| 1. |
- Wallin, Ewa, et al.
(författare)
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Acute brain lesions on magnetic resonance imaging in relation to neurological outcome after cardiac arrest
- 2018
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 62:5, s. 625-647
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Magnetic resonance imaging (MRI) of the brain including diffusion-weighted imaging (DWI) is reported to have high prognostic accuracy in unconscious post-cardiac arrest (CA) patients. We documented acute MRI findings in the brain in both conscious and unconscious post-CA patients treated with target temperature management (TTM) at 32-34°C for 24 h as well as the relation to patients' neurological outcome after 6 months.METHODS:A prospective observational study with MRI was performed regardless of the level of consciousness in post-CA patients treated with TTM. Neurological outcome was assessed using the Cerebral Performance Categories scale and dichotomized into good and poor outcome.RESULTS:Forty-six patients underwent MRI at 3-5 days post-CA. Patients with good outcome had minor, mainly frontal and parietal, lesions. Acute hypoxic/ischemic lesions on MRI including DWI were more common in patients with poor outcome (P = 0.007). These lesions affected mostly gray matter (deep or cortical), with or without involvement of the underlying white matter. Lesions in the occipital and temporal lobes, deep gray matter and cerebellum showed strongest associations with poor outcome. Decreased apparent diffusion coefficient, was more common in patients with poor outcome.CONCLUSIONS:Extensive acute hypoxic/ischemic MRI lesions in the cortical regions, deep gray matter and cerebellum detected by visual analysis as well as low apparent diffusion coefficient values from quantitative measurements were associated with poor outcome. Patients with good outcome had minor hypoxic/ischemic changes, mainly in the frontal and parietal lobes.
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| 2. |
- Wallin, Ewa, et al.
(författare)
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Acute brain lesions on MRI in relation to neurological outcome 6 months after cardiac arrest treated with hypothermia.
- 2015
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Ingår i: Resuscitation. - : Elsevier BV. - 0300-9572 .- 1873-1570. ; 96:Suppl1, s. 147-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Aim of the study: To document the acute magnetic resonance imaging (MRI) findings on the brain in cardiac arrest (CA) patients treated with therapeutic hypothermia (TH) and their relation to patients’ neurological outcome after 6 months.Method: A prospective observational study with MRI was performed regardless the level of consciousness in 56 post-CA patients treated with TH.Results: MRI of the brain was obtained at a median of 4 days (3-13 days). At 6 months, 32/56 had survived with good neurological outcome. The MMSE was performed in 28/32 (88%) patients with a median of 28 (24-30). Acute ischemic lesions were found on diffusion-weighted MRI (DWI) in 34 (61%) patients and were more common in patients with poor outcome (p=0.006). Acute ischemic injuries affected mostly gray matter, deep or cortical and with or without involvement of the underlying white matter. Very few lesions were pure white matter lesions. Lesions in the occipital and temporal lobes, deep gray matter and cerebellum were most associated with poor outcome. Reductions in the apparent diffusion coefficient (ADC) were more common in patients with poor outcome, particularly in the occipital lobes. None of the patients with an ADC below 600x10-6 mm2/s in any region survived to 6 months.Conclusions: In visual analyses of acute MRI, extensive acute lesions were found in the cortical regions and gray matter and were associated with poor outcome. In ADC measurements, low values were associated with poor outcome. Patients with good outcome showed a minor pathological pattern mainly in the frontal and parietal lobes.
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| 3. |
- Wallin, Ewa, et al.
(författare)
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Relationship of acute brain lesions on MRI after cardiac arrest treated with hypothermia to neurological outcome 6 months later
- 2016
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Ingår i: Insights into Imaging 7:Suppl 1, 2016. - : Springer.
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Konferensbidrag (refereegranskat)abstract
- Relationship of acute brain lesions on MRI after cardiac arrest treated with hypothermia to neurological outcome 6 months later,Purpose: To document the acute MRI findings in the brain of post-cardiac arrest (CA) patients treated with therapeutic hypothermia and their relationship to patient outcome after 6 months.Methods and Materials: MRI was performed prospectively 3-13 days (median 4) after CA in 56 patients regardless of the level of consciousness in three hospitals. The images were interpreted visually by two neuroradiologists. Apparent diffusion coefficient (ADC) was measured in predetermined areas in cerebral white matter, deep grey matter, cerebellar grey and white matter and the brainstem. Outcome was assessed using the Cerebral Performance Categories Scale (CPC ) and dichotomized into good and poor outcome.Results: Acute hypoxic lesions on diffusion-weighted MRI (DWI) were more common in patients with poor outcome (p=0.006) and affected mostly grey matter, deep or cortical, with or without involvement of underlying white matter. Pure white matter lesions were very few. Lesions in the occipital and temporal lobes, deep white matter and cerebellum were most associated with poor outcome. Reductions in the ADC, particularly in the occipital lobes, were more common in patients with poor outcome. None of the patients with an ADC below 604-678 x10-6 mm2/s (variation depending on the equipment and technique) in any region survived to 6 months.Conclusion: Extensive acute lesions in cortical regions and deep grey matter in visual analysis and regions with an ADC under the level 600-680 x10-6 mm2/s are associated with poor outcome. Lesions are fewer and mainly situated in the frontal and parietal lobes in patients with good outcome.
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| 4. |
- Blystad, Ida, 1972-
(författare)
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Clinical Applications of Synthetic MRI of the Brain
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Magnetic Resonance Imaging (MRI) has a high soft-tissue contrast with a high sensitivity for detecting pathological changes in the brain. Conventional MRI is a time-consuming method with multiple scans that relies on the visual assessment of the neuroradiologist. Synthetic MRI uses one scan to produce conventional images, but also quantitative maps based on relaxometry, that can be used to quantitatively analyse tissue properties and pathological changes. The studies presented here apply the use of synthetic MRI of the brain in different clinical settings.In the first study, synthetic MR images were compared to conventional MR images in 22 patients. The contrast, the contrast-to-noise ratio, and the diagnostic quality were assessed. Image quality was perceived to be inferior in the synthetic images, but synthetic images agreed with the clinical diagnoses to the same extent as the conventional images.Patients with early multiple sclerosis were analysed in the second study. In patients with multiple sclerosis, contrast-enhancing white matter lesions are a sign of active disease and can indicate a need for a change in therapy. Gadolinium-based contrast agents are used to detect active lesions, but concern has been raised regarding the long-term effects of repeated use of gadolinium. In this study, relaxometry was used to evaluate whether pre-contrast injection tissue-relaxation rates and proton density can identify active lesions without gadolinium. The findings suggest that active lesions often have relaxation times and proton density that differ from non-enhancing lesions, but with some overlap. This makes it difficult to replace gadolinium-based contrast agent injection with synthetic MRI in the monitoring of MS patients.Malignant gliomas are primary brain tumours with contrast enhancement due to a defective blood-brain barrier. However, they also grow in an infiltrative, diffuse manner, making it difficult to clearly delineate them from surrounding normal brain tissue in the diagnostic workup, at surgery, and during follow-up. The contrast-enhancing part of the tumour is easily visualised, but not the diffuse infiltration. In studies three and four, synthetic MRI was used to analyse the peritumoral area of malignant gliomas, and revealed quantitative findings regarding peritumoral relaxation changes and non-visible contrast enhancement suggestive of non-visible infiltrative tumour growth.In conclusion, synthetic MRI provides quantitative information about the brain tissue and this could improve the diagnosis and treatment for patients.
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| 5. |
- Blystad, Ida, et al.
