Dokumentåtgärder
Magnetic Resonance Imaging
Upp en nivåThe following CMIV projects conducts research related to Magnetic Resonance Imaging.
1H-MRS in ALS and Unverricht-Lundborgs disease
ALS and Unverricht Lundborg myoclonic epilepsy are two neurodegenerative diseases without curing treatment. Two pts with ALS and two with U-L are investigated with 1H-MRS of the white matter over a two year period in order to analyse the character of the neurodegenerative course. NAA, Cho, myo-Ins and Lac are analysed according to the LC model. Clinical status is checked and compared. Pharmacological intervention is tried.
3D and 4D Adaptive Filtering for Image Denoising and Patient Safety
The aim of this medical image science project is to increase patient safety in terms of improved image quality and reduced exposure to ionizing radiation in CT. The means to achieve these goals is to develop and evaluate an efficient adaptive filtering (denoising/image enhancement) method that fully explores true 3D and 4D image acquisition modes. Four-dimensional (4D) medical image data are captured as a time sequence of image volumes. During 4D image acquisition, a 3D image of the patient is recorded at regular time intervals. The resulting data will consequently have three spatial dimensions and one temporal dimension. Increasing the dimensionality of the data impose a major increase the computational demands. The initial linear filtering which is the cornerstone in all adaptive image enhancement algorithms increase exponentially with the dimensionality. On the other hand the potential gain in Signal to Noise Ratio (SNR) also increase exponentially with the dimensionality. This means that the same gain in noise reduction that can be attained by performing the adaptive filtering in 3D as opposed to 2D can be expected to occur once more by moving from 3D to 4D.
3D-4D Medical Image Enhancement using Filter Networks
Most signal processing tools, for feature extraction, image enhancement and visualization are still limited to 2D, while multi-dimensional imaging of the human body is clinical routine. The computational complexity significantly increases, when extending dimensionality beyond 2D. The need for efficient filtering on volumes and volume sequences is therefore increasing. This project focuses on efficient methods for local feature extraction and enhancement of multi-dimensional images. The fundamental approach is to find a methodology to achieve efficient implementations of filter networks for medical image processing of volumes and volume sequences.
A new perspective on selective attention: is there a link between the physiology and cognitive mechanisms of hearing?
What enables us to follow a voice in the presence of other voices? A number of psychological theories compete to give the best answer to this question. The debate mainly concerns where the filtering of the irrelevant material (i.e., in this case the voices we don’t wish to follow) takes place: Some suggest that the filtering takes place early (i.e., before the irrelevant material is processed) whereas others suggest that the filtering is late (i.e., after some processing). Our previous (psychological) research has repeatedly found a relationship between cognitive capacities and the capability to control the extent to which irrelevant sound is processed, and within the physiological/biological research tradition one has found outer hair cells to be involved in the filtering of irrelevant sound. In a series of experiments, the research project proposed here will juxtapose psychological and physiological/biological theories and methods to investigate whether there is a relation between cognitive capacities and the capability to control various stages of sound processing. The relationship would show that cognitive abilities modulate the filtering of irrelevant sound at various stages of the sound processing chain (i.e., the inner ear, the brainstem, and cortex). The project has consequences for theories of selective attention and it has its most prominent application in the understanding of hearing impairment.
Absolute Quantification of Multinuclear Magnetic Resonance Spectroscopy
The major aim of this project is in collaboration with several clinics to expand the scope of medical magnetic resonance methods of water to a large number of metabolites and other functional tissue properties in order to significantly enhance the level of todays applications of clinical MR. The work covers developing novel acquisition technologies and hardware, as well as clinical applications of quantitative molecular spectroscopy and imaging. A major long-term aim is to shift MR-applications from a qualitative to a quantitative mode.
Advanced signal processing methods for high quality funtional magnetic resonance imaging
Functional Magnetic Resonance Imaging (fMRI) is a tool for noninvasively exploring the functionality of the human brain. The method has already provided many insights to the function of the brain. Since examinations can be performed on widely available clinical MR scanners and without using exogenous contrast agents, the potential use for preoperative investigations and following up neurological diseases are important goals within reach. The proposed project aims at developing analysis methods that are able to extract relevant information from the large amount of data acquired in an fMRI examination. This includes many challenging problems such as compensating for patient motion, modeling brain hemodynamics, fusion between different MR images for neurological interpretation and efficient filtering approaches to locate active brain areas. To achieve the robustness required for routine clinical use of fMRI, advanced signal and image processing procedures that solve the above issues need to be developed and evaluated.
