| 1. |
- Ziegler, Magnus, et al.
(författare)
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Towards Automated Quantification of Vessel Wall Composition Using MRI
- 2020
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Ingår i: Journal of Magnetic Resonance Imaging. - : WILEY. - 1053-1807 .- 1522-2586. ; 52:3, s. 710-719
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Tidskriftsartikel (refereegranskat)abstract
- Background MRI can be used to generate fat fraction (FF) and R2* data, which have been previously shown to characterize the plaque compositional features lipid-rich necrotic core (LRNC) and intraplaque hemorrhage (IPH) in the carotid arteries (CAs). Previously, these data were extracted from CA plaques using time-consuming manual analyses. Purpose To design and demonstrate a method for segmenting the CA and extracting data describing the composition of the vessel wall. Study Type Prospective. Subjects 31 subjects from the Swedish CArdioPulmonary bioImage Study (SCAPIS). Field Strength/Sequences T-1-weighted (T1W) quadruple inversion recovery, contrast-enhanced MR angiography (CE-MRA), and 4-point Dixon data were acquired at 3T. Assessment The vessel lumen of the CA was automatically segmented using support vector machines (SVM) with CE-MRA data, and the vessel wall region was subsequently delineated. Automatically generated segmentations were quantitatively measured and three observers visually compared the segmentations to manual segmentations performed on T(1)w images. Dixon data were used to generate FF and R2* maps. Both manually and automatically generated segmentations of the CA and vessel wall were used to extract compositional data. Statistical Tests Two-tailedt-tests were used to examine differences between results generated using manual and automated analyses, and among different configurations of the automated method. Interobserver agreement was assessed with Fleiss kappa. Results Automated segmentation of the CA using SVM had a Dice score of 0.89 +/- 0.02 and true-positive ratio 0.93 +/- 0.03 when compared against ground truth, and median qualitative score of 4/5 when assessed visually by multiple observers. Vessel wall regions of 0.5 and 1 mm yielded compositional information similar to that gained from manual analyses. Using the 0.5 mm vessel wall region, the mean difference was 0.1 +/- 2.5% considering FF and 1.1 +/- 5.7[1/s] for R2*. Level of Evidence 1. Technical Efficacy Stage 1. J. Magn. Reson. Imaging 2020;52:710-719.
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| 2. |
- Blystad, Ida, 1972-, et al.
(författare)
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Quantitative MRI using relaxometry in malignant gliomas detects contrast enhancement in peritumoral oedema
- 2020
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Malignant gliomas are primary brain tumours with an infiltrative growth pattern, often with contrast enhancement on magnetic resonance imaging (MRI). However, it is well known that tumour infiltration extends beyond the visible contrast enhancement. The aim of this study was to investigate if there is contrast enhancement not detected visually in the peritumoral oedema of malignant gliomas by using relaxometry with synthetic MRI. 25 patients who had brain tumours with a radiological appearance of malignant glioma were prospectively included. A quantitative MR-sequence measuring longitudinal relaxation (R-1), transverse relaxation (R-2) and proton density (PD), was added to the standard MRI protocol before surgery. Five patients were excluded, and in 20 patients, synthetic MR images were created from the quantitative scans. Manual regions of interest (ROIs) outlined the visibly contrast-enhancing border of the tumours and the peritumoral area. Contrast enhancement was quantified by subtraction of native images from post GD-images, creating an R-1-difference-map. The quantitative R-1-difference-maps showed significant contrast enhancement in the peritumoral area (0.047) compared to normal appearing white matter (0.032), p = 0.048. Relaxometry detects contrast enhancement in the peritumoral area of malignant gliomas. This could represent infiltrative tumour growth.
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| 3. |
- Chougar, Lydia, et al.
