30 research outputs found
Illumination methods for optical wear detection
The paper presents some results of a study on optical wear detection. The focus of the paper is on the illumination, to optimize the contrast of the images. Various illumination methods are compared: bright field versus dark field illumination, and various kind of light sources: laser light, diffuse light and ring-light
Real-time navigator gating in proton liver spectroscopy at 3T
Navigator gated proton MR spectroscopy with inner volume saturation allows free breathing measurements of liver molecules while ensuring a precise location of the measured voxel. It is shown in 5 healthy volunteers that the spectral quality is improved and the variation of molecule ratios are decreased compared to measurements without gating. This technique may thus improve the quality of the diagnostic procedure of liver disease
Biogenic Magnetite Nanoparticle Ensemble Use in MRI Diagnostics
We present a simple analytical tool, which allows the calculation of the MRI diagnostics feasibility of the biogenic magnetite nanoparticles. Elevated levels of these particles are usually linked to the pathological processes, especially to neurodegenerative disorders. We showed theoretically that the biogenic magnetite itself is not sufficient for the non-invasive diagnostics and must be extended with the total iron incorporated in other biological structures
Effects of contrast agents on relaxation properties of 31P metabolites
Purpose
Phosphorous MR spectroscopy (31PâMRS) forms a powerful, nonâinvasive research tool to quantify the energetics of the heart in diverse patient populations. 31PâMRS is frequently applied alongside other radiological examinations, many of which use various contrast agents that shorten relaxation times of water in conventional proton MR, for a better characterisation of cardiac function, or following prior computed tomography (CT). It is, however, unknown whether these agents confound 31PâMRS signals, for example, 2,3âdiphosphoglycerate (2,3âDPG).
Methods
In this work, we quantitatively assess the impact of nonâionic, low osmolar iodinated CT contrast agent (iopamidol/Niopam), gadolinium chelates (linear gadopentetic acid dimeglumine/Magnevist and macrocyclic gadoterate meglumine/Dotarem) and superparamagnetic iron oxide nanoparticles (ferumoxytol/Feraheme) on the nuclear T1 and T2 of 31P metabolites (ie, 2,3âDPG), and 1H in water in live human blood and saline phantoms at 11.7 T.
Results
Addition of all contrast agents led to significant shortening of all relaxation times in both 1H and 31P saline phantoms. On the contrary, the T1 relaxation time of 2,3âDPG in blood was significantly shortened only by Magnevist (P = .03). Similarly, the only contrast agent that influenced the T2 relaxation times of 2,3âDPG in blood samples was ferumoxytol (P = .02).
Conclusion
Our results show that, unlike conventional proton MR, phosphorus MRS is unconfounded in patients who have had prior CT with contrast, not all gadoliniumâbased contrast agents influence 31PâMRS data in vivo, and that ferumoxytol is a promising contrast agent for the reduction in 31PâMRS bloodâpool signal