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Craven AR, Bell TK, Ersland L, Harris AD, Hugdahl K, Oeltzschner G. Linewidth-related bias in modelled concentration estimates from GABA-edited 1H-MRS. bioRxiv 2024:2024.02.27.582249. [PMID: 38464094 PMCID: PMC10925149 DOI: 10.1101/2024.02.27.582249] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
J-difference-edited MRS is widely used to study GABA in the human brain. Editing for low-concentration target molecules (such as GABA) typically exhibits lower signal-to-noise ratio (SNR) than conventional non-edited MRS, varying with acquisition region, volume and duration. Moreover, spectral lineshape may be influenced by age-, pathology-, or brain-region-specific effects of metabolite T2, or by task-related blood-oxygen level dependent (BOLD) changes in functional MRS contexts. Differences in both SNR and lineshape may have systematic effects on concentration estimates derived from spectral modelling. The present study characterises the impact of lineshape and SNR on GABA+ estimates from different modelling algorithms: FSL-MRS, Gannet, LCModel, Osprey, spant and Tarquin. Publicly available multi-site GABA-edited data (222 healthy subjects from 20 sites; conventional MEGA-PRESS editing; TE = 68 ms) were pre-processed with a standardised pipeline, then filtered to apply controlled levels of Lorentzian and Gaussian linebroadening and SNR reduction. Increased Lorentzian linewidth was associated with a 2-5% decrease in GABA+ estimates per Hz, observed consistently (albeit to varying degrees) across datasets and most algorithms. Weaker, often opposing effects were observed for Gaussian linebroadening. Variations are likely caused by differing baseline parametrization and lineshape constraints between models. Effects of linewidth on other metabolites (e.g., Glx and tCr) varied, suggesting that a linewidth confound may persist after scaling to an internal reference. These findings indicate a potentially significant confound for studies where linewidth may differ systematically between groups or experimental conditions, e.g. due to T2 differences between brain regions, age, or pathology, or varying T2* due to BOLD-related changes. We conclude that linewidth effects need to be rigorously considered during experimental design and data processing, for example by incorporating linewidth into statistical analysis of modelling outcomes or development of appropriate lineshape matching algorithms.
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Affiliation(s)
- Alexander R. Craven
- Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
- Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway
| | - Tiffany K. Bell
- Department of Radiology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Lars Ersland
- Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
- Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway
| | - Ashley D. Harris
- Department of Radiology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Kenneth Hugdahl
- Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
- Division of Psychiatry, Haukeland University Hospital, Bergen, Norway
- Department of Radiology, Haukeland University Hospital, Bergen, Norway
| | - Georg Oeltzschner
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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La PL, Walker R, Bell TK, Craig W, Doan Q, Beauchamp MH, Zemek R, Yeates KO, Harris AD. Longitudinal changes in brain metabolites following pediatric concussion. Sci Rep 2024; 14:3242. [PMID: 38331924 PMCID: PMC10853495 DOI: 10.1038/s41598-024-52744-7] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 01/23/2024] [Indexed: 02/10/2024] Open
Abstract
Concussion is commonly characterized by a cascade of neurometabolic changes following injury. Magnetic Resonance Spectroscopy (MRS) can be used to quantify neurometabolites non-invasively. Longitudinal changes in neurometabolites have rarely been studied in pediatric concussion, and fewer studies consider symptoms. This study examines longitudinal changes of neurometabolites in pediatric concussion and associations between neurometabolites and symptom burden. Participants who presented with concussion or orthopedic injury (OI, comparison group) were recruited. The first timepoint for MRS data collection was at a mean of 12 days post-injury (n = 545). Participants were then randomized to 3 (n = 243) or 6 (n = 215) months for MRS follow-up. Parents completed symptom questionnaires to quantify somatic and cognitive symptoms at multiple timepoints following injury. There were no significant changes in neurometabolites over time in the concussion group and neurometabolite trajectories did not differ between asymptomatic concussion, symptomatic concussion, and OI groups. Cross-sectionally, Choline was significantly lower in those with persistent somatic symptoms compared to OI controls at 3 months post-injury. Lower Choline was also significantly associated with higher somatic symptoms. Although overall neurometabolites do not change over time, choline differences that appear at 3 months and is related to somatic symptoms.
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Affiliation(s)
- Parker L La
- Department of Radiology, University of Calgary, Calgary, AB, Canada.
- Alberta Children's Hospital Research Institute, Calgary, AB, Canada.
