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AbstractThe aim of this research was to evaluate the stress distribution in the ‘All-on-Four’ prosthesis and the surrounding bone, with different framework materials and thicknesses. Five frameworks (alumina, zirconia, titanium, fiberglass reinforced resin (FRR), and polyether ether ketone (PEEK)) with two thicknesses (3.5 &5.5 mm) were stimulated in this research. A vertical force of 200 N was applied on a 1 mm circular area, at the cantilever, and at the region of the incisors, simulating different mastication mechanisms. The results illustrated that the 5.5 mm framework reduced the stresses on most parts, mucosa, and bone tissues, compared to 3.5 mm. [ABSTRACT FROM AUTHOR]

Bioimpedance is an electrical property, which is measured to indicate related parameters and diagnose several diseases of the body. The heart pulsatile is a blood flow with periodic variations as a result of heart beats. The main objective of this article is studying the effect of the heart pulsatile on the measurements of artery bioimpedance. However, neglecting the heart pulsatile leads to error in calculations of many applications based on artery bioimpedance measurement such as glucose monitoring, stenosis, and cholesterol detection. Furthermore, the studying of the heart pulsatile effect could be developed to measure the heart rate as a novel method based on bioimpedance phenomena. A simple model of electrodes and composite layers (skin, fat, muscle, and artery) is simulated using COMSOL. In this work, a model of noninvasive electrodes for measuring an artery bioimpedance is described to show the best method to take into consideration the effect of heart pulsatile.

Hybrid prostheses have recently been used as suitable treatment alternatives for edentulous individuals to restore the mastication mechanism. These prostheses utilize "All on four" concept, in which four implants are inserted into the jaw bone, and supported by a bar. Titanium is usually used in the fabrication of "All on four" parts due to its good mechanical properties. However, it has many drawbacks including esthetic impairment, casting issues, hypersensitivity reactions, stress shielding, and incompatibility with imaging techniques. These drawbacks have prompted researchers to find alternative materials (e.g., polymers). Recently, the new polymeric material PEEK has a major role in dentistry, due to its biocompatibility, shock-absorbing ability, and good mechanical properties. This work used the finite-element method to conduct stress–strain analysis on mandible rehabilitated with a hybrid prosthesis, using PEEK in the fabrication of "All on four" parts instead of titanium, using different densities of spongy bone. As the density of spongy bone is expected to influence the choice of "All on four" fabrication material. A 300 N vertical force was applied unilaterally, bilaterally, and anteriorly to stimulate the different mastication mechanisms. The results illustrated that PEEK material reduced the stresses and strains on bone tissues and increased the mucosal stress, compared to titanium. Consequently, this material was recommended to be used in the fabrication of "All on four" parts, especially in the low-density model. However, further research on PEEK implants and abutments is required in near future. [ABSTRACT FROM AUTHOR]

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Tagged Magnetic Resonance Imaging (tMRI) is considered to be the gold standard for quantitative assessment of the cardiac local functions. However, the tagging patterns and low myocardium-to-blood-pool contrast of tagged images bring great challenges to cardiac image processing and analysis tasks such as myocardium segmentation and tracking. Hence, there has been growing interest in techniques for removing tagging lines. In this work, a method for removing tagging patterns in tagged MR images using a coupled dictionary learning (CDL) model is proposed. In this model, identical sparse representations are assumed for image patches in the tagged MRI and corresponding cine MRI image spaces. First, we learn a dictionary for the tagged MRI image space. Then, we compute a dictionary for the cine MRI image space so that corresponding tagged and cine patches have the same sparse codes in terms of their respective dictionaries. Finally, in order to produce the de-tagged (cine version) of a test tagged image, the sparse codes of the tagged patches and the trained cine dictionary are used together to construct the de-tagged patches. We have tested this tag removal method on a dataset of tagged cardiac MR images. Our experimental results compared favorably with a recently proposed tag removal method that removes tags in the frequency domain using an optimal band-stop filter of harmonic peaks.

Coronary heart disease (CHD) is the leading cause of death worldwide. Cardiac magnetic resonance imaging (MRI) is a valuable imaging modality, as it can noninvasively provide information about myocardial function, viability, and morphology. Viability delayed-enhancement (DE) images are acquired at a single timeframe while myocardial functional (tagged) images are acquired as a cine loop of timeframes throughout the cardiac cycle. In this work, we propose a method for estimating DE images at all timeframes in the cardiac cycle without additional scan time to show both viability and functional information in the same image. The method is based on generating a dense motion field of the heart from the acquired tagged images, and then applying the extracted field to the acquired DE image. The developed technique is accurate in generating cine DE images and providing simultaneous information about myocardial viability and wall motion for comprehensive patient evaluation and optimal treatment selection.