In Vivo Molecular MRI of ICAM-1 Expression on Endothelium and Leukocytes from Subacute to Chronic Stages After Experimental Stroke.

Molecular MRI allows in vivo detection of vascular cell adhesion molecules expressed on inflamed endothelium, which enables detection of specific targets for anti-neuroinflammatory treatment. We explored to what extent MR contrast agent targeted to intercellular adhesion molecule-1 (ICAM-1) could detect endothelial- and leukocyte-associated ICAM-1 expression at different stages after experimental stroke. Furthermore, we assessed potential interfering effects of ICAM-1-targeted contrast agent on post-stroke lesion growth.

Development of a high resolution MRI intracranial atherosclerosis imaging phantom.

Background And Purpose: Currently, there is neither a standard protocol for vessel wall MR imaging of intracranial atherosclerotic disease (ICAD) nor a gold standard phantom to compare MR sequences. In this study, a plaque phantom is developed and characterized that provides a platform for establishing a uniform imaging approach for ICAD.

Materials And Methods: A patient specific injection mold was 3D printed to construct a geometrically accurate ICAD phantom.

Reduced Patient Radiation Exposure during Neurodiagnostic and Interventional X-Ray Angiography with a New Imaging Platform.

Background And Purpose: Advancements in medical device and imaging technology as well as accruing clinical evidence have accelerated the growth of the endovascular treatment of cerebrovascular diseases. However, the augmented role of these procedures raises concerns about the radiation dose to patients and operators. We evaluated patient doses from an x-ray imaging platform with radiation dose-reduction technology, which combined image noise reduction, motion correction, and contrast-dependent temporal averaging with optimized x-ray exposure settings.

In situ tissue engineering: endothelial growth patterns as a function of flow diverter design.

Background: Vascular remodeling in response to implantation of a tissue engineering scaffold such as a flow diverter (FD) leads to the cure of intracranial aneurysms. We hypothesize that the vascular response is dependent on FD design, and CD34+ progenitor cells play an important role in the endothelialization of the implant.

Methods: Sixteen rabbit aneurysms were randomly treated with two different single-layer braided FDs made of cobalt-chrome alloys.

Intracochlear Position of Cochlear Implants Determined Using CT Scanning versus Fitting Levels: Higher Threshold Levels at Basal Turn.

Objectives: In this study, the effects of the intracochlear position of cochlear implants on the clinical fitting levels were analyzed.

Design: A total of 130 adult subjects who used a CII/HiRes 90K cochlear implant with a HiFocus 1/1J electrode were included in the study. The insertion angle and the distance to the modiolus of each electrode contact were determined using high-resolution CT scanning.

Quantitative assessment of device-clot interaction for stent retriever thrombectomy.

Purpose: Rapid revascularization in emergent large vessel occlusion with endovascular embolectomy has proven clinical benefit. We sought to measure device-clot interaction as a potential mechanism for efficient embolectomy.

Methods: Two different radiopaque clot models were injected to create a middle cerebral artery occlusion in a patient-specific vascular phantom.

Development of Insertion Models Predicting Cochlear Implant Electrode Position.

Objectives: To assess the possibility to define a preferable range for electrode array insertion depth and surgical insertion distance for which frequency mismatch is minimalized. To develop a surgical insertion guidance tool by which a preferred target angle can be attained using preoperative available anatomical data and surgically controllable insertion distance.

Design: Multiplanar reconstructions of pre- and post-operative CT scans were evaluated in a population of 336 patients implanted with the CII HiFocus1 or HiFocus1J implant (26 bilaterally implantees included).

Imaging Inflammation in Cerebrovascular Disease.

Imaging inflammation in large intracranial artery pathology may play an important role in the diagnosis of and risk stratification for a variety of cerebrovascular diseases. Looking beyond the lumen has already generated widespread excitement in the stroke community, and the potential to unveil molecular processes in the vessel wall is a natural evolution to develop a more comprehensive understanding of the pathogenesis of diseases, such as ICAD and brain aneurysms.

