A5040293704- Advanced MRI Techniques and Applications
- Advanced Neuroimaging Techniques and Applications
- Functional Brain Connectivity Studies
- Neural dynamics and brain function
- MRI in cancer diagnosis
- Traumatic Brain Injury Research
- Traumatic Brain Injury and Neurovascular Disturbances
- Neuroscience and Neuropharmacology Research
- Olfactory and Sensory Function Studies
- Photoreceptor and optogenetics research
- Research in Social Sciences
- Bone and Joint Diseases
- Fetal and Pediatric Neurological Disorders
- Cell Image Analysis Techniques
- Electron Spin Resonance Studies
- Epilepsy research and treatment
- Neonatal and fetal brain pathology
- Medical Imaging Techniques and Applications
- Multiple Sclerosis Research Studies
- Nuclear Structure and Function
- Elasticity and Material Modeling
- Pain Management and Treatment
- Glioma Diagnosis and Treatment
- Atomic and Subatomic Physics Research
- Transcranial Magnetic Stimulation Studies
University of Eastern Finland
2015-2025
Finland University
2020-2024
Oslo University Hospital
2012-2014
Resting-state functional magnetic resonance imaging (rsfMRI) is a translational method with great potential in several neurobiologic applications. Most preclinical rsfMRI studies are performed anesthetized animals, but the confounding effects of anesthesia on measured connectivity (FC) poorly understood. Therefore, we FC under six commonly used protocols and compared findings data obtained from awake rats. The results demonstrated that each protocol uniquely modulated FC. Connectivity...
Zero echo time (zero-TE) pulse sequences provide a quiet and artifact-free alternative to conventional functional magnetic resonance imaging (fMRI) sequences. The fast readouts (<1 ms) utilized in zero-TE fMRI produce an image contrast with negligible contributions from blood oxygenation level-dependent (BOLD) mechanisms, yet the is highly sensitive brain function. However, precise relationship between neuronal activity has not been determined. Therefore, we aimed derive function model...
Functional magnetic resonance imaging (fMRI) is a powerful noninvasive tool for studying spontaneous resting state functional connectivity (RSFC) in laboratory animals. Brain function can be significantly affected by generally used anesthetics, however, rendering the need awake imaging. Only few different animal habituation protocols have been presented, and there critical practical improved low-stress techniques. Here we demonstrate novel restraint approach rat RSFC studies. Our custom-made...
Diffusion tensor imaging (DTI) reveals microstructural features of grey and white matter non-invasively. The contrast produced by DTI, however, is not fully understood requires further validation. We used serial block-face scanning electron microscopy (SBEM) to acquire tissue metrics, i.e., anisotropy orientation, using three-dimensional Fourier transform-based (3D-FT) analysis, correlate with fractional orientation in DTI. SBEM produces high-resolution 3D data at the mesoscopic scale good...
Functional magnetic resonance imaging (fMRI) studies in animal models provide invaluable information regarding normal and abnormal brain function, especially when combined with complementary stimulation recording techniques. The echo planar (EPI) pulse sequence is the most common choice for fMRI investigations, but it has several shortcomings. EPI one of loudest sequences very prone to movement susceptibility-induced artefacts, making suboptimal awake imaging. Additionally, fast...
Abstract Biophysical modeling of diffusion MRI (dMRI) offers the exciting potential bridging gap between macroscopic resolution and microscopic cellular features, effectively turning scanner into a noninvasive in vivo microscope. In brain white matter, Standard Model (SM) interprets dMRI signal terms axon dispersion, intra- extra-axonal water fractions, diffusivities. However, for SM to be fully applicable correctly interpreted, it needs carefully evaluated using histology. Here, we perform...
Abstract Purpose Functional assessments of the central nervous system (CNS) are essential for many areas research. MRI (fMRI) typically targets either brain or spinal cord, but usually not both, due to obstacles associated with simultaneous image acquisitions from distant fields view (FOVs) conventional MRI. In this work, we establish a novel approach that enables artefact-free, quiet, fMRI both and avoiding need dynamic shimming procedures. Methods We utilized zero echo time (TE)...
Massively multidimensional diffusion-relaxation correlation MRI provides detailed information on tissue microstructure by analyzing water populations at a sub-voxel level. This method correlates frequency-dependent tensor-valued diffusion with longitudinal and transverse relaxation rates, generating nonparametric D ( ω )- R 1 - 2 distributions. Traditionally, distributions are separated using manual binning of the diffusivity anisotropy space to differentiate white matter (WM), gray (GM),...
Purpose To study the potential of diffusion tensor imaging (DTI) to serve as a biomarker for radiation‐induced brain injury during chemo‐radiotherapy (RT) treatment. Materials and Methods Serial DTI data were collected from 18 high‐grade glioma (HGG) patients undergoing RT 7 healthy controls. Changes across time in mean, standard deviation (SD), skewness, kurtosis fractional anisotropy (FA), mean diffusivity (MD), axial (λ ), transversal t ) within normal‐appearing white matter (NAWM)...
