High-resolution/high-contrast MRI of human articular cartilage lesions.

BACKGROUND: Magnetic resonance microscopy (MRM) is an important experimental tool in the identification of early cartilage lesions. METHODS: Normal and degenerated cartilage samples were imaged at 11.74 T using a standard spin echo sequence. Quantitative MR measurements for T1, T2, and ADC were obtained and mapping for T2 and ADC was performed. The bi-exponential model for T2 relaxation was also explored. Histology was carried out for comparison with MR images. RESULTS: MR images of cartilage samples displaying early stages of degeneration were positively correlated to their histological appearance in 23-microm high-resolution images and also with much shorter imaging times at 47-microm resolution. T2 maps enable delineation of the actual cartilage zones, distinguishing the superficial zone in particular. The bi-exponential model can reflect cartilage components at different stages of degeneration. INTERPRETATION: At 11.74 T, with 23-microm resolution or with 47-microm resolution and shorter imaging times, MRM provides images that allow visualization of early stages of cartilage degeneration, including superficial fibrillation. This has not been shown previously. The images also allow quantitative measurements (T1, T2, and ADC) in each cartilage region, which can be indicative of different stages of cartilage degeneration

Diffraction-Enhanced Imaging of Musculoskeletal Tissues Using a Conventional X-Ray Tube

In conventional projection radiography, cartilage and other soft tissues do not produce enough radiographic contrast to be distinguishable from each other. Diffraction-enhanced imaging (DEI) uses a monochromatic x-ray beam and a silicon crystal analyzer to produce images in which attenuation contrast is greatly enhanced and x-ray refraction at tissue boundaries can be detected. Here we test the efficacy of conventional x-ray tube-based DEI for the detection of soft tissues in experimental samples

X-ray detection of structural orientation in human articular cartilage

AbstractObjective: To determine the feasibility of detecting the structural orientation in cartilage with Diffraction Enhanced X-Ray Imaging.Design: Human tali and femoral head specimens were Diffraction Enhanced X-Ray Imaged (DEI) at the SYRMEP beamline at Elettra at various energy levels to detect the architectural arrangement of collagen within cartilage. DEI utilizes a monochromatic and highly collimated beam, with an analyzer crystal that selectively weights out photons according to the angle they have been deviated with respect to the original direction. This provides images of very high contrast, and with the rejection of X-ray scatter.Results: DEI allowed the visualization of articular cartilage and a structural orientation, resembling arcades, within.Conclusion: Our diffraction enhanced images represent the first radiographic detection of the structural orientation in cartilage. Our data are in line with previous studies on the structural organization of joint cartilage. They confirm the model of a vaulting system of collagen fiber bundles interrupted by proteoglycan aggregates

Relationship between knee and ankle degeneration in a population of organ donors

<p>Abstract</p> <p>Background</p> <p>Osteoarthritis (OA) is a progressive degenerative condition of synovial joints in response to both internal and external factors. The relationship of OA in one joint of an extremity to another joint within the same extremity, or between extremities, has been a topic of interest in reference to the etiology and/or progression of the disease.</p> <p>Methods</p> <p>The prevalence of articular cartilage lesions and osteophytes, characteristic of OA, was evaluated through visual inspection and grading in 1060 adult knee/tali pairs from 545 cadaveric joint donors.</p> <p>Results</p> <p>Joint degeneration increased more rapidly with age for the knee joint, and significantly more knee joints displayed more severe degeneration than ankle joints from as early as the third decade. Women displayed more severe knee degeneration than did men. Severe ankle degeneration did not exist in the absence of severe knee degeneration. The effect of weight on joint degeneration was joint-specific whereby weight had a significantly greater effect on the knee. Ankle grades increasingly did not match within a donor as the grade of degeneration in either the left or the right knee increased.</p> <p>Conclusions</p> <p>Gender and body type have a greater effect on knee joint integrity as compared to the ankle, suggesting that knees are more prone to internal causative effects of degeneration. We hypothesize that the greater variability in joint health between joints within an individual as disease progresses from normal to early signs of degeneration may be a result of mismatched limb kinetics, which in turn might lead to joint disease progression.</p

THE INDUCTION OF IMMUNOLOGIC TOLERANCE FOLLOWING CLOACAL ADMINISTRATION OF ANTIGEN.

THE INDUCTION OF IMMUNOLOGIC TOLERANCE FOLLOWING CLOACAL ADMINISTRATION OF ANTIGEN

Las Inhibition of Diffusion and Uptake of Tritiated Uridine During Teleost Embryogenesis

Conférence de presse annonçant la naissance de l’Association Tunisienne de la Culture Amazighe, 30 juillet 2011© CMA Avant l’implosion révolutionnaire, l’officialisation de la culture berbère butait sur le système totalitaire. Aujourd’hui surgit et sévit un nouvel adversaire. Le 27 mars, Hamadi Ben Yahia, fondateur de la troupe « Imazighen », concluait la conférence de presse tenue à la maison de la culture « Ibn Rachiq » par ce propos : « on ne baissera pas les bras. La lutte continuera ». À..

A densitometric analysis of the human first metatarsal bone

Bone responds to the stresses placed on it by remodeling its structure, which includes shape, trabecular distribution and density distribution. We studied 49 pairs of cadaveric human 1st metatarsal bones in an attempt to establish the pattern of density distribution and to correlate it with the biomechanical function of the bone. We found that the head is denser than the base, the dorsal portion of the whole metatarsal is denser than the plantar portion and the lateral portion of the whole metatarsal is denser than the medial aspect. The same pattern of density with respect to dorsal vs plantar and lateral vs medial was also seen in the head when it was examined alone. When we compared the 4 portions of the head with the same portion of the metatarsal as a whole we found that only the medial portion of the head was less dense than its respective portion of the whole metatarsal. All of these patterns of density distribution are consistent with respect to age, sex and laterality. We have also hypothesised as to the relationship between density distribution seen both in the whole metatarsal and in the metatarsal head and their biomechanical function in the gait cycle