(författare)
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Synthetic MRI of the brain in a clinical setting
- 2012
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Ingår i: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455. ; 53:10, s. 1158-1163
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Conventional magnetic resonance imaging (MRI) has relatively long scan times for routine examinations, and the signal intensity of the images is related to the specific MR scanner settings. Due to scanner imperfections and automatic optimizations, it is impossible to compare images in terms of absolute image intensity. Synthetic MRI, a method to generate conventional images based on MR quantification, potentially both decreases examination time and enables quantitative measurements.PURPOSE:To evaluate synthetic MRI of the brain in a clinical setting by assessment of the contrast, the contrast-to-noise ratio (CNR), and the diagnostic quality compared with conventional MR images.MATERIAL AND METHODS:Twenty-two patients had synthetic imaging added to their clinical MR examination. In each patient, 12 regions of interest were placed in the brain images to measure contrast and CNR. Furthermore, general image quality, probable diagnosis, and lesion conspicuity were investigated.RESULTS:Synthetic T1-weighted turbo spin echo and T2-weighted turbo spin echo images had higher contrast but also a higher level of noise, resulting in a similar CNR compared with conventional images. Synthetic T2-weighted FLAIR images had lower contrast and a higher level of noise, which led to a lower CNR. Synthetic images were generally assessed to be of inferior image quality, but agreed with the clinical diagnosis to the same extent as the conventional images. Lesion conspicuity was higher in the synthetic T1-weighted images, which also had a better agreement with the clinical diagnoses than the conventional T1-weighted images.CONCLUSION:Synthetic MR can potentially shorten the MR examination time. Even though the image quality is perceived to be inferior, synthetic images agreed with the clinical diagnosis to the same extent as the conventional images in this study.
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| 6. |
- Falk, Anna, et al.
(författare)
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Discrimination between glioma grades II and III in suspected low-grade gliomas using dynamic contrast-enhanced and dynamic susceptibility contrast perfusion MR imaging : a histogram analysis approach
- 2014
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 0028-3940 .- 1432-1920. ; 56:12, s. 1031-1038
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionPerfusion magnetic resonance imaging (MRI) can be used in the pre-operative assessment of brain tumours. The aim of this prospective study was to identify the perfusion parameters from dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast (DSC) perfusion imaging that could best discriminate between grade II and III gliomas.MethodsMRI (3 T) including morphological ((T2 fluid attenuated inversion recovery (FLAIR) and T1-weighted (T1W)+Gd)) and perfusion (DCE and DSC) sequences was performed in 39 patients with newly diagnosed suspected low-grade glioma after written informed consent in this review board-approved study. Regions of interests (ROIs) in tumour area were delineated on FLAIR images co-registered to DCE and DSC, respectively, in 25 patients with histopathological grade II (n = 18) and III (n = 7) gliomas. Statistical analysis of differences between grade II and grade III gliomas in histogram perfusion parameters was performed, and the areas under the curves (AUC) from the ROC analyses were evaluated.ResultsIn DCE, the skewness of transfer constant (k trans) was found superior for differentiating grade II from grade III in all gliomas (AUC 0.76). In DSC, the standard deviation of relative cerebral blood flow (rCBF) was found superior for differentiating grade II from grade III gliomas (AUC 0.80).ConclusionsHistogram parameters from k trans (DCE) and rCBF (DSC) could most efficiently discriminate between grade II and grade III gliomas.
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| 7. |
- Holzgraefe, Bernhard, et al.
(författare)
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Does permissive hypoxaemia during extracorporeal membrane oxygenation cause long-term neurological impairment? : A study in patients with H1N1-induced severe respiratory failure
- 2017
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Ingår i: European Journal of Anaesthesiology. - 0265-0215 .- 1365-2346. ; 34:2, s. 98-103
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The Extracorporeal Life Support Organisation accepts permissive hypoxaemia in adult patients during extracorporeal membrane oxygenation (ECMO). The neurological long-term outcome of this approach has not yet been studied.OBJECTIVES: We investigated the prevalence of brain lesions and cognitive dysfunction in survivors from the Influenza A/H1N1 2009 pandemic treated with permissive hypoxaemia during ECMO for severe acute respiratory distress syndrome (ARDS). Our hypothesis was that this method is reasonable if tissue hypoxia is avoided.DESIGN: Long-term follow-up study after ECMO.SETTING: Karolinska University Hospital, Sweden, from October 2012 to July 2013.PATIENTS: Seven patients treated with ECMO for severe influenza A/H1N1-induced ARDS were studied 3.2 years after treatment. Blood lactate concentrations were used as a surrogate for tissue oxygenation.INTERVENTIONS: Neurocognitive outcome was studied with standardised cognitive tests and MRI of the brain.MAIN OUTCOME MEASURES: Cognitive functioning and hypoxic brain lesions after permissive hypoxaemia during ECMO. The observation period was the first 10 days of ECMO or the entire treatment period if shorter than 10 days.RESULTS: Eleven of 13 patients were still alive 3 years after ECMO. We were able to contact seven of these patients (mean age 31 years), who all agreed to participate in this study. Mean +/- SD peripherally measured arterial saturation during the observation period was 79 +/- 10%. Full-scale Intelligence Quotient was within one standard deviation or above from the mean of a healthy population in five patients, and was 1.5 SD below the mean in one patient. In one other patient, it could not be determined because of a lack of formal education. Memory functioning was normal in all patients. MRI showed no changes related to cerebral hypoxia.CONCLUSIONS: Permissive hypoxaemia during ECMO might not negatively affect long-term cognitive outcome if adequate organ perfusion is maintained.
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| 8. |
- Laustsen, Søren Ravn, et al.
(författare)
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Præoperativ funktionel magnetisk resonans-billeddannelse hos patienter med hjernetumor
- 2010
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Ingår i: Ugeskrift for læger. - 0041-5782 .- 1603-6824. ; 172:35, s. 2370-2376
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Functional Magnetic Resonance Imaging (fMRI) allows important functions in the brain cortex to be mapped noninvasively. The purpose with this work was to investigate a possible correlation between the distance from the tumour margin to fMRI activity and postoperative neurological deficits by means of a standardised method for measurement of distance. A second purpose was to investigate the influence of preoperative fMRI on the neurosurgical decision-making process. MATERIAL AND METHODS: Retrospective study of 25 patients. The inclusion criteria were surgery or biopsy after fMRI plus a three-month postoperative assessment. A total of 14 patients complied with these requirements (six men and eight women, the mean age was 39 years). fMRI raw data was collected using a three tesla magnetic resonance scanner (Signa HDx R14M5, GE Healthcare). The distance from the tumour margin to fMRI activation was measured using GE-reformat version 4.2 after raw data had been postprocessed using GE BrainwavePA version 1.3.08130. The neurosurgeons valuation of fMRI in the preoperative decision-making process was obtained using a standard questionnaire. RESULTS: There was a trend of association between distance from tumour to eloquent functional areas and the patients' postoperative neurological outcome (Fisher's exact test: distance < 15 mm, p = 0.43; distance < 10 mm, p = 0.14). fMRI proved very useful when deciding whether to operate or not (42%), when deciding the surgical approach (50%) and when deciding the extent of the surgical approach (83%). CONCLUSION: The standardised method for measurement of distance between tumour margin and fMRI activity can contribute to the preoperative risk assessment in patients with brain tumours.
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| 9. |
- Nordanskog, Pia, et al.
(författare)
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Hippocampal volume in relation to clinical and cognitive outcome after electroconvulsive therapy in depression
- 2014
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Ingår i: Acta Psychiatrica Scandinavica. - United States : Wiley-Blackwell. - 0001-690X .- 1600-0447. ; 129:4, s. 303-311
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:In a previous magnetic resonance imaging (MRI) study, we found a significant increase in hippocampal volume immediately after electroconvulsive therapy (ECT) in patients with depression. The aim of this study was to evaluate hippocampal volume up to 1 year after ECT and investigate its possible relation to clinical and cognitive outcome.METHOD:Clinical and cognitive outcome in 12 in-patients with depression receiving antidepressive pharmacological treatment referred for ECT were investigated with the Montgomery-Asberg Depression Rating Scale (MADRS) and a broad neuropsychological test battery within 1 week before and after ECT. The assessments were repeated 6 and 12 months after baseline in 10 and seven of these patients, respectively. Hippocampal volumes were measured on all four occasions with 3 Tesla MRI.RESULTS:Hippocampal volume returned to baseline during the follow-up period of 6 months. Neither the significant antidepressant effect nor the significant transient decrease in executive and verbal episodic memory tests after ECT could be related to changes in hippocampal volume. No persistent cognitive side effects were observed 1 year after ECT.CONCLUSION:The immediate increase in hippocampal volume after ECT is reversible and is not related to clinical or cognitive outcome.