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
| | - Robyn Walker
- Department of Radiology, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Tiffany K Bell
- Department of Radiology, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - William Craig
- Department of Pediatrics, Stollery Children's Hospital, University of Alberta, Edmonton, AB, Canada
| | - Quynh Doan
- Department of Pediatrics, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - Miriam H Beauchamp
- Department of Psychology, Ste Justine Hospital Research Centre, University of Montreal, Montreal, QC, Canada
| | - Roger Zemek
- Department of Pediatrics and Emergency Medicine, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON, Canada
- Childrens' Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
| | - Keith Owen Yeates
- Department of Psychology, University of Calgary, Calgary, AB, Canada
| | - Ashley D Harris
- Department of Radiology, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, Calgary, AB, Canada
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Perdue MV, DeMayo MM, Bell TK, Boudes E, Bagshawe M, Harris AD, Lebel C. Changes in brain metabolite levels across childhood. Neuroimage 2023; 274:120087. [PMID: 37080345 DOI: 10.1016/j.neuroimage.2023.120087] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/05/2023] [Accepted: 04/03/2023] [Indexed: 04/22/2023] Open
Abstract
Metabolites play important roles in brain development and their levels change rapidly in the prenatal period and during infancy. Metabolite levels are thought to stabilize during childhood, but the development of neurochemistry across early-middle childhood remains understudied. We examined the developmental changes of key metabolites (total N-acetylaspartate, tNAA; total choline, tCho; total creatine, tCr; glutamate+glutamine, Glx; and myo-inositol, mI) using short echo-time magnetic resonance spectroscopy (MRS) in the anterior cingulate cortex (ACC) and the left temporo-parietal cortex (LTP) using a mixed cross-sectional/longitudinal design in children aged 2-11 years (ACC: N=101 children, 112 observations; LTP: N=95 children, 318 observations). We found age-related effects for all metabolites. tNAA increased with age in both regions, while tCho decreased with age in both regions. tCr increased with age in the LTP only, and mI decreased with age in the ACC only. Glx did not show linear age effects in either region, but a follow-up analysis in only participants with ≥3 datapoints in the LTP revealed a quadratic effect of age following an inverted U-shape. These substantial changes in neurochemistry throughout childhood likely underlie various processes of structural and functional brain development.
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Affiliation(s)
- Meaghan V Perdue
- Department of Radiology, University of Calgary; Alberta Children's Hospital Research Institute; Hotchkiss Brain Institute, University of Calgary
| | - Marilena M DeMayo
- Department of Radiology, University of Calgary; Alberta Children's Hospital Research Institute; Hotchkiss Brain Institute, University of Calgary; Mathison Centre for Mental Health Research and Education; Department of Psychiatry, University of Calgary
| | - Tiffany K Bell
- Department of Radiology, University of Calgary; Alberta Children's Hospital Research Institute; Hotchkiss Brain Institute, University of Calgary
| | | | - Mercedes Bagshawe
- Alberta Children's Hospital Research Institute; Werklund School of Education, University of Calgary
| | - Ashley D Harris
- Department of Radiology, University of Calgary; Alberta Children's Hospital Research Institute; Hotchkiss Brain Institute, University of Calgary
| | - Catherine Lebel
- Department of Radiology, University of Calgary; Alberta Children's Hospital Research Institute; Hotchkiss Brain Institute, University of Calgary.
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La PL, Joyce JM, Bell TK, Mauthner M, Craig W, Doan Q, Beauchamp MH, Zemek R, Yeates KO, Harris AD. Brain metabolites measured with magnetic resonance spectroscopy in pediatric concussion and orthopedic injury: An Advancing Concussion Assessment in Pediatrics (A-CAP) study. Hum Brain Mapp 2023; 44:2493-2508. [PMID: 36763547 PMCID: PMC10028643 DOI: 10.1002/hbm.26226] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/18/2022] [Accepted: 01/25/2023] [Indexed: 02/11/2023] Open
Abstract
Millions of children sustain a concussion annually. Concussion disrupts cellular signaling and neural pathways within the brain but the resulting metabolic disruptions are not well characterized. Magnetic resonance spectroscopy (MRS) can examine key brain metabolites (e.g., N-acetyl Aspartate (tNAA), glutamate (Glx), creatine (tCr), choline (tCho), and myo-Inositol (mI)) to better understand these disruptions. In this study, we used MRS to examine differences in brain metabolites between children and adolescents with concussion versus orthopedic injury. Children and adolescents with concussion (n = 361) or orthopedic injury (OI) (n = 184) aged 8 to 17 years were recruited from five emergency departments across Canada. MRS data were collected from the left dorsolateral prefrontal cortex (L-DLPFC) using point resolved spectroscopy (PRESS) at 3 T at a mean of 12 days post-injury (median 10 days post-injury, range 2-33 days). Univariate analyses for each metabolite found no statistically significant metabolite differences between groups. Within each analysis, several covariates were statistically significant. Follow-up analyses designed to account for possible confounding factors including age, site, scanner, vendor, time since injury, and tissue type (and interactions as appropriate) did not find any metabolite group differences. In the largest sample of pediatric concussion studied with MRS to date, we found no metabolite differences between concussion and OI groups in the L-DLPFC. We suggest that at 2 weeks post-injury in a general pediatric concussion population, brain metabolites in the L-DLPFC are not specifically affected by brain injury.