An uncertainty-aware visualization pipeline for volume rendering
Within Direct Volume Rendering (DVR) there is one important aspect of knowledge and data representation that has been largely overlooked - Uncertainty. In all measurement and simulations there are inherent inaccuracies and throughout the visualization pipeline additional uncertainties in processing, rendering and interaction are introduced. If these uncertainties are not conveyed the result may be misinterpretations and false conclusions. In medical visualization the problem is particularly pertinent with the hazards of wrong diagnosis and mistreatment of medical conditions. The overall goal in this project is: To develop an uncertainty aware real-time Direct Volume Rendering pipeline based on domain knowledge.
Application of novel image filters to MR image data
Background: Although time taken for completing MR exams has decreased substantially in recent past, it is still considerably longer than some other imaging examinations such as CT scanning. Radiologists have to manage a careful balance between examination duration and image quality. Image filters have been applied in past to CT, plain film radiography, and ultrasound. Purpose and scientific questions: The aim of our study is to assess if special 3D image filters can help quality of MR images compared to unprocessed and 2D filtered images. Another scientific question pertains to reduction of time required for performing MR examination with 3D filters. Most important variables: Image quality of MR images with and without application of the image filter will be compared by multiple independent radiologists. Assessment of image quality will include both the standard deviation of the MR signal as well as the subjective assessment of the image quality by multiple radiologists. Time saved with the use of 3D filters will be estimated for each subject. Advances in Knowledge and significance: Use of 3D filters for enhancing MR capabilities has not described before. Our study intends to determine if 3D filters for MR exams can help improve image quality and/or aid in reducing MR examination duration compared to use of either no filter or 2D filters. If found useful, the 3D filters will help us improve patient throughput in MRI and at the same time will enhance image quality of MR images.
Augmented Reality In the Operating Room (ARIOR)
To avoid postoperative complications at brain tumour surgery, the surgeon must visualise both the tumour and functional brain centres for, e.g., speech and motion. This project, representing image-guided surgery, aims at using augmented reality techniques for presenting preoperative Magnetic resonance imaging (MRI) data merged with the optical view of the patient. MRI images will be presented in the operating room with one or more of the following techniques: 1. Operating microscope 2. Video see-through micro-display 3. Hand-held devices 4. Projector-based augmented reality. The augmented reality image will contain MRI information superimposed on the optical image and will be deformed in real time as the brain is deformed during operation, using video angiography or ultrasound to follow the brain deformation. The demonstrator project, to be performed in collaboration by LiU’s Center for Medical Image Science and Visualization (CMIV), XMReality Research AB and clinically active neurosurgeons as well as experts in human-system interaction, comprises construction of a tool for this purpose and evaluation by laboratory tests where neurosurgeons will attempt to reach predefined anatomical targets with and without access to the novel technique. If successful, this project has the potential to reduce the rate of tumor recurrence as well as the risk of post-operative paresis or aphasia, thus reducing human suffering and society’s costs for medical care.
Biofunctionalised nanoparticles - new MRI contrast agents
Research within this project is based on the discovery of unique magnetic properties of nanosized materials. Gadolinium-containing nanoparticles can be used as tracers in molecular Magnetic Resonance Imaging (mMRI) for functional assessment of human tissue. These particles are designed for MRI applications, with high potential for microscopic imaging. The main advantages are the high contrast efficacy for each particle and the capacity to provide positive contrast, i.e. signal enhancement.
