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- Adam, A, et al.
(författare)
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Abstracts from Hydrocephalus 2016.
- 2017
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Ingår i: Fluids and Barriers of the CNS. - : Springer Science and Business Media LLC. - 2045-8118. ; 14:Suppl 1
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Aguilar, C., et al.
(författare)
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Automated CT-based segmentation and quantification of total intracranial volume
- 2015
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Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 25:11, s. 3151-3160
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To develop an algorithm to segment and obtain an estimate of total intracranial volume (tICV) from computed tomography (CT) images. Materials and methods Thirty-six CT examinations from 18 patients were included. Ten patients were examined twice the same day and eight patients twice six months apart (these patients also underwent MRI). The algorithm combines morphological operations, intensity thresholding and mixture modelling. The method was validated against manual delineation and its robustness assessed from repeated imaging examinations. Using automated MRI software, the comparability with MRI was investigated. Volumes were compared based on average relative volume differences and their magnitudes; agreement was shown by a Bland-Altman analysis graph. Results We observed good agreement between our algorithm and manual delineation of a trained radiologist: the Pearson's correlation coefficient was r = 0.94, tICVml[manual] = 1.05 x tICVml[automated] - 33.78 (R-2 = 0.88). Bland-Altman analysis showed a bias of 31 mL and a standard deviation of 30 mL over a range of 1265 to 1526 mL. Conclusions tICV measurements derived from CT using our proposed algorithm have shown to be reliable and consistent compared to manual delineation. However, it appears difficult to directly compare tICV measures between CT and MRI.
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- Falk Delgado, Anna, et al.
(författare)
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Diagnostic value of alternative techniques to gadolinium-based contrast agents in MR neuroimaging : a comprehensive overview
- 2019
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Ingår i: Insights into Imaging. - : Springer Science and Business Media LLC. - 1869-4101. ; 10:1
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Forskningsöversikt (refereegranskat)abstract
- Gadolinium-based contrast agents (GBCAs) increase lesion detection and improve disease characterization for many cerebral pathologies investigated with MRI. These agents, introduced in the late 1980s, are in wide use today. However, some non-ionic linear GBCAs have been associated with the development of nephrogenic systemic fibrosis in patients with kidney failure. Gadolinium deposition has also been found in deep brain structures, although it is of unclear clinical relevance. Hence, new guidelines from the International Society for Magnetic Resonance in Medicine advocate cautious use of GBCA in clinical and research practice. Some linear GBCAs were restricted from use by the European Medicines Agency (EMA) in 2017.This review focuses on non-contrast-enhanced MRI techniques that can serve as alternatives for the use of GBCAs. Clinical studies on the diagnostic performance of non-contrast-enhanced as well as contrast-enhanced MRI methods, both well established and newly proposed, were included. Advantages and disadvantages together with the diagnostic performance of each method are detailed. Non-contrast-enhanced MRIs discussed in this review are arterial spin labeling (ASL), time of flight (TOF), phase contrast (PC), diffusion-weighted imaging (DWI), magnetic resonance spectroscopy (MRS), susceptibility weighted imaging (SWI), and amide proton transfer (APT) imaging.Ten common diseases were identified for which studies reported comparisons of non-contrast-enhanced and contrast-enhanced MRI. These specific diseases include primary brain tumors, metastases, abscess, multiple sclerosis, and vascular conditions such as aneurysm, arteriovenous malformation, arteriovenous fistula, intracranial carotid artery occlusive disease, hemorrhagic, and ischemic stroke.In general, non-contrast-enhanced techniques showed comparable diagnostic performance to contrast-enhanced MRI for specific diagnostic questions. However, some diagnoses still require contrast-enhanced imaging for a complete examination.
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- Fällmar, David, et al.
(författare)
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Arterial spin labeling-based Z-maps have high specificity and positive predictive value for neurodegenerative dementia compared to FDG-PET.
- 2017
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Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 27:10, s. 4237-4246
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Cerebral perfusion analysis based on arterial spin labeling (ASL) MRI has been proposed as an alternative to FDG-PET in patients with neurodegenerative disease. Z-maps show normal distribution values relating an image to a database of controls. They are routinely used for FDG-PET to demonstrate disease-specific patterns of hypometabolism at the individual level. This study aimed to compare the performance of Z-maps based on ASL to FDG-PET.METHODS: Data were combined from two separate sites, each cohort consisting of patients with Alzheimer's disease (n = 18 + 7), frontotemporal dementia (n = 12 + 8) and controls (n = 9 + 29). Subjects underwent pseudocontinuous ASL and FDG-PET. Z-maps were created for each subject and modality. Four experienced physicians visually assessed the 166 Z-maps in random order, blinded to modality and diagnosis.RESULTS: Discrimination of patients versus controls using ASL-based Z-maps yielded high specificity (84%) and positive predictive value (80%), but significantly lower sensitivity compared to FDG-PET-based Z-maps (53% vs. 96%, p < 0.001). Among true-positive cases, correct diagnoses were made in 76% (ASL) and 84% (FDG-PET) (p = 0.168).CONCLUSION: ASL-based Z-maps can be used for visual assessment of neurodegenerative dementia with high specificity and positive predictive value, but with inferior sensitivity compared to FDG-PET.KEY POINTS: • ASL-based Z-maps yielded high specificity and positive predictive value in neurodegenerative dementia. • ASL-based Z-maps had significantly lower sensitivity compared to FDG-PET-based Z-maps. • FDG-PET might be reserved for ASL-negative cases where clinical suspicion persists. • Findings were similar at two study sites.
