A5010293746- Advanced MRI Techniques and Applications
- Advanced Neuroimaging Techniques and Applications
- MRI in cancer diagnosis
- Atomic and Subatomic Physics Research
- Radiation Dose and Imaging
- Lanthanide and Transition Metal Complexes
- Digital Radiography and Breast Imaging
- Advanced NMR Techniques and Applications
- Electron Spin Resonance Studies
- Mitochondrial Function and Pathology
- Advanced X-ray and CT Imaging
- Medical Imaging Techniques and Applications
- Functional Brain Connectivity Studies
- Cardiac Imaging and Diagnostics
- Regulation of Appetite and Obesity
- Genetic Neurodegenerative Diseases
- Eating Disorders and Behaviors
- Intraocular Surgery and Lenses
- Neuroscience and Neuropharmacology Research
- Meningioma and schwannoma management
- Ultrasound and Hyperthermia Applications
- Venomous Animal Envenomation and Studies
- Rabies epidemiology and control
- Dietary Effects on Health
- Drug-Induced Ocular Toxicity
Leiden University Medical Center
2013-2023
Leiden University
2009-2017
Amsterdam UMC Location University of Amsterdam
2011
University Medical Center Utrecht
2011
Abstract The use of high‐permittivity materials has been shown to be an effective method for increasing transmit and receive sensitivity in areas low‐signal intensity the brain at high field. Results this article show that these does not increase intercoil coupling a phased array coil, have any detrimental effects on B 0 homogeneity within brain, affect specific absorption rate distribution head. Areas close pads exhibit significant increases (>100%) field efficiency, but further away...
Abstract Since the invention of arterial spin labeling (ASL) it has been acknowledged that ASL does not allow reliable detection a white matter (WM) perfusion signal. However, recent developments such as pseudo‐continuous and background suppression have improved quality. The goal this research was to study ability these newer sequences detect WM Background suppressed implemented at 3T with multislice 2D readout after 1525 ms. In five volunteers shown 10 min scanning resulted in significant...
The longitudinal relaxation time of blood is a crucial parameter for quantification cerebral flow by arterial spin labeling and one the main determinants signal‐to‐noise ratio resulting perfusion maps. Whereas at low medium magnetic field strengths ( B 0 ), its in vivo value well established; ultra‐high field, this still uncertain. In study, sagittal sinus was measured 1.5 T, 3 7 T. A nonselective inversion pulse preceding Look‐Locker echo planar imaging sequence performed to obtain recovery...
The predatory ecology of Varanus komodoensis (Komodo Dragon) has been a subject long-standing interest and considerable conjecture. Here, we investigate the roles potential interplay between cranial mechanics, toxic bacteria, venom. Our analyses point to presence sophisticated combined-arsenal killing apparatus. We find that lightweight skull is relatively poorly adapted generate high bite forces but better resist pulling loads. reject popular notion regarding bacteria utilization. Instead,...
Intra- and multicenter reproducibility of currently used arterial spin labeling (ASL) methods were assessed at three imaging centers in the Netherlands, equipped with Philips 3TMR scanners. Six healthy participants scanned twice each site. The protocol consisted continuous ASL (CASL), pseudo-continuous (p-CASL) without background suppression, pulsed (PASL) single multiple inversion times (TIs), selective for segmentation. Reproducibility was expressed terms coefficient repeatability index....
Abstract High permittivity “dielectric pads” have been shown to increase image quality at high magnetic fields in regions of low radiofrequency transmit efficiency. This article presents a series electromagnetic simulations determine the effects pad size and geometry, relative value, as well thickness on for neuroimaging 7 T. For 5‐mm thick pad, there is virtually no effect field values lower than ∼90. Significant improvements are found between 90 ∼180. If increased above ∼180 then areas...
Purpose To design a low‐cost, portable permanent magnet‐based MRI system capable of obtaining in vivo MR images within reasonable scan time. Methods A discretized Halbach magnet array with clear bore diameter 27 cm was designed for operation at 50 mT. Custom‐built gradient coils, RF coil, amplifiers, and amplifier were integrated tested on both phantoms vivo. Results Phantom results showed that the nonlinearity y‐direction z‐direction less than 5% over 15‐cm FOV did not need correcting. For...
To describe the construction and testing of a portable point-of-care low-field MRI system on site in Africa.
Purpose In this study, the basic properties and requirements of time‐encoded pseudocontinuous arterial spin labeling (te‐pCASL) are investigated. Also, extra degree freedom delivered by changing block durations is explored. Methods First, minimal duration encoding blocks, influence cardiac triggering, effect dividing period into blocks evaluated. Two new strategies for timing in te‐pCASL introduced: variable to compensate T1‐decay free lunch approach that uses postlabeling delay time idle...
