| 1. |
- Alamidi, Daniel, et al.
(författare)
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T1 Relaxation Time in Lungs of Asymptomatic Smokers.
- 2016
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:3
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Alamidi, Daniel, et al.
(författare)
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COPD Patients Have Short Lung Magnetic Resonance T1 Relaxation Time.
- 2016
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Ingår i: COPD. - : Informa UK Limited. - 1541-2563 .- 1541-2555. ; 13:2, s. 153-159
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Alamidi, Daniel, et al.
(författare)
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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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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 48:3, s. 846-852
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Bech-Hanssen, Odd, 1956, et al.
(författare)
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Left ventricular volumes by echocardiography in chronic aortic and mitral regurgitation.
- 2016
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Ingår i: Scandinavian cardiovascular journal : SCJ. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 50:3, s. 154-161
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Tidskriftsartikel (refereegranskat)abstract
- Cut-off values for left ventricular (LV) dimensions indicating severe valve regurgitation have not been defined. The aim of the study was to establish echocardiographic cut-off values for LV dimensions indicating severe chronic aortic (AR) or mitral (MR) regurgitation.
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| 5. |
- Belavy, D. L., et al.
(författare)
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Characterization of Intervertebral Disc Changes in Asymptomatic Individuals with Distinct Physical Activity Histories Using Three Different Quantitative MRI Techniques
- 2020
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Ingår i: Journal of Clinical Medicine. - : MDPI AG. - 2077-0383. ; 9:6
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Tidskriftsartikel (refereegranskat)abstract
- (1) Background: Assessments of intervertebral disc (IVD) changes, and IVD tissue adaptations due to physical activity, for example, remains challenging. Newer magnetic resonance imaging techniques can quantify detailed features of the IVD, where T2-mapping and T2-weighted (T2w) and Dixon imaging are potential candidates. Yet, their relative utility has not been examined. The performances of these techniques were investigated to characterize IVD differences in asymptomatic individuals with distinct physical activity histories. (2) Methods: In total, 101 participants (54 women) aged 25-35 years with distinct physical activity histories but without histories of spinal disease were included. T11/12 to L5/S1 IVDs were examined with sagittal T2-mapping, T2w and Dixon imaging. (3) Results: T2-mapping differentiated Pfirrmann grade-1 from all other grades (p< 0.001). Most importantly, T2-mapping was able to characterize IVD differences in individuals with different training histories (p< 0.005). Dixon displayed weak correlations with the Pfirrmann scale, but presented significantly higher water content in the IVDs of the long-distance runners (p< 0.005). (4) Conclusions: Findings suggested that T2-mapping best reflects IVD differences in asymptomatic individuals with distinct physical activity histories changes. Dixon characterized new aspects of IVD, probably associated with IVD hypertrophy. This complementary information may help us to better understand the biological function of the disc.
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| 6. |
- Cetinic, I., et al.
(författare)
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Ultrasound Shear Wave Elastography, Shear Wave Dispersion and Attenuation Imaging of Pediatric Liver Disease with Histological Correlation
- 2022
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Ingår i: Children. - : MDPI AG. - 2227-9067. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To evaluate the feasibility of multiple ultrasound markers for the non-invasive characterization of fibrosis, inflammation and steatosis in the liver in pediatric patients. Materials and methods: The quantitative ultrasound measures shear wave elastography (SWE), shear wave dispersion (SWD) and attenuation imaging (ATI) were compared and correlated with percutaneous liver biopsies and corresponding measures in a control cohort. Results: The median age of the 32 patients was 12.1 years (range 0.1-17.9), and that of the 15 controls was 11.8 years (range: 2.6-16.6). Results: There was a significant difference in SWE values between histologic grades of fibrosis (p = 0.003), with a positive correlation according to the grade (r = 0.7; p < 0.0001). Overall, a difference in SWD values between grades of inflammation was found (p = 0.009) but with a lack of correlation (r = 0.1; p = 0.67). Comparing inflammation grades 0-1 (median:13.6 m/s kHz [min; max; 8.4; 17.5]) versus grades 2-3 (16.3 m/s kHz [14.6; 24.2]) showed significant differences between the groups (p = 0.003). In the 30 individuals with a steatosis score of 0, ATI was measured in 23 cases with a median value of 0.56 dB/cm/MHz. Conclusion: Comprehensive ultrasound analysis was feasible to apply in children and has the potential to reflect the various components of liver affection non-invasively. Larger studies are necessary to conclude to what extent these image-based markers can classify the grade of fibrosis, inflammation and steatosis.