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Affiliation(s)
- Parker L La
- Department of Radiology, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Julie M Joyce
- Department of Radiology, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Tiffany K Bell
- Department of Radiology, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Micaela Mauthner
- Department of Radiology, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - William Craig
- Department of Pediatrics, University of Alberta and Stollery Children's Hospital, Edmonton, Alberta, Canada
| | - Quynh Doan
- Department of Pediatrics, University of British Columbia and BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Miriam H Beauchamp
- Department of Psychology, University of Montreal and Ste Justine Hospital Research Center, Montreal, Quebec, Canada
| | - Roger Zemek
- Department of Pediatrics and Emergency Medicine, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada
- Childrens' Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Keith Owen Yeates
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Ashley D Harris
- Department of Radiology, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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Bell TK, Craven AR, Hugdahl K, Noeske R, Harris AD. Functional Changes in GABA and Glutamate during Motor Learning. eNeuro 2023; 10:ENEURO.0356-20.2023. [PMID: 36754626 PMCID: PMC9961379 DOI: 10.1523/eneuro.0356-20.2023] [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: 01/18/2023] [Accepted: 01/23/2023] [Indexed: 02/10/2023] Open
Abstract
Functional magnetic resonance spectroscopy (fMRS) of GABA at 3 T poses additional challenges compared with fMRS of other metabolites because of the difficulties of measuring GABA levels; GABA is present in the brain at relatively low concentrations, and its signal is overlapped by higher concentration metabolites. Using 7 T fMRS, GABA levels have been shown to decrease specifically during motor learning (and not during a control task). Though the use of 7 T is appealing, access is limited. For GABA fMRS to be widely accessible, it is essential to develop this method at 3 T. Nine healthy right-handed participants completed a motor learning and a control button-pressing task. fMRS data were acquired from the left sensorimotor cortex during the task using a continuous GABA-edited MEGA-PRESS acquisition at 3 T. We found no significant changes in GABA+/tCr, Glx/tCr, or Glu/tCr levels in either task; however, we show a positive relationship between motor learning and glutamate levels both at rest and at the start of the task. Though further refinement and validation of this method is needed, this study represents a further step in using fMRS at 3 T to probe GABA levels in both healthy cognition and clinical disorders.
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Affiliation(s)
- Tiffany K Bell
- Department of Radiology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Alexander R Craven
- Department of Biological and Medical Psychology, University of Bergen, NO-5020 Bergen, Norway
- Department of Clinical Engineering, Haukeland University Hospital, N-5021 Bergen, Norway
| | - Kenneth Hugdahl
- Department of Biological and Medical Psychology, University of Bergen, NO-5020 Bergen, Norway
- Division of Psychiatry, Haukeland University Hospital, N-5021 Bergen, Norway
- Department of Radiology, Haukeland University Hospital, N-5021 Bergen, Norway
- NORMENT Center for the Study of Mental Disorders, Oslo University Hospital HF, N-0450 Bergen, Norway
| | | | - Ashley D Harris
- Department of Radiology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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La PL, Bell TK, Craig W, Doan Q, Beauchamp MH, Zemek R, Yeates KO, Harris AD. Comparison of different approaches to manage multi-site magnetic resonance spectroscopy clinical data analysis. Front Psychol 2023; 14:1130188. [PMID: 37151330 PMCID: PMC10157208 DOI: 10.3389/fpsyg.2023.1130188] [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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 03/31/2023] [Indexed: 05/09/2023] Open
Abstract
Introduction The effects caused by differences in data acquisition can be substantial and may impact data interpretation in multi-site/scanner studies using magnetic resonance spectroscopy (MRS). Given the increasing use of multi-site studies, a better understanding of how to account for different scanners is needed. Using data from a concussion population, we compare ComBat harmonization with different statistical methods in controlling for site, vendor, and scanner as covariates to determine how to best control for multi-site data. Methods The data for the current study included 545 MRS datasets to measure tNAA, tCr, tCho, Glx, and mI to study the pediatric concussion acquired across five sites, six scanners, and two different MRI vendors. For each metabolite, the site and vendor were accounted for in seven different models of general linear models (GLM) or mixed-effects models while testing for group differences between the concussion and orthopedic injury. Models 1 and 2 controlled for vendor and site. Models 3 and 4 controlled for scanner. Models 5 and 6 controlled for site applied to data harmonized by vendor using ComBat. Model 7 controlled for scanner applied to data harmonized by scanner using ComBat. All the models controlled for age and sex as covariates. Results Models 1 and 2, controlling for site and vendor, showed no significant group effect in any metabolites, but the vendor and site were significant factors in the GLM. Model 3, which included a scanner, showed a significant group effect for tNAA and tCho, and the scanner was a significant factor. Model 4, controlling for the scanner, did not show a group effect in the mixed model. The data harmonized by the vendor using ComBat (Models 5 and 6) had no significant group effect in both the GLM and mixed models. Lastly, the data harmonized by the scanner using ComBat (Model 7) showed no significant group effect. The individual site data suggest there were no group differences. Conclusion Using data from a large clinical concussion population, different analysis techniques to control for site, vendor, and scanner in MRS data yielded different results. The findings support the use of ComBat harmonization for clinical MRS data, as it removes the site and vendor effects.
