (p < 0.001). Marked regional variations in rCBF-to-rPET correlation were observed, with the highest associations in the caudate and cingulate and the lowest in limbic structures. All findings were well matched to observations from previous studies conducted with PET data reconstructed with computed tomography derived AC maps. CONCLUSION Adding bone information derived from T1-weighted MRI to Dixon AC maps can improve underestimation of PET activity in hybrid PET-MRI neuroimaging.
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Affiliation(s)
- Udunna C Anazodo
- Lawson Health Research Institute London, ON, Canada ; Medical Biophysics, Western University London, ON, Canada
| | - Jonathan D Thiessen
- Lawson Health Research Institute London, ON, Canada ; Medical Biophysics, Western University London, ON, Canada
| | - Tracy Ssali
- Lawson Health Research Institute London, ON, Canada ; Medical Biophysics, Western University London, ON, Canada
| | - Jonathan Mandel
- Diagnostic Imaging, St. Joseph's Health Care London, ON, Canada
| | - Matthias Günther
- Fraunhofer Institute for Medical Image Computing MEVIS Bremen, Germany
| | - John Butler
- Lawson Health Research Institute London, ON, Canada
| | | | - Frank S Prato
- Lawson Health Research Institute London, ON, Canada ; Medical Biophysics, Western University London, ON, Canada
| | - R Terry Thompson
- Lawson Health Research Institute London, ON, Canada ; Medical Biophysics, Western University London, ON, Canada
| | - Keith S St Lawrence
- Lawson Health Research Institute London, ON, Canada ; Medical Biophysics, Western University London, ON, Canada
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14
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Laksman Z, Yee R, Stirrat J, Gula LJ, Skanes AC, Leong-Sit P, Manlucu J, McCarty D, Turkistani Y, Scholl D, Rajchl M, Goela A, Islam A, Thompson RT, Drangova M, White JA. Model-based navigation of left and right ventricular leads to optimal targets for cardiac resynchronization therapy: a single-center feasibility study. Circ Arrhythm Electrophysiol 2014; 7:1040-7. [PMID: 25221334 DOI: 10.1161/circep.114.001729] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Left ventricular (LV) and right ventricular pacing site characteristics have been shown to influence response to cardiac resynchronization therapy (CRT). This study aimed to determine the clinical feasibility of image-guided lead delivery using a 3-dimensional navigational model displaying both LV and right ventricular (RV) pacing targets. Serial echocardiographic measures of clinical response and procedural metrics were evaluated. METHODS AND RESULTS Thirty-one consecutive patients underwent preimplant cardiac MRI with the generation of a 3-dimensional navigational model depicting optimal segmental targets for LV and RV leads. Lead delivery was guided by the model in matched views to intraprocedural fluoroscopy. Blinded assessment of final lead tip location was performed from postprocedural cardiac computed tomography. Clinical and LV remodeling response criteria were assessed at baseline, 3 months, and 6 months using a 6-minute hall walk, quality of life questionnaire, and echocardiography. Mean age and LV ejection fraction was 66 ± 8 years and 26 ± 8%, respectively. LV leads were successfully delivered to a target or adjacent segment in 30 of 31 patients (97%), 68% being nonposterolateral. RV leads were delivered to a target or adjacent segment in 30 of 31 patients (97%), 26% being nonapical. Twenty-three patients (74%) met standard criteria for response (LV end-systolic volume reduction ≥ 15%), 18 patients (58%) for super-response (LV end-systolic volume reduction ≥ 30%). LV ejection fraction improved at 6 months (31 ± 8 versus 26 ± 8%, P=0.04). CONCLUSIONS This study demonstrates clinical feasibility of dual cardiac resynchronization therapy lead delivery to optimal targets using a 3-dimensional navigational model. High procedural success, acceptable procedural times, and a low rate of early procedural complications were observed. CLINICAL TRIAL REGISTRATION URL http://www.clinicaltrials.gov. Unique identifier: NCT01640769.
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Affiliation(s)
- Zachary Laksman
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Raymond Yee
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - John Stirrat
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Lorne J Gula
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Allan C Skanes
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Peter Leong-Sit
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Jamie Manlucu
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - David McCarty
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Yosra Turkistani
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - David Scholl
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Martin Rajchl
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Aashish Goela
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Ali Islam
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - R Terry Thompson
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - Maria Drangova
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.)
| | - James A White
- From the Division of Cardiology, Department of Medicine (Z.L., R.Y., L.J.G., A.C.S., P.L.-S., J.M., D.M.C., Y.T., J.A.W.), Imaging Laboratories, Robarts Research Institute (J.S., D.S., M.R., M.D.), and Lawson Health Research Institute (R.T.T.), University of Western Ontario, London, Ontario; Department of Medical Imaging, Schulich School of Medicine and Dentistry, London, Ontario (A.G., A.I., R.T.T., M.D.); and Department of Medicine, Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada (J.A.W.).
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15
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Rohani R, Figueredo R, Bureau Y, Koropatnick J, Foster P, Thompson RT, Prato FS, Goldhawk DE. Imaging tumor growth non-invasively using expression of MagA or modified ferritin subunits to augment intracellular contrast for repetitive MRI. Mol Imaging Biol 2014; 16:63-73. [PMID: 23836502 DOI: 10.1007/s11307-013-0661-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE The bacterial gene MagA imparts magnetic properties to mammalian cells and provides a basis for cell tracking by magnetic resonance imaging (MRI). In a mouse model of tumor growth from transplanted cells, we used repetitive MRI to demonstrate the in vivo imaging potential of MagA expression relative to a modified ferritin overexpression system, lacking regulation through iron response elements (HF + LF). PROCEDURES Subcutaneous tumor xenografts were monitored weekly from days 2 to 34 post-injection. Small animal MRI employed balanced steady-state free precession. Imaging was correlated with tumor histology using hematoxylin, Prussian Blue, Ki-67, and BS-1 lectin. RESULTS Tumor heterogeneity with respect to tissue morphology and magnetic resonance (MR) contrast was apparent within a week of cell transplantation. In MagA- and HF + LF-expressing tumors, MR contrast enhancement was recorded up to day 20 post-injection and 0.073-cm(3) tumor volumes. MagA-expressing tumors showed increases in both quantity and quality of MR contrast as measured by fractional void volume and contrast-to-noise ratio, respectively. MR contrast in both MagA- and HF + LF-expressing tumors was maximal by day 13, doubling fractional void volume 1 week ahead of controls. CONCLUSIONS MagA- and HF + LF-expressing tumor xenografts augment MR contrast after 1 week of growth. MagA expression increases MR contrast within days of cell transplantation and provides MR contrast comparable to HF + LF. MagA has utility for monitoring cell growth and differentiation, with potential for in vivo detection of reporter gene expression using MRI.