Grading of Regional Apposition after Flow-Diverter Treatment (GRAFT): a comparative evaluation of VasoCT and intravascular OCT.

Background: Poor vessel wall apposition of flow diverter (FD) stents poses risks for stroke-related complications when treating intracranial aneurysms, necessitating long-term surveillance imaging. To facilitate quantitative evaluation of deployed devices, a novel algorithm is presented that generates intuitive two-dimensional representations of wall apposition from either high-resolution contrast-enhanced cone-beam CT (VasoCT) or intravascular optical coherence tomography (OCT) images.

Methods: VasoCT and OCT images were obtained after FD implant (n=8 aneurysms) in an experimental sidewall aneurysm model in canines.

Altered contralateral sensorimotor system organization after experimental hemispherectomy: a structural and functional connectivity study.

Hemispherectomy is often followed by remarkable recovery of cognitive and motor functions. This reflects plastic capacities of the remaining hemisphere, involving large-scale structural and functional adaptations. Better understanding of these adaptations may (1) provide new insights in the neuronal configuration and rewiring that underlies sensorimotor outcome restoration, and (2) guide development of rehabilitation strategies to enhance recovery after hemispheric lesioning.

Effects of long-term methylphenidate treatment in adolescent and adult rats on hippocampal shape, functional connectivity and adult neurogenesis.

Methylphenidate (MPH) is a widely prescribed stimulant drug for the treatment of attention deficit hyperactivity disorder (ADHD) in children and adolescents. Its use in this age group raises concerns regarding the potential interference with ongoing neurodevelopmental processes. Particularly the hippocampus is a highly plastic brain region that continues to develop postnatally and is involved in cognition and emotional behavior, functions known to be affected by MPH.

The influence of cochlear implant electrode position on performance.

Objectives: To study the relation between variables related to cochlear implant electrode position and speech perception performance scores in a large patient population.

Design: The study sample consisted of 203 patients implanted with a CII or HiRes90K implant with a HiFocus 1 or 1J electrode of Advanced Bionics. Phoneme and word score averages for the 1- and 2-year follow-up were calculated for 41 prelingually deaf and 162 postlingually deaf patients.

Stress-induced alterations in large-scale functional networks of the rodent brain.

Stress-related psychopathology is associated with altered functioning of large-scale brain networks. Animal research into chronic stress, one of the most prominent environmental risk factors for development of psychopathology, has revealed molecular and cellular mechanisms potentially contributing to human mental disease. However, so far, these studies have not addressed the system-level changes in extended brain networks, thought to critically contribute to mental disorders.

Effects of transient unilateral functional brain disruption on global neural network status in rats: a methods paper.

Permanent focal brain damage can have critical effects on the function of nearby as well as remote brain regions. However, the effects of transient disturbances on global brain function are largely unknown. Our goal was to develop an experimental in vivo model to map the impact of transient functional brain impairment on large-scale neural networks in the absence of structural damage.

Diversity in cochlear morphology and its influence on cochlear implant electrode position.

Objectives: To define a minimal set of descriptive parameters for cochlear morphology and study its influence on the cochlear implant electrode position in relation to surgical insertion distance.

Design: Cochlear morphology and electrode position were analyzed using multiplanar reconstructions of the pre- and postoperative CT scans in a population of 336 patients (including 26 bilaterally implanted ones) with a CII HiFocus1 or HiRes90K HiFocus1J implant. Variations in cochlear diameter and cochlear canal size were analyzed.

Experimental focal neocortical epilepsy is associated with reduced white matter volume growth: results from multiparametric MRI analysis.

Focal epilepsy has recently been associated with remote white matter damage, including reduced white matter volume. Longitudinal assessment of these white matter changes, in relation to functional mechanisms and consequences, may be ideally done by in vivo neuroimaging in well-controlled experimental animal models. We assessed whether advanced machine learning algorithm models could accurately detect volumetric changes in white matter from multiparametric MR images, longitudinally collected in a neocortical focal epilepsy rat model.

Long-term oral methylphenidate treatment in adolescent and adult rats: differential effects on brain morphology and function.