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Affiliation(s)
- Parker L. La
- Department of Radiology, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- *Correspondence: Parker L. La,
| | - Tiffany K. Bell
- Department of Radiology, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - William Craig
- Department of Pediatrics, Stollery Children’s Hospital, University of Alberta, Edmonton, AB, Canada
| | - Quynh Doan
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Miriam H. Beauchamp
- Department of Psychology, Ste-Justine Hospital Research Centre, University of Montreal, Montreal, QC, Canada
| | - Roger Zemek
- Department of Pediatrics and Emergency Medicine, Children’s Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON, Canada
| | - Keith Owen Yeates
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Department of Psychology, University of Calgary, Calgary, AB, Canada
| | - Ashley D. Harris
- Department of Radiology, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB, Canada
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Clarke WT, Bell TK, Emir UE, Mikkelsen M, Oeltzschner G, Shamaei A, Soher BJ, Wilson M. NIfTI-MRS: A standard data format for magnetic resonance spectroscopy. Magn Reson Med 2022; 88:2358-2370. [PMID: 36089825 PMCID: PMC7613677 DOI: 10.1002/mrm.29418] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/26/2022] [Accepted: 07/29/2022] [Indexed: 01/11/2023]
Abstract
PURPOSE Multiple data formats in the MRS community currently hinder data sharing and integration. NIfTI-MRS is proposed as a standard spectroscopy data format, implemented as an extension to the Neuroimaging informatics technology initiative (NIfTI) format. This standardized format can facilitate data sharing and algorithm development as well as ease integration of MRS analysis alongside other imaging modalities. METHODS A file format using the NIfTI header extension framework incorporates essential spectroscopic metadata and additional encoding dimensions. A detailed description of the specification is provided. An open-source command-line conversion program is implemented to convert single-voxel and spectroscopic imaging data to NIfTI-MRS. Visualization of data in NIfTI-MRS is provided by development of a dedicated plugin for FSLeyes, the FMRIB Software Library (FSL) image viewer. RESULTS Online documentation and 10 example datasets in the proposed format are provided. Code examples of NIfTI-MRS readers are implemented in common programming languages. Conversion software, spec2nii, currently converts 14 formats where data is stored in image-space to NIfTI-MRS, including Digital Imaging and Communications in Medicine (DICOM) and vendor proprietary formats. CONCLUSION NIfTI-MRS aims to solve issues arising from multiple data formats being used in the MRS community. Through a single conversion point, processing and analysis of MRS data are simplified, thereby lowering the barrier to use of MRS. Furthermore, it can serve as the basis for open data sharing, collaboration, and interoperability of analysis programs. Greater standardization and harmonization become possible. By aligning with the dominant format in neuroimaging, NIfTI-MRS enables the use of mature tools present in the imaging community, demonstrated in this work by using a dedicated imaging tool, FSLeyes, for visualization.
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Affiliation(s)
- William T. Clarke
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUnited Kingdom
| | - Tiffany K. Bell
- Department of RadiologyUniversity of CalgaryCalgaryAlbertaCanada,Alberta Children's Hospital Research InstituteUniversity of CalgaryCalgaryAlbertaCanada,Hotchkiss Brain InstituteUniversity of CalgaryCalgaryAlbertaCanada
| | - Uzay E. Emir
- School of Health SciencesPurdue UniversityWest LafayetteIndianaUSA,Weldon School of Biomedical EngineeringPurdue UniversityWest LafayetteIndianaUSA
| | - Mark Mikkelsen
- Department of RadiologyWeill Cornell MedicineNew YorkNew YorkUSA
| | - Georg Oeltzschner
- Russell H. Morgan Department of Radiology and Radiological ScienceThe Johns Hopkins University School of MedicineBaltimoreMarylandUSA,F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger InstituteBaltimoreMarylandUSA
| | - Amirmohammad Shamaei
- Czech Academy of SciencesInstitute of Scientific InstrumentsBrnoCzech Republic,Department of Biomedical EngineeringBrno University of TechnologyBrnoCzech Republic
| | - Brian J. Soher
- Center for Advanced MR Development, Department of RadiologyDuke University Medical CenterDurhamNorth CarolinaUSA
| | - Martin Wilson
- Centre for Human Brain Health and School of PsychologyUniversity of BirminghamBirminghamUnited Kingdom
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Bell TK, Godfrey KJ, Ware AL, Yeates KO, Harris AD. Harmonization of multi-site MRS data with ComBat. Neuroimage 2022; 257:119330. [PMID: 35618196 DOI: 10.1016/j.neuroimage.2022.119330] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 05/20/2022] [Accepted: 05/23/2022] [Indexed: 12/22/2022] Open
Abstract
Magnetic resonance spectroscopy (MRS) is a non-invasive neuroimaging technique used to measure brain chemistry in vivo and has been used to study the healthy brain as well as neuropathology in numerous neurological disorders. The number of multi-site studies using MRS are increasing; however, non-biological variability introduced during data collection across multiple sites, such as differences in scanner vendors and site-specific acquisition implementations for MRS, can obscure detection of biological effects of interest. ComBat is a data harmonization technique that can remove non-biological sources of variance in multisite studies. It has been validated for use with structural and functional MRI metrics but not for MRS metabolites. This study investigated the validity of using ComBat to harmonize MRS metabolites for vendor and site differences. Analyses were performed using data acquired across 20 sites and included edited MRS for GABA+ (N=218) and macromolecule-suppressed GABA data (N=209), as well as standard PRESS data to quantify NAA, creatine, choline, and glutamate (N=190). ComBat harmonization successfully mitigated vendor and site differences for all metabolites of interest. Moreover, significant associations were detected between sex and choline levels and between age and glutamate and GABA+ levels that were not detectable prior to harmonization, confirming the importance of removing site and vendor effects in multi-site data. In conclusion, ComBat harmonization can be successfully applied to MRS data in multi-site MRS studies.
