| 1. |
- Alamidi, Daniel, et al.
(author)
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COPD Patients Have Short Lung Magnetic Resonance T1 Relaxation Time.
- 2016
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In: COPD. - : Informa UK Limited. - 1541-2563 .- 1541-2555. ; 13:2, s. 153-159
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Journal article (peer-reviewed)abstract
- Magnetic resonance imaging (MRI) may provide attractive biomarkers for assessment of pulmonary disease in clinical trials as it is free from ionizing radiation, minimally invasive and allows regional information. The aim of this study was to characterize lung MRI T1 relaxation time as a biomarker of chronic obstructive pulmonary disease (COPD); and specifically its relationship to smoking history, computed tomography (CT), and pulmonary function test (PFT) measurements in comparison to healthy age-matched controls. Lung T1 and inter-quartile range (IQR) of T1 maps from 24 COPD subjects and 12 healthy age-matched non-smokers were retrospectively analyzed from an institutional review board approved study. The subjects underwent PFTs and two separate MR imaging sessions at 1.5 tesla to test T1 repeatability. CT scans were performed on the COPD subjects. T1 repeatability (intraclass correlation coefficient) was 0.72 for repeated scans acquired on two visits. The lung T1 was significantly shorter (p < 0.0001) and T1 IQR was significantly larger (p = 0.0002) for the COPD subjects compared to healthy controls. Lung T1 significantly (p = 0.001) correlated with lung density assessed with CT. Strong significant correlations (p < 0.0001) between lung T1 and all PFT measurements were observed. Cigarette exposure did not correlate with lung T1 in COPD subjects. In conclusion, lung MRI T1 mapping shows potential as a repeatable, radiation free, non-invasive imaging technique in the evaluation of COPD.
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| 2. |
- Alamidi, Daniel
(author)
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Measurement of T1 relaxation time in lungs - Preclinical and clinical MRI applications to COPD
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Monitoring of regional lung function in clinical trials of chronic obstructive pulmonary disease (COPD) requires alternative endpoints beyond global pulmonary function tests (PFTs), which is the most common approach for diagnosing lung function abnormalities in humans. A promising magnetic resonance imaging (MRI) biomarker of lung disease in humans and animals is the T1 relaxation parameter. Only a limited amount of data on native T1 behaviour in COPD patients and animal models of COPD are available, especially in relation to other relevant markers such as computed tomography (CT) and PFTs in humans; and bronchoalveolar lavage (BAL) fluid analysis and histology in animals. The smoking history in humans and tobacco smoke (TS) exposure in animals are important factors that need to be investigated in relation to lung T1 since tobacco smoking is the major cause for development of COPD. Therefore, we have investigated whether lung T1 can be used as a biomarker of COPD in man, if there is a direct effect of TS on lung T1 in healthy current smokers, and the repeatability of T1 measurements acquired at two visits. T1 was also related to smoking history, CT and PFTs. Subsequently, lung T1 was investigated in a mouse model of COPD and correlated to BAL, lung mechanics and histology to increase the understanding of how T1 relates to the pathophysiological aspects of COPD. A preclinical three dimensional (3D) ultra-short echo time (UTE) T1 mapping protocol was developed to enable the COPD study in mouse. We found from the human studies that: lung T1 shortens in COPD patients, ageing shortens T1 and that TS exposure does not affect T1 in healthy smokers. Additionally, lung T1 was repeatable and correlated with CT lung density and PFT parameters. Lung T1 was also shortened in the TS exposed mice, most likely due to early signs of disease. In naive mice, high lung T1 repeatability over one month was found. In conclusion, lung T1 mapping is an attractive imaging biomarker of COPD in mouse and man for future longitudinal studies. The potential of MRI-based T1 mapping to evaluate early COPD has been enhanced by the advances in this thesis.
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| 3. |
- Alamidi, Daniel, et al.
(author)
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T1 Relaxation Time in Lungs of Asymptomatic Smokers.