(författare)
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Signal Intensity within Cerebral Venous Sinuses on Synthetic MRI
- 2020
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Ingår i: MAGNETIC RESONANCE IN MEDICAL SCIENCES. - : JPN SOC MAGNETIC RESONANCE MEDICINE. - 1347-3182 .- 1880-2206. ; 19:1, s. 56-63
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Flowing blood sometimes appears bright on synthetic T-1-weighted images, which could be misdiagnosed as a thrombus. This study aimed to investigate the frequency of hyperintensity within cerebral venous sinuses on synthetic MR images and to evaluate the influence of increasing flow rates on signal intensity using a flow phantom. Materials and Methods: Imaging data, including synthetic and conventional MRI scans, from 22 patients were retrospectively analyzed. Signal intensities at eight locations of cerebral venous sinuses on synthetic images were graded using the following three-point scale: 0, "dark vessel"; 1, "hyperintensity within the walls"; and 2, "hyperintensity within the lumen:" A phantom with gadolinium solution inside a U-shaped tube was acquired without flow and then with increasing flow rates (60, 100, 200, 300, 400 ml/min). Results: Considering all sinus locations, the venous signal intensity on synthetic T-1-weighted images was graded as 2 in 79.8% of the patients. On synthetic T-2-weighted images, all sinuses were graded as 0. On fluid-attenuated inversion recovery (FLAIR) images, sinuses were almost always graded as 0 (99.4%). In the phantom study, the signal initially became brighter on synthetic T-1-weighted images as the flow rate increased. Above a certain flow rate, the signal started to decrease. Conclusion: High signal intensity within the cerebral venous sinuses is a frequent finding on synthetic T-1-weighted images. This corresponds to the hyperintensity noted at certain flow rates in the phantom experiment.
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| 4. |
- Fujita, Shohei, et al.
(författare)
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Cross-vendor multiparametric mapping of the human brain using 3D-QALAS: A multicenter and multivendor study
- 2024
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Ingår i: Magnetic Resonance in Medicine. - : WILEY. - 0740-3194 .- 1522-2594.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate a vendor-agnostic multiparametric mapping scheme based on 3D quantification using an interleaved Look-Locker acquisition sequence with a T2 preparation pulse (3D-QALAS) for whole-brain T1, T2, and proton density (PD) mapping.Methods: This prospective, multi-institutional study was conducted between September 2021 and February 2022 using five different 3T systems from four prominent MRI vendors. The accuracy of this technique was evaluated using a standardized MRI system phantom. Intra-scanner repeatability and inter-vendor reproducibility of T1, T2, and PD values were evaluated in 10 healthy volunteers (6 men; mean age +/- SD, 28.0 +/- 5.6 y) who underwent scan-rescan sessions on each scanner (total scans = 100). To evaluate the feasibility of 3D-QALAS, nine patients with multiple sclerosis (nine women; mean age +/- SD, 48.2 +/- 11.5 y) underwent imaging examination on two 3T MRI systems from different manufacturers.Results: Quantitative maps obtained with 3D-QALAS showed high linearity (R2 = 0.998 and 0.998 for T1 and T2, respectively) with respect to reference measurements. The mean intra-scanner coefficients of variation for each scanner and structure ranged from 0.4% to 2.6%. The mean structure-wise test-retest repeatabilities were 1.6%, 1.1%, and 0.7% for T1, T2, and PD, respectively. Overall, high inter-vendor reproducibility was observed for all parameter maps and all structure measurements, including white matter lesions in patients with multiple sclerosis.Conclusion: The vendor-agnostic multiparametric mapping technique 3D-QALAS provided reproducible measurements of T1, T2, and PD for human tissues within a typical physiological range using 3T scanners from four different MRI manufacturers.
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| 5. |
- Good, Elin, et al.
(författare)
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18Fluorodeoxyglucose uptake in relation to fat fraction and R2*in atherosclerotic plaques, using PET/MRI : a pilot study
- 2021
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Inflammation inside Atherosclerotic plaques represents a major pathophysiological process driving plaques towards rupture. Pre-clinical studies suggest a relationship between lipid rich necrotic core, intraplaque hemorrhage and inflammation, not previously explored in patients. Therefore, we designed a pilot study to investigate the feasibility of assessing the relationship between these plaque features in a quantitative manner using PET/MRI. In 12 patients with high-grade carotid stenosis the extent of lipid rich necrotic core and intraplaque hemorrhage was quantified from fat and R2* maps acquired with a previously validated 4-point Dixon MRI sequence in a stand-alone MRI. PET/MRI was used to measure 18F-FDG uptake. T1-weighted images from both scanners were used for registration of the quantitative Dixon data with the PET images. The plaques were heterogenous with respect to their volumes and composition. The mean values for the group were as follows: fat fraction (FF) 0.17% (± 0.07), R2* 47.6 s−1 (± 10.9) and target-to-blood pool ratio (TBR) 1.49 (± 0.48). At group level the correlation between TBR and FFmean was − 0.406, p 0.19 and for TBR and R2*mean 0.259, p 0.42. The lack of correlation persisted when analysed on a patient-by-patient basis but the study was not powered to draw definitive conclusions. We show the feasibility of analysing the quantitative relationship between lipid rich necrotic cores, intraplaque haemorrhage and plaque inflammation. The 18F-FDG uptake for most patients was low. This may reflect the biological complexity of the plaques and technical aspects inherent to 18F-FDG measurements.