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Affiliation(s)
- Tiffany K Bell
- Department of Radiology, University of Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, 28 Oki Drive, Calgary, AB T3B 6A9, Canada.
| | - Kate J Godfrey
- Department of Radiology, University of Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, 28 Oki Drive, Calgary, AB T3B 6A9, Canada
| | - Ashley L Ware
- Hotchkiss Brain Institute, University of Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, 28 Oki Drive, Calgary, AB T3B 6A9, Canada; Department of Psychology, University of Calgary, AB Canada; Department of Neurology, University of Utah, UT, United States
| | - Keith Owen Yeates
- Hotchkiss Brain Institute, University of Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, 28 Oki Drive, Calgary, AB T3B 6A9, Canada; Department of Psychology, University of Calgary, AB Canada
| | - Ashley D Harris
- Department of Radiology, University of Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, 28 Oki Drive, Calgary, AB T3B 6A9, Canada
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McGinnity CJ, Smith AB, Yaakub SN, Weidenbach Gerbase S, Gammerman A, Tyson AL, Bell TK, Elmasri M, Barker GJ, Richardson MP, Pal DK. Decreased functional connectivity within a language subnetwork in benign epilepsy with centrotemporal spikes. Epilepsia Open 2017; 2:214-225. [PMID: 29588950 PMCID: PMC5719846 DOI: 10.1002/epi4.12051] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [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] [Accepted: 02/20/2017] [Indexed: 01/11/2023] Open
Abstract
Objective Benign epilepsy with centrotemporal spikes (BECTS, also known as Rolandic epilepsy) is a common epilepsy syndrome that is associated with literacy and language impairments. The neural mechanisms of the syndrome are not known. The primary objective of this study was to test the hypothesis that functional connectivity within the language network is decreased in children with BECTS. We also tested the hypothesis that siblings of children with BECTS have similar abnormalities. Methods Echo planar magnetic resonance (MR) imaging data were acquired from 25 children with BECTS, 12 siblings, and 20 healthy controls, at rest. After preprocessing with particular attention to intrascan motion, the mean signal was extracted from each of 90 regions of interest. Sparse, undirected graphs were constructed from adjacency matrices consisting of Spearman's rank correlation coefficients. Global and nodal graph metrics and subnetwork and pairwise connectivity were compared between groups. Results There were no significant differences in graph metrics between groups. Children with BECTS had decreased functional connectivity relative to controls within a four-node subnetwork, which consisted of the left inferior frontal gyrus, the left superior frontal gyrus, the left supramarginal gyrus, and the right inferior parietal lobe (p = 0.04). A similar but nonsignificant decrease was also observed for the siblings. The BECTS groups had significant increases in connectivity within a five-node, five-edge frontal subnetwork. Significance The results provide further evidence of decreased functional connectivity between key mediators of speech processing, language, and reading in children with BECTS. We hypothesize that these decreases reflect delayed lateralization of the language network and contribute to specific cognitive impairments.