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| 7. |
- Hebelka, Hanna, 1977, et al.
(författare)
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Lumbar vertebral T2-relaxation time investigated with T2-mapping at multiple time points in a day demonstrate large individual variations
- 2022
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Ingår i: Diagnostic and Interventional Radiology. - : Galenos Yayinevi. - 1305-3825. ; 28:1, s. 92-97
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE The increasing interest of endplate and Modic changes as potential pain generators in low back pain (LBP), along with advancement of functional quantitative magnetic resonance imaging (MRI) techniques, makes it important to characterize the vertebral dynamic behavior in detail. This study aims to perform characterization of the dynamic behavior of the vertebral bodies (VB) by investigating the VB diurnal variation in T2-relaxation time in a cross-sectional asymptomatic group of individuals. METHODS T2-mapping of 30 VBs (L1-L5) in six healthy volunteers (mean age, 40 years; range, 29-65 years) was performed with a 1.5 Tesla MRI at three time points over the day (7 am, 12 am, 5 pm). Volumetric regions of interest were segmented manually to determine VB T2-relaxation time, which was compared between the three time points. RESULTS On a group level only small and not significant diurnal VB variation was detected (all P >.10), with median T2 (ms) (quartiles; Q1, Q3) at the three time points 88.7 (84.1, 99.1), 87.3 (85.0, 96.1) and 87.8 (84.4, 99.2). However, in some VBs up to 7% increase respectively 9% decrease in T2-relaxation time was found during the day. Further, there was a relatively large variation between the individuals in absolute VB T2-relaxation times (range 73.2-108.3 ms), but small differences between the VBs within an individual. CONCLUSION This first T2-mapping study of the VB signal dynamics, in repeated investigations during one day, display variation in T2-relaxation time in specific individual VBs but were negligible on a group level. The result may be of importance when evaluating patients with spinal pathologies and suggest further examinations of dynamic changes not only of the disc but also vertebrae. © Turkish Society of Radiology 2021.
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| 8. |
- Hebelka, Hanna, 1977, et al.
(författare)
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The importance of level stratification for quantitative MR studies of lumbar intervertebral discs: a cross-sectional analysis in 101 healthy adults
- 2019
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Ingår i: European Spine Journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 28:9, s. 2153-2161
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate whether quantitative T2-times depend on lumbar intervertebral disc (IVD) level. Methods: The lumbar spine (Th12/L1–L5/S1) of 101 participants (53.5% female, 30.0[± 3.6]years, 173.5[± 9.6]cm and 69.9[± 13.4]kg), without history of back pain, was examined on a 3T scanner with sagittal T2-mapping. All IVDs were stratified according to Pfirrmann grade and lumbar level, with mean T2-time determined for the entire IVD volume and in five subregions of interests. Results: Significant level-dependent T2-time differences were detected, both for the entire IVD volume and its subregions. For the entire IVD volume, Pfirrmann grade 2 IVDs displayed 9–18% higher T2-times in Th12/L1 IVDs compared to L2/L3–L5/S1 IVDs (0.001 > p < 0.004) and significantly different T2-times in L1/L2–L2/L3 IVDs compared to most of the IVDs in the lower lumbar spine. In Pfirrmann grades 1, 3 and 4 IVDs, no significant level-dependent T2-time differences were observed for the entire IVD. More pronounced results were observed when comparing IVD subregions, with significant level-dependent differences also within Pfirrmann grade 1 and grade 3 IVDs. For example, in posterior IVD subregions mean T2-time was 80–82% higher in Th12/L1 compared to L3/L4–L4/L5 Pfirrmann grade 1 IVDs (p < 0.05) and 10–14% higher in L5/S1 compared to L3/L4–L4/L5 Pfirrmann grade 3 IVDs (0.02 > p < 0.001). Discussion: Significant level-dependent T2-time differences within several Pfirrmann grades, both for the entire IVD volume and for multiple IVD subregions, were shown in this large cohort study. The T2-time differences between levels existed in both non-degenerated and degenerated IVDs. These findings show the importance of stratifying for lumbar level when quantitative IVD studies are performed using T2-mapping. Graphic abstract: These slides can be retrieved under Electronic Supplementary Material.[Figure not available: see fulltext.]. © 2019, The Author(s).