Cardiovascular blood flow assessment
The primary purpose of the cardiovascular system is to drive, control and maintain blood flow to all parts of the body. Despite the primacy of flow, cardiovascular diagnostics still rely almost exclusively on tools focused on morphological assessment. Powerful techniques emphasizing blood flow assessment are needed. Phase contrast magnetic resonance imaging (PC-MRI) allows flow quantification in three dimensions and in three directions. Recently, our group has presented a generalization of the PC-MRI technique, which utilizes not only the signal phase to quantify the mean velocity of a voxel, as in conventional velocity mapping, but also the signal magnitude to quantify the distribution of the velocities within the voxel. We will exploit this feature in order to develop methods for the assessment of wall shear stress, turbulent stresses, and pressure loss in both laminar and turbulent cardiovascular blood flow. Validation of these tools will be performed in phantom studies by comparison with laser Doppler anemometry and computational fluid dynamics simulations, in addition to in-vivo studies. The techniques developed thereby will initially be used to assess patients with aortic coarctation, prosthetic aortic valve, dilated cardiomyopathy, and mitral valve insufficiency.
Clinical Application of Synthetic MRI on Patients with Malignant Gliomas
Patients with malignant gliomas are treated with surgery, chemo- and radiotherapy and then followed with MRI-examinations to detect early signs of tumour recurrence. Almost 25% of patients react to the treatment with oedema and contrast-enhancement in the affected area of the brain, and this image is difficult to distinguish from tumour recurrence. Since the image is non-specific, radiologists in these cases look to more quantitative methods such as MR Spectroscopy and PET-CT, but there are still cases where it is unclear if the patient should be treated with further surgery or just followed with further imaging. Synthetic MRI is a quantitative MR-method that enables quantitative measurement of the tissue. If it is possible to find tumour specific quantitative values, it might be possible to distinguish tumour from treatment effects and thereby improving the diagnostic arsenal in these difficult cases.
Comparison of anal fistula treatment outcome – collagen plug vs advancement-flap (lambeau) surgery. A randomised prospective blinded multi-centre study
Perianal fistula is a common condition, with reported incidence of 5,6 pr 100.000 women and 12,3 pr 100.000 men and occurs most often between 20 – 40 years of age. The direct cause of the development of an anal fistula is often unclear but it commonly starts with an infected anal gland and may first present as a perianal abscess formation. Perianal fistulas may also arise as a complication in patients with Crohn´s disease. They seldom heal spontaneously or by medication and surgical intervention is often needed. Low trans sphincteric fistulas, involving less than 1/3 of the external sphincteric muscle, is often easily treated by fistulotomy with a high success-rate. High sphincteric fistulas still remain a challenge. Traditional surgical treatment can vary from long-term treatment with draining seton or instillation of fibrin glue, to major surgical debridement with extirpation of the fistula tract and a mucosal flap to cover the internal fistula opening (”advancement flap”) or other lambeau-techniques. All these techniques have disappointing success-rates. A new technique have been introduced were the fistula is treated with a bioabsorbable collagen plug (Cook Surgical, Inc., Bloomington, IN) and initial results are promising. The study is designed as a randomised prospective blinded multi centre trial and 148 patients will be included. Clinical examinations pre – and post operatively are supplemented with imaging techniques i.e. endo rectal ultrasound and pelvic MRI. In addition to the mandatory MRI sequences regulated in the study protocol two extra sequences, according to local clinical practise and including i. v. contrast, is added to the patients examined at CMIV The overall aim of the study is to evaluate if the anal plug technique is an alternative compared to the traditional advancement flap operation. From a visualization/ radiological point of view the aim is to evaluate the mandatory and added MR protocols with regard to diagnostic accuracy of anal fistulas, and compare it with the clinical, per operative and ultrasonography findings. Secondly, to apply and develop new visualization tools.
