Efficient Strike Artifact Reduction Based on 3D-Morphological Structure Operators from Filtered Back-Projection PET Images.

Positron emission tomography (PET) can provide functional images and identify abnormal metabolic regions of the whole-body to effectively detect tumor presence and distribution. The filtered back-projection (FBP) algorithm is one of the most common images reconstruction methods. However, it will generate strike artifacts on the reconstructed image and affect the clinical diagnosis of lesions. Past studies have shown reduction in strike artifacts and improvement in quality of images by two-dimensional morphological structure operators (2D-MSO). The morphological structure method merely processes the noise distribution of 2D space and never considers the noise distribution of 3D space. This study was designed to develop three-dimensional-morphological structure operators (3D MSO) for nuclear medicine imaging and effectively eliminating strike artifacts without reducing image quality. A parallel operation was also used to calculate the minimum background standard deviation of the images for three-dimensional morphological structure operators with the optimal response curve (3D-MSO/ORC). As a result of Jaszczak phantom and rat verification, 3D-MSO/ORC showed better denoising performance and image quality than the 2D-MSO method. Thus, 3D MSO/ORC with a 3 × 3 × 3 mask can reduce noise efficiently and provide stability in FBP images.

Osteoblastogenesis of Mesenchymal Stem Cells in 3-D Culture Enhanced by Low-Intensity Pulsed Ultrasound through Soluble Receptor Activator of Nuclear Factor Kappa B Ligand.

This study was performed to investigate osteoblastogenesis of human mesenchymal stem cells (hMSCs) cultured in 3-D scaffolds stimulated with low-intensity pulsed ultrasound and to identify the underlying mechanism mediated by soluble receptor activator of nuclear factor kappa B ligand (sRANKL) secreted by hMSCs. The results indicate that the mRNA levels of core-binding factor subunit alpha subunit 1 (CBFA1), osterix (OSX), alkaline phosphatase (ALP), osteocalcin and osteoprotegerin (OPG) and sRANKL production of hMSCs stimulated by ultrasound were significantly increased compared with the levels without ultrasound stimulation. Attenuating the sRANKL activity of ultrasound-treated hMSCs significantly reduced the mRNA expression of CBFA1, OSX, ALP and OPG. Adding sRANKL in hMSC culture significantly increased the mRNA expression of CBFA1, OSX and OPG. Together, the results suggest that osteoblastogenesis of hMSCs enhanced by ultrasound stimulation is mediated by endogenous sRANKL.

Effect of ultrasound doses on the amyloid-beta 25-35 induced PC12 apoptosis.

Previous studies have shown that Amyloid-beta (A beta) may induce the apoptosis of neuronal cells leading to the syndrome of Alzheimer's disease (AD). The stimulation by optical energy was found able to greatly inhibit A beta induced apoptosis. This study aims to further explore the effect of different doses of ultrasonic insonification on neuronal cells. Experiments were carried out using PC12 cells added with A beta 25-35 of a 20 microM during pre-cultured preparation. These cells were respectively stimulated by a single and multiple insonification for three minutes with a 20% duty cycle ultrasound of the intensity of 150 mW/cm2 (SATA). The cellular response was assessed, using the microscopic morphology, cell death measured by the typical MTT assay, and annexin V/PI double stain assay, for 8 times within 72 hours after that cells were stimulated. Results showed that both stimulations by single and multiple does ultrasound may diminish A beta induced neuronal cells apoptosis. The diminish effects tend to be time dependent corresponding to 72 and 12 hours after ultrasound exposure by single and multiple insonification, respectively. Fluorescence stain results indicated that those cells stimulated by a single dose ultrasound tended to slightly inhibit A beta-induced PC12 to apoptosis. This study demonstrated that the effect of diminishing neuronal cells from apoptosis could be regulated with the insonation of appropriate ultrasonic doses.

Effect of low intensity ultrasounds on the growth of osteoblasts.

Previous studies have indicated that low intensity ultrasounds could accelerate the repair of fibula fracture and facilitate the proliferation of osteoblasts. To further investigate the effect of low intensity ultrasounds, two different frequency of ultrasound, 1 MHz and 3 MHz, were applied to osteoblasts. The cells were stimulated for a typical 20% duty cycle of ultrasound with various intensities ranged from 50 to 150 mW/cm2 (ISATA) for 3 minutes once daily for 6 days. The cellular responses, in terms of cell number and morphological change, associated with ultrasound stimulations were estimated using a hemocytometer and microscopic morphology in which cells were stained with trypan blue. Results showed that the proliferation rates of osteoblasts for particular stimulated group are larger than those of control groups. The largest proliferation rate corresponds to those cells culture at 24 hours after seeding. Ultrasound increased approximately the cell proliferation proportional to ultrasonic intensity at which the exposure of 100 mW/cm2 intensity of 1 MHz ultrasound 1.1 fold, and 50 mW/cm2 intensity of 3 MHz ultrasound 1.2 fold than that of the control group. These finding suggest that the growth of cell may be controlled by appropriate ultrasonic mechanical stress.