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Affiliation(s)
- Colm J. McGinnity
- Department of Basic and Clinical NeuroscienceInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
| | - Anna B. Smith
- Department of Basic and Clinical NeuroscienceInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
| | - Siti N. Yaakub
- Department of Basic and Clinical NeuroscienceInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
| | - Sofia Weidenbach Gerbase
- Department of Basic and Clinical NeuroscienceInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
| | - Anya Gammerman
- Faculty of Life Sciences & MedicineSchool of Bioscience EducationKing's College LondonLondonUnited Kingdom
| | - Adam L. Tyson
- Department of Forensic and Neurodevelopmental SciencesInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
- Centre for Developmental NeurobiologyInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
| | - Tiffany K. Bell
- Department of Basic and Clinical NeuroscienceInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
| | - Marwa Elmasri
- Faculty of Life Sciences & MedicineSchool of Bioscience EducationKing's College LondonLondonUnited Kingdom
| | - Gareth J. Barker
- Department of NeuroimagingInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
| | - Mark P. Richardson
- Department of Basic and Clinical NeuroscienceInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
| | - Deb K. Pal
- Department of Basic and Clinical NeuroscienceInstitute of Psychiatry, Psychology & NeuroscienceKing's College LondonLondonUnited Kingdom
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10
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Affiliation(s)
| | - T K Bell
- Royal Victoria Hospital, Belfast
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11
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Lazary S, Antczak DF, Bailey E, Bell TK, Bernoco D, Byrns G, McClure JJ. Joint Report of the Fifth International Workshop on Lymphocyte Alloantigens of the Horse, Baton Rouge, Louisiana, 31 October-1 November 1987. Anim Genet 2009; 19:447-56. [PMID: 2466424 DOI: 10.1111/j.1365-2052.1988.tb00836.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [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: 01/01/2023]
Abstract
Six laboratories participated in the Fifth International Workshop on Lymphocyte Alloantigens of the Horse, testing 132 alloantisera against lymphocytes of 880 horses chosen to represent different families and breeds. Most of the alloantisera were produced by lymphocyte immunization between horses matched at the ELA-A locus. All horses were also tested with antisera contributed to the workshop by participating laboratories which identified ELA specificities A1-A10 and W12-W21. Previously identified workshop specificities ELA-W14, W15 and W19 were accepted as products of the ELA-A locus based on family and population studies by the workshop. Their designations were changed to ELA-A14, ELA-A15 and ELA-A19, respectively. Two new specificities were identified, namely ELA-W22 (W22) and ELA-W23 (W23). Population and family studies indicated that W22 and W23 as well as W13 are products of an ELA locus other than ELA-A. The presence of these specificities was correlated with the presence of certain ELA-A locus specificities, e.g. W13 with A3, W22 with A2 and W23 with A5. However, the association was not complete and W13, W22 and W23 also segregated with other ELA-A specificities in some families. Evidence for recombination was found between the ELA-A locus and the locus or loci encoding these specificities resulting in seven recombinant haplotypes found among the data presented in this workshop. Further studies are required for definitive assignment of the specificities to a class I or class II locus.
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Affiliation(s)
- S Lazary
- Division of Immunogenetics, School of Veterinary Medicine, University of Berne, Switzerland
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Abstract
42 dyslexic and 42 ordinary readers were given a rapid sequential short-term memory task using materials adapted from the Illinois Test of Psycholinguistic Abilities Visual Sequential Memory subset. Dyslexic readers performed at a similar level to ordinary readers. In Study 2, the same readers were given a 10-piece form board to complete as quickly as possible. Dyslexic readers were significantly slower on this task. Since short-term memory was not a feature of the second task, it was reasoned that short-term memory problems were unlikely to be a feature of dyslexic's performances on rapid sequential processing tasks.
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Affiliation(s)
- T K Bell
- County Psychological Service Cheshire County Council, Northwich, England
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13
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Bell TK. Rapid sequential processing in dyslexic and ordinary readers. Percept Mot Skills 1990. [PMID: 2087370 DOI: 10.2466/pms.71.8.1155-1159] [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: 04/23/2023]
Abstract
42 dyslexic and 42 ordinary readers were given a rapid sequential short-term memory task using materials adapted from the Illinois Test of Psycholinguistic Abilities Visual Sequential Memory subset. Dyslexic readers performed at a similar level to ordinary readers. In Study 2, the same readers were given a 10-piece form board to complete as quickly as possible. Dyslexic readers were significantly slower on this task. Since short-term memory was not a feature of the second task, it was reasoned that short-term memory problems were unlikely to be a feature of dyslexic's performances on rapid sequential processing tasks.
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Affiliation(s)
- T K Bell
- County Psychological Service Cheshire County Council, Northwich, England
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Brannigan PD, Bell TK. Quality assurance of ultrasound test objects. Br J Radiol 1990; 63:584. [PMID: 2202482 DOI: 10.1259/0007-1285-63-751-584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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15
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Cranley K, Webb JA, Bell TK. A refinement to a radiation dose reduction modification for an EMI CT 5005 whole body scanner filtration system. Br J Radiol 1983; 56:770-2. [PMID: 6616145 DOI: 10.1259/0007-1285-56-670-770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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16
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Webb JA, Cranley K, Bell TK. A preliminary investigation of radiation dose reduction on an EMI CT5005 whole body scanner using a copper wedge. Br J Radiol 1982; 55:634-9. [PMID: 7127004 DOI: 10.1259/0007-1285-55-657-634] [Citation(s) in RCA: 3] [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: 01/23/2023] Open
Abstract
The effects of the existing filtration system upon a narrow, parallel beam of X rays were considered. The profile of a Cu filter to be placed on the tube-side A1 wedge was calculated on the basis that the total energy incident on the detector box would remain unchanged when the other A1 wedge was removed. A Cu wedge was machined according to this profile. The effects of this modification on surface radiation dose delivered to a 25 cm EMI water phantom were both predicted and measured for horizontal traverses, and were in broad agreement. The reduction in integral radiation dose to the 25 cm water phantom was predicted as 39%. Dose reductions measured at several points on the surface and within an Alderson Rando anthropomorphic phantom head averaged 53% and 20% respectively. The modified system was evaluated in terms of imaging ability, and although some degradation was seen, images of the EMI composite phantom remained "diagnostic" in quality, despite non-ideal responses of some photomultiplier tubes at intermediate and extreme positions of the traverse periphery.