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| 10. |
- Nordanskog, Pia, et al.
(författare)
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Increase in Hippocampal Volume After Electroconvulsive Therapy in Patients With Depression : A Volumetric Magnetic Resonance Imaging Study
- 2010
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Ingår i: JOURNAL OF ECT. - 1095-0680 .- 1533-4112. ; 26:1, s. 62-67
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Tidskriftsartikel (refereegranskat)abstract
- Background: Major depression has traditionally been regarded as a neurochemical disease, but findings of a decreased hippocampal volume in patients with depression have turned the pathophysiological focus toward impairments in structural plasticity. The mechanisms of action of the most effective antidepressive treatment, electroconvulsive therapy (ECT), still remains elusive, but recent animal research has provided evidence for a cell proliferative effect in the hippocampus. The aim of this prospective study was to determine if hippocampal volume changes after ECT in patients with depression.Methods: Twelve patients with depression and ongoing antidepressive pharmacological treatment were investigated with clinical ratings and 3 T magnetic resonance imaging within 1 week before and after the ECT series. Each hippocampus was manually outlined on coronal slices, and the volume was calculated.Results: The left as well as the right hippocampal volume increased significantly after ECT.Conclusions: The hippocampal volume increases after ECT, supporting the hypothesis that hippocampus may play a central role in the treatment of depression.
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| 11. |
- Nylander, Ruta, et al.
(författare)
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Relation between cardiovascular disease risk markers and brain infarcts detected by magnetic resonance imaging in an elderly population
- 2015
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Ingår i: Journal of Stroke & Cerebrovascular Diseases. - : Elsevier BV. - 1052-3057 .- 1532-8511. ; 24:2, s. 312-318
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Established cardiovascular risk markers, such as hypertension, are associated with increased risk of brain infarcts. The newer markers N-terminal pro-brain natriuretic peptide, troponin I, C-reactive protein, and cystatin C may affect the risk of cardiovascular events and potentially, thereby, also stroke. We investigated the association between established and new risk markers for cardiovascular disease and brain infarcts detected by magnetic resonance imaging (MRI) at age 75.METHODS: Four hundred six randomly selected subjects from the Prospective Investigation of the Vasculature in Uppsala Seniors study were examined with MRI of the brain at age 75. Blood samples, measurements, and dedicated questionnaires at age 70 were used for analysis of risk markers. A history of diseases had been obtained at age 70 and 75. MRI was evaluated regarding lacunar and cortical infarcts. Univariate associations between outcomes and risk markers were assessed with logistic regression models.RESULTS: One or more infarcts were seen in 23% of the subjects (20% had only lacunar infarcts, 1% had only cortical infarcts, and 2% had both). Hypertension (odds ratio [OR] 2.6, 95% confidence interval [CI] 1.4, 4.7) and obesity (OR 1.3; CI 1.0, 1.8) were significantly associated with increased risk of brain infarction. The newer risk markers were not significantly associated with the brain infarcts.CONCLUSIONS: The new markers were not associated with the predominantly lacunar infarcts in our 75-year-old population, why troponin I and NT-proBNP may be associated mainly with cardioembolic infarcts as shown recently.
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| 12. |
- Roodakker, Kenney Roy, 1989-
(författare)
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Towards new tools for clinical evaluation and visualization of tumor growth in patients with glioma
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gliomas are derived from glial cells and are the most common type of primary brain tumors in adults. Gliomas are classified by the World Health Organization (WHO) according to their malignancy grade and histological and molecular features. Malignancy grades range from I to IV. WHO grade I tumors are benign tumors, mostly occurring in childhood. High-grade gliomas (WHO grades III and IV) are undifferentiated and fast-growing tumors, with glioblastoma being the most common and malignant form. Patients with glioblastomas have a median survival of only 15 months. Clinical outcomes vary, however, and markers are needed to assist in the decision-making process and management of these patients. PROX1 is a transcription factor critical for embryonic development, with a role in cell cycle control and progenitor cell differentiation. Apart from its role in normal central nervous system development, PROX1 has been ascribed both tumor suppressive and oncogenic roles in several human cancers. The role of PROX1 as a prognostic factor for survival in patients with glioblastomas was the focus of paper I.Gliomas WHO grade II, also called diffuse low-grade gliomas (DLGGs), are well-differentiated tumors that occur mainly in adult life, with a peak incidence at around 30–35 years of age and a median survival of 5–10 years. DLGGs grow continuously at a rate of a few mm per year and have a strong tendency to infiltrate the white matter tracts surrounding the tumor. Eventually these tumors transform into high-grade gliomas, but, as is the case with glioblastomas, there is a large variety of clinical outcomes. For radiological diagnosis, magnetic resonance imaging (MRI) is routinely used, often in combination with advanced MRI. Positron emission tomography with amino acid tracers provides additional diagnostic accuracy. From a histological as well as imaging point of view, DLGGs are heterogeneous tumors. The heterogeneity of DLGGs, in particular the correlation between radiological and histological tumor features, was the focus of paper II & paper III.Seizures are amongst the most common presenting symptoms of patients with gliomas. Seizure semiology in patients with brain tumors and other structural brain lesions is closely related to the anatomical location of the lesion and the involvement of functional networks. A possible dynamic interplay between the anatomical region of seizure onset and connected target areas within the network was the focus of paper IV.
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| 13. |
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| 14. |
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| 15. |
- Zetterling, Maria, et al.
(författare)
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Extension of diffuse low-grade gliomas beyond radiological borders as shown by the coregistration of histopathological and magnetic resonance imaging data
- 2016
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Ingår i: Journal of Neurosurgery. - : AMER ASSOC NEUROLOGICAL SURGEONS. - 0022-3085 .- 1933-0693. ; 125:5, s. 1155-1166
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Tidskriftsartikel (refereegranskat)abstract
- Background: Magnetic resonance imaging tends to underestimate the extent of diffuse low-grade gliomas (DLGGs). With the aim of studying the presence of tumor cells outside the radiological border, the authors developed a method of correlating MRI findings with histological data in patients with suspected DLGGs in whom en bloc resections were performed.Methods: Five patients with suspected DLGG suitable for en bloc resection were recruited from an ongoing prospective study. Sections of the entire tumor were immunostained with antibodies against mutated IDH1 protein (IDH1-R132H). Magnetic resonance images were coregistered with corresponding IDH1 images. The growth pattern of tumor cells in white and gray matter was assessed in comparison with signal changes on corresponding MRI slices.Results: Neuropathological assessment revealed DLGG in 4 patients and progression to WHO Grade III glioma in 1 patient. The tumor core consisted of a high density of IDH1-R132H–positive tumor cells and was located in both gray and white matter. Tumor cells infiltrated along the peripheral fibers of the white matter tracts. In all cases, tumor cells were found outside the radiological tumor border delineated on T2-FLAIR MRI sequences.Conclusions: The authors present a new method for the coregistration of histological and radiological characteristics of en bloc–removed infiltrative brain tumors that discloses tumor invasion at the radiological tumor borders. This technique can be applied to evaluate the sensitivity of alternative imaging methods to detect scattered tumor cells at tumor borders. Accurate methods for detection of infiltrative tumor cells will improve the possibility of performing radical tumor resection. In future studies, the method could also be used for in vivo studies of tumor invasion.
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| 16. |
- 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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| 17. |
- 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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| 18. |
- Arvanitis, Panagiotis, et al.