Patient and staff dose during CT guided coagulation of osteoid osteoma, tissue biopsy abcess drainage were evaluated retrospectively on a conventional scanner prospectively equipped with fluoroscopic CT. The computed tomography index (CTDI) the individual equivalent, i.e. penetrating for workers at depth 10 mm tissue, measured. Evaluation CTDI enabled effective maximum skin entrance doses patient to be determined. Doses assessed 96 interventions, including 16 drainages average 13.5 mSv 9.3...
Venom has only been recently discovered to be a basal trait of the Anguimorpha lizards. Consequently, very little is known about timings toxin recruitment events, venom protein molecular evolution, or even relative physical diversifications system itself. A multidisciplinary approach was used examine evolution across full taxonomical range this ∼130 million-year-old clade. Analysis cDNA libraries revealed complex transcriptomes. Most notably, three new cardioactive peptide types were...
Huntington's disease (HD) is a neurodegenerative genetic disorder that affects the brain. Atrophy of deep grey matter structures has been reported and it likely underlying pathologic processes occur before, or in concurrence with, volumetric changes. Measurement metabolite concentrations these brain potential to provide insight into pathological processes. We aim gain understanding changes with respect stage pathophysiological studied five regions using magnetic resonance spectroscopy (MRS)...
To assess the tumour dimensions in uveal melanoma patients using 7-T ocular MRI and compare these values with conventional ultrasound imaging to provide improved information for treatment options. Ten were examined on a system custom-built eye coil dedicated 3D scan sequences minimise eye-motion-induced image artefacts. The maximum prominence was estimated from three-dimensional images compared standard clinical evaluation 2D images. protocols resulted high-resolution motion-free of which...
Abstract The intrinsic nonuniformities in the transmit radiofrequency field from standard quadrature volume resonators at high are particularly problematic for localized MRS areas such as temporal lobe, where a low signal‐to‐noise ratio and poor metabolite quantification result destructive B interference, addition to line broadening signal loss strong susceptibility gradients. of lobe has been performed number neurodegenerative diseases clinical fields, but relatively prevented reliable of,...
To determine the subjective experiences and sources of discomfort for subjects undergoing 7 T magnetic resonance imaging (MRI) examinations on a whole-body system in hospital settingA postscan survey was filled out by 101 healthy who participated examination. All participants answered questions regarding different potential sensations including dizziness, claustrophobia, scanner noise.Dizziness reported most frequently, with 34% experiencing dizziness while moving into 30% magnet. Scanner...
PurposeTo investigate the displacement forces and image artifacts associated with passive medical implants for recently-developed low-field (<100 mT) MRI systems, to compare these values from higher field strengths used clinical diagnosis.MethodsSetups were constructed measure in a permanent magnet-based Halbach array vivo at 50 mT, results compared measurements 7 T. Image assessed using turbo (fast) spin echo imaging sequences four different implants: septal occluder, iliac stent, pedicle...
The cerebral blood flow (CBF) is a potential biomarker for neurological disease. However, the arterial transit time (ATT) of labeled known to potentially affect CBF quantification. Furthermore, ATT could be an interesting in itself, as it may reflect underlying macro‐ and microvascular pathologies. Currently, no optimized magnetic resonance imaging (MRI) sequence exists measure mice. Recently, time‐encoded labeling schemes have been implemented rats humans, enabling mapping with higher...
The purpose of this work is to investigate the use ceramic materials (based on BaTiO3 with ZrO2 and CeO2-additives) very high relative permittivity (εr ∼ 4500) increase local transmit field signal-to-noise ratio (SNR) for commercial extremity coils a clinical 1.5 T MRI system.Electromagnetic simulations efficiency specific absorption rate (SAR) were performed using four ferroelectric blocks placed around cylindrical phantom, as well placing these ceramics wrist human body model. Results...
Background: Previous cross-sectional magnetic resonance spectroscopy (MRS) studies in Huntington's disease (HD) have demonstrated differences metabolite concentrations several regions of interest, especially the putamen and caudate nucleus. Obj
In this study, a new arterial spin labeling (ASL) method with spatially nonselective is introduced, based on the acceleration of flowing spins, which able to image brain perfusion minimal contamination from venous signal. This termed acceleration‐selective ASL (AccASL) and resembles velocity‐selective (VSASL), difference that AccASL discriminate between components in single preparation module due higher side microvasculature, whereas VSASL cannot make distinction unless second used. A mainly...