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Affiliation(s)
- Roja Rohani
- Imaging Program, Lawson Health Research Institute, London, ON, Canada
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Power GA, Allen MD, Booth WJ, Thompson RT, Marsh GD, Rice CL. The influence on sarcopenia of muscle quality and quantity derived from magnetic resonance imaging and neuromuscular properties. Age (Dordr) 2014; 36:9642. [PMID: 24658708 PMCID: PMC4082576 DOI: 10.1007/s11357-014-9642-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 03/05/2014] [Indexed: 06/03/2023]
Abstract
The relative contributions of intrinsic and extrinsic neuromuscular factors on sarcopenia are poorly understood. The associations among age-related declines of strength, muscle mass, and muscle quality in response to motor unit (MU) loss have not been systematically investigated in the same groups of subjects. The purpose was to assess MU loss, MRI-derived muscle cross-sectional area (CSA), muscle protein quantity (MPQ), and normalized strength of the dorsiflexors in one group of young (~25 years) adult males compared with two groups of healthy men aged 60–85 years. Muscle strength was assessed on a dynamometer and was ~25 % lower in both older groups, but CSA was less only in the older (>75 years) men, with no differences between the young and old (60–73 years). Normalized strength tended to be lower in both groups of aged men compared to young. For MPQ, only the older men showed ~8 % lower values than the young and old men. Older men had fewer functioning MUs than old, and both groups of aged men had fewer MUs than young men. Muscle quality appears to be maintained in the old likely due to compensatory MU remodeling, but in the older group (>75 years), MU loss was higher and MPQ was lower.
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Affiliation(s)
- Geoffrey A. Power
- />Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Calgary, Alberta Canada
- />Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario N6G 1H1 Canada
| | - Matti D. Allen
- />Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario N6G 1H1 Canada
| | - William J. Booth
- />Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario N6G 1H1 Canada
| | - R. Terry Thompson
- />Department of Medical Biophysics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario Canada
| | - Greg D. Marsh
- />Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario N6G 1H1 Canada
- />Department of Medical Biophysics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario Canada
| | - Charles L. Rice
- />Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario N6G 1H1 Canada
- />Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario Canada
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Sengupta A, Quiaoit K, Thompson RT, Prato FS, Gelman N, Goldhawk DE. Biophysical features of MagA expression in mammalian cells: implications for MRI contrast. Front Microbiol 2014; 5:29. [PMID: 24550900 PMCID: PMC3913841 DOI: 10.3389/fmicb.2014.00029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 01/17/2014] [Indexed: 12/28/2022] Open
Abstract
We compared overexpression of the magnetotactic bacterial gene MagA with the modified mammalian ferritin genes HF + LF, in which both heavy and light subunits lack iron response elements. Whereas both expression systems have been proposed for use in non-invasive, magnetic resonance (MR) reporter gene expression, limited information is available regarding their relative potential for providing gene-based contrast. Measurements of MR relaxation rates in these expression systems are important for optimizing cell detection and specificity, for developing quantification methods, and for refinement of gene-based iron contrast using magnetosome associated genes. We measured the total transverse relaxation rate (R2*), its irreversible and reversible components (R2 and R2', respectively) and the longitudinal relaxation rate (R1) in MDA-MB-435 tumor cells. Clonal lines overexpressing MagA and HF + LF were cultured in the presence and absence of iron supplementation, and mounted in a spherical phantom for relaxation mapping at 3 Tesla. In addition to MR measures, cellular changes in iron and zinc were evaluated by inductively coupled plasma mass spectrometry, in ATP by luciferase bioluminescence and in transferrin receptor by Western blot. Only transverse relaxation rates were significantly higher in iron-supplemented, MagA- and HF + LF-expressing cells compared to non-supplemented cells and the parental control. R2* provided the greatest absolute difference and R2' showed the greatest relative difference, consistent with the notion that R2' may be a more specific indicator of iron-based contrast than R2, as observed in brain tissue. Iron supplementation of MagA- and HF + LF-expressing cells increased the iron/zinc ratio approximately 20-fold, while transferrin receptor expression decreased approximately 10-fold. Level of ATP was similar across all cell types and culture conditions. These results highlight the potential of magnetotactic bacterial gene expression for improving MR contrast.
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Affiliation(s)
- Anindita Sengupta
- Imaging Program, Lawson Health Research InstituteLondon, ON, Canada
- Medical Biophysics, Western UniversityLondon, ON, Canada
- Collaborative Graduate Program in Molecular Imaging, Western UniversityLondon, ON, Canada
| | - Karina Quiaoit
- Imaging Program, Lawson Health Research InstituteLondon, ON, Canada
- Medical Biophysics, Western UniversityLondon, ON, Canada
- Collaborative Graduate Program in Molecular Imaging, Western UniversityLondon, ON, Canada
| | - R. Terry Thompson
- Imaging Program, Lawson Health Research InstituteLondon, ON, Canada
- Medical Biophysics, Western UniversityLondon, ON, Canada
| | - Frank S. Prato
- Imaging Program, Lawson Health Research InstituteLondon, ON, Canada
- Medical Biophysics, Western UniversityLondon, ON, Canada
| | - Neil Gelman
- Imaging Program, Lawson Health Research InstituteLondon, ON, Canada
- Medical Biophysics, Western UniversityLondon, ON, Canada
| | - Donna E. Goldhawk
- Imaging Program, Lawson Health Research InstituteLondon, ON, Canada
- Medical Biophysics, Western UniversityLondon, ON, Canada
- Collaborative Graduate Program in Molecular Imaging, Western UniversityLondon, ON, Canada
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White JA, Rajchl M, Butler J, Sykes J, Blackwood K, Thompson RT, Prato FS, Wisenberg G. Influence of Microvascular Obstruction on Cellular Inflammation During Early Stages of Acute Myocardial Infarction: Evaluation Using Hybrid Pet-MRI Imaging. Can J Cardiol 2013. [DOI: 10.1016/j.cjca.2013.07.191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Marshall HR, Patrick J, Laidley D, Prato FS, Butler J, Théberge J, Thompson RT, Stodilka RZ. Description and assessment of a registration-based approach to include bones for attenuation correction of whole-body PET/MRI. Med Phys 2013; 40:082509. [DOI: 10.1118/1.4816301] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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20
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Walia J, Crone J, Liang J, Niknam M, Lemaire C, Terry Thompson R, Peemoeller H. Temperature and hydration dependence of proton MAS NMR spectra in MCM-41: model based on motion induced chemical shift averaging. Solid State Nucl Magn Reson 2013; 49-50:26-32. [PMID: 23266020 DOI: 10.1016/j.ssnmr.2012.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Revised: 11/12/2012] [Accepted: 11/19/2012] [Indexed: 06/01/2023]
Abstract
The proton MAS NMR spectra in MCM-41 at low hydration levels (less than hydration amounting to one water molecule per surface hydroxyl group) show complex proton resonance peak structures, with hydroxyl proton resonances seen in dry MCM-41 disappearing as water is introduced into the pores and new peaks appearing, representing water and hydrated silanol groups. Surface hydroxyl group-water molecule chemical exchange and chemical shift averaging brought about by a water molecule visiting different surface hydrogen bonding sites have been proposed as possible causes for the observed spectral changes. In this report a simple model based on chemical shift averaging, due to the making and breaking of hydrogen bonds as water molecules move on the MCM-41 surface, is shown to fully reproduce the NMR spectra, both as a function of hydration and temperature. Surface proton-water proton chemical exchange is not required in this model at low hydration levels.