(författare)
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Recent-onset atrial fibrillation : a study exploring the elements of Virchow's triad after cardioversion
- 2022
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Ingår i: Journal of Interventional Cardiac Electrophysiology. - : Springer Science and Business Media LLC. - 1383-875X .- 1572-8595. ; 64:1, s. 49-58
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Tidskriftsartikel (refereegranskat)abstract
- PurposeAtrial fibrillation (AF) imposes an inherent risk for stroke and silent cerebral emboli, partly related to left atrial (LA) remodeling and activation of inflammatory and coagulation systems. The aim was to explore the effects of cardioversion (CV) and short-lasting AF on left atrial hemodynamics, inflammatory, coagulative and cardiac biomarkers, and the association between LA functional recovery and the presence of a prior history of AF.MethodsPatients referred for CV within 48 h after AF onset were prospectively included. Echocardiography and blood sampling were performed immediately prior, 1–3 h after, and at 7–10 days after CV. The presence of chronic white matter hyperintensities (WMH) on magnetic resonance imaging was related to biomarker levels.ResultsForty-three patients (84% males), aged 55±9.6 years, with median CHA2DS2-VASc score 1 (IQR 0–1) were included. The LA emptying fraction (LAEF), LA peak longitudinal strain during reservoir, conduit, and contractile phases improved significantly after CV. Only LAEF normalized within 10 days. Interleukin-6, high-sensitivity cardiac-troponin-T (hs-cTNT), N-terminal-pro-brain-natriuretic peptide, prothrombin-fragment 1+2 (PTf1+2), and fibrinogen decreased significantly after CV. There was a trend towards higher C-reactive protein, hs-cTNT, and PTf1+2 levels in patients with WMH (n=21) compared to those without (n=22). At 7–10 days, the LAEF was significantly lower in patients with a prior history of AF versus those without.ConclusionAlthough LA stunning resolved within 10 days, LAEF remained significantly lower in patients with a prior history of AF versus those without. Inflammatory and coagulative biomarkers were higher before CV, but subsided after 7–10 days, which altogether might suggest an enhanced thrombogenicity, even in these low-risk patients.
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| 19. |
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| 20. |
- Arvanitis, Panagiotis, et al.
(författare)
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Timing and degree of left atrial stunning and reverse functional remodeling following electrical cardioversion in patients with recent onset atrial fibrillation
- 2020
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Ingår i: European Heart Journal, Supplement. - : Oxford University Press (OUP). - 1520-765X .- 1554-2815 .- 0195-668X .- 1522-9645. ; 41:Supplement_2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundAtrial fibrillation (AF) results in left atrial electrical, structural and functional remodeling. Restoration of sinus rhythm hallmarks the beginning of reverse remodeling, the extent of which may depend on the type of AF.PurposeThe aim of the study was to assess resumption of left atrial function after electric cardioversion in patients with recent onset AF and to explore the association between reverse remodeling and the type of atrial fibrillation.MethodsPatients with AF duration <48 hours were prospectively included. Trans-thoracic echocardiography was performed prior, immediately after (2–4 hours) and 7–10 days following CV. Left atrial volume index (LAVI), left atrial global longitudinal strain during reservoir (LAGLS-res), conduit (LAGLS-cond) and contractile (LAGLS-contr) phases, left atrial ejection fraction (LAEF) and left ventricular ejection fraction (LVEF) were measured.ResultsForty-three patients (84% males) aged 55±9.6 years, (mean±SD), with median CHA2DS2-VASc score 1 (interquartile range 0–1) were included. Repeated measure analysis of variance revealed a statistically significant overall change for LAGLS-res F(2,78)=55.4, p<0,001, LAGLS-cond F(2,78)=23.3, p<0,001, LAGLS-contr F(2,78)=39.7, p<0,001, LAEF F(2,80)=28.5, p<0.001 and LVEF F(2,80)=8.4, p<0.001. At 7–10 days, LAGLS-contr 12±4%, LAEF 53±9% and LVEF 60±6 (mean±SD) return within normal reference intervals. Notably left atrial recovery seems to precede left ventricular recovery. No statistical significant interaction with the type of atrial fibrillation could be shown.ConclusionLeft atrial functional reverse remodeling occurs within ten days after successful electric cardioversion of patients with recent onset atrial fibrillation.
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| 21. |
- Benedict, Christian, et al.
(författare)
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Acute Sleep Deprivation Enhances the Brain's Response to Hedonic Food Stimuli : An fMRI Study
- 2012
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 97:3, s. E443-447
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Tidskriftsartikel (refereegranskat)abstract
- Context:There is growing recognition that a large number of individuals living in Western society are chronically sleep deprived. Sleep deprivation is associated with an increase in food consumption and appetite. However, the brain regions that are most susceptible to sleep deprivation-induced changes when processing food stimuli are unknown.Objective:Our objective was to examine brain activation after sleep and sleep deprivation in response to images of food.Intervention:Twelve normal-weight male subjects were examined on two sessions in a counterbalanced fashion: after one night of total sleep deprivation and one night of sleep. On the morning after either total sleep deprivation or sleep, neural activation was measured by functional magnetic resonance imaging in a block design alternating between high- and low-calorie food items. Hunger ratings and morning fasting plasma glucose concentrations were assessed before the scan, as were appetite ratings in response to food images after the scan.Main Outcome Measures:Compared with sleep, total sleep deprivation was associated with an increased activation in the right anterior cingulate cortex in response to food images, independent of calorie content and prescan hunger ratings. Relative to the postsleep condition, in the total sleep deprivation condition, the activation in the anterior cingulate cortex evoked by foods correlated positively with postscan subjective appetite ratings. Self-reported hunger after the nocturnal vigil was enhanced, but importantly, no change in fasting plasma glucose concentration was found.Conclusions:These results provide evidence that acute sleep loss enhances hedonic stimulus processing in the brain underlying the drive to consume food, independent of plasma glucose levels. These findings highlight a potentially important mechanism contributing to the growing levels of obesity in Western society.
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| 22. |
- Benedict, Christian, et al.
(författare)
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Association between physical activity and brain health in older adults
- 2013
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 34:1, s. 83-90
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Tidskriftsartikel (refereegranskat)abstract
- In the present cross-sectional study, we examined physical activity (PA) and its possible association with cognitive skills and brain structure in 331 cognitively healthy elderly. Based on the number of self-reported light and hard activities for at least 30 minutes per week, participants were assigned to 4 groups representing different levels of PA. The cognitive skills were assessed by the Mini Mental State Examination score, a verbal fluency task, and the Trail-making test as a measure of visuospatial orientation ability. Participants also underwent a magnetic resonance imaging of the brain. Multiple regression analysis revealed that greater PA was associated with a shorter time to complete the Trail-making test, and higher levels of verbal fluency. Further, the level of self-reported PA was positively correlated with brain volume, white matter, as well as a parietal lobe gray matter volume, situated bilaterally at the precuneus. These present cross-sectional results indicate that PA is a lifestyle factor that is linked to brain structure and function in late life.
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| 23. |
- Benedict, Christian, et al.
(författare)
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Impaired Insulin Sensitivity as Indexed by the HOMA Score Is Associated With Deficits in Verbal Fluency and Temporal Lobe Gray Matter Volume in the Elderly
- 2012
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 35:3, s. 488-494
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVEImpaired insulin sensitivity is linked to cognitive deficits and reduced brain size. However, it is not yet known whether insulin sensitivity involves regional changes in gray matter volume. Against this background, we examined the association between insulin sensitivity, cognitive performance, and regional gray matter volume in 285 cognitively healthy elderly men and women aged 75 years from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study.RESEARCH DESIGN AND METHODSInsulin sensitivity was calculated from fasting serum insulin and plasma glucose determinations using the homeostasis model assessment of insulin resistance (HOMA-IR) method. Cognitive performance was examined by a categorical verbal fluency. Participants also underwent a magnetic resonance imaging (MRI) brain scan. Multivariate analysis using linear regression was conducted, controlling for potential confounders (sex, education, serum LDL cholesterol, mean arterial blood pressure, and abdominal visceral fat volume).RESULTSThe HOMA-IR was negatively correlated with verbal fluency performance, brain size (S1), and temporal lobe gray matter volume in regions known to be involved in speech production (Brodmann areas 21 and 22, respectively). No such effects were observed when examining diabetic (n = 55) and cognitively impaired (n = 27) elderly subjects as separate analyses.CONCLUSIONSThese cross-sectional findings suggest that both pharmacologic and lifestyle interventions improving insulin signaling may promote brain health in late life but must be confirmed in patient studies.
