15 research outputs found
Potential to Inhibit Growth of Atherosclerotic Plaque development through Modulation of Macrophage neopterin /7,8-dihydroneopterin synthesis
SP Gieseg, EM Crone, EA Flaval, Z Amit
Oxidant Production, oxLDL uptake and CD36 levels in Human Monocyte Derived Macrophages are down regulated by the macrophage - generated antioxidant 7,8-dihydroneopterin
Ex-vivo atherosclerotic plaque characterization using spectral photon-counting CT: Comparing material quantification to histology.
Atherosclerotic plaques are characterized as being vulnerable to rupture based on a series of histologically defined features, including a lipid-rich necrotic core, spotty calcification and ulceration. Existing imaging modalities have limitations in their ability to distinguish between different materials and structural features. We examined whether X-ray spectral photon-counting computer tomography (SPCCT) images were able to distinguish key plaque features in a surgically excised specimen from the carotid artery with comparison to histological images.
An excised carotid plaque was imaged in the diagnostic X-ray energy range of 30-120 keV using a small-bore SPCCT scanner equipped with a Medipix3RX photon-counting spectral X-ray detector with a cadmium telluride (CdTe) sensor. Material identification and quantification (MIQ) images of the carotid plaque were generated using proprietary MIQ software at 0.09 mm volumetric pixels (voxels). The plaque was sectioned, stained and photographed at high resolution for comparison.
A lipid-rich core with spotty calcification was identified in the MIQ images and confirmed by histology. MIQ showed a core region containing lipid, with a mean concentration of 260 mg lipid/ml corresponding to a mean value of -22HU. MIQ showed calcified regions with mean concentration of 41 mg Ca/ml corresponded to a mean value of 123HU. An ulceration of the carotid wall at the bifurcation was identified to be lipid-lined, with a small calcification identified near the breach of the artery wall.
SPCCT derived material identification and quantification images showed hallmarks of vulnerable plaque including a lipid-rich necrotic core, spotty calcifications and ulcerations
Reducing beam hardening effects and metal artefacts using Medipix3RX: With applications from biomaterial science
This paper discusses methods for reducing beam hardening effects using spectral data for biomaterial applications. A small-animal spectral scanner operating in the diagnostic energy range was used. We investigate the use of photon-processing features of the Medipix3RX ASIC in reducing beam hardening and associated artefacts. A fully operational charge summing mode was used during the imaging routine. We present spectral data collected for metal alloy samples, its analysis using algebraic 3D reconstruction software and volume visualisation using a custom volume rendering software. Narrow high energy acquisition using the photon-processing detector revealed substantial reduction in beam hardening effects and metal artefacts
Serum Protein-Bound 3,4-Dihydroxyphenylalanine and Related Products of Protein Oxidation and Chronic Hemodialysis
MARS-MD: rejection based image domain material decomposition
This paper outlines image domain material decomposition algorithms that have
been routinely used in MARS spectral CT systems. These algorithms (known
collectively as MARS-MD) are based on a pragmatic heuristic for solving the
under-determined problem where there are more materials than energy bins. This
heuristic contains three parts: (1) splitting the problem into a number of
possible sub-problems, each containing fewer materials; (2) solving each
sub-problem; and (3) applying rejection criteria to eliminate all but one
sub-problem's solution. An advantage of this process is that different
constraints can be applied to each sub-problem if necessary. In addition, the
result of this process is that solutions will be sparse in the material domain,
which reduces crossover of signal between material images. Two algorithms based
on this process are presented: the Segmentation variant, which uses segmented
material classes to define each sub-problem; and the Angular Rejection variant,
which defines the rejection criteria using the angle between reconstructed
attenuation vectors