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Affiliation(s)
- Jaspreet Walia
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
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Belfry GR, Raymer GH, Marsh GD, Paterson DH, Thompson RT, Thomas SG. Muscle metabolic status and acid-base balance during 10-s work:5-s recovery intermittent and continuous exercise. J Appl Physiol (1985) 2012; 113:410-7. [PMID: 22604889 DOI: 10.1152/japplphysiol.01059.2011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gastrocnemius muscle phosphocreatine ([PCr]) and hydrogen ion ([H(+)]) were measured using (31)P-magnetic resonance spectroscopy during repeated bouts of 10-s heavy-intensity (HI) exercise and 5-s rest compared with continuous (CONT) HI exercise. Recreationally active male subjects (n = 7; 28 yr ± 9 yr) performed on separate occasions 12 min of isotonic plantar flexion (0.75 Hz) CONT and intermittent (INT; 10-s exercise, 5-s rest) exercise. The HI power output in both CONT and INT was set at 50% of the difference between the power output associated with the onset of intracellular acidosis and peak exercise determined from a prior incremental plantar flexion protocol. Intracellular concentrations of [PCr] and [H(+)] were calculated at 4 s and 9 s of the work period and at 4 s of the rest period in INT and during CONT exercise. [PCr] and [H(+)] (mean ± SE) were greater at 4 s of the rest periods vs. 9 s of exercise over the course of the INT exercise bout: [PCr] (20.7 mM ± 0.6 vs. 18.7 mM ± 0.5; P < 0.01); [H(+)] (370 nM ± 13.50 vs. 284 nM ± 13.6; P < 0.05). Average [H(+)] was similar for CONT vs. INT. We therefore suggest that there is a glycolytic contribution to ATP recovery during the very short rest period (<5 s) of INT and that the greater average power output of CONT did not manifest in greater [H(+)] and greater glycolytic contribution compared with INT exercise.
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Affiliation(s)
- Glen R Belfry
- University of Western Ontario, London, Ontario, Canada.
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Marshall HR, Prato FS, Deans L, Théberge J, Thompson RT, Stodilka RZ. Variable Lung Density Consideration in Attenuation Correction of Whole-Body PET/MRI. J Nucl Med 2012; 53:977-84. [DOI: 10.2967/jnumed.111.098350] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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Khan R, Massel D, Scholl D, Stiratt J, Wisenberg G, Thompson RT, Prato F, Boughner D, Drangova M, White JA. Myocardial fibrosis is not associated with reduced quality of life in patients with dilated or hypertrophic cardiomyopathy. J Cardiovasc Magn Reson 2011. [PMCID: PMC3106746 DOI: 10.1186/1532-429x-13-s1-p292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Marshall HR, Stodilka RZ, Theberge J, Sabondjian E, Legros A, Deans L, Sykes JM, Thompson RT, Prato FS. A comparison of MR-based attenuation correction in PET versus SPECT. Phys Med Biol 2011; 56:4613-29. [PMID: 21725141 DOI: 10.1088/0031-9155/56/14/024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Attenuation correction (AC) is a critical step in the reconstruction of quantitatively accurate positron emission tomography (PET) and single photon emission computed tomography (SPECT) images. Several groups have proposed magnetic resonance (MR)-based AC algorithms for application in hybrid PET/MR systems. However, none of these approaches have been tested on SPECT data. Since SPECT/MR systems are under active development, it is important to ascertain whether MR-based AC algorithms validated for PET can be applied to SPECT. To investigate this issue, two imaging experiments were performed: one with an anthropomorphic chest phantom and one with two groups of canines. Both groups of canines were imaged from neck to abdomen, one with PET/CT and MR (n = 4) and the other with SPECT/CT and MR (n = 4), while the phantom was imaged with all modalities. The quality of the nuclear medicine reconstructions using MR-based attenuation maps was compared between PET and SPECT on global and local scales. In addition, the sensitivity of these reconstructions to variations in the attenuation map was ascertained. On both scales, it was found that the SPECT reconstructions were of higher fidelity than the PET reconstructions. Further, they were less sensitive to changes to the MR-based attenuation map. Thus, MR-based AC algorithms that have been designed for PET/MR can be expected to demonstrate improved performance when used for SPECT/MR.
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Affiliation(s)
- H R Marshall
- The Lawson Health Research Institute, Imaging Program, London, Ontario, Canada.
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25
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Burgess RA, Pavlosky WF, Thompson RT. MRI-identified abnormalities and wrist range of motion in asymptomatic versus symptomatic computer users. BMC Musculoskelet Disord 2010; 11:273. [PMID: 21108817 PMCID: PMC2998464 DOI: 10.1186/1471-2474-11-273] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Accepted: 11/25/2010] [Indexed: 11/20/2022] Open
Abstract
Background Previous work has shown an association between restricted wrist range of motion (ROM) and upper extremity musculoskeletal disorders in computer users. We compared the prevalence of MRI-identified wrist abnormalities and wrist ROM between asymptomatic and symptomatic computer users. Methods MR images at 1.5 T of both wrists were obtained from 10 asymptomatic controls (8 F, 2 M) and 14 computer users (10 F, 4 M) with chronic wrist pain (10 bilateral; 4 right-side). Maximum wrist range of motion in flexion and radioulnar deviation was measured with an electrogoniometer. Results Extraosseous ganglia were identified in 66.6% of asymptomatic wrists and in 75% of symptomatic wrists. Intraosseous ganglia were identified in 45.8% of asymptomatic wrists and in 75% of symptomatic wrists, and were significantly (p < .05) larger in the symptomatic wrists. Distal ECU tendon instability was identified in 58.4% of both asymptomatic and symptomatic wrists. Dominant wrist flexion was significantly greater in the asymptomatic group (68.8 ± 6.7 deg.) compared to the symptomatic group (60.7 ± 7.3 deg.), p < .01. There was no significant correlation between wrist flexion and intraosseous ganglion burden (p = .09) Conclusions This appears to be the first MRI study of wrist abnormalities in computer users. This study demonstrates that a variety of wrist abnormalities are common in computer users and that only intraosseous ganglia prevalence and size differed between asymptomatic and symptomatic wrists. Flexion was restricted in the dominant wrist of the symptomatic group, but the correlation between wrist flexion and intraosseous ganglion burden did not reach significance. Flexion restriction may be an indicator of increased joint loading, and identifying the cause may help to guide preventive and therapeutic interventions.
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Affiliation(s)
- Ronald A Burgess
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.
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Vasileiadis GT, Thompson RT, Han VKM, Gelman N. Females follow a more "compact" early human brain development model than males. A case-control study of preterm neonates. Pediatr Res 2009; 66:551-5. [PMID: 19668102 DOI: 10.1203/pdr.0b013e3181ba1ae7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The pattern of sexual differentiation of the human brain is not well understood, particularly at the early stages of development when intense growth and multiple maturational phenomena overlap and interrelate. A case-control study of 20 preterm males and females matched for age was conducted. Three-dimensional images were acquired with 3 T MRI. The cerebral volume and the cortical folding area (FA), defined as the surface area of the interface between cortical gray and white matter, were compared between males and females. Females had smaller cerebra than males even after removing the influence of overall size differences between the subjects. The cortical FA increased in relation to volume by a power of 4/3 in both groups. Females had larger cortical FA compared with males with similar cerebral volumes. The study provides in vivo evidence of sexually dimorphic early human brain development. The relatively more "compact" female model may well relate to sex differences in neural circuitry and cognitive domains.