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| 24. |
- Berntsson, Shala Ghaderi, et al.
(författare)
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Perfusion and diffusion MRI combined with (11)C-methionine PET in the preoperative evaluation of suspected adult low-grade gliomas
- 2013
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Ingår i: Journal of Neuro-Oncology. - : Springer Science and Business Media LLC. - 0167-594X .- 1573-7373. ; 114:2, s. 241-249
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Tidskriftsartikel (refereegranskat)abstract
- Perfusion and diffusion magnetic resonance imaging (pMRI, dMRI) are valuable diagnostic tools for assessing brain tumors in the clinical setting. The aim of this study was to determine the correlation of pMRI and dMRI with (11)C-methionine positron emission tomography (MET PET) in suspected low-grade gliomas (LGG) prior to surgery. Twenty-four adults with suspected LGG were enrolled in an observational study and examined by MET PET, pMRI and dMRI. Histological tumor diagnosis was confirmed in 23/24 patients (18 gliomas grade II, 5 gliomas grade III). The maximum relative cerebral blood volume (rCBVmax) and the minimum mean diffusivity (MDmin) were measured in tumor areas with highest MET uptake (hotspot) on PET by using automated co-registration of MRI and PET scans. A clearly defined hotspot on PET was present in all 23 tumors. Regions with rCBVmax corresponded with hotspot regions in all tumors, regions with MDmin corresponded with hotspot regions in 20/23 tumors. The correlation between rCBVmax (r = 0.19, P = 0.38) and MDmin (r = -0.41, P = 0.053) with MET uptake in the hotspot was not statistically significant. Taken into account the difficulties of measuring perfusion abnormalities in non-enhancing gliomas, this study demonstrates that co-registered MET PET and pMRI facilitates the identification of regions with rCBVmax. Furthermore, the lack of a clear positive correlation between tumor metabolism in terms of MET uptake and tumor vascularity measured as rCBVmax suggests that combined pMRI/PET provides complementary baseline imaging data in these tumors.
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| 25. |
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| 26. |
- Björkman, Anders, et al.
(författare)
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Cortical sensory and motor response in a patient whose hand has been replanted: One-year follow up with functional magnetic resonance imaging
- 2007
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Ingår i: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. - : Informa UK Limited. - 1651-2073 .- 0284-4311. ; 41:2, s. 70-76
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Tidskriftsartikel (refereegranskat)abstract
- Functional magnetic resonance imaging (fMRI) was used to study how a replanted hand regained its cortical territory parallel to recovery. The cortical response to sensory stimulation shifts from an ipsilateral to a bilateral pattern, and then to a predominantly contralateral activation. The cortical response to motor stimulation was normal from the first investigation.
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| 27. |
- Björkstrand, Johannes, et al.
(författare)
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Disrupting Reconsolidation Attenuates Long-Term Fear Memory in the Human Amygdala and Facilitates Approach Behavior
- 2016
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 26:19, s. 2690-95
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Tidskriftsartikel (refereegranskat)abstract
- Memories become labile and malleable to modification when recalled [1]. Fear-conditioning experiments in both rodents and humans indicate that amygdala-localized short-term fear memories can be attenuated by disruption of their reconsolidation with extinction training soon after memory activation [2-7]. However, this may not be true for natural long-term fears. Studies in rodents indicate that although it is possible to disrupt the reconsolidation of older memories [8-11], they appear to be more resistant [1, 3, 9, 12, 13]. In humans, 1-week-old conditioned fear memories have been attenuated by behaviorally induced disruption of reconsolidation [14], but it remains to be seen whether this is possible for naturally occurring long-term fears and whether the underlying neural mechanisms are similar to those found in experimental fear-conditioning paradigms. Using functional brain imaging in individuals with a lifelong fear of spiders, we show that fear memory activation followed by repeated exposure to feared cues after 10 min, which disrupts reconsolidation, attenuates activity in the basolateral amygdala at re-exposure 24 hr later. In contrast, repeated exposure 6 hr after fear memory activation, which allows for reconsolidation, did not attenuate amygdala activity. Disrupted, but not undisrupted, reconsolidation facilitated approach behavior to feared cues, and approach behavior was inversely related to amygdala activity during re-exposure. We conclude that memory activation immediately preceding exposure attenuates the neural and behavioral expression of decades-old fear memories and that, similar to experimentally induced fear memories, the basolateral amygdala is crucially involved in this process.
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| 28. |
- Björkstrand, Johannes, et al.
(författare)
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Disruption of Memory Reconsolidation Erases a Fear Memory Trace in the Human Amygdala : An 18-Month Follow-Up.
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:7, s. e0129393-
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Tidskriftsartikel (refereegranskat)abstract
- Fear memories can be attenuated by reactivation followed by disrupted reconsolidation. Using functional magnetic resonance imaging we recently showed that reactivation and reconsolidation of a conditioned fear memory trace in the basolateral amygdala predicts subsequent fear expression over two days, while reactivation followed by disrupted reconsolidation abolishes the memory trace and suppresses fear. In this follow-up study we demonstrate that the behavioral effect persists over 18 months reflected in superior reacquisition after undisrupted, as compared to disrupted reconsolidation, and that neural activity in the basolateral amygdala representing the initial fear memory predicts return of fear. We conclude that disrupting reconsolidation have long lasting behavioral effects and may permanently erase the fear component of an amygdala-dependent memory.
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| 29. |
- Björkstrand, Johannes, et al.
(författare)
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Think twice, it's all right : Long lasting effects of disrupted reconsolidation on brain and behavior in human long-term fear
- 2017
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Ingår i: Behavioural Brain Research. - : Elsevier BV. - 0166-4328 .- 1872-7549. ; 324, s. 125-129
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Tidskriftsartikel (refereegranskat)abstract
- Memories can be modified when recalled. Experimental fear conditioning studies support that amygdala-localized fear memories are attenuated when reconsolidation is disrupted through extinction training immediately following memory activation. Recently, using functional brain imaging in individuals with lifelong spider fears, we demonstrated that fear memory activation followed by repeated exposure to feared cues after 10 min, thereby disrupting reconsolidation, attenuated activity in the amygdala during later re-exposure, and also facilitated approach behavior to feared cues. In contrast, repeated exposure 6 h after fear memory activation, allowing for reconsolidation, did not attenuate amygdala activity and resulted in less approach behavior as compared to the group that received disrupted reconsolidation. We here evaluated if these effects are stable after 6 months and found that amygdala activity was further reduced in both groups, with a tendency towards greater reductions in the 10 min than the 6 h group. Hence, disrupted reconsolidation results in long lasting attenuation of amygdala activity. The behavioral effect, with more approach towards previously feared cues, in the 10 min than the 6 h group also persisted. Thus, the brain effect of disrupted reconsolidation is stable over 6 months and the behavioral effect also remained. We therefore conclude that disrupted reconsolidation result in a long-lasting diminished fear memory representation in the amygdala which may have clinical importance.
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| 30. |
- Blystad, Ida, et al.