Isoflurane, the most commonly used preclinical anesthetic, induces brain plasticity and long-term cellular molecular changes leading to behavioral and/or cognitive consequences. These are likely associated with network-level in function. To elucidate mechanisms underlying effects of isoflurane, we investigated influence a single isoflurane exposure on functional connectivity, electrical activity, gene expression. Male Wistar rats (n = 22) were exposed 1.8% for 3 h. Control spent h same room...
Abstract Functional MRI (fMRI) is a flexible tool for sensory perception studies in animal models. However, fMRI are generally performed under anesthesia. Unfortunately, anesthesia affects brain function and processing, complicating the interpretation of findings. Since there growing need protocols applicable awake animals, we optimized zero echo time Multi-Band Sweep Imaging with Fourier Transformation (MB-SWIFT) approach imaging mice. We implemented 14-day habituation protocol that...
Purpose To evaluate the importance of T2*-effects on arterial input function (AIF) and resulting dynamic parameter estimation in contrast-enhanced (DCE) MRI high-grade gliomas. Materials Methods Seven patients with gliomas were imaged total 50 times using a double-echo DCE sequence. Kinetic analysis extended Tofts model was performed AIFs without correction for T2*-effects, estimates transfer constant (Ktrans), blood plasma volume (vp), rate (kep) compared. Numerical simulations done...
To investigate the effect of variations in temporal resolution and total measurement times on estimations kinetic parameters derived from dynamic contrast-enhanced (DCE) MRI patients with high-grade gliomas (HGGs).DCE-MRI high (dynamic sampling time (T(s)) = 2.1 s 3.4 s) (T(acq)) 5.2 min was acquired 101 examinations 15 patients. Using modified Tofts model K(trans), k(ep) v(e) v(p) were estimated. The effects increasing T(s) reducing T(acq) estimated through down-sampling data truncation,...
Sleep is essential for nervous system functioning and sleep disorders are associated with several neurodegenerative diseases. However, the macroscale connectivity changes in brain networking during different states poorly understood. One of hindering factors difficulty to combine functional investigation methods spontaneously sleeping animals, which prevents use numerous preclinical animal models. Recent studies, however, have implicated that urethane anesthesia can uniquely induce...
Simultaneous EEG-fMRI is a valuable tool in the clinic as it provides excellent temporal and spatial information about normal diseased brain function. In pre-clinical research with small rodents, obtaining simultaneous longitudinal studies faces number of challenges, including issues related to magnetic susceptibility artifacts.Here, we demonstrate method for permanent MRI RF-coil EEG electrode implantation rats that suitable long-term chronic follow-up both stimulus resting-state fMRI...
Mild traumatic brain injury (mTBI) is the most common form of TBI with 10–25% patients experiencing long-lasting symptoms. The potential diffusion tensor imaging (DTI) for evaluating microstructural damage after widely recognized, but interpretation DTI changes and their relationship underlying tissue unclear. We studied how both axonal gliosis contribute to alterations mTBI. induced mTBI using lateral fluid percussion (LFP) model in adult male Sprague Dawley rats scanned them at 3 28 d...
Purpose Anesthesia is a major confounding factor in functional MRI (fMRI) experiments attributed to its effects on brain function. Recent evidence suggests that parameters obtained with resting‐state fMRI (rs‐fMRI) are coupled anesthetic depth. Therefore, we investigated whether rs‐fMRI, such as connectivity (FC), also directly related blood‐oxygen‐level–dependent (BOLD) responses. Methods A simple rs‐fMRI protocol was implemented pharmacological study evaluate the coupling between...
To evaluate and quantify a scheme for correcting susceptibility artifacts in spin-echo echo-planar-imaging-based dynamic contrast (DSC) perfusion MRI of high-grade gliomas at 3 Tesla.Sixteen patients with total 78 scans were studied. DSC-MRI images corrected using displacement map generated from opposite phase-encoding polarity images. Two methods used quantification the correction: (i) linear regression pixel-by-pixel comparisons, performed both globally relative to anterior posterior...
Electrical epidural spinal cord stimulation (SCS) is used as a treatment for chronic pain well to partially restore motor function after injury. Monitoring the activity during SCS with fMRI could provide important and objective measures of integrative responses treatment. Unfortunately, severely challenged by motion susceptibility artifacts induced implanted electrode bones. This pilot study introduces multi-band sweep imaging Fourier transformation (MB-SWIFT) technique in rats. Given close...
Our study investigates the potential of diffusion MRI (dMRI), including tensor imaging (DTI), fixel-based analysis (FBA) and neurite orientation dispersion density (NODDI), to detect microstructural tissue abnormalities in rats after mild traumatic brain injury (mTBI). The brains sham-operated mTBI 35 days lateral fluid percussion were imaged ex vivo a 11.7-T scanner. Voxel-based analyses DTI-, fixel- NODDI-based metrics detected extensive changes directly affected areas close primary...