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Affiliation(s)
- George T Vasileiadis
- School of Clinical Sciences, Division of Human Development, The University of Nottingham, Nottingham, United Kingdom.
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Goldhawk DE, Lemaire C, McCreary CR, McGirr R, Dhanvantari S, Thompson RT, Figueredo R, Koropatnick J, Foster P, Prato FS. Magnetic Resonance Imaging of Cells Overexpressing MagA, an Endogenous Contrast Agent for Live Cell Imaging. Mol Imaging 2009. [DOI: 10.2310/7290.2009.00006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Molecular imaging with magnetic resonance imaging (MRI) may benefit from the ferrimagnetic properties of magnetosomes, membrane-enclosed iron biominerals whose formation in magnetotactic bacteria is encoded by multiple genes. One such gene is MagA, a putative iron transporter. We have examined expression of MagA in mouse neuroblastoma N2A cells and characterized their response to iron loading and cellular imaging by MRI. MagA expression augmented both Prussian blue staining and the elemental iron content of N2A cells, without altering cell proliferation, in cultures grown in the presence of iron supplements. Despite evidence for iron incorporation in both MagA and a variant, MagAE137V, only MagA expression produced intracellular contrast detectable by MRI at 11 Tesla. We used this stable expression system to model a new sequence for cellular imaging with MRI, using the difference between gradient and spin echo images to distinguish cells from artifacts in the field of view. Our results show that MagA activity in mammalian cells responds to iron supplementation and functions as a contrast agent that can be deactivated by a single point mutation. We conclude that MagA is a candidate MRI reporter gene that can exploit more fully the superior resolution of MRI in noninvasive medical imaging.
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Affiliation(s)
- Donna E. Goldhawk
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
| | - Claude Lemaire
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
| | - Cheryl R. McCreary
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
| | - Rebecca McGirr
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
| | - Savita Dhanvantari
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
| | - R. Terry Thompson
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
| | - Rene Figueredo
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
| | - Jim Koropatnick
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
| | - Paula Foster
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
| | - Frank S. Prato
- From the Imaging and Diabetes and Metabolism Programs, Lawson Health Research Institute, St. Joseph's Health Care, London, ON; Department of Physics and Astronomy, University of Waterloo, Waterloo, ON; Hotchkiss Brain Institute, University of Calgary, Calgary, AB; Departments of Medical Biophysics, Pathology and Medicine, and Medical Imaging, University of Western Ontario, London, ON; London Regional Cancer Program, London, ON; and Robarts Research Institute, University of Western Ontario, London, ON
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Goldhawk DE, Lemaire C, McCreary CR, McGirr R, Dhanvantari S, Thompson RT, Figueredo R, Koropatnick J, Foster P, Prato FS. Magnetic resonance imaging of cells overexpressing MagA, an endogenous contrast agent for live cell imaging. Mol Imaging 2009; 8:129-139. [PMID: 19723470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Abstract
Molecular imaging with magnetic resonance imaging (MRI) may benefit from the ferrimagnetic properties of magnetosomes, membrane-enclosed iron biominerals whose formation in magnetotactic bacteria is encoded by multiple genes. One such gene is MagA, a putative iron transporter. We have examined expression of MagA in mouse neuroblastoma N2A cells and characterized their response to iron loading and cellular imaging by MRI. MagA expression augmented both Prussian blue staining and the elemental iron content of N2A cells, without altering cell proliferation, in cultures grown in the presence of iron supplements. Despite evidence for iron incorporation in both MagA and a variant, MagAE137V, only MagA expression produced intracellular contrast detectable by MRI at 11 Tesla. We used this stable expression system to model a new sequence for cellular imaging with MRI, using the difference between gradient and spin echo images to distinguish cells from artifacts in the field of view. Our results show that MagA activity in mammalian cells responds to iron supplementation and functions as a contrast agent that can be deactivated by a single point mutation. We conclude that MagA is a candidate MRI reporter gene that can exploit more fully the superior resolution of MRI in noninvasive medical imaging.
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Affiliation(s)
- Donna E Goldhawk
- Imaging Program, Lawson Health Research Institute, St. Joseph's Health Care, London, ON.
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30
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Thompson RT. Clinical MR Imaging and Physics: A Tutorial. Med Phys 2009. [DOI: 10.1118/1.3118965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Raymer GH, Green HJ, Ranney DA, Marsh GD, Thompson RT. Muscle metabolism and acid-base status during exercise in forearm work-related myalgia measured with31P-MRS. J Appl Physiol (1985) 2009; 106:1198-206. [PMID: 19112160 DOI: 10.1152/japplphysiol.90925.2008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this study, we examined muscle metabolic and acid-base status during incremental wrist extension exercise in the forearm of individuals with work-related myalgia (WRM). Eighteen women employed in full-time occupations involving repetitive forearm labor were recruited in this cross-sectional study. Nine of these women were diagnosed with WRM, while the other nine had no previous WRM history and were used as age-matched controls (Con). Phosphorus-31 magnetic resonance spectroscopy (31P-MRS) was used to noninvasively monitor the intracellular concentrations of phosphocreatine ([PCr]) and inorganic phosphate ([Pi]) as well as intracellular pH (pHi) status during exercise in WRM and Con. We observed a 38% decreased work capacity in WRM compared with Con [0.18 W (SD 0.03) vs. 0.28 W (SD 0.10); P = 0.007]. Piecewise linear regression of the incremental exercise data revealed that the onset of a faster decrease in pHi(i.e., the pH threshold, pHT) and the onset of a faster increase in log([Pi]/[PCr]) (i.e., the phosphorylation threshold, PT) occurred at a 14% relatively lower power output in WRM [pHT: 45.2% (SD 5.3) vs. 59.0% (SD 4.6), P < 0.001; PT: 44.8% (SD 4.3) vs. 57.8% (SD 3.1), P < 0.001; % of peak power output, Con vs. WRM, respectively]. Monoexponential modeling of the kinetics of [PCr] and pHirecovery following exercise demonstrated a slower ( P = 0.005) time constant (τ) for [PCr] in WRM [113 s (SD 25)] vs. Con [77 s (SD 23)] and a slower ( P = 0.007) τ for pHiin WRM [370 s (SD 178)] vs. Con [179 s (SD 52)]. In conclusion, our results suggest that WRM is associated with an increased reliance on nonoxidative metabolism. Possible mechanisms include a reduction in local muscle blood flow and perfusion, an increased ATP cost of force production, or both.
