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Elna-Marie Larsson

Publications and source records attributed to Elna-Marie Larsson.

16 recordsLinked to original sources
PubMed2006

Calculation of cerebral perfusion parameters using regional arterial input functions identified by factor analysis.

PURPOSE: To calculate regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and regional mean transit time (rMTT) accurately, an arterial input function (AIF) is required. In this study we identified a number of AIFs using factor analysis of dynamic studies (FADS), and performed the cerebral perfusion calculation pixel by pixel using the AIF that was located geometrically closest to a certain voxel. MATERIALS AND METHODS: To verify the robustness of the method, simulated images were generated in which dispersion or delay was added in some arteries and in the corresponding cerebral gray matter (GM), white matter (WM), and ischemic tissue. Thereafter, AIFs were determined using the FADS method and simulations were performed using different signal-to-noise ratios (SNRs). Simulations were also carried out using an AIF from a single pixel that was manually selected. In vivo results were obtained from normal volunteers and patients. RESULTS: The FADS method reduced the underestimation of rCBF due to dispersion or delay that often occurs when only one AIF represents the entire brain. CONCLUSION: This study indicates that the use of FADS and the nearest-AIF method is preferable to manual selection of one single AIF.

Adult↗
PubMed2006

It's like being in another world--patients' lived experience of magnetic resonance imaging.

AIM: The aim of this study was to illuminate patients' lived experience during magnetic resonance imaging. BACKGROUND: Magnetic resonance imaging has increased in importance since the early 1980s and is today a common useful diagnostic tool. Although magnetic resonance imaging are non-invasive and considered painless, many patients experience anxiety, sometimes so strong that the scan has to be terminated. DESIGN AND METHODS: The study had an inductive design and a hermeneutic phenomenological methodology was used. RESULTS: The essential theme of going through magnetic resonance imaging was a feeling of being in another world. The strange environment and isolation inside the scanner made the participants' experiences unusual, with varying degrees of difficulty dealing with it. Being in the other world caused a threat to the participants' self-control. There was a relation between threat to self-control, effort and need for support in the sense that the magnitude of threat to self-control had an impact on the effort it took to handle the situation and on the need for support, and conversely that the support received could affect the effort and threat to self-control. CONCLUSIONS: The study shows that the information received and the interaction between patients and staff have a significant influence on patients' lived experiences. The individual experience of threat to self-control requires the need for support to be individualized and care need to be adjusted for each patient.

Adaptation, Psychological↗
PubMed2006

Spontaneous intracranial hypotension resulting in coma: case report.

OBJECTIVE: Spontaneous intracranial hypotension is a potentially severe condition characterized by a distinct clinical picture caused by low cerebrospinal fluid pressure. Although coma has been reported previously as a presentation of this condition, this is the first report in which misdiagnosis of this condition and unwarranted surgery led to coma. CLINICAL PRESENTATION: A 62-year-old man presented with a history of headache, and cranial magnetic resonance imaging showed bilateral chronic subdural hematomas. After evacuation of the hematoma, the patient's condition deteriorated into a state of profound depression of consciousness. Repeated cranial computed tomographic scans showed intracranial air, and intracranial pressure monitoring showed negative recording. Spinal magnetic resonance imaging demonstrated epidural cerebrospinal fluid leaks at the middle and lower thoracic levels. INTERVENTION: Epidural blood patch resulted in almost immediate improvement in the patient's condition, and he was fully awake 24 hours later. CONCLUSION: This case report expands the presently known clinical spectrum of this uncommon and generally benign illness.

Blood Patch, Epidural↗
PubMed2005

fMRI activity in the medial temporal lobe during famous face processing.

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.

Adult↗
PubMed2005

Predicting the outcome of optic neuritis: evaluation of risk factors after 30 years of follow-up.

BACKGROUND: Multiple sclerosis (MS) is a common disease with considerable risk for disability. Optic neuritis (ON) is a common first symptom of MS but it can also remain an isolated episode. Therefore, predicting the outcome of ON has gained in importance, particularly in light of current discussions of early disease modifying treatments in individuals at risk of developing MS. We reported previously on our cohort of 86 patients with acute monosymptomatic unilateral ON of whom 33 had progressed to MS after up to 18 years. Three patients had died. The present study extends the observation period to 31 years. METHODS: Patients were followed for up to 31 years or until a diagnosis of MS was made. Cerebrospinal fluid (CSF) was examined at onset. HLA class I and II antigens were determined. Magnetic Resonance Imaging (MRI) was performed during follow up. FINDINGS: Only one of 50 patients at risk developed clinical manifestations of MS during the extended follow up period. The estimated 15-year-risk of MS was 40 % (confidence interval [CI] 31%-52%). Most cases, 20 of 34 or 60%, occurred within three years. Among factors present at onset, CSF with mononuclear pleocytosis and/or oligoclonal Ig increased the risk for subsequent MS significantly, 49% (CI 38%-65%) compared with 23 % (CI 12%-44%) for those with normal CSF, p=0.02. Younger patients and those with winter onset also had greater risk. Recurrence of ON similarly elevated the risk significantly, p<0.001. After 19-31 years MRI lesions suggestive of demyelinating disease were detected in 20 of 30 individuals although no clinical manifestations of MS had occurred. CONCLUSION: The risk of MS in this large population-based prospective ON patient series was 40% and significantly higher in those with inflammatory CSF abnormalities at onset. Clinically silent MRI lesions suggestive of MS were detected in a majority of those with "ON-only". This finding should be taken into account when discussing prognosis and early intervention in patients with clinically isolated ON.