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- Grankvist, J, et al.
(författare)
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MRI and PET/CT of patients with bone metastases from breast carcinoma
- 2012
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Ingår i: European Journal of Radiology. - : Elsevier BV. - 0720-048X .- 1872-7727. ; 81:1, s. e13-e18
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Tidskriftsartikel (refereegranskat)abstract
- 3.0Tesla magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) was compared with combined 18F-fluorodeoxyglucose positron emission tomography and computed tomography (PET/CT) in patients with suspected bone metastases from breast cancer. A prospective clinical study was performed in 13 female breast cancer patients (mean age 61years; range 45-85 years). The spine was imaged in the sagittal plane with T1-weighted (T1), short tau inversion recovery (STIR), and T2-weighted fat-saturated (T2) sequences. The pelvis was imaged similarly in the coronal plane. Axial DWI was performed from the skull base to the mid-thigh. MRI and PET/CT were performed in all patients at a maximum interval of 10 working days and at least 14 days after chemotherapy. MRI was reviewed by two radiologists, and their consensus on potential metastases in 27 predefined locations was recorded. The predefined locations were the vertebral bodies (24), the left (1) and right (1) pelvic bones, and the sacral bone (1). The PET/CT was reviewed by a radiologists and a nuclear medicine physician. MRI detected 59 of the 60 active metastases found with our gold standard modality PET/CT. T1 had the highest sensitivity (98%) but rather low specificity (77%), but with the addition of STIR and DWI, the specificity increased to 95%. The additional metastases detected with MRI most likely represented postherapeutic residual scars without active tumour. In conclusion, 3.0Tesla MRI with T1, STIR, and DWI is useful for the clinical evaluation of bone metastases from breast cancer and compares well to PET/CT.
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| 9. |
- Joelsson, L. M. T., et al.
(författare)
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Relative rate study of the kinetic isotope effect in the (CH3D)-C-13 + Cl reaction
- 2014
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 605, s. 152-157
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Tidskriftsartikel (refereegranskat)abstract
- The (CH3D)-C-13/(CH4)-C-12 kinetic isotope effect, alpha((CH3D)-C-13), of CH4 + Cl is determined for the first time, using the relative rate technique and Fourier transform infrared (FTIR) spectroscopy. alpha((CH3D)-C-13) is found to be 1.60 +/- 0.04. In addition, a quantum chemistry/transition state theory model with tunneling correction is constructed and the primary cause for alpha((CH3D)-C-13) is found to be the substantially reduced reactivity of the D atom, which, in turn, can be explained by a significant increase in the reaction barrier due to changes in the vibrational zero point energy and to a lesser extent tunneling. (C) 2014 Elsevier B.V. All rights reserved.
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| 10. |
- Järnum, Hanna, et al.
(författare)
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Perfusion MRI of brain tumours : a comparative study of pseudo-continuous arterial spin labelling and dynamic susceptibility contrast imaging
- 2010
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 0028-3940 .- 1432-1920. ; 52:4, s. 307-317
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The purpose of this study was to compare the non-invasive 3D pseudo-continuous arterial spin labelling (PC ASL) technique with the clinically established dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC-MRI) for evaluation of brain tumours. METHODS: A prospective study of 28 patients with contrast-enhancing brain tumours was performed at 3 T using DSC-MRI and PC ASL with whole-brain coverage. The visual qualitative evaluation of signal enhancement in tumour was scored from 0 to 3 (0 = no signal enhancement compared with white matter, 3 = pronounced signal enhancement with equal or higher signal intensity than in grey matter/basal ganglia). The extent of susceptibility artefacts in the tumour was scored from 0 to 2 (0 = no susceptibility artefacts and 2 = extensive susceptibility artefacts (maximum diameter > 2 cm)). A quantitative analysis was performed with normalised tumour blood flow values (ASL nTBF, DSC nTBF): mean value for region of interest (ROI) in an area with maximum signal enhancement/the mean value for ROIs in cerebellum. RESULTS: There was no difference in total visual score for signal enhancement between PC ASL and DSC relative cerebral blood flow (p = 0.12). ASL had a lower susceptibility-artefact score than DSC-MRI (p = 0.03). There was good correlation between DSC nTBF and ASL nTBF values with a correlation coefficient of 0.82. CONCLUSION: PC ASL is an alternative to DSC-MRI for the evaluation of perfusion in brain tumours. The method has fewer susceptibility artefacts than DSC-MRI and can be used in patients with renal failure because no contrast injection is needed.
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