Methylphenidate is a widely prescribed psychostimulant for treatment of attention deficit hyperactivity disorder (ADHD) in children and adolescents, which raises questions regarding its potential interference with the developing brain. In the present study, we investigated effects of 3 weeks oral methylphenidate (5 mg/kg) vs vehicle treatment on brain structure and function in adolescent (post-natal day [P]25) and adult (P65) rats. Following a 1-week washout period, we used multimodal magnetic resonance imaging (MRI) to assess effects of age and treatment on independent component analysis-based functional connectivity (resting-state functional MRI), D-amphetamine-induced neural activation responses (pharmacological MRI), gray and white matter tissue volumes and cortical thickness (postmortem structural MRI), and white matter structural integrity (postmortem diffusion tensor imaging (DTI)).

Functional and structural neural network characterization of serotonin transporter knockout rats.

Brain serotonin homeostasis is crucially maintained by the serotonin transporter (5-HTT), and its down-regulation has been linked to increased vulnerability for anxiety- and depression-related behavior. Studies in 5-HTT knockout (5-HTT(-/-)) rodents have associated inherited reduced functional expression of 5-HTT with increased sensitivity to adverse as well as rewarding environmental stimuli, and in particular cocaine hyperresponsivity. 5-HTT down-regulation may affect normal neuronal wiring of implicated corticolimbic cerebral structures.

MRI of ICAM-1 upregulation after stroke: the importance of choosing the appropriate target-specific particulate contrast agent.

Purpose: Magnetic resonance imaging (MRI) with targeted contrast agents provides a promising means for diagnosis and treatment monitoring after cerebrovascular injury. Our goal was to demonstrate the feasibility of this approach to detect the neuroinflammatory biomarker intercellular adhesion molecule-1 (ICAM-1) after stroke and to establish a most efficient imaging procedure.

Procedures: We compared two types of ICAM-1-functionalized contrast agent: T 1-shortening gadolinium chelate-containing liposomes and T2(*)-shortening micron-sized iron oxide particles (MPIO).

Electrode migration in cochlear implant patients: not an exception.

Objective: It was the aim of this study to investigate the occurrence of electrode migration of a cochlear implant in patients with and without complaints.

Methods: We performed a retrospective case review in a tertiary referral center. The electrode position was evaluated in 35 cochlear implantees, 16 with a CII HiFocus1 (non-positioner) and 19 with a HiRes90K HiFocus1J, using multiplanar reconstructions of the postoperative CT scans.

Extent of bilateral neuronal network reorganization and functional recovery in relation to stroke severity.

Remodeling of neuronal structures and networks is believed to significantly contribute to (partial) restoration of functions after stroke. However, it has been unclear to what extent the brain reorganizes and how this correlates with functional recovery in relation to stroke severity. We applied serial resting-state functional MRI and diffusion tensor imaging together with behavioral testing to relate longitudinal modifications in functional and structural connectivity of the sensorimotor neuronal network to changes in sensorimotor function after unilateral stroke in rats.

Functional MRI and diffusion tensor imaging of brain reorganization after experimental stroke.

The potential of the adult brain to reorganize after ischemic injury is critical for functional recovery and provides a significant target for therapeutic strategies to promote brain repair. Despite the accumulating evidence of brain plasticity, the interaction and significance of morphological and physiological modifications in post-stroke brain tissue remain mostly unclear. Neuroimaging techniques such as functional MRI (fMRI) and diffusion tensor imaging (DTI) enable in vivo assessment of the spatial and temporal pattern of functional and structural changes inside and outside ischemic lesion areas.

Cochlear reimplantation with same device: surgical and audiologic results.

Objectives/hypothesis: To study to what extent it is possible to achieve identical insertion depths and to maintain the same performance after cochlear reimplantation.

Study Design: Outcome research on a retrospective case series in a tertiary university referral center.

Methods: Data were collected for 12 adults and three children who underwent reimplantation during the last 3 years with a new HiRes90K device with HiFocus 1J electrode owing to failure of the feed-through seal.