Age Factors↗
PubMed2005

Comparison of contrast agents with high molarity and with weak protein binding in cerebral perfusion imaging at 3 T.

PURPOSE: To examine and compare properties of high-molarity contrast agent gadobutrol (Gadovist) and weakly protein-binding agent gadobenate-dimeglumine (MultiHance in dynamic susceptibility contrast (DSC) perfusion imaging at 3 T. MATERIALS AND METHODS: Sixteen healthy volunteers underwent three separate examinations with contrast agent doses of 0.1 and 0.2 mmol/kg body weight (bw) gadobutrol and 0.1 mmol/kg bw gadobenate-dimeglumine. Maps of relative regional cerebral blood volume (rCBV) and blood flow (rCBF) were calculated using deconvolution based on singular value decomposition. Signal and concentration time curves, the concentration-to-noise ratio (SNR(c)), and gray matter (GM)-to-white matter (WM) rCBV and rCBF contrast and ratios were evaluated in a region of interest (ROI)-based analysis. Image quality of calculated parametric maps was assessed in direct visual comparison and with respect to suitability for diagnostic purposes. RESULTS: The contrast agents displayed very similar results in the 0.1 mmol/kg examinations, both with respect to the quantitative evaluation parameters and in the qualitative assessment of the calculated parametric maps. Maps from 0.2 mmol/kg examinations were rated as being superior in quality, but with respect to diagnostic suitability all contrast agents and doses yielded images of sufficient quality. CONCLUSION: At 3 T, a gadobutrol or gadobenate-dimeglumine dose of 0.1 mmol/kg is sufficient for DSC magnetic resonance imaging (MRI) perfusion assessment. At the used small injection volumes, the tissue concentration curve was determined only by the gadolinium (Gd) dosage in mmol/kg, and the T2* relaxation effects of the two agents can be considered to be nearly identical in the applied gradient-echo (GRE) sequence.

Adult↗
PubMed2004

Acute improvement of contralateral hand function after deafferentation.

To study cortical reorganisation after acute hand deafferentation, we investigated 10 experimental subjects and 10 controls for function in the left hand, before, during and after tourniquet induced anaesthesia of the right hand. fMRI was performed in three experimental subjects. Right hand anaesthesia resulted in rapid significant improvement in grip strength, tactile discrimination and sensibility in the left hand. Tactile discrimination and grip strength improvements lasted at least 15 mins after anaesthesia. fMRI showed increased activation in the right primary motor cortex after anaesthesia. We conclude that tourniquet induced anaesthesia is an easy way to induce rapid and significant improvement in contralateral hand function. This finding may have a potential clinical application for evolving sensory relearning strategies after nerve repair.

Adult↗
PubMed2004

Fingersomatotopy in area 3b: an fMRI-study.

BACKGROUND: The primary sensory cortex (S1) in the postcentral gyrus is comprised of four areas that each contain a body map, where the representation of the hand is located with the thumb most laterally, anteriorly and inferiorly and the little finger most medially, posteriorly and superiorly. Previous studies on somatotopy using functional MRI have either used low field strength, have included a small number of subjects or failed to attribute activations to any area within S1. In the present study we included twenty subjects, who were investigated at 3 Tesla (T). We focused specifically on Brodmann area 3b, which neurons have discrete receptive fields with a potentially more clearcut somatotopic organisation. The spatial distribution for all fingers' peak activation was determined and group as well as individual analysis was performed. RESULTS: Activation maps from 18 subjects were of adequate quality; in 17 subjects activations were present for all fingers and these data were further analysed. In the group analysis the thumb was located most laterally, anteriorly and inferiorly with the other fingers sequentially positioned more medially, posteriorly and superiorly. At the individual level this somatotopic relationship was present for the thumb and little finger, with a higher variability for the fingers in between. The Euclidian distance between the first and fifth finger was 17.2 mm, between the first and second finger 10.6 mm and between the remaining fingers on average 6.3 mm. CONCLUSION: Results from the group analysis, that is both the location of the fingers and the Euclidian distances, are well comparable to results from previous studies using a wide range of modalities. On the subject level the spatial localisation of the fingers showed a less stringent somatotopic order so that the location of a finger in a single subject cannot be predicted from the group result.

Adult↗
PubMed2004

Familial presenile dementia with bitemporal atrophy.