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Winter JD, Tichauer KM, Gelman N, Thompson RT, Lee TY, St Lawrence K. Changes in cerebral oxygen consumption and high-energy phosphates during early recovery in hypoxic-ischemic piglets: a combined near-infrared and magnetic resonance spectroscopy study. Pediatr Res 2009; 65:181-7. [PMID: 18852691 DOI: 10.1203/pdr.0b013e31818f06fb] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Near-infrared spectroscopy (NIRS) offers the ability to assess brain function at the bedside of critically ill neonates. Our group previously demonstrated a persistent reduction in the cerebral metabolic rate of oxygen (CMRO(2)) after hypoxia-ischemia (HI) in newborn piglets. The purpose of this current study was to determine the causes of this reduction by combining NIRS with magnetic resonance spectroscopy (MRS) to measure high-energy metabolites and diffusion-weighted imaging to measure cellular edema. Nine piglets were exposed to 30 min of HI and nine piglets served as controls. Proton and phosphorous MRS spectra, apparent diffusion coefficient (ADC) maps, and CMRO(2) measurements were collected periodically before and for 5.5 h after HI. A significant decrease in CMRO(2) (26 +/- 7%) was observed after HI. Incomplete recovery of nucleotide triphosphate concentration (8 +/- 3% <controls) and reduced ADC (16 +/- 5%) suggested mitochondrial dysfunction. However, CMRO(2) did not correlate with any metabolite concentration during the last 3 h of the recovery period, and no significant changes were found in phosphocreatine and lactate levels. Therefore, the CMRO(2) decrease is likely a combination of impaired mitochondrial function and reduced energy demands during the acute phase, which has been previously observed in the mature brain.
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Affiliation(s)
- Jeff D Winter
- Imaging Division, Lawson Health Research Institute, London, Ontario, N6A 4V2, Canada
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Koziak AM, Winter J, Lee TY, Thompson RT, St. Lawrence KS. Validation study of a pulsed arterial spin labeling technique by comparison to perfusion computed tomography. Magn Reson Imaging 2008; 26:543-53. [DOI: 10.1016/j.mri.2007.10.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 08/15/2007] [Accepted: 10/08/2007] [Indexed: 10/22/2022]
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Burgess RA, Thompson RT, Rollman GB. The effect of forearm posture on wrist flexion in computer workers with chronic upper extremity musculoskeletal disorders. BMC Musculoskelet Disord 2008; 9:47. [PMID: 18405370 PMCID: PMC2362125 DOI: 10.1186/1471-2474-9-47] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Accepted: 04/11/2008] [Indexed: 11/14/2022] Open
Abstract
Background Occupational computer use has been associated with upper extremity musculoskeletal disorders (UEMSDs), but the etiology and pathophysiology of some of these disorders are poorly understood. Various theories attribute the symptoms to biomechanical and/or psychosocial stressors. The results of several clinical studies suggest that elevated antagonist muscle tension may be a biomechanical stress factor. Affected computer users often exhibit limited wrist range of motion, particularly wrist flexion, which has been attributed to increased extensor muscle tension, rather than to pain symptoms. Recreational or domestic activities requiring extremes of wrist flexion may produce injurious stress on the wrist joint and muscles, the symptoms of which are then exacerbated by computer use. As these activities may involve a variety of forearm postures, we examined whether changes in forearm posture have an effect on pain reports during wrist flexion, or whether pain would have a limiting effect on flexion angle. Methods We measured maximum active wrist flexion using a goniometer with the forearm supported in the prone, neutral, and supine postures. Data was obtained from 5 subjects with UEMSDs attributed to computer use and from 13 control subjects. Results The UEMSD group exhibited significantly restricted wrist flexion compared to the control group in both wrists at all forearm postures with the exception of the non-dominant wrist with the forearm prone. In both groups, maximum active wrist flexion decreased at the supine forearm posture compared to the prone posture. No UEMSD subjects reported an increase in pain symptoms during testing. Conclusion The UEMSD group exhibited reduced wrist flexion compared to controls that did not appear to be pain related. A supine forearm posture reduced wrist flexion in both groups, but the reduction was approximately 100% greater in the UEMSD group. The effect of a supine forearm posture on wrist flexion is consistent with known biomechanical changes in the distal extensor carpi ulnaris tendon that occur with forearm supination. We infer from these results that wrist extensor muscle passive tension may be elevated in UEMSD subjects compared to controls, particularly in the extensor carpi ulnaris muscle. Measuring wrist flexion at the supine forearm posture may highlight flexion restrictions that are not otherwise apparent.
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Affiliation(s)
- Ronald A Burgess
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.
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Conklin J, Winter JD, Thompson RT, Gelman N. High-contrast 3D neonatal brain imaging with combinedT1- andT2-weighted MP-RAGE. Magn Reson Med 2008; 59:1190-6. [DOI: 10.1002/mrm.21548] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Truong VD, McFeeters RF, Thompson RT, Dean LL, Shofran B. Phenolic acid content and composition in leaves and roots of common commercial sweetpotato (Ipomea batatas L.) cultivars in the United States. J Food Sci 2007; 72:C343-9. [PMID: 17995676 DOI: 10.1111/j.1750-3841.2007.00415.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Phenolic acids in commercially important sweet potato cultivars grown in the United States were analyzed using reversed-phase high-performance liquid chromatography (HPLC). Caffeic acid, chlorogenic acid, 4,5-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 3,4-di-O-caffeoylquinic acid were well separated with an isocratic elution in less than 25 min compared to about 120 min for analyzing and re-equilibrating the column with a gradient method. The isocratic elution order of these caffeoylquinic acid derivatives was confirmed by LC-MS/MS. Chlorogenic acid was the highest in root tissues, while 3,5-di-O-caffeoylquinic acid and/or 4,5-di-O-caffeoylquinic acid were predominant in the leaves. Steam cooking resulted in statistically nonsignificant increases in the concentration of total phenolics and all the individual phenolic acids identified. Sweetpotato leaves had the highest phenolic acid content followed by the peel, whole root, and flesh tissues. However, there was no significant difference in the total phenolic content and antioxidant activity between purees made from the whole and peeled sweet potatoes.
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Affiliation(s)
- V-D Truong
- North Carolina Agricultural Research Service, Department of Food Science, NC State University, Raleigh, NC 27695-7624, USA.
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Williams LA, DeVito TJ, Winter JD, Orr TN, Thompson RT, Gelman N. Optimization of 3D MP-RAGE for neonatal brain imaging at 3.0 T. Magn Reson Imaging 2007; 25:1162-70. [PMID: 17391887 DOI: 10.1016/j.mri.2007.01.119] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2006] [Revised: 01/28/2007] [Accepted: 01/29/2007] [Indexed: 11/29/2022]
Abstract
Three-dimensional (3D) magnetic resonance imaging (MRI) has shown great potential for studying the impact of prematurity and pathology on brain development. We have investigated the potential of optimized T1-weighted 3D magnetization-prepared rapid gradient-echo imaging (MP-RAGE) for obtaining contrast between white matter (WM) and gray matter (GM) in neonates at 3 T. Using numerical simulations, we predicted that the inversion time (TI) for obtaining strongest contrast at 3 T is approximately 2 s for neonates, whereas for adults, this value is approximately 1.3 s. The optimal neonatal TI value was found to be insensitive to reasonable variations of the assumed T1 relaxation times. The maximum theoretical contrast for neonates was found to be approximately one third of that for adults. Using the optimized TI values, MP-RAGE images were obtained from seven neonates and seven adults at 3 T, and the contrast-to-noise ratio (CNR) was measured for WM versus five GM regions. Compared to adults, neonates exhibited lower CNR between cortical GM and WM and showed a different pattern of regional variation in CNR. These results emphasize the importance of sequence optimization specifically for neonates and demonstrate the challenge in obtaining strong contrast in neonatal brain with T1-weighted 3D imaging.