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| 6. |
- Good, Elin, 1983-, et al.
(författare)
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Quantitative Magnetic Resonance Imaging Assessment of the Relationships Between Fat Fraction and R2*Inside Carotid Plaques, and Circulating Lipoproteins
- 2022
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 55:4, s. 1260-1270
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Tidskriftsartikel (refereegranskat)abstract
- Background Lipid-rich necrotic core (LRNC) and intraplaque hemorrhage (IPH) are morphological features of high-risk atherosclerotic plaques. However, their relationship to circulating lipoproteins is unclear. Purpose To study associations between changes in lipoproteins vs. changes in LRNC (represented by fat fraction [FF]) and IPH (represented by R2*). Study Type Prospective. Subjects Fifty-two patients with carotid plaques, 33 males (63.5%), mean age 72 (+/- 5). Field Strength/Sequence Four-point fast gradient Dixon magnetic resonance imaging (MRI) was used to quantify FF and R2* (to measure IPH) inside plaques and in vessel wall. Turbo-spin echo was used for T-1 weighted sequences to guide manual segmentation. Assessment Carotid MRI and serum lipid levels were assessed at baseline and at 1-year follow-up. For patients, lipid-lowering therapy was customized to reduce low-density lipoprotein (LDL) levels below 1.8 mmol/L. Segmentation was performed with one set of regions of interest for the plaque and one for the vessel wall at the location of the plaque. Thereby MRI data for FF, R2*, and volumes in plaque- and vessel-wall segmentations could be obtained from baseline and follow-up, as well as changes over the study year. Statistical Tests Pearson correlation coefficient for correlations. Paired samples t-test for changes over time. Significance at P < 0.05, 95% confidence interval. Results LDL decreased significantly (2.19-1.88 mmol/L, Z - 2.9), without correlation to changes in plaque composition, nor to the significant reduction in vessel-wall volume (-106.3 mm(3)). Plaque composition remained unchanged, FF +8.5% (P = 0.366) and R2* +3.5% (P = 0.304). Compared to plaque segmentations, R2* was significantly lower in the vessel-wall segmentations both at baseline (-9.3%) and at follow-up (-9.1%). Data Conclusion The absence of correlations between changes in lipoproteins and changes in plaque composition indicates more complex relationships between these parameters than previously anticipated. The significant differences in both R2* and volume dynamics comparing plaque segmentations and vessel-wall segmentations suggest differences in their pathobiology of atherosclerosis. Level of Evidence 1 Technical Efficacy Stage 4
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| 7. |
- Lundberg, Peter, et al.
(författare)
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Low-dose acetylsalicylic acid reduces local inflammation and tissue perfusion in dense breast tissue in postmenopausal women
- 2024
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Ingår i: Breast Cancer Research. - : BMC. - 1465-5411 .- 1465-542X. ; 26:1
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Tidskriftsartikel (refereegranskat)abstract
- Purpose One major risk factor for breast cancer is high mammographic density. It has been estimated that dense breast tissue contributes to similar to 30% of all breast cancer. Prevention targeting dense breast tissue has the potential to improve breast cancer mortality and morbidity. Anti-estrogens, which may be associated with severe side-effects, can be used for prevention of breast cancer in women with high risk of the disease per se. However, no preventive therapy targeting dense breasts is currently available. Inflammation is a hallmark of cancer. Although the biological mechanisms involved in the increased risk of cancer in dense breasts is not yet fully understood, high mammographic density has been associated with increased inflammation. We investigated whether low-dose acetylsalicylic acid (ASA) affects local breast tissue inflammation and/or structural and dynamic changes in dense breasts. Methods Postmenopausal women with mammographic dense breasts on their regular mammography screen were identified. A total of 53 women were randomized to receive ASA 160 mg/day or no treatment for 6 months. Magnetic resonance imaging (MRI) was performed before and after 6 months for a sophisticated and continuous measure breast density by calculating lean tissue fraction (LTF). Additionally, dynamic quantifications including tissue perfusion were performed. Microdialysis for sampling of proteins in vivo from breasts and abdominal subcutaneous fat, as a measure of systemic effects, before and after 6 months were performed. A panel of 92 inflammatory proteins were quantified in the microdialysates using proximity extension assay. Results After correction for false discovery rate, 20 of the 92 inflammatory proteins were significantly decreased in breast tissue after ASA treatment, whereas no systemic effects were detected. In the no-treatment group, protein levels were unaffected. Breast density, measured by LTF on MRI, were unaffected in both groups. ASA significantly decreased the perfusion rate. The perfusion rate correlated positively with local breast tissue concentration of VEGF. Conclusions ASA may shape the local breast tissue microenvironment into an anti-tumorigenic state. Trials investigating the effects of low-dose ASA and risk of primary breast cancer among postmenopausal women with maintained high mammographic density are warranted.hic density are warranted.