This study describes the clinical, neuropsychological, neuroimaging and genetic characteristics in two generations of a Swedish family affected by presenile dementia. The pedigree includes 5 cases (mother and 4 of 5 children) of progressive dementia with onset between 54 and 62 years. The clinical picture is characterized by insidious onset and progressive decline in episodic memory without spatial impairment or dyspraxia, followed by changes in personality and behaviour, with signs of disinhibition, irritability, impulsivity and loss of social awareness. Three siblings, examined after 10 years of duration, showed moderate language deficits but preserved spatial function and praxis. CT and MRI showed progressive bilateral temporal atrophy and moderate frontal white matter changes. Regional cerebral blood flow measurements showed hypoperfusion in temporal areas bilaterally. Quantitative EEG was normal within 5 years after symptom onset and thereafter showed a moderate increase in relative theta power. Sequencing of the tau gene (chromosome 17) revealed the previously described R406W mutation in exon 13 as a likely cause of the disease. This mutation was identified in all affected cases. The clinical picture of this family shows striking similarities not only to frontotemporal dementia but also to Alzheimer's disease.

Alzheimer Disease↗
PubMed2004

MRI with diffusion tensor imaging post-mortem at 3.0 T in a patient with frontotemporal dementia.

The formalin-fixed brain of a patient with clinically diagnosed frontotemporal dementia (FTD) was examined post-mortem using magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI) at 3.0 T. Frontotemporal atrophy as well as bilateral frontal white matter abnormalities were seen. The white matter changes were slightly more extensive on DTI than on conventional MRI. Correlation with histopathology of the corresponding regions revealed typical frontal lobe degeneration of non-Alzheimer type, with mild frontotemporal degeneration in the outer cortical layers and a moderate frontal white matter gliosis with demyelination. Post-mortem MRI/DTI with histopathologic correlation will enhance our understanding of the basis of white matter changes observed in dementia patients and may improve the in vivo MRI/DTI diagnostic assessment in FTD.

Aged↗
PubMed2003

MR venography using an intravascular contrast agent: results from a multicenter phase 2 study of dosage.

OBJECTIVE: The objective of this study was to determine the optimal dose of the iron oxide contrast agent feruglose for contrast-enhanced MR venography of the abdominopelvic and lower extremity veins and to evaluate its safety and tolerability in patients with deep venous thrombosis. SUBJECTS AND METHODS: We enrolled in our study a total of 45 patients at six centers who had lower extremity deep venous thrombosis documented on radiographic venography. Forty-four patients received the study drug; 39 completed the study. Each patient received three sequential IV injections of feruglose at doses of 0.75, 1.25, and 3.0 mg Fe/kg body weight. MR venography at 1.5 T was repeated at three levels after each dose. Safety was evaluated. RESULTS: The agreement between contrast-enhanced MR venography and radiographic venography with regard to deep venous thrombosis above the knee was zero at the lowest dose (0.75 mg Fe/kg body weight), 43% at the dose 2.0 mg Fe/kg body weight, and 49% at the dose 5.0 mg Fe/kg body weight. No significant difference was seen between the two highest doses. The highest cumulative dose provided the greatest diagnostic usefulness score. No serious adverse events occurred. CONCLUSION: The two highest doses of feruglose showed the best agreement between contrast-enhanced MR venography and radiographic venography for deep venous thrombosis above the knee. The safety and tolerability of feruglose were confirmed.

Adult↗
PubMed2002

Collateral flow in coarctation of the aorta with magnetic resonance velocity mapping: correlation to morphological imaging of collateral vessels.

PURPOSE: To correlate quantification of collateral flow in aortic coarctation with the morphological visualization of the collateral vessels and to compare different approaches to measurement of collateral flow. MATERIALS AND METHODS: Thirteen children with coarctation were examined with T1-weighted spin-echo (T1-W SE) imaging and 3D contrast-enhanced magnetic resonance angiography (MRA). MR velocity mapping was performed at four levels in the descending aorta. RESULTS: The flow immediately above and below the coarctation did not differ significantly. Measuring within the coarctation resulted in flow overestimation. The increase of flow from proximal to distal aorta was 12 +/- 21% in patients with no or uncertain collaterals and 69 +/- 55% in patients with pronounced collaterals. Spin-echo images and MRA were comparable in visualizing collateral vessels. The visual estimation of collaterals correlated reasonably well with flow quantification MR velocity mapping. CONCLUSION: Collateral flow assessment with MR velocity mapping is an accurate technique for evaluating the hemodynamic importance of a coarctation and is recommended if abundant collaterals are not visualized with spin echo or MRA.

Aortic Coarctation↗
PubMedDate not supplied

[3 Tesla magnetic resonance imaging of the brain. Better morphological and functional images with higher magnetic field strength].

3T MRI offers improved morphological and functional studies of the brain compared with the more commonly used field strength 1.5T. Clinical 3T MRI of the brain is beneficial for high resolution morphological imaging, MR angiography, diffusion-MRI including diffusion tensor imaging, perfusion-MRI, functional MRI (fMRI), and MR spectroscopy. The performance is enhanced by the combination with powerful magnetic field gradients.

Brain↗