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Bell TK, Cranley K. An evaluation of count rate losses due to dead time in static and mobile gamma camera data analysis systems. Br J Radiol 1981; 54:1093-7. [PMID: 7296236 DOI: 10.1259/0007-1285-54-648-1093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The count rate responses of a gamma camera and data analysis system have been shown to behave as two separate components. Five systems made up of combinations of two static gamma cameras, two data analysis systems, and a mobile gamma camera system were investigated. Camera and data analysis system dead times are quoted and percentage corrections are plotted against radioactivity of 99 Tcm in a patient phantom within the field of view. It is recommended that such a detailed study should be performed for any gamma camera system as part of a quality assurance programme.
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Abstract
Axillary lymphoscintigraphy using 99Tcm antimony sulphide colloid has been carried out in 29 patients with suspected breast cancer and was correlated with histology. Of the 23 with proved tumour, axillary node metastases were found in 19 and, although 10 did have diminished uptake on the side of the lesion, 5 had an equal uptake in both sides and 4 had an increased uptake on the side of the lesion. Further, some of the nodes in which the high uptake had occurred were those heavily infiltrated by tumour. It is concluded that: a, lymphoscintigraphy with antimony sulphide colloid is not a reliable technique for the detection of metastatic disease in the regional nodes; b, any lymphoscintigraphy with this or any other agent requires more meticulous histological correlation than hitherto before it can be assumed to have any proved clinical value.
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Webb JA, Bell TK, Grebbell FS. A colour video enhancement terminal for computerised tomography. Phys Med Biol 1981; 26:329-33. [PMID: 7220609 DOI: 10.1088/0031-9155/26/2/013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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20
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Abstract
In quantitative analyses of dynamic radionuclide studies, using large activities of 99mTc flowing through organs it is necessary to determine accurately count-rate losses and to provide appropriate corrections. A method is described for estimating deadtimes and applying corrections to the observed counting rates using a two component model where the gamma camera is considered to have a purely paralyzable deadtime and the data analysis system a purely non-paralyzable deadtime.
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21
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Cranley K, Bell TK. 125I thyroid intakes: consideration of thyroid radiation dose, and air and water concentration limits. Int J Appl Radiat Isot 1979; 30:161-3. [PMID: 447422 DOI: 10.1016/0020-708x(79)90124-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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22
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Bell TK, Lappin TR. A chemiluminescent effect encountered in the liquid scintillation counting of 32P phosphate. Ann Clin Biochem 1978; 15:37-9. [PMID: 24405 DOI: 10.1177/000456327801500110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During the course of a kinetic enzyme study of bisphosphoglyceromutase (EC 2.7.5.4.) a chemiluminescent effect was encountered in the liquid scintillation counting of the beta-emission from 32Pi. A method is described for overcoming the effect, thereby permitting the accurate determination of the radioactive compounds. It is important to check for chemiluminescent effects early in the development of new procedures that involve liquid scintillation counting.
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Bell TK, Cranley K. Rapid investigation of the response of focusing and non-focusing collimators. Br J Radiol 1975; 48:759-60. [PMID: 1182435 DOI: 10.1259/0007-1285-48-573-759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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25
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Bell TK. High counting rates from 125I in radioimmunoassays. J Clin Pathol 1974; 27:860-2. [PMID: 4443405 PMCID: PMC475513 DOI: 10.1136/jcp.27.11.860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Responses from one manual and four automatic gamma counters for assaying (125)I were compared. The resolution times quoted by manufacturers when applied in a standardized correction formula to obtain true counts from observed counting rates above 10(4) counts per second appeared to be inadequate. The need to investigate the errors associated with high counting rates for all instruments and electronic settings employed to determine (125)I in radioimmunoassays is emphasized.
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26
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Bell TK, Boyle DA, Montgomery DA, Todd SJ. An evaluation of absorbent granule kits for determining serum thyroxine concentration and free thyroxine index in the diagnosis of thyroid function. J Clin Pathol 1974; 27:372-6. [PMID: 4850538 PMCID: PMC478129 DOI: 10.1136/jcp.27.5.372] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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27
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Johnson AR, Earnshaw JC, Cranley K, Bell TK. Further investigations into a method of background subtraction in the simultaneous use of 59Fe and 51Cr in a scattering medium. Phys Med Biol 1974; 19:105-6. [PMID: 4438438 DOI: 10.1088/0031-9155/19/1/012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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28
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Abstract
Evidence from both animal and human studies had been presented by various authors to suggest that reduction of pancreatic function increased iron absorption. The present experimental studies in rats showed that there was increased radioiron ((59)Fe) absorption after pancreatectomy, but this appeared to be due to the operative procedure as there was a similar increased absorption in animals who had sham operations performed. There was no certain evidence that pancreatic enzymes or extract had a specific inhibitory effect on the absorption of iron. But with increased doses of pancreatic extract, above the normal doses, the amount of radioiron absorption was greatly enhanced.A significant increase in hepatic storage iron was found in the groups of rats who had been fed a diet supplemented with dl-ethionine. All these animals showed extensive damage and atrophy of the pancreas, with degeneration and considerable regenerative activity in the liver. The absolute increased hepatic storage iron was not due to the liberation and laying down of haemosiderin from the damaged cells or to decreased liver mass. Rats who had carbon tetrachloride-induced liver cirrhosis without pancreatic damage showed no increased hepatic storage iron. It was observed that in liver damage with considerable cellular proliferation there was increased liver iron content. As this was found only when there was associated pancreatic injury, it is suggested that decreased pancreatic function in the presence of liver cell injury with cellular proliferation leads to increased iron absorption and storage. The relationship of liver injury with cellular proliferation and pancreatic damage to increased hepatic storage iron merits further study.