- 2016
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:3
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Journal article (peer-reviewed)abstract
- Interest in using T1 as a potential MRI biomarker of chronic obstructive pulmonary disease (COPD) has recently increased. Since tobacco smoking is the major risk factor for development of COPD, the aim for this study was to examine whether tobacco smoking, pack-years (PY), influenced T1 of the lung parenchyma in asymptomatic current smokers.
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| 4. |
- Alamidi, Daniel, et al.
(author)
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Variable Flip Angle 3D Ultrashort Echo Time (UTE) T-1 Mapping of Mouse Lung: A Repeatability Assessment
- 2018
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In: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 48:3, s. 846-852
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Journal article (peer-reviewed)abstract
- Background: Lung T-1 is a potential translational biomarker of lung disease. The precision and repeatability of variable flip angle (VFA) T-1 mapping using modern 3D ultrashort echo time (UTE) imaging of the whole lung needs to be established before it can be used to assess response to disease and therapy. Purpose: To evaluate the feasibility of regional lung T-1 quantification with VFA 3D-UTE and to investigate long-and short-term T-1 repeatability in the lungs of naive mice. Field strength/Sequence: 3D free-breathing radial UTE (8 mu s) at 4.7T. Assessment: VFA 3D-UTE T-1 calculations were validated against T-1 values measured with inversion recovery (IR) in phantoms. Lung T-1 and proton density (S-0) measurements of whole lung and muscle were repeated five times over 1 month in free-breathing naive mice. Two consecutive T-1 measurements were performed during one of the imaging sessions. Statistical Tests: Agreement in T-1 between VFA 3D-UTE and IR in phantoms was assessed using Bland-Altman and Pearson's correlation analysis. The T-1 repeatability in mice was evaluated using coefficient of variation (CV), repeated-measures analysis of variance (ANOVA), and paired t-test. Results: Good T-1 agreement between the VFA 3D-UTE and IR methods was found in phantoms. T-1 in lung and muscle showed a 5% and 3% CV (1255 +/- 63 msec and 1432 +/- 42 msec, respectively, mean +/- SD) with no changes in T-1 or S-0 over a month. Consecutive measurements resulted in an increase of 2% in both lung T-1 and S-0. Data Conclusion: VFA 3D-UTE shows promise as a reliable T-1 mapping method that enables full lung coverage, high signal-to-noise ratio (similar to 25), and spatial resolution (300 mu m) in freely breathing animals. The precision of the VFA 3D-UTE method will enable better design and powering of studies.
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| 5. |
- Weis, Jan, 1956-, et al.
(author)
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GABA quantification in human anterior cingulate cortex
- 2021
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In: PLOS ONE. - : PLOS. - 1932-6203. ; 16:1
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Journal article (peer-reviewed)abstract
- γ-Aminobutyric acid (GABA) is a primary inhibitory neurotransmitter in the human brain. It has been shown that altered GABA concentration plays an important role in a variety of psychiatric and neurological disorders. The main purpose of this study was to propose a combination of PRESS and MEGA-PRESS acquisitions for absolute GABA quantification and to compare GABA estimations obtained using total choline (tCho), total creatine (tCr), and total N-acetyl aspartate (tNAA) as the internal concentration references with water referenced quantification. The second aim was to demonstrate the fitting approach of MEGA-PRESS spectra with QuasarX algorithm using a basis set of GABA, glutamate, glutamine, and NAA in vitro spectra. Thirteen volunteers were scanned with the MEGA-PRESS sequence at 3T. Interleaved water referencing was used for quantification, B0 drift correction and to update the carrier frequency of RF pulses in real time. Reference metabolite concentrations were acquired using a PRESS sequence with short TE (30 ms) and long TR (5000 ms). Absolute concentration were corrected for cerebrospinal fluid, gray and white matter water fractions and relaxation effects. Water referenced GABA estimations were significantly higher compared to the values obtained by metabolite references. We conclude that QuasarX algorithm together with the basis set of in vitro spectra improves reliability of GABA+ fitting. The proposed GABA quantification method with PRESS and MEGA-PRESS acquisitions enables the utilization of tCho, tCr, and tNAA as internal concentration references. The use of different concentration references have a good potential to improve the reliability of GABA estimation.
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