(författare)
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Quantitative MRI for Analysis of Active Multiple Sclerosis Lesions without Gadolinium-Based Contrast Agent
- 2016
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Ingår i: American Journal of Neuroradiology. - : American Society of Neuroradiology (ASNR). - 0195-6108 .- 1936-959X. ; 37:1, s. 94-100
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Contrast-enhancing MS lesions are important markers of active inflammation in the diagnostic work-up of MS and in disease monitoring with MR imaging. Because intravenous contrast agents involve an expense and a potential risk of adverse events, it would be desirable to identify active lesions without using a contrast agent. The purpose of this study was to evaluate whether pre-contrast injection tissue-relaxation rates and proton density of MS lesions, by using a new quantitative MR imaging sequence, can identify active lesions.MATERIALS AND METHODS: Forty-four patients with a clinical suspicion of MS were studied. MR imaging with a standard clinical MS protocol and a quantitative MR imaging sequence was performed at inclusion (baseline) and after 1 year. ROIs were placed in MS lesions, classified as nonenhancing or enhancing. Longitudinal and transverse relaxation rates, as well as proton density were obtained from the quantitative MR imaging sequence. Statistical analyses of ROI values were performed by using a mixed linear model, logistic regression, and receiver operating characteristic analysis.RESULTS: Enhancing lesions had a significantly (P < .001) higher mean longitudinal relaxation rate (1.22 ± 0.36 versus 0.89 ± 0.24), a higher mean transverse relaxation rate (9.8 ± 2.6 versus 7.4 ± 1.9), and a lower mean proton density (77 ± 11.2 versus 90 ± 8.4) than nonenhancing lesions. An area under the receiver operating characteristic curve value of 0.832 was obtained.CONCLUSIONS: Contrast-enhancing MS lesions often have proton density and relaxation times that differ from those in nonenhancing lesions, with lower proton density and shorter relaxation times in enhancing lesions compared with nonenhancing lesions.
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| 31. |
- Blystad, Ida, 1972-, et al.
(författare)
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Quantitative MRI for analysis of peritumoral edema in malignant gliomas
- 2017
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 12:5
-
Tidskriftsartikel (refereegranskat)abstract
- Background and purpose Damage to the blood-brain barrier with subsequent contrast enhancement is a hallmark of glioblastoma. Non-enhancing tumor invasion into the peritumoral edema is, however, not usually visible on conventional magnetic resonance imaging. New quantitative techniques using relaxometry offer additional information about tissue properties. The aim of this study was to evaluate longitudinal relaxation R-1, transverse relaxation R-2, and proton density in the peritumoral edema in a group of patients with malignant glioma before surgery to assess whether relaxometry can detect changes not visible on conventional images. Methods In a prospective study, 24 patients with suspected malignant glioma were examined before surgery. A standard MRI protocol was used with the addition of a quantitative MR method (MAGIC), which measured R-1, R-2, and proton density. The diagnosis of malignant glioma was confirmed after biopsy/surgery. In 19 patients synthetic MR images were then created from the MAGIC scan, and ROIs were placed in the peritumoral edema to obtain the quantitative values. Dynamic susceptibility contrast perfusion was used to obtain cerebral blood volume (rCBV) data of the peritumoral edema. Voxel-based statistical analysis was performed using a mixed linear model. Results R-1, R-2, and rCBV decrease with increasing distance from the contrast-enhancing part of the tumor. There is a significant increase in R1 gradient after contrast agent injection (P<.0001). There is a heterogeneous pattern of relaxation values in the peritumoral edema adjacent to the contrast-enhancing part of the tumor. Conclusion Quantitative analysis with relaxometry of peritumoral edema in malignant gliomas detects tissue changes not visualized on conventional MR images. The finding of decreasing R-1 and R-2 means shorter relaxation times closer to the tumor, which could reflect tumor invasion into the peritumoral edema. However, these findings need to be validated in the future.
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| 32. |
- 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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| 33. |
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| 34. |
- Bodén, Robert, et al.
(författare)
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Striatal phosphodiesterase 10A and medial prefrontal cortical thickness in patients with schizophrenia : a PET and MRI study
- 2017
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Ingår i: Translational Psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 7:3
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Tidskriftsartikel (refereegranskat)abstract
- The enzyme phosphodiesterase 10A (PDE10A) is abundant in striatal medium spiny neurons and has been implicated in the pathophysiology of schizophrenia in animal models and is investigated as a possible new pharmacological treatment target. A reduction of prefrontal cortical thickness is common in schizophrenia, but how this relates to PDE10A expression is unknown. Our study aim was to compare, we believe for the first time, the striatal non-displaceable binding potential (BPND) of the new validated PDE10A ligand [(11)C]Lu AE92686 between patients with schizophrenia and healthy controls. Furthermore, we aimed to assess the correlation of PDE10A BPND to cortical thickness. Sixteen healthy male controls and 10 male patients with schizophrenia treated with clozapine, olanzapine or quetiapine were investigated with positron emission tomography (PET) and magnetic resonance imaging (MRI). Striatal binding potential (BPND) of [(11)C]Lu AE92686 was acquired through dynamic PET scans and cortical thickness by structural MRI. Clinical assessments of symptoms and cognitive function were performed and the antipsychotic dosage was recorded. Patients with schizophrenia had a significantly lower BPND of [(11)C]Lu AE92686 in striatum (P=0.003) than healthy controls. The striatal BPND significantly correlated to cortical thickness in the medial prefrontal cortex and superior frontal gyrus across patients with schizophrenia and healthy controls. No significant correlation was observed between the BPND for [(11)C]Lu AE92686 in striatum and age, schizophrenia symptoms, antipsychotic dosage, coffee consumption, smoking, duration of illness or cognitive function in the patients. In conclusion, PDE10A may be important for functioning in the striato-cortical interaction and in the pathophysiology of schizophrenia.
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| 35. |
- Brockstedt, Sara, et al.
(författare)
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SchnelleMagnetresonanz-Bildgebung
- 2002
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Ingår i: Radiologie Up2Date. - : Georg Thieme Verlag KG. - 1616-0681 .- 1617-8300. ; :4, s. 413-438
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in German Die Verkürzung der Untersuchungszeiten bei der klinischen Magnetresonanztomographie (MRT) bietet für den Patienten den Vorteil einer angenehmeren und schnelleren Untersuchung und erhöht gleichzeitig den Patientendurchsatz. Dies erfordert schnelle und robuste Aufnahmetechniken, welche beispielsweise auch bei der Aufnahme bewegter Organe oder für atemangehaltene Messungen eingesetzt werden können. Durch die Entwicklung leistungsfähiger Gradientensysteme konnten in den letzten Jahren neue und schnelle Pulssequenzen entwickelt werden. Die rasante Entwicklung neuer Aufnahmemethoden und Rekonstruktionstechniken macht es für den Anwender immer wichtiger, die grundlegenden Prinzipien schneller Aufnahmetechniken zu verstehen. In diesem Übersichtsartikel wird versucht, die Grundlagen der schnellen Pulssequenzen und deren klinische Anwendungsbereiche darzustellen. Dies beinhaltet die schnelle Spin-Echo-Technik und deren Kombination mit selektiven Präparationstechniken, die schnelle und ultraschnelle Gradienten-Echo-Technik sowie die echoplanare Bildgebung. Abschließend werden kurz neueste Entwicklungen wie die parallele Bildgebung beschrieben.Zusammenfassung auf S. 434
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| 36. |
- Brockstedt, Sara, et al.
(författare)
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Vertical field MR imaging of upper thorax and spine in small children. Evaluation of a new surface coil
- 1993
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Ingår i: Acta Radiologica. - 1600-0455. ; 34:6, s. 549-553
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Tidskriftsartikel (refereegranskat)abstract
- To improve image quality in a vertical field MR imaging unit, operating at low field strength (0.3 T), we have designed a half-elliptical coil for use in the upper thoracic region of small children. Our intention was also to shorten the examination time, which until now has been long, because several scans with different coils have been necessary to cover the thoracic region. The experimental coil is designed so that a child's shoulders fit into the central region. The coil consists of 2 serially connected cable-loops, mounted on a foam rubber vest. The coil performance was tested in a phantom and improvements relative to standard coils were demonstrated in in vivo studies. The results indicate that by using the half-elliptical coil, the signal-to-noise (S/N) ratio can be improved by a factor of 2 to 3 in the thoracic region of a child.