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Affiliation(s)
- Lori-Anne Williams
- Imaging Division, Lawson Health Research Institute, London, ON, Canada N6A 4V2
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Winter JD, Lee DS, Hung RM, Levin SD, Rogers JM, Thompson RT, Gelman N. Apparent diffusion coefficient pseudonormalization time in neonatal hypoxic-ischemic encephalopathy. Pediatr Neurol 2007; 37:255-62. [PMID: 17903669 DOI: 10.1016/j.pediatrneurol.2007.06.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 02/15/2007] [Accepted: 06/06/2007] [Indexed: 11/30/2022]
Abstract
The apparent diffusion coefficient changes with time after hypoxic-ischemic brain injury. In this study, we quantitatively examined the relationship between the apparent diffusion coefficient and postnatal age for neonates with hypoxic-ischemic encephalopathy and poor outcome, and determined the postnatal age at which these values cannot be distinguished from those of neonates without hypoxic-ischemic encephalopathy (pseudonormalization time). Diffusion-weighted brain images were obtained from clinical scans of term neonates with hypoxic-ischemic encephalopathy and poor outcome (12 neonates, 23 scans) and from control subjects (30 neonates, 31 scans). The correlation between apparent diffusion coefficient and postnatal age was investigated for several brain regions. Pseudonormalization times were determined (1) from the intersection of the regression lines for the hypoxic-ischemic encephalopathy and control groups, as well as (2) from intrasubject apparent diffusion coefficient changes between two scans within a small subgroup. Pseudonormalization times from the regression ranged from 8.3 +/- 1.9 days to 10.1 +/- 2.1 days. Slightly (approximately 1 day) longer values were obtained from the intrasubject analysis. The results suggest that, although abnormally decreased apparent diffusion coefficient values may be evident from approximately 2 days to almost 1 week of postnatal age, abnormally elevated values may not be apparent until late in the second week of life.
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Affiliation(s)
- Jeff D Winter
- Imaging Division, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada
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Winter JD, Thompson RT, Gelman N. Efficacy of motion artifact reduction in neonatal DW segmented EPI at 3 T using phase correction by numerical optimization and segment data swapping. Magn Reson Imaging 2007; 25:1283-91. [PMID: 17490841 DOI: 10.1016/j.mri.2007.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 03/05/2007] [Accepted: 03/05/2007] [Indexed: 11/18/2022]
Abstract
Segmented echoplanar imaging (EPI) is a potentially valuable acquisition method for neonatal diffusion-weighted imaging (DWI) due to the lower acoustic noise levels as well as reduced blurring and distortion associated with it, as compared with single-shot EPI. Reduced acoustic noise may be important for the safety of neonates. However, little information regarding the efficacy of segmented EPI motion correction schemes is available for the neonatal population. We quantitatively assessed the efficacy of a postprocessing technique for motion artifact reduction involving phase correction by nonlinear optimization, alone and in combination with a novel method of utilizing a second data set (referred to as segment data swapping). These methods were applied to three-directional eight-segment echoplanar DW images obtained from 13 sedated neonates and to nine-directional DW images from 3 unsedated neonates. For comparison, the efficacy of the nonlinear optimization method was also evaluated in four adults. Motion correction efficacy was quantified using the motion artifact-to-signal ratio (ASR). The median, 70th percentile and 90th percentile ASR values obtained from neonatal three-directional DWI using nonlinear optimization alone were 2.8%, 4.6% and 9.6%, respectively. Efficacy improved (P<.005), particularly in dealing with the images most difficult to correct, when the phase correction by numerical optimization was combined with segment data swapping (median ASR=1.9%, 70th percentile ASR=2.7%, 90th percentile ASR=4.3%). Similar results were obtained for nine-directional diffusion tensor imaging. Nonlinear optimization alone applied to adult images showed significantly (P<.001) lower ASR values (median ASR=0.9%, 70th percentile ASR=2.1%, 90th percentile ASR=4.1%), demonstrating the greater challenge in DWI of neonates with segmented EPI. In conclusion, phase correction by nonlinear optimization provides effective motion correction for neonatal DW eight-segment EPI, especially when used in conjunction with segment data swapping.
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Affiliation(s)
- Jeff D Winter
- Imaging Division, Lawson Health Research Institute, London, ON, Canada
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Forbes SC, Kowalchuk JM, Thompson RT, Marsh GD. Effects of hyperventilation on phosphocreatine kinetics and muscle deoxygenation during moderate-intensity plantar flexion exercise. J Appl Physiol (1985) 2007; 102:1565-73. [PMID: 17218429 DOI: 10.1152/japplphysiol.00895.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effects of controlled voluntary hyperventilation (Hyp) on phosphocreatine (PCr) kinetics and muscle deoxygenation were examined during moderate-intensity plantar flexion exercise. Male subjects ( n = 7) performed trials consisting of 20-min rest, 6-min exercise, and 10-min recovery in control [Con; end-tidal Pco2(PetCO2) ∼ 33 mmHg] and Hyp (PetCO2∼17 mmHg) conditions. Phosphorus-31 magnetic resonance and near-infrared spectroscopy were used simultaneously to monitor intramuscular acid-base status, high-energy phosphates, and muscle oxygenation. Resting intracellular hydrogen ion concentration ([H+]i) was lower ( P < 0.05) in Hyp [90 nM (SD 3)] than Con [96 nM (SD 4)]; however, at end exercise, [H+]iwas greater ( P < 0.05) in Hyp [128 nM (SD 19)] than Con [120 nM (SD 17)]. At rest, [PCr] was not different between Con [36 mM (SD 2)] and Hyp [36 mM (SD 1)]. The time constant (τ) of PCr breakdown during transition from rest to exercise was greater ( P < 0.05) in Hyp [39 s (SD 22)] than Con [32 s (SD 22)], and the PCr amplitude was greater ( P < 0.05) in Hyp [26% (SD 4)] than Con [22% (SD 6)]. The deoxyhemoglobin and/or deoxymyoglobin (HHb) τ was similar between Hyp [13 s (SD 8)] and Con [10 s (SD 3)]; however, the amplitude was increased ( P < 0.05) in Hyp [40 arbitrary units (au) (SD 23)] compared with Con [26 au (SD 17)]. In conclusion, our results indicate that Hyp-induced hypocapnia enhanced substrate-level phosphorylation during moderate-intensity exercise. In addition, the increased amplitude of the HHb response suggests a reduced local muscle perfusion in Hyp compared with Con.