Determining Optimal non-invasive Parameters for the Prediction of Left vEntricular morphologic and functional Remodeling in Chronic Ischemic Patients (DOPPLER-CIP)
Coronary artery disease (CAD) remains the primary cause of cardiovascular morbidity and mortality in Europe. In current clinical practice, patients with chronic CAD are followed using non-invasive imaging methodologies for possible adverse morphologic remodelling and functional recovery of the myocardium before the decision for invasive examinations and treatments is taken. Technological developments have brought about several newer imaging methodologies (and associated parameters) that have shown accurate prognostic results under study conditions in selected patient populations. Each of these methodologies offers intrinsic advantages and disadvantages due to the physiologic processes it tries to assess, due to the technology it requires or due to its availability (often determined by its associated cost). However, to date, no large scale studies have made a direct comparison of the different methodologies towards predicting adverse morphologic remodelling or functional recovery of the myocardium after medical therapy. The lack of such information results in a sub-optimal use of the methodologies at hand. The aim of DOPPLER-CIP is therefore to conduct a multi-centre clinical study including about 1200 patients in order to determine the optimal prognostic parameters derived from (new) non-invasive imaging for a patient presenting with suspected chronic ischemic heart disease. The modality used to extract these parameters is of secondary importance. However, as both the accuracy and the cost related to extracting a particular parameter is modality-dependent, DOPPLER-CIP will also make a cost-effective analysis in order to determine which modality should preferentially be used to extract the clinically most relevant parameter. The study is financed by the European Union and is coordinated from Leuven, Belgium with cooperating centers in Linkoping, London, Madrid, Oslo, Pisa and Turku. Several add-on studies in Linköping will have access to this wealth of patient data for more in-depth analysis of wall motion and blood flow.
Development of functional Magnetic Resonance Imaging (fMRI) for clinical applications
Functional magnetic resonance imaging (fMRI) is a non-invasive method to study localisation of brain function. The method is based upon the increased blood flow that follows neuronal activity. Blood oxygen level dependent (BOLD) fMRI utilise the difference in magnetic properties between oxygenated and deoxygenated blood as image contrast. Research within fMRI has mainly been focused on method development and normal cognition. Today, there is a considerable interest in using fMRI as a clinical tool for presurgical mapping and studies of impaired brain function and rehabilitation. However, fMRI in clinical settings is a challenge. Patients may be affected by pain, anxiety, and cognitive impairments. These are conditions that might cause reduced task focusing, perception, and attention. Patient adapted tasks are therefore crucial for clinical fMRI.
Effect of reperfusion on infarct size and cardiac function evaluated with MRI and echocardiography - MrSTEMI
Mechanical opening of the infarct related artery (primary PCI) in patients with ST-elevation myocardial infarction (STEMI) seems to produce better results than iv thrombolysis. Our hypothesis is that primary PCI saves myocardium, that the size of myocardial damage is best quantified with contrast-enhanced MR (CEMR), that salvaged myocardium translates into better cardiac function, and that the time to opening of the artery is directly related to the size of the infarct. We will attempt to study the effect of the delay between the start of symptoms and the opening of the infarct related artery. The infarct risk area will be estimated from echocardiography performed in the cath lab during initiation of treatmentand expressed in terms of wall motion score index, WMSI. The final damage will be assessed from a comprehensive MR study with late enhancement performed at 6 weeks post PCI.
fMRI of deep tissue pain in generalised pain conditions
This project aims to elucidate pain processing mechanisms in patients with chronic widespread pain and compare the findings with those in healthy controls. The neural correlates of deep tissue pain are investigated by functional Magnetic Resonance Imaging (fMRI).
fMRI studies of meditation
Meditation is a conscious mental process that influences attention and emotional regulation. It has also been shown that meditation involves health-promoting benefits like stress reduction, decreased blood pressure, and higher pain threshold. However, the biological mechanisms behind the body’s response to meditation are poorly understood. Neuro-imaging is regarded as one of the most promising tools for investigations of the coupling between the mind and the body during meditation. Within this project the neural correlates to meditation are investigated by functional Magnetic Resonance Imaging (fMRI).
Functional MRI studies of normal and impaired language function
Language ability plays an important role when communicating with others. Before a-typical language activation can be detected in patient populations, normal language function has to be explored. In this project we intend to study the influence of performance and difficulty related language ability on cortical activation in healthy subjects and in patients with language disability.
Functioning and disability in adults after obstetric brachial plexus (OBP) injury - an fMRI study
In complicated deliveries, traction of the nerve plexus responsible for arm and hand sensibility and motor function can occur resulting in transient or permanent nerve dysfunction. This injury is referred to as brachial plexus (OBP) injury and occur in about 2-3% of all deliveries. In this project we intend to study the consequences of OBP on cortical activation in patients.
Dissertation by Daniel Forsberg