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| 8. |
- Ouellette, R., et al.
(författare)
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Validation of Rapid Magnetic Resonance Myelin Imaging in Multiple Sclerosis
- 2020
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Ingår i: Annals of Neurology. - : Wiley. - 0364-5134 .- 1531-8249. ; 87:5, s. 710-724
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Magnetic resonance imaging (MRI) is essential for multiple sclerosis diagnostics but is conventionally not specific to demyelination. Myelin imaging is often hampered by long scanning times, complex postprocessing, or lack of clinical approval. This study aimed to assess the specificity, robustness, and clinical value of Rapid Estimation of Myelin for Diagnostic Imaging, a new myelin imaging technique based on time-efficient simultaneous T1/T2 relaxometry and proton density mapping in multiple sclerosis. Methods: Rapid myelin imaging was applied using 3T MRI ex vivo in 3 multiple sclerosis brain samples and in vivo in a prospective cohort of 71 multiple sclerosis patients and 21 age/sex-matched healthy controls, with scan–rescan repeatability in a subcohort. Disability in patients was assessed by the Expanded Disability Status Scale and the Symbol Digit Modalities Test at baseline and 2-year follow-up. Results: Rapid myelin imaging correlated with myelin-related stains (proteolipid protein immunostaining and Luxol fast blue) and demonstrated good precision. Multiple sclerosis patients had, relative to controls, lower normalized whole-brain and normal-appearing white matter myelin fractions, which correlated with baseline cognitive and physical disability. Longitudinally, these myelin fractions correlated with follow-up physical disability, even with correction for baseline disability. Interpretation: Rapid Estimation of Myelin for Diagnostic Imaging provides robust myelin quantification that detects diffuse demyelination in normal-appearing tissue in multiple sclerosis, which is associated with both cognitive and clinical disability. Because the technique is fast, with automatic postprocessing and US Food and Drug Administration/CE clinical approval, it can be a clinically feasible biomarker that may be suitable to monitor myelin dynamics and evaluate treatments aiming at remyelination.
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| 9. |
- Warntjes, Marcel Jan Bertus, et al.
(författare)
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Brain Parcellation Repeatability and Reproducibility Using Conventional and Quantitative 3D MR Imaging
- 2023
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Ingår i: American Journal of Neuroradiology. - : AMER SOC NEURORADIOLOGY. - 0195-6108 .- 1936-959X. ; 44:8, s. 910-915
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Automatic brain parcellation is typically performed on dedicated MR imaging sequences, which require valuable examination time. In this study, a 3D MR imaging quantification sequence to retrieve R-1 and R-2 relaxation rates and proton density maps was used to synthesize a T1-weighted image stack for brain volume measurement, thereby combining image data for multiple purposes. The repeatability and reproducibility of using the conventional and synthetic input data were evaluated.MATERIALS AND METHODS: Twelve subjects with a mean age of 54?years were scanned twice at 1.5T and 3T with 3D-QALAS and a conventionally acquired T1-weighted sequence. Using SyMRI, we converted the R-1, R-2, and proton density maps into synthetic T1-weighted images. Both the conventional T1-weighted and the synthetic 3D-T1-weighted inversion recovery images were processed for brain parcellation by NeuroQuant. Bland-Altman statistics were used to correlate the volumes of 12 brain structures. The coefficient of variation was used to evaluate the repeatability.RESULTS: A high correlation with medians of 0.97 for 1.5T and 0.92 for 3T was found. A high repeatability was shown with a median coefficient of variation of 1.2% for both T1-weighted and synthetic 3D-T1-weighted inversion recovery at 1.5T, and 1.5% for T1-weighted imaging and 4.4% for synthetic 3D-T1-weighted inversion recovery at 3T. However, significant biases were observed between the methods and field strengths.CONCLUSIONS: It is possible to perform MR imaging quantification of R-1, R-2, and proton density maps to synthesize a 3D-T1-weighted image stack, which can be used for automatic brain parcellation. Synthetic parameter settings should be reinvestigated to reduce the observed bias.
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