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Affiliation(s)
- S C Forbes
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
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Abstract
The effects of prior moderate- and prior heavy-intensity exercise on the subsequent metabolic response to incremental exercise were examined. Healthy, young adult subjects (n = 8) performed three randomized plantar-flexion exercise tests: 1) an incremental exercise test (approximately 0.6 W/min) to volitional fatigue (Ramp); 2) Ramp preceded by 6 min of moderate-intensity, constant-load exercise below the intracellular pH threshold (pHT; Mod-Ramp); and 3) Ramp preceded by 6 min of heavy-intensity, constant-load exercise above pHT (Hvy-Ramp); the constant-load and incremental exercise periods were separated by 6 min of rest. (31)P-magnetic resonance spectroscopy was used to continuously monitor intracellular pH, phosphocreatine concentration ([PCr]), and inorganic phosphate concentration ([P(i)]). No differences in exercise performance or the metabolic response to exercise were observed between Ramp and Mod-Ramp. However, compared with Ramp, a 14% (SD 10) increase (P < 0.01) in peak power output (PPO) was observed in Hvy-Ramp. The improved exercise performance in Hvy-Ramp was accompanied by a delayed (P = 0.01) onset of intracellular acidosis [Hvy-Ramp 60.4% PPO (SD 11.7) vs. Ramp 45.8% PPO (SD 9.4)] and a delayed (P < 0.01) onset of rapid increases in [P(i)]/[PCr] [Hvy-Ramp 61.5% PPO (SD 12.0) vs. Ramp 45.1% PPO (SD 9.1)]. In conclusion, prior heavy-intensity exercise delayed the onset of intracellular acidosis and enhanced exercise performance during a subsequent incremental exercise test.
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Affiliation(s)
- Graydon H Raymer
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada N6A 3K7
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Forbes SC, Raymer GH, Kowalchuk JM, Thompson RT, Marsh GD. Phosphocreatine Metabolism and Acidosis during Repeated Bouts of Heavy-Intensity Exercise Separated by 15-min Rest. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200611001-00108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Raja MK, Raymer GH, Moran GR, Marsh G, Thompson RT. Changes in tissue water content measured with multiple-frequency bioimpedance and metabolism measured with 31P-MRS during progressive forearm exercise. J Appl Physiol (1985) 2006; 101:1070-5. [PMID: 16794019 DOI: 10.1152/japplphysiol.01322.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Multiple-frequency bioimpedance analysis (MFBIA) has been used to determine the cellular water composition in the human body. It is noninvasive and has demonstrated good correlations with other invasive measures of tissue water. However, the ability of this method to study transient changes in tissue water in specific muscle groups has not been explored. In this study, MFBIA was used to assess changes in forearm intracellular water (ICW), extracellular water (ECW), and total water (TW) in seven healthy volunteers during and after a progressive wrist flexion exercise protocol. In an identical trial, (31)P magnetic resonance spectroscopy ((31)P-MRS) was used to assess changes in intracellular pH and phosphocreatine (PCr). At the completion of exercise, forearm ICW increased 12.6% (SD 0.07, P = 0.003), TW increased 10.1% (SD 0.06, P = 0.005), and no significant changes were recorded for ECW. A significant correlation was found between the changes in intracellular pH and changes in ICW during exercise (r = -0.84, P = 0.018). With the use of regression analysis, average changes in P(i), PCr, and pH were found to predict changes in ICW (R(2) = 0.98, P = 0.005). In conclusion, MFBIA was sensitive enough to measure transient changes in the exercising forearm muscle. The changes seen were consistent with the hypothesis that intracellular acidification and PCr hydrolysis are important mediators of cellular osmolality and therefore may be responsible for the increased volume of water in the intracellular space that is often recorded after short-term high-intensity exercise.
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Affiliation(s)
- Mohan K Raja
- Department of Radiology, St. Joseph's Health Center, University of Western Ontario, 268 Grosvenor St., London, Ontario, Canada, N6A 4V2
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Affiliation(s)
- R T Thompson
- Department of Internal Medicine of the College of Medicine, University of Cincinnati, Cincinnati
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Forbes SC, Kowalchuk JM, Thompson RT, Marsh GD, Paterson DH. Effects of Respiratory Alkalosis on Phosphocreatine Kinetics During Moderate-Intensity Plantar Flexion Exercise. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-03047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bartolini ME, Wilson K, Raja M, Raymer GH, Thompson RT, Webber CE, Moran GR. Dual X-ray absorptiometry model for characterizing water in the human forearm using multiple frequency bioimpedance analysis. Can J Physiol Pharmacol 2006; 84:181-93. [PMID: 16900944 DOI: 10.1139/y05-125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to develop a method for measuring intracellular (ICW) and extracellular water (ECW) in the human forearm using multiple frequency bioimpedance analysis (MFBIA). The approach was (i) to measure whole-body and forearm fat-free mass using dual X-ray absorptiometry (DXA); (ii) to use these measurements to estimate the fat-free mass (FFM) resistivity in both the forearm and in the whole body; and (iii) to use the ratio of these FFM resistivities to estimate the resistivity in the ICW and ECW compartments of the forearm. To first demonstrate the accuracy of the DXA software in differentiating lean body mass from fat and bone within a volume of tissue, ex-vivo bovine muscle tissue samples (n = 3) were used to approximate the physical properties of the human forearm. It was found that although the human whole-body software overestimates FFM, it was slightly underestimated by the small animal software. Using this technique, DXA measures of FFM were obtained from human volunteers (n = 11; age = 20 ± 5 years; height = 170 ± 12 cm; mass = 64 ± 16 kg). These measures were used in conjunction with MFBIA measures of impedance of the whole body and of the forearm to determine the resistivities of the ICW and ECW compartments of the forearm, namely 375.8 ± 25.2 Ωcm and 55.6 ± 3.7 Ωcm, respectively. These were used in MFBIA equations to calculate the ICW, ECW, and total arm water (TAW) volumes of the human forearm. The calculated TAW and the ECW (± SD) volume fraction (667.29 ± 200.15 mL and 0.169 ± 0.039 mL, respectively) were in agreement with literature values. MFBIA results were compared with those obtained using nuclear magnetic resonance relaxometry (NMRR). MFBIA was performed on 15 subjects before and after an intense maximal handgrip exercise to estimate changes in water volume in muscle. Following exercise, the total and intracellular water of the forearm increased on average by 8% ± 3% and 10% ± 4% (mean ± SD), respectively. In 5 healthy volunteers, MFBIA and NMRR were performed before and after a similar exercise of the forearm muscle. The changes with exercise of intracellular and total arm water volumes as measured by MFBIA were estimated. The percent increases in total water were found to be 9.4% ± 4.2% and 9.4% ± 2.6% and in intracellular water were found to be 10.6% ± 4.6% and 12.0% ± 2.8% (mean ± SD) for NMRR and MFBIA, respectively. The results show that the exercise-induced changes in ICW and TAW determined with the MFBIA model are consistent with those observed with NMRR and radiotracer literature.
