Visualization and Image EnhancementUp one level
The following CMIV projects conducts research related to Visualization and Image Enhancement.
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.
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.
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.
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.
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.
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.
Automated Generation of Patient Specific Models for Visual and Haptic Simulation of Hip Fracture Surgery
The goal of this project is an auto-generated patient specific model for haptic and visual simulation of hip fracture surgery. Osteoporotic fractures constitute a problem of increasing clinical importance. A problem with the cervical type of hip fracture is the great risk of complications. A patient-specific simulation model would enable the surgeon to perform simulated surgery on the patient. Instead of discussing alternative techniques using plain X-ray films, the surgeon would have the chance to test several operative approaches, resulting in a safer and more rapid real operation. In addition, these models would be useful in the training of surgeons and development of new techniques. The first step in the generation of the model is segmentation of the bone in a CT-volume. Then, the local bone density will be estimated from the CT-data. The resulting information will then be converted to fit models suitable for visual and haptic simulation.
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.
Computer systems tailored for diagnostic tasks can help increase resource efficiency in the healthcare. With systems that help in classifying medical image data, the time spent on time-consuming manual tasks can be cut and diagnostic accuracy can be increased. The recent development of new imaging techniques and scanners, such as synthetic MR and dual-energy CT, has given rise to datasets that comprise of several measurements at a single spatio-temporal position. The added information presents new possibilities to extract relevant features from the data.
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.
The indication for surgery with STT - fusion includes Kienböck´s disease, STTarthrosis and radiocarpal instability combined with pain. Methods: 25 patients, 15 women and 10 men, underwent STT arthrodesis between January 2000 and June 2005. 15 patients suffered from arthrosis, 7 from Kienböck´s disease and 3 had pain combined with radiocarpal instability. Conventional X-ray was performed approxymately 10 weeks after surgery. A long term follow up is planned where the patients will be re-examined at a mean follow –up time of 35 months. Active range of motion (AROM) will be verified with a goniometer; grip strength measured with a JAMAR-Dynamometer II. The Key pressure grip measured with pinch gauge. Pain will be evaluated by a visual analogue scale (VAS) from zero to ten for stress and during resting conditions. We will use a Disabilities of the Arm, Shoulder and Hand questionnaire (DASH) to capture the patients´ upper-extremity function. Occupational conditions shall be evaluated. CT scan with 3D reformation will be used to evaluate degree of bone fusion, scafolunar angel and signs of arthrosis.
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).
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.
Synthetic MRI is the approach of rapid quantification of MRI parameters and the subsequent synthesis of a whole range of contrast images based on the quantified data. This implies that a single scan is sufficient to generate any conventional T1- or T2 weighted image. It is even possible to visualize far stronger, non-physical contrast such as tissue specific imaging. Application of Synthetic MRI might save up to a third of the patient examination time and will make MRI more reliable and quantitative. The project aims at the clinical implementation of the approach into the PACS system. The technique of rapid quantification is more or less mature but the general use of Synthetic MRI in daily clinic needs to be introduced and validated. In addition to the investigation of the quality of the resulting images the specification of the time-saving aspect will be important. Cardiac Late Enhancement is implemented first and the validation is on-going. Synthetic Brain imaging is implemented at the moment. Future directions will concern the liver.
The purpose of this prospective study is to assess if CT images acquired with less than 1 mSv can provide diagnostic information similar to that obtained with current standard of care CT scanning. In this study, we will assess if currently used filtered back projection (FBP) technique or newer full and hybrid iterative reconstruction techniques (IRT) can provide diagnostically acceptable CT images with less than 1 mSv radiation dose. We will enroll 100 adults each from CT of head, chest, abdomen-pelvis, heart. All examinations will be performed at CMIV using the dual-source CT there. The raw data from low dose acquisitions is reconstructed with different iterative reconstruction parameters. The resulting image series are compared with the standard-of-care CT images according to both objective and subjective parameters. The project is done in collaboration with Mannudeep Kalra MD PhD and former visiting researcher at CMIV, now at MGH and Harvard medical school, Boston, USA.
Magnetic resonance imaging of the biliary system - technical and clinical aspects of the acquisition and visualization
A project that aims at developing new methods to visualize the biliary system by combining specific contrast agents and modern visualization techniques.
The data sets produced by state-of-the-art medical imaging modalities can be extremely large, and there is a clear trend that they are rapidly increasing even further. Such data sets cannot be handled by traditional viewing systems. This project aims to develop new visualization and data management techniques that enables efficient human anlysis of large medical data sets in the clinical environment.
Contained Smart Folders:
- Extensions of Tensor Voting and Their Applications to Medical Image Analysis
- Many problems in medical image analysis have not completely been solved due to low resolution and noise present in the images. Using perception-based methods for this type of problems is promising given the largely reported success in computer vision applications in noisy conditions. One of the most versatile of these techniques is Tensor Voting, which is based on the propagation of local information encoded through tensors by means of perception-based rules. This method may potentially be beneficial for problems in medical images, such as blood vessel segmentation, detection of bifurcations, detection of separation points and vortices in blood flow, tractography, and detection of nodes in trabecular bone. However, important theoretical extensions of tensor voting are still required to tackle these problems using this approach. These extensions are not straightforward due to the inherent complexity of the theory of tensors and the difficulty of proposing efficient implementations. Therefore, the aims of this project are twofold: first, to propose efficient theoretical extensions of tensor voting for higher-order tensors, multi-scale image analysis, gray-scale-, vector-, and tensor-valued images. Second, to apply the proposed extensions of tensor voting to the specific applications of blood vessel segmentation, detection of bifurcations in blood vessels, detection of separation points and vortices in blood flow images, tractography, and detection of nodes in trabecular bone. Principal Investigator: Rodrigo Moreno. Grant: 800 kSEK / year. Project Duration: 01/01/2013 - 31/12/2015. Financial Body: VR - The Swedish Research Council.