Henryk Faas

Henryk Faas
University of Nottingham | Notts

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24
Publications
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Introduction
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Publications

Publications (24)
Article
Full-text available
Paramagnetic gadolinium ions (GdIII), complexed within DOTA-based chelates, have become useful tools to increase the magnetic resonance imaging (MRI) contrast in tissues of interest. Recently, "on/off" probes serving as 19F·MRI biosensors for target enzymes have emerged that utilize the increase in transverse (T2 ∗ or T2) relaxation times upon clea...
Article
Full-text available
Neuroinflammation plays an important role in the pathogenesis of a range of brain disorders. Non-invasive imaging of neuroinflammation is critical to help improve our understanding of the underlying disease mechanisms, monitor therapies and guide drug development. Generally, MRI lacks specificity to molecular imaging biomarkers, but molecular MR im...
Data
Response to LPS. Histology was used to divide animals into Iba1+ and Iba1- to the LPS intervention. Shown here are a larger view of an example histology slide (A) with the corresponding CEST signal (B) for an Iba1+ animal with higher levels of microglial response on the LPS injection site, compared with the contralateral vehicle injection site. (EP...
Data
Quantitative histology measures vs CEST signal. In addition to the classification into Iba1+ and Iba1-, which was based on the judgement of an experienced pathologist, we correlated a quantitative, morphometric marker of microglia activation (soma size) with the CEST response. The difference between the LPS injection side and the contralateral vehi...
Data
CEST signal variability in control animals. To improve field homogeneity, we applied a gel cap to the top of the skull, which improved B0 homogeneity across the brain: (A) After shimming but without gel cap the B0 map, CEST map and the asymmetry spectrum from an ROI on the hippocampus; (B) with the 3% agarose gel cap. The CEST spectrum showed less...
Data
Details of experiment and resulting classification into iba1+ animals (responders) or Iba1—Non-responders, with contributing factors experimenter and genotype). In highlighted animals, there was at least a 20% change in CEST signal between LPS and PBS side. (PDF)
Data
Contribution of different metabolites to CEST signal. While the drug (LPS) itself does not have a measurable effect in the CEST MRI acquisition, several metabolites overlap and contribute to the CEST effect around 0.6 ppm. (A) Z spectrum and asymmetry spectrum of LPS in saline solution (5ng/μL concentration, pH 7.4). (B) Z-spectrum of several brain...
Data
T2 weighted images. T2 weighted images were acquired for all animals, while T2 maps were acquired for a subset of n = 6 animals. A) Representative T2 weighted image, with no visible effect from the injections (edema or hemorrhage). B) Both injections were visible in T2 maps (increased contrast in injection sites), however T2 values did not differ s...
Conference Paper
Full-text available
Blood vessel segmentation helps to know the progress of the disease during diagnosis. The presence of intensity in-homogeneity, conglutination tissue and noise in medical images has led to difficulty in extraction of different sizes of blood vessels, difficulty in separating vessels for further analysis (such as quantification of angiogenesis), dif...
Article
Full-text available
NAD metabolism and the NAD biosynthetic enzymes nicotinamide nucleotide adenylyltransferases (NMNATs) are thought to play a key neuroprotective role in tauopathies, including Alzheimer's disease. Here, we investigated whether modulating the expression of the NMNAT nuclear isoform NMNAT1, which is important for neuronal maintenance, influences the d...
Article
Full-text available
Due to low fluorine background signal in vivo, ¹⁹F is a good marker to study the fate of exogenous molecules by magnetic resonance imaging (MRI) using equilibrium nuclear spin polarization schemes. Since ¹⁹F MRI applications require high sensitivity, it can be important to assess experimental feasibility during the design stage already by estimatin...
Data
Detection limits at low fluorine SNR regimes. Spectra showing the signal from a 1 mM and 0.4 mM TFA (C3) sample. An SNR of 5.8 was measured for the 1 mM sample, although the linewidth was 5.1 Hz rather than between 7 and 8 Hz used for the line of best fit. Accounting for this in Eq 5 gives an SNR of 3.8, close to the predicted 3.5. For the 0.4 mM s...
Data
Derivation of Theoretical SNR and description of relaxometry. (DOCX)
Data
Effect of line broadening (LB) on the SNR. (A) Line broadening with an exponentially decaying window function corresponding to a linewidth of 25 Hz and 50 Hz applied to a sample spectrum of gadolinium doped sample C3, compared with the original spectrum. (B) The optimal line broadening factor was 50 Hz, corresponding to 100% relative LB to FWHM. Th...
Data
A complex fluorine signal from the lung vasculature. To demonstrate the application of the approach, we estimated the SNR from the synthetic blood Perftoran, which carries 41 fluorine atoms and a complex line shape, in the vasculature of an excised rat lung. To estimate the gauge factor, a standard spectrum of Perftoran in a 1 ml test tube was meas...
Data
Representative 1H MGE image used to calculate T2*. A proton image from a MGE scan is shown, (TE = 1.98 ms), which was part of a series of images with different echo times used to obtain a T2* value for comparison with spectral T2* (12 echo images, 1 ms spacing). (EPS)
Article
Full-text available
Segmentation and analysis of histological images provides a valuable tool to gain insight into the biology and function of microglial cells in health and disease. Common image segmentation methods are not suitable for inhomogeneous histology image analysis and accurate classification of microglial activation states has remained a challenge. In this...
Article
Full-text available
Microglia activation has emerged as a potential key factor in the pathogenesis of Alzheimer’s disease. Metabolite levels assessed by magnetic resonance spectroscopy (MRS) are used as markers of neuroinflammation in neurodegenerative diseases, but how they relate to microglial activation in health and chronic disease is incompletely understood. Usin...
Article
A cryptophane cage in the vicinity of a paramagnetic center causes hyperpolarized 129Xe in solution (blue color) to rapidly depolarize (red), due to chemical exchange relaxation transfer, as reported by N. R. Thomas, H. M. Faas, T. Meersmann et al. on p. 2294. Interactions that deactivate this effect will preserve the hyperpolarized state for molec...
Article
An approach for hyperpolarized (129) Xe molecular sensors is explored using paramagnetic relaxation agents that can be deactivated upon chemical or enzymatic reaction with an analyte. Cryptophane encapsulated (129) Xe within the vicinity of the paramagnetic center experiences fast relaxation that, through chemical exchange of xenon atoms between ca...
Conference Paper
Full-text available
Introduction: Neuroinflammation is a normal response to pathological insult in the CNS, but also plays an important role in many neurological disorders. Imaging biomarkers for neuroinflammation through noninvasive molecular imaging techniques (in particular using MRI) could lead to improved diagnosis, allow monitoring and guide therapy of these dis...
Conference Paper
Full-text available
Chemical Exchange Saturation Transfer (CEST) has the potential to monitor molecular markers of disease with improved spatial resolution and sensitivity over magnetic resonance spectroscopy (MRS). In Alzheimer’s disease (AD), MRS has shown increased levels of myo-inositol, which also exhibits a CEST effect due to its six hydroxyl groups (MICEST) . W...

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Projects (3)
Project
The aim of this research is to come up with a 3D robust automated blood vessel segmentation for the extraction of blood vessels from intensity in-homogeneous medical images