BackgroundTo identify changes in brain activation patterns in bipolar disorder (BD) and unipolar depression (UD) patients.Methodology/Principal FindingsResting-state fMRI scans of 16 healthy controls, 17 BD and 16 UD patients were obtained. T-test of normalized regional homogeneity (ReHo) was performed in a voxel-by-voxel manner. A combined threshold of á = 0.05, minimum cluster volume of V = 10503 mm3 (389 voxels) were used to determine ReHo differences between groups. In UD group, fMRI revealed ReHo increases in the left middle occipital lobe, right inferior parietal lobule, right precuneus and left convolution; and ReHo decreases in the left parahippocampalgyrus, right precentralgyrus, left postcentralgyrus, left precentralgyrus and left cingulated. In BD group, ReHo increases in the right insular cortex, left middle frontal gyrus, left precuneus, left occipital lobe, left parietal, left superior frontal gyrus and left thalamus; and ReHo decreases in the right anterior lobe of cerebellum, pons, right precentralgyrus, left postcentralgyrus, left inferior frontal gyrus, and right cingulate. There were some overlaps in ReHo profiles between UD and BD groups, but a marked difference was seen in the thalamus of BD.Conclusions/SignificanceThe resting-state fMRI and ReHo mapping are a promising tool to assist the detection of functional deficits and distinguish clinical and pathophysiological signs of BD and UD.

Purpose: To investigate how to label macrophages in atherosclerotic plaques with superparamagnetic iron oxide (SPIO) nanoparticles and trace SPIO with MR imaging. Materials and Methods:Atherosclerotic lesions of a rabbit model were induced by a combination of high-fat and high-cholesterol diet and subsequent endothelial abrasion of the abdominal aorta. SPIO particles were pretreated with poly-L-lysine. SPIO nanoparticles and SPIO-labeled human endothelial cells (ECV-304) were IV injected into model animals, respectively. The MRI scans and histopathological examination were performed 12 h and 24 h after the injection. The imaging and histopathological data were analyzed.Results: Prussian blue staining of the vessel specimens indicated that SPIO particles were not found in the atheroma but in the Kupffer's cells of the liver after SPIO injection. However, the accumulation of SPIO particles in the atheroma was confirmed in animals received SPIO-labeled endothelial cell transplantation. The best quality MR scan sequences of rabbit abdominal aorta were T 2 WI fat suppression, T 1 WI, and DIR series, on which of MR image had a higher quality. Signal loss of the original incrassate plaque in the vessel wall on T 2 WI was found in 6 of 10 animals received SPIO-labeled endothelial cell transplantation.Conclusion: SPIO-labeled endothelial cells were superior to SPIO for MR imaging of atherosclerotic plaques.

Dendritic cells (DCs) play an important role in atherosclerosis plaque formation, but the mechanism has not been elucidated clearly. This study is designed to establish a method for tracing DCs in vivo facilitating the investigation of the DCs' specific roles in atherosclerosis. Rabbit DCs labeled by different concentrations of ultra small superparamagnetic iron oxide (USPIO) were injected into atherosclerosis rabbit model and traced with magnetic resonance imaging (MRI). Results showed that USPIO labeling nearly have no cytotoxicity to DCs in low concentrations (<500 µg/mL) but induced some decrease of cell viability at high concentrations (>500 µg/mL). Moreover, USPIO labeling, from 200 to 2000 µg/mL, caused a dose-dependent decrease of the mitochondrial membrane potential in DCs. The high labeling concentration (2000 µg/mL) triggered necrosis instead of apoptosis in DCs. By T2WI and fs T2WI sequence imaging comparison, DCs were found to exist in rabbit abdominal artery plaques after 24 h of transplantation and in spleen after one week detected by Prussian blue staining of tissue sections. We concluded that about 200 µg/mL USPIO is ideal to effectively label DCs for MRI tracing in vivo without a threat to cell viability. Combining USPIO labeling and MRI to track the movement of injected DCs in vivo is a feasible method.