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Taylor AR, Crockard HA, Bell TK. Radiocirculography--a profile of cerebral circulation. Clinical uses and limitations. Prog Brain Res 1972; 35:263-83. [PMID: 5009558 DOI: 10.1016/s0079-6123(08)60096-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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30
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Bell TK, Logan JS. The half-life of immune globulin G in chronic benign cryptogenic hypergammaglobulinaemic purpura with pigmentation. And a report of a case. Ulster Med J 1972; 41:140-8. [PMID: 5084692 PMCID: PMC2385357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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32
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Bell TK, Johnston AR, Spiers EW. The calculation of collimator penetration effects. Phys Med Biol 1971; 16:331-3. [PMID: 5581637 DOI: 10.1088/0031-9155/16/2/417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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34
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35
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Bayly RJ, Bell TK, Waters AH. A dual isotope modification of the Schilling test. Br J Radiol 1970; 43:829. [PMID: 5475789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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36
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Bell TK, Johnston AR, Spiers EW. A new three-gate method for measuring 51Cr in the presence of 59Fe in sources in a scattering medium. Phys Med Biol 1970; 15:475-82. [PMID: 5485458 DOI: 10.1088/0031-9155/15/3/008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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37
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Abstract
A procedure is described for the determination of the separate amounts of two gamma-emitting radioisotopes present simultaneously in large liquid volumes using an annular cell placed over a standard well-type crystal of sodium iodide and a reference source of (137)Cs. This sensitive technique is illustrated with particular reference to the double radioisotope urinary excretion test, using orally administered (57)CoB(12) bound to human gastric juice and (58)CoB(12) simultaneously, for the differentiation between patients with intrinsic factor deficiency and other causes of vitamin B(12) malabsorption.
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38
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Bell TK, Spiers EW, Johnston AR. Calculation of penetration factors for point gamma-ray sources off the axis of cylindrical hole collimators. Phys Med Biol 1970; 15:47-56. [PMID: 5460576 DOI: 10.1088/0031-9155/15/1/307] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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39
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Bhatia SK, Bell TK, Love AH, Montgomery DA. An evaluation of a test using 14C labelled triglyceride in the diagnosis of steatorrhoea. Ir J Med Sci 1969; 8:545-52. [PMID: 5370508 DOI: 10.1007/bf02955466] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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40
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Bell TK, Taylor AR. Cerebral circulation time estimation--Its usefulness in clinical practice. Br J Radiol 1969; 42:638. [PMID: 5801691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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41
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Hadden DR, Bell TK, McDevitt DG, Shanks RG, Montgomery DA, Weaver JA. Propranolol and the utilization of radioiodine by the human thyroid gland. Acta Endocrinol (Copenh) 1969; 61:393-9. [PMID: 4184991 DOI: 10.1530/acta.0.0610393] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
ABSTRACT
The effect of propranolol on radioiodine utilization by the thyroid gland has been studied in 18 patients. All parameters of iodine uptake by the thyroid – initial 5–20 minutes after intravenous administration, 2, 4, 24 and 48 hours after oral administration were unaltered by propranolol administration. In three of four patients studied an increase in isotopically labelled serum PBI was observed after 8 days propranolol therapy.
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42
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Bell TK. Assay of diagnostic radioisotopes in large liquid volumes with a well-type crystal in the end-on position. J Clin Pathol 1969; 22:240-1. [PMID: 5776560 PMCID: PMC474042 DOI: 10.1136/jcp.22.2.240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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43
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44
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46
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Bell TK, Mackay JS. Effect of 20 micro c 131-I doses on protein-bound iodine concentrations in serum. J Nucl Med 1968; 9:263. [PMID: 4172463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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47
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48
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49
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Bell TK, McKittrick N, Taylor AR. A simple differentiator unit for determining the mean circulation time of a radioactive bolus. Lab Pract 1968; 17:359-60. [PMID: 5642229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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50
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Abstract
Lung scanning with macroaggregated albumin 131I was carried out in 128 patients. The technique appears to be without hazard. It is particularly useful in the detection of pulmonary embolism, but the pattern is non-specific and changes occur in other cardio-respiratory diseases. On the basis of these observations pulmonary scanning is regarded as a useful adjunct in the study of pulmonary embolism, but it cannot serve as a specific diagnostic procedure since similar patterns of scan may be found in many conditions.
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