Data Acquisition and ReconstructionUpp en nivå
The following CMIV projects conducts research related to the Data Acquisition and Reconstruction.
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.
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.
Until now, scoliosis has been diagnosed with a standing X-ray to determine the size of the deformity in the frontal plane, the Cobb angle. New technology based on low-dose CT makes it possible to reconstruct the deformity in 3D. This provides better possibilities to assess the vertebral rotation. The rotation seems to be of greater importance than previously thought. The project consists of the following four studies: 1. Investigation of the correlation between the size of the deformity on pictures from standing X-ray and supine computer tomography. The deformity increases when put under pressure. 2. Development and evaluation of a new software/method to take measurements and do calculations in 3D-reconstructions of scoliosis based on low-dose CT. The software will be developed in collaboration with Sectra. 3. Investigation of the correlation between the rotation of the vertebrae and the size of the deformity. The correlation will be investigated both pre- and post-operatively. 4. Comparison of how well two different surgical approaches work to correct the deformity in scoliosis. The project has natural ties to CMIV. The low-dose CT examinations are performed at CMIV and require optimal use of the new CT equipment there and the new software will be developed and evaluated in collaboration with Sectra. It also seems very natural to work with CMIV because of their great knowledge in 3D-reconstructions from different radiological examinations. Moreover, collaboration with researchers in the technical field will also most likely be beneficial for the project.
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.
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.
Application of novel iterative reconstruction algorithms (IRA) and noise reduction filters (NRF) for reducing CT radiation dose
Background: Worldwide there have been concerns about increased risk of cancer with radiation dose from CT scanning. Reduction of radiation dose from CT will also decrease the risk of radiation induced cancer. Therefore, several techniques such as automatic exposure control techniques, and bow tie filters have been developed and assessed to reduce radiation dose with CT. Despite these developments, the radiation dose with CT scanning continues to increase each year as number of CT examinations performed each year keeps on increasing. Purpose and scientific questions: The aim of our study is to acquire low radiation dose CT data and assess if iterative reconstruction algorithms (IRA) and advanced noise reduction filters (ANRF) techniques can help improve image quality and acceptability of low dose CT images. Most important variables: CMIV has recently obtained access to novel IRA and NRF techniques for improving image quality of low dose CT images. Dose reduced CT images typically have higher noise and lower signal to noise ratio. We believe that IRA and ANRF, which work in different data domains to improve image quality and enable acquisition of low radiation dose CT. After acquisition of CT image data at different lower dose levels, we will independently process the data with IRA and ANRF and see if there is an improvement in the image quality with these techniques. The intent will be to see if variables such as image noise, artifacts, image contrast, sharpness as well as lesion conspicuity on low dose post processed images are similar to unprocessed higher dose images. In addition, quantitative measures of image quality such as quantitative image noise, and contrast to noise ratio will be performed. Advances in Knowledge and significance: This study will give information on use of IRA and ANRF for reducing radiation dose to patients undergoing CT scanning and quantify need and advantage of IRA and ANRF over unprocessed CT images reconstructed using conventional filtered back projection technique. If found useful, these techniques will help cut the radiation dose without sacrificing image quality, a result that may help save radiation dose from CT scanning.
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.
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.
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.
Cone-beam CT using 2D detectors and 3D reconstruction algorithms has recently become commercially available for dental use and offers isotropic, high resolution. This project aims at evaluating this technique for clinical purposes in odontological radiology and studying skeletal microstructure. In particular, imaging of the temporal bone will be evaluated.
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.
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.
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).
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.
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.
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, cardiac diagnostics still rely almost exclusively on tools focused on morphological assessment. The objective of the HEART4FLOW project is to develop the next generation of methods for the non-invasive quantitative assessment of cardiac diseases and therapies by focusing on blood flow dynamics, with the goals of earlier and more accurate detection and improved management of cardiac diseases.
Histological and functional effects of aortic valve disease on left ventricular function prior to and after surgical intervention
This research project aims to apply, modify and validate cardiac magnetic resonance imaging (cMRI) as a diagnostic tool for identification of fibrotic changes in the heart muscle due to pressure and volume overload caused by aortic valve disease. Furthermore, we hypothesize that these tissue changes (the amount and the location of the fibrotic tissue) can be connected to the impairment of the left ventricular function (LVF) in the advanced natural history of aortic valve disease. By using cMRI we hope to gain further information by non-invasive means on whether this impairment is reversible following surgical therapy. In addition to histological and functional studies at rest we plan to survey the anaerobe (physical) capacity of the study persons by performing cardiopulmonary exercise testing pre- and postoperatively and study the relationship between physical performance capacity and left ventricular function (LVF).
Identification of cognitive processes with fMRI and auditory stimulation in hearing impaired with and without hearing aids
Within this project, we will investigate the neural correlates of cognitive processes during speech intelligibility in noise. The data will be analysed according to the working memory framework of Ease of Language Understanding (ELU) developed by Rönnberg and colleagues. This model states that the demands on cognitive (‘explicit’) processing increase when speech comprehension is impaired by background noise, hearing loss, or altered by the type of signal processing in the hearing instrument.
We will develop non-invasive methods for measurements of human Brown Adipose Tissue (hBAT) tissue mass and activity. Our hypothesis is that this can be achieved by means of magnetic resonance imaging (MRI) and dual energy computed tomography (DECT). Initial studies will be performed using rodents (mice and rats). An important next step will be to use human postmortem material, which will enable us to confirm the true identity of hBAT images by genetic and morphological analysis of biopsies. The validated methods will then be used for in vivo studies. We will use phase sensitive reconstruction of complex images acquired with the water and fat resonance in- and out- of-phase, so called Dixon imaging.