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Affiliation(s)
- Miria E Bartolini
- Medical Physics and Applied Radiation Sciences Unit, McMaster University, 1280 Main St. W, Hamilton, ON L8S 4K1, Canada
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Kakule JF, Sharp AR, Schreiner LJ, Thompson RT, Kupka T, Holly R, Peemoeller H. Cross-relaxation bottleneck in water–lysozyme proton magnetization exchange. Biopolymers 2006; 83:11-9. [PMID: 16615066 DOI: 10.1002/bip.20522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The proton spin-lattice relaxation parameters in natural and deuterated lysozyme solutions have been measured as a function of temperature (0-50 degrees C). The variation of the apparent magnitudes of the water proton magnetizations in the solutions with temperature indicates that magnetic coupling mixes protein and water proton magnetizations. The results are consistent with an exchange cross-relaxation model (Hills, B. P., Mol Phys 1992, 76, 489-508) in which the cross-relaxation acts between the labile and nonlabile protons, rather than between water and protein protons. Although this cross-relaxation pathway clearly affects the observed magnetization fractions in this protein solution, its influence on the relaxation rates is less apparent.
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Affiliation(s)
- J F Kakule
- Department of Physics, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3
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Raymer GH, Allman BL, Rice CL, Marsh GD, Thompson RT. Characteristics of a MR-compatible ankle exercise ergometer for a 3.0 T head-only MR scanner. Med Eng Phys 2005; 28:489-94. [PMID: 16162418 DOI: 10.1016/j.medengphy.2005.07.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Revised: 07/19/2005] [Accepted: 07/26/2005] [Indexed: 11/26/2022]
Abstract
An exercise ergometer, for isometric or dynamic contraction of both dorsiflexion and/or plantarflexion exercise, was designed and constructed for a 3.0 T head-only MR scanner. The principal features of this MR-compatible ergometer include electronic devices for quantification of force (during isometric exercise) and angular displacement (during dynamic exercise), without any significant losses to external motions or frictions. The ergometer was also made to be adjustable for subject leg length and was designed for suspension within the bore of the magnet to eliminate transmission of force and vibration to the MR scanner. A description of the design and construction, as well as the important technical features, is presented herein.
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Affiliation(s)
- Graydon H Raymer
- Department of Medical Biophysics, The University of Western Ontario, London, Ont., Canada N6A 5C1.
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Williams LA, Gelman N, Picot PA, Lee DS, Ewing JR, Han VK, Thompson RT. Neonatal Brain: Regional Variability of in Vivo MR Imaging Relaxation Rates at 3.0 T—Initial Experience. Radiology 2005; 235:595-603. [PMID: 15858099 DOI: 10.1148/radiol.2352031769] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To retrospectively investigate regional in vivo magnetic resonance (MR) imaging transverse and longitudinal relaxation rates at 3.0 T in neonatal brain, the relationship between these rates, and their potential use for gray matter (GM) versus white matter (WM) tissue discrimination. MATERIALS AND METHODS Informed parental consent for performance of imaging procedures was obtained in each infant. Informed consent for retrospective image analysis was not required; ethics approval was obtained from institutional review board. At 3.0 T, R1 and R2 were measured in brain regions (frontal WM, posterior WM, periventricular WM, frontal GM, posterior GM, basal ganglia, and thalamus) in 13 infants with suspected neurologic abnormality (two term, 11 preterm). Maps of R1 and R2 were acquired with T1 by multiple readout pulses and segmented spin-echo echo-planar imaging sequences, respectively. Accuracy of R1 and R2 map acquisition methods was tested in phantoms by comparing them with inversion-recovery and spin-echo sequences, respectively. Statistical analysis included linear regression analysis to determine relationship between R1 and R2 and Wilcoxon signed rank test to investigate the potential for discrimination between GM and WM. RESULTS In phantoms, R1 values measured with T1 by multiple readout pulses sequence were 3%-8% lower than those measured with inversion recovery sequence, and R2 values measured with segmented echo-planar sequence were 1%-8% lower than those measured with spin-echo sequence. A strong correlation of 0.944 (P < .001) between R1 and R2 in neonatal brain was observed. For R2, relative differences between GM and WM were larger than were those for R1 (z = -2.366, P < .05). For frontal GM and frontal WM, (R2(GM) - R2(WM))/R2(WM) yielded 0.8 +/- 0.2 (mean +/- standard deviation) and (R1(GM) - R1(WM))/R1(WM) yielded 0.3 +/- 0.09. CONCLUSION Results at 3.0 T indicate that R1 decreases with increasing field strength, while R2 values are similar to those reported at lower field strengths. For neonates, R2 image contrast may be more advantageous than R1 image contrast for differentiation between GM and WM.
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Affiliation(s)
- Lori-Anne Williams
- Imaging Division, Lawson Health Research Institute, London, Ontario, Canada.
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Vasileiadis GT, Gelman N, Han VKM, Williams LA, Mann R, Bureau Y, Thompson RT. Uncomplicated intraventricular hemorrhage is followed by reduced cortical volume at near-term age. Pediatrics 2004; 114:e367-72. [PMID: 15342899 DOI: 10.1542/peds.2004-0500] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Intraventricular hemorrhage (IVH) is the most common brain injury among premature infants. Neonates with IVH are at greater risk of impaired neurodevelopmental outcomes, compared with those without IVH. IVH causes destruction of the germinal matrix and glial precursor cells, with possible effects on cortical development. OBJECTIVE To investigate cortical development after uncomplicated IVH (with no parenchymal involvement and no posthemorrhagic hydrocephalus). We hypothesized that uncomplicated IVH would be followed by reduced cortical volume among premature infants at near-term age. METHODS A prospective cohort study was conducted, with preset selection criteria. Infants with small-for-gestational age birth weight, congenital abnormalities or brain malformations, metabolic disorders, recurrent sepsis, or necrotizing enterocolitis were excluded. Also, infants with posthemorrhagic hydrocephalus, parenchymal involvement of hemorrhage, cystic periventricular leukomalacia, or persistent ventriculomegaly were excluded, on the basis of routine serial ultrasonographic assessments. Three-dimensional images were acquired for 23 infants at near-term age, with 3-T magnetic resonance imaging and a magnetization-prepared rapid gradient echo sequence. Image analysis and segmentation of the cerebrum in different tissue types were based on signal contrast and anatomic localization. The cortical gray matter (CGM), subcortical gray matter, white matter, and intraventricular cerebrospinal fluid volumes of 12 infants with uncomplicated IVH were compared with those of 11 infants without IVH, using multivariate analysis of variance. RESULTS The multivariate analysis of variance for the regional brain volumes in the 2 groups indicated significance (Wilks' lambda = 0.546). The CGM volume was significantly reduced in the IVH group (no-IVH group: 122 +/- 12.9 mL; IVH group: 102 +/- 14.6 mL; F = 13.218). This finding remained significant after testing for possible confounding factors and adjustment for size differences between the infants (F = 9.415). There was no difference in the volumes of subcortical gray matter, white matter, and cerebrospinal fluid. CONCLUSIONS This is the first study to document impaired cortical development after uncomplicated IVH. The impairment was demonstrated by a 16% reduction in cerebral CGM volume at near-term age. The finding supports concerns regarding possible glial precursor cell loss after germinal matrix IVH, but its clinical significance is still unclear. The alteration in brain development demonstrated in this report supports closer neurodevelopmental follow-up monitoring of preterm infants with uncomplicated IVH.
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Affiliation(s)
- George T Vasileiadis
- Department of Pediatrics, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada.
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