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| 37. |
- Brooks, Samantha J, et al.
(författare)
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Late-life obesity is associated with smaller global and regional gray matter volumes : a voxel-based morphometric study
- 2013
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 37:2, s. 230-236
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Obesity adversely affects frontal lobe brain structure and function. Here we sought to show that people who are obese versus those who are of normal weight over a 5-year period have differential global and regional brain volumes.DESIGN: Using voxel-based morphometry, contrasts were done between those who were recorded as being either obese or of normal weight over two time points in the 5 years prior to the brain scan. In a post-hoc preliminary analysis, we compared scores for obese and normal weight people who completed the trail-making task.SUBJECTS: A total of 292 subjects were examined following exclusions (for example, owing to dementia, stroke and cortical infarcts) from the Prospective Investigation of the Vasculature in Uppsala Seniors cohort with a body mass index of normal weight (<25 kg m−2) or obese (30 kg m−2).RESULTS: People who were obese had significantly smaller total brain volumes and specifically, significantly reduced total gray matter (GM) volume (GMV) (with no difference in white matter or cerebrospinal fluid). Initial exploratory whole brain uncorrected analysis revealed that people who were obese had significantly smaller GMV in the bilateral supplementary motor area, bilateral dorsolateral prefrontal cortex (DLPFC), left inferior frontal gyrus and left postcentral gyrus. Secondary more stringent corrected analyses revealed a surviving cluster of GMV difference in the left DLPFC. Finally, post-hoc contrasts of scores on the trail-making task, which is linked to DLPFC function, revealed that obese people were significantly slower than those of normal weight.CONCLUSION: These findings suggest that in comparison with normal weight, people who are obese have smaller GMV, particularly in the left DLPFC. Our results may provide evidence for a potential working memory mechanism for the cognitive suppression of appetite that may lower the risk of developing obesity in later life.
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| 38. |
- Brooks, Samantha J, et al.
(författare)
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Obsessive-compulsivity and working memory are associated with differential prefrontal cortex and insula activation in adolescents with a recent diagnosis of an eating disorder
- 2014
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Ingår i: Psychiatry Research. - : Elsevier BV. - 0165-1781 .- 1872-7123 .- 0925-4927. ; 224:3, s. 246-253
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Tidskriftsartikel (refereegranskat)abstract
- The role of rumination at the beginning of eating disorder (ED) is not well understood. We hypothesised that impulsivity, rumination and restriction could be associated with neural activity in response to food stimuli in young individuals with eating disorders (ED). We measured neural responses with functional magnetic resonance imaging (fMRI), tested working memory (WM) and administered the eating disorders examination questionnaire (EDE-Q), Barratt impulsivity scale (BIS-11) and obsessive-compulsive inventory (OCI-R) in 15 adolescent females with eating disorder not otherwise specified (EDNOS) (mean age 15 years) and 20 age-matched healthy control females. We found that EDNOS subjects had significantly higher scores on the BIS 11, EDE-Q and OCI-R scales. Significantly increased neural responses to food images in the EDNOS group were observed in the prefrontal circuitry. OCI-R scores in the EDNOS group also significantly correlated with activity in the prefrontal circuitry and the cerebellum. Significantly slower WM responses negatively correlated with bilateral superior frontal gyrus activity in the EDNOS group. We conclude that ruminations, linked to WM, are present in adolescent females newly diagnosed with EDNOS. These may be risk factors for the development of an eating disorder and may be detectable before disease onset.
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| 39. |
- Christensen, Ib Thrane, et al.
(författare)
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Olfactory testing in consecutive patients referred with suspected dementia.
- 2017
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Ingår i: BMC Geriatrics. - : Springer Science and Business Media LLC. - 1471-2318. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Alzheimer's disease (AD) is the most common cause of dementia and early and accurate diagnosis is important. Olfactory dysfunction is an early sign of AD. The contribution by test of olfactory function has been surveyed in AD vs a line of conditions but remains to be settled in the workup of unselected patients referred with suspected dementia.METHODS: We performed a two-step investigation: first, a comparative study of healthy controls and probable AD patients to test the applicability of the chosen scents (cuisine study); second, a study of consecutive patients referred to our geriatric outpatient clinic for suspected dementia with the investigating personnel blinded to the results of the Olfactory Test (blinded study).RESULTS: The sum of scents detected discriminated patients with probable AD from controls in the cuisine study (n = 40; p < 0.001; area under ROC curve 0.94). In the blinded study (n = 50) the diagnosis was probable AD in 48%, minimal cognitive impairment in 24%, vascular dementia in 8%, alcohol induced impairment in 12%, depression in 4%, and Parkinson's disease and Lewy body dementia in 2%. Area under the ROC-curve was 0.67. The odds ratio for probable AD with 2+ smell errors was 12 (95%-CI: 1.3-101; p = 0.026 (reference 0-1 smell errors)) age adjusted. None in the AD group had zero smell errors (Negative Predictive Value 100%).CONCLUSION: Olfactory testing may support to dismiss the diagnosis of probable AD in the workup of a mixed group of patients referred with cognitive impairment. Still, it had a low sensitivity for probable AD.
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| 40. |
- Clement, Patricia, et al.
(författare)
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Variability of physiological brain perfusion in healthy subjects : A systematic review of modifiers. Considerations for multi-center ASL studies
- 2018
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - 0271-678X .- 1559-7016. ; 38:9, s. 1418-1437
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Forskningsöversikt (refereegranskat)abstract
- Quantitative measurements of brain perfusion are influenced by perfusion-modifiers. Standardization of measurement conditions and correction for important modifiers is essential to improve accuracy and to facilitate the interpretation of perfusion-derived parameters. An extensive literature search was carried out for factors influencing quantitative measurements of perfusion in the human brain unrelated to medication use. A total of 58 perfusion modifiers were categorized into four groups. Several factors (e.g., caffeine, aging, and blood gases) were found to induce a considerable effect on brain perfusion that was consistent across different studies; for other factors, the modifying effect was found to be debatable, due to contradictory results or lack of evidence. Using the results of this review, we propose a standard operating procedure, based on practices already implemented in several research centers. Also, a theory of ' deep MRI physiotyping' is inferred from the combined knowledge of factors influencing brain perfusion as a strategy to reduce variance by taking both personal information and the presence or absence of perfusion modifiers into account. We hypothesize that this will allow to personalize the concept of normality, as well as to reach more rigorous and earlier diagnoses of brain disorders.
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| 41. |
- Cronberg, Carin, et al.
(författare)
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Peripheral arterial disease.
- 2003
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 44:1, s. 59-66
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Tidskriftsartikel (refereegranskat)
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| 42. |
- Cronqvist, Mats, et al.
(författare)
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Diffusion and perfusion MRI in patients with ruptured and unruptured intracranial aneurysms treated by endovascular coiling: complications, procedural results, MR findings and clinical outcome.
- 2005
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 47:11, s. 855-873
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Tidskriftsartikel (refereegranskat)abstract
- Our purpose was to evaluate treatment safety as well as complications frequency and management in endovascular coiling of intracerebral aneurysms using MR diffusion and perfusion imaging. In this prospective study, 77 MR examinations were performed in conjunction with 43 procedures in 40 patients, 14 patients presented with ruptured and 26 with unruptured aneurysms. Mean time interval between treatment and post-procedure MRI was 29 and 25 h for the ruptured and unruptured aneurysm group, respectively. Peri-procedural complications, including five major events and five minor transient events, occurred in 10/43 procedures (23%), necessitating thrombolytic therapy in two patients and angioplasty in one, all three within the unruptured aneurysm group. Fifty-one new lesions were found on post-treatment DWI and 47 of them were regarded as of ischemic origin. Most lesions were small (< 3 mm), ipsilateral to the treated aneurysm and asymptomatic (37/40 patients). Sixty-seven percent of the lesions were found in the ruptured and 33% in the unruptured aneurysm group. The ischemic lesions did occur more frequently in patients treated for aneurysm of large neck size and according to the remodelling technique. The overall morbidity and mortality rates were 14.6 and 7.3% whereas morbidity and mortality rates related to the technique were only 2.6 and 0%, respectively. Silent embolism seems to be more common than clinically evident and partially related to patient presentation, heparinazation and treatment strategy. The capability to depict early complications and analyse their potential causes by using MR with DWI has been of great importance in our modification and improvement of therapeutic protocols, evaluations and strategies.