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| 9. |
- Rasmussen, A. M., et al.
(författare)
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Repeatability of diffusion-based stiffness prediction – A healthy volunteer study
- 2024
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Ingår i: Radiography. - 1078-8174 .- 1532-2831. ; 30:2, s. 524-530
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The study investigated the repeatability of brain diffusion-based stiffness prediction (DWIstiff) in healthy volunteers. Methods: Thirty-one healthy volunteers were examined with DWIstiff using two different sets of b-values: b200-1500 s/mm2 (DWIstiff, 1500) and b200-1000 s/mm2 (DWIstiff, 1000). Each b-value set was scanned twice per imaging session without repositioning the participants. DWIstiff images were reconstructed from each set. Two observers delineated regions of interest (ROIs) on each DWIstiff image. The repeatability coefficient (RC), coefficient of variation (CV), inter- and intraobserver agreement were calculated. Results: After excluding three participants due to image artifacts, the study included twenty-eight volunteers (mean age (range)) 37 years (24–62), 10 males, 18 females). For DWIstiff, 1500, the lowest and the highest RCs were in the parietal lobe (0.52) and respectively the brain stem (1.17). The lowest RC for DWIstiff, 1000 was in the frontal lobe (0.42) and the highest in the brain stem (1.58). The CV for whole brain measurements was 3.83 % for DWIstiff, 1500 and 4.93 % for DWIstiff, 1000. The Bland‒Altman (BA) limits of agreement (LoA) for the intraobserver agreement of DWIstiff, 1500 were −0.90 to 1.06 and respectively −0.78 to 0.88 for DWIstiff, 1000. Regarding interobserver agreement, the LoA were −0.85 to 0.94 for DWIstiff, 1500 and −0.61 to 0.66 for DWIstiff, 1000. Conclusion: DWIstiff is a precise technique with some observer dependence. Repeatability is higher for DWIstiff, 1000 s/mm2 than for DWIstiff 1500 s/mm2. Implications for practice: Our findings suggest that DWIstiff can reliably detect stiffness changes larger than 4.93 % in healthy volunteers. Further studies should investigate whether the repeatability of DWIstiff may be affected by the presence of pathology such as a brain tumor.
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| 10. |
- Agerskov, Simon, et al.
(författare)
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MRI diffusion and perfusion alterations in the mesencephalon and pons as markers of disease and symptom reversibility in idiopathic normal pressure hydrocephalus
- 2020
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:10
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Core symptomatology in idiopathic normal pressure hydrocephalus (iNPH) points at dysfunction in the mesencephalon and pons indicating pathological changes in these regions, but only a few studies have addressed the issue. The aim of this study was to investigate diffusion (ADC) and perfusion patterns pre- and postoperatively in these areas in iNPH. Methods Twenty iNPH patients and 15 healthy controls were included. Patients underwent a clinical examination and brain MRI pre- and 3-6 months postoperatively. The MRI-scan included diffusion and dynamic susceptibility contrast perfusion weighted sequences. Regions of interest in the mesencephalon and pons were drawn on a FLAIR sequence and co-registered to ADC maps and perfusion data. Results There were no significant differences in pre or postoperative ADC compared to the control group, however postoperative ADC increased by 10% (p = 0.026) in the mesencephalon and 6% (p = 0.016) in the pons in all patients and also in the subgroup of shunt responders by 11% (p = 0.021) and 4% (p = 0.020), respectively. Preoperative relative cerebral blood flow (rCBF) was similar in iNPH patients and controls. Postoperatively, rCBF increased in shunt responders by 6% (p = 0.02) in the mesencephalon and 11% (p = 0.004) in the pons. This increase correlated with the degree of clinical improvement (r(s)= 0.80, p = 0.031 and r(s)= 0.66, p = 0.021, respectively). Conclusion The postoperative increase in ADC and the correlation between postoperative increase in rCBF and clinical improvement in the mesencephalon and pons shown in this study point at an involvement of these areas in the core pathophysiology and its reversibility in iNPH.
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