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Abstract: Structural brain abnormalities have been widely reported in major depressive disorder (MDD). However, many previous results cannot exclude the interferences of medication or multiple recurrent episodes. In this study, we examined structural brain abnormalities by comparing 68 drug-naïve first-episode adult-onset MDD and 68 healthy controls (HCs). Structural magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) methods were used. The mean values of grey matter volume/white matter volume (GMV/WMV) were calculated, then the differences between MDD and HCs were analyzed, and the associations of the differences with clinical characteristics of depression were discussed. The whole brain GMV/WMV did not differ between MDD patients and HCs; however, the regional GMV of the right pre-supplementary motor area (pre-SMA) was smaller in MDD patients. The GMV of both hippocampi was positively correlated with symptom severity and lower in patients with long durations. These results indicate the GMV reduction of the pre-SMA at an early stage of depression, whereas the GMV of the hippocampus is associated with depressive characteristics. Moreover, the whole brain GMV/WMV was negatively related to the duration of depression, supporting that volume loss could become progressive during the development of disease. These results may suggest the importance of identifying and intervening depression at an early stage, especially the first year after onset, to prevent volume loss in the brain. [Copyright &y& Elsevier]

X-ray Computed Tomography (CT) method is an integral part of hydraulic-fracture imaging, but its application to micro-fractures in cores is limited. This paper documents the visualization of fractured cores via an accessorial PET-CT approach to improve both spatial resolution and image contrast. PET-CT approach combines X-ray Computed Tomography (CT) and positron emission tomography (PET) method. CT technique provides information of core structure and accurate location of fractures based on density variations. PET is a nuclear imaging technique through inducing radionuclide into fractures, offering the potential to overcome CT limitations by providing information of micro-fractures. Combined PET-CT approach has been demonstrated as a technical advancement for imaging fractured cores better than simply CT or PET method. Comprehensive information of core structure, micro-fractures and connected fractures could be provided by PET-CT method. The applicability of each visualization technique was evaluated, the favorable implementation of combined PET-CT for laboratory core analysis was discussed. • Combined PET-CT technique was introduced to imaging hydraulic fractures in shale cores. • Improved image fusion method was proposed to fuse PET images and CT images. • Images with high resolution and contrast were obtained. • Combined PET-CT method shows superior to CT and PET method alone in providing comprehensive information of fractured cores. [ABSTRACT FROM AUTHOR]

For radiation detection, the imaging system should have a large field of view (FOV) and high detection efficiency because it has to be used in a radiation environment where the quantity and direction of radioactive sources are unknown. A panorama coded-aperture gamma camera optimized for use in complex nuclear environment has been developed and evaluated with an angular resolution of 3.5°. Typical gamma cameras have the limited field of view ranging from 10° to 60° in both horizontal and vertical direction. The system presented in this paper extends the field of view to 360° in the horizontal direction and 60° in the vertical direction. The partial encoding of coded aperture imaging is mitigated by convolving the data of diverse adjacent modules with a partial transmission function. The experimental feasibility of measuring multiple sources in the 360° horizontal field of view was demonstrated with a panoramic image. The results showed that the system could clearly identify the direction of multiple radiation sources in an unknown extended radiation environment. The system can help to simplify the clean up and decommissioning of nuclear sites. [ABSTRACT FROM AUTHOR]

Abstract: A depth discrimination method is devised based on a multirow linear array detector for push-broom Compton scatter imaging. Two or more rows of detector modules are placed at different positions towards a sample. An improved parallel-hole collimator is fixed in front of the modules to restrict their fields of view. The depth information could be indicated by comparing the signal differences. In addition, an available detector and several related simulations using GEANT4 are given to support the method well. [Copyright &y& Elsevier]

Abstract: A PET module that comprises a pair of compact, high-resolution and large-area detectors based on silicon photomultipliers (SiPM) was developed and evaluated. The detector''s effective area was 24mm×24mm. LYSO crystals measuring 1.9mm×1.9mm×10mm and charge division circuit were employed to obtain high spatial resolution with relatively concise Front-end electronics (FEE). Initial results showed the detector to be compatible with 1.5T magnetic fields. The system''s intrinsic FWHM spatial resolution is 1.50mm. The average energy resolution is 18.5% and the coincidence timing resolution is 2.6ns. [Copyright &y& Elsevier]