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| 43. |
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| 44. |
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| 45. |
- Dhara, Ashis Kumar, et al.
(författare)
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Segmentation of Post-operative Glioblastoma in MRI by U-Net with Patient-specific Interactive Refinement
- 2019
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Ingår i: Brainlesion. - Cham : Springer. - 9783030117221 - 9783030117238 ; , s. 115-122
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Konferensbidrag (refereegranskat)abstract
- Accurate volumetric change estimation of glioblastoma is very important for post-surgical treatment follow-up. In this paper, an interactive segmentation method was developed and evaluated with the aim to guide volumetric estimation of glioblastoma. U-Net based fully convolutional network is used for initial segmentation of glioblastoma from post contrast MR images. The max flow algorithm is applied on the probability map of U-Net to update the initial segmentation and the result is displayed to the user for interactive refinement. Network update is performed based on the corrected contour by considering patient specific learning to deal with large context variations among different images. The proposed method is evaluated on a clinical MR image database of 15 glioblastoma patients with longitudinal scan data. The experimental results depict an improvement of segmentation performance due to patient specific fine-tuning. The proposed method is computationally fast and efficient as compared to state-of-the-art interactive segmentation tools. This tool could be useful for post-surgical treatment follow-up with minimal user intervention.
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| 46. |
- Ebeling Barbier, Charlotte, et al.
(författare)
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Prevalence of unrecognized myocardial infarction detected with magnetic resonance imaging and its relationship to cerebral ischemic lesions in both sexes
- 2011
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Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097 .- 1558-3597. ; 58:13, s. 1372-1377
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The purpose of this study was to investigate the prevalence of unrecognized myocardial infarction (UMI) detected with magnetic resonance imaging (MRI) and whether it is related to cerebral ischemic lesions on MRI in an elderly population-based cohort. BACKGROUND: There is a correlation between stroke and recognized myocardial infarction (RMI) and between stroke and UMI detected with electrocardiography, whereas the prevalence of stroke in subjects with MRI-detected UMI is unknown. METHODS: Cerebral MRI and cardiac late-enhancement MRI were performed on 394 randomly selected 75-year-old subjects (188 women, 206 men). Images were assessed for cerebral ischemic lesions and myocardial infarction (MI) scars. Medical records were scrutinized. Subjects with MI scars, with or without a hospital diagnosis of MI, were classified as RMI or UMI, respectively. RESULTS: UMIs were found in 120 subjects (30%) and RMIs in 21 (5%). The prevalence of UMIs (p = 0.004) and RMIs (p = 0.02) was greater in men than in women. Men with RMI displayed an increased prevalence of cortical and lacunar cerebral infarctions, whereas women with UMI more frequently had cortical cerebral infarctions (p = 0.003). CONCLUSIONS: MI scars are more frequent in men than in women at 75 years of age. The prevalence of RMI is related to that of cerebral infarctions.
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| 47. |
- Elfgren, Christina, et al.
(författare)
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fMRI activity in the medial temporal lobe during famous face processing
- 2006
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Ingår i: NeuroImage. - : Elsevier BV. - 1095-9572 .- 1053-8119. ; 30:2, s. 609-616
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Tidskriftsartikel (refereegranskat)abstract
- The current event-related fMRI study examined the relative involvement of different parts of the medial temporal lobe (MTL), particularly the contribution of hippocampus and perirhinal cortex, in either intentional or incidental recognition of famous faces in contrast to unfamiliar faces. Our intention was to further explore the controversial contribution of MTL in the processing of semantic memory tasks. Subjects viewed a sequence of famous and unfamiliar faces. Two tasks were used encouraging attention to either fame or gender. In the fame task, the subjects were requested to identify the person when seeing his/her face and also to try to generate the name of this person. In the gender task, the subjects were asked to conduct a judgement of a person's gender when seeing his/her face. The visual processing was hence directed to gender and thereby expected to diminish attention to semantic information leading only to a “passive” registration of famous and non-familiar faces. Recognition of famous faces, in both contrasts, produced significant activations in the MTL. First, during the intentional recognition (the person identification task) increased activity was observed in the anterolateral part of left hippocampus, in proximity to amygdala. Second, during the incidental recognition of famous faces (the gender classification task), there was increased activity in the left posterior MTL with focus in the perirhinal cortex. Our results suggest that the hippocampus may be centrally involved in the intentional retrieval of semantic memories while the perirhinal cortex is associated with the incidental recognition of semantic information.
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| 48. |
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| 49. |
- Engellau, Lena, et al.
(författare)
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Long-term results after endovascular repair of abdominal aortic aneurysms with the Stentor and Vanguard stent-graft.
- 2004
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 45:3, s. 275-283
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To present a single institution experience of long‐term results after endovascular repair of abdominal aortic aneurysms (AAA) with the Stentor and Vanguard stent‐grafts. Material and Methods: Twenty‐three patients (20 men, 3 women; mean age 68 years, range 53–81 years) were included in this prospective study. A first generation nitinol stent‐graft (Stentor™) was used in 12 patients and a second generation (Vanguard™) in 11 patients. Follow‐up was performed with magnetic resonance imaging (MRI) with contrast‐enhanced MR angiography (CE MRA) at 1, 6, and 12 months, and thereafter annually (median follow‐up 3 years; range 8 months to 8 years). A conventional radiograph of the abdomen was also performed. Before secondary intervention the findings on MRI with CE MRA were confirmed with spiral computed tomography (CT) and/or angiography (DSA). Results: Only one patient (4%) had no complication. Endoleak was found in 15 patients (65%), graft migration in 8 (35%), and graft deformation in 18 (78%). Secondary endovascular repair was required in 7 patients (30%) and 7 (30%) were converted to open repair. Conclusion: Complications with the Stentor and Vanguard stent‐grafts were common. Long‐term follow‐up of endovascularly repaired AAA is mandatory.
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| 50. |
- Engellau, Lena, et al.
(författare)
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Magnetic resonance imaging and MR angiography of endoluminally treated abdominal aortic aneurysms
- 1998
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Ingår i: European Journal of Vascular and Endovascular Surgery. - 1532-2165. ; 15:3, s. 212-219
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To evaluate magnetic resonance imaging (MRI) with gadolinium-based contrast medium-enhanced MR angiography (MRA) for the follow-up of endoluminally treated abdominal aortic aneurysms. DESIGN: MRI/MRA, angiography and computed tomography (CT) were performed 1 month after endoluminal stent-graft placement. MRI/MRA was repeated at 6 and 12 months and angiography and CT were added to confirm unexpected findings. MATERIALS: Fifteen male patients with endoluminally treated abdominal aortic aneurysms. METHODS: MRI with MRA, spiral CT with transverse images and angiography were performed. RESULTS: MRI/MRA demonstrated changes of stent-graft morphology, aortic neck- and aneurysmal diameter, stent-graft blood flow, stent-graft leakage, blood flow in lumbar arteries, intra-aneurysmal thrombus, periaortic inflammation and vertebral body infarction. For most of these features MRI/MRA provided more information than angiography and/or CT. MRI was the only method demonstrating thrombus reorganisation and vertebral body infarction. CONCLUSIONS: MRI with MRA provides the relevant information needed for follow-up of endoluminally treated abdominal aortic aneurysms (AAA). This may be the method of choice because of its use of contrast media with very low nephrotoxicity, lack of ionising radiation and non-invasiveness.
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