Publications (19)45.51 Total impact
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Article: Overlapping and segregated resting-state functional connectivity in patients with major depressive disorder with and without childhood neglect.
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ABSTRACT: Many studies have suggested that childhood maltreatment increase risk of adulthood major depressive disorder (MDD) and predict its unfavorable treatment outcome, yet the neural underpinnings associated with childhood maltreatment in MDD remain poorly understood. Here, we seek to investigate the whole-brain functional connectivity patterns in MDD patients with childhood maltreatment. Resting-state functional magnetic resonance imaging was used to explore intrinsic or spontaneous functional connectivity networks of 18 MDD patients with childhood neglect, 20 MDD patients without childhood neglect, and 20 healthy controls. Whole-brain functional networks were constructed by measuring the temporal correlations of every pairs of brain voxels and were further analyzed by using graph-theory approaches. Relative to the healthy control group, the two MDD patient groups showed overlapping reduced functional connectivity strength in bilateral ventral medial prefrontal cortex/ventral anterior cingulate cortex. However, compared with MDD patients without a history of childhood maltreatment, those patients with such a history displayed widespread reduction of functional connectivity strength primarily in brain regions within the prefrontal-limbic-thalamic-cerebellar circuitry, and these reductions significantly correlated with measures of childhood neglect. Together, we showed that the MDD groups with and without childhood neglect exhibited overlapping and segregated functional connectivity patterns in the whole-brain networks, providing empirical evidence for the contribution of early life stress to the pathophysiology of MDD. Hum Brain Mapp, 2013. © 2013 Wiley Periodicals, Inc.Human Brain Mapping 02/2013; · 5.88 Impact Factor -
Article: Dynamic characteristics of MR diffusion-weighted imaging in a rabbit liver VX-2 tumor model.
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ABSTRACT: PURPOSE: To investigate prospectively dynamic characteristics of the apparent diffusion coefficient (ADC) on MR diffusion-weighted imaging (DWI) in a rabbit VX-2 tumor model. MATERIALS AND METHODS: Forty New Zealand rabbits were included in the study, and 47 rabbit VX-2 tumor models were developed by direct and intrahepatic implantation after opening the abdominal cavities. DWI was carried out periodically and respectively on days 7, 14 and 21 after implantation. The VX-2 tumor samples were studied by pathology. The distinction of VX-2 tumors on DWI was assessed by their ADC values by analysis of variance (ANOVA) using SPSS12.0 software. RESULTS: The ADC values (mean ± SD) × 10(-3) mm(2)/s of 47 VX-2 tumors in the peripheral and central areas were 2.18 ± 0.29, 1.96 ± 0.33, 1.80 ± 0.35, 2.20 ± 0.29, 2.05 ± 0.30 and 1.96 ± 0.48, respectively, on days 7, 14 and 21 after implantation. ADC values of 47 VX-2 tumors in the area of the tumor periphery, center and normal parenchyma were higher when the b-value was 100 s/mm(2) than those when the b-value was 300 s/mm(2) (F = 17.964, p < 0.001; F = 13.986, p < 0.001; F = 128.681, p < 0.001). ADC values in the area of normal liver parenchyma were higher than those in the area of the VX-2 tumor periphery and center when the b-value was 100 or 300 s/mm(2). ADCs of viable tumor cells in VX-2 tumors were lower on DWI than those in the area of normal liver parenchyma around the tumor, and ADCs of dead tumor cells in VX-2 tumors were unequal, including high, equal and low values, but they were higher than in the area of normal liver parenchyma around tumors after dead tumor cells had been liquefied or had become cystic. CONCLUSION: ADC is correlated with the tumor histology and degree of malignancy, and DWI has potential value for dynamically monitoring tumors and evaluating the degree of malignancy and therapeutic effect.Japanese journal of radiology 12/2012; · 0.65 Impact Factor -
Article: [A functional MRI study in ADHD children with impulsivity].
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ABSTRACT: Impulsivity is one of the core symptoms of children with attention deficit hyperactivity disorder (ADHD). In order to understand the neuromechanism of the impulsive behaviors in ADHD children, this study investigated the specific functional areas of the brain by functional MRI. The subjects consisted of 10 ADHD children with impulsivity, 7 ADHD children without impulsivity and 9 normal children. A functional MRI examination was performed when the subjects were instructed to finish GO and STOP tasks with the GO-STOP impulsivity paradigm. The MRI data during the two tasks of GO and STOP were averaged and the corresponding activation regions between groups were compared. The data from the GO task revealed that the main activation regions of the normal children included frontal pole (superior frontal gyrus, middle frontal gyrus and medial frontal gyrus); the main activation regions of ADHD children without impulsivity were cerebellum (posterior lobe and anterior lobe bouton) and cingulated gyrus; those of ADHD children with impulsivity were medial globus pallidus and insula. The data from the STOP task showed that the main activation regions of normal children included superior frontal gyrus and middle frontal gyrus; those of ADHD children without impulsivity were middle frontal gyrus and cingulate gyrus; those of ADHD children with impulsivity were uncus and putamen. The activation regions of ADHD children with impulsivity were much fewer than the other two groups. The behavior of impulsivity-control involves a number of specific functional areas in the cerebral cortex. Compared with normal children, ADHD children without impulsivity have weaker brain function and brain activation, and ADHD children with impulsivity demonstrate much fewer brain activation regions, worse brain function and little awareness of the cerebral cortex.Zhongguo dang dai er ke za zhi = Chinese journal of contemporary pediatrics 01/2010; 12(1):24-8. -
Article: [Comparison between pathological findings and MR diffusion-weighted imaging in primary hepatocellular carcinoma after transcatheter arterial chemoembolization].
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ABSTRACT: To explore the pathological basis of diffusion-weighted imaging (DWI) findings in hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE). DWI was performed in 15 patients with HCC treated by TACE within 24 - 48 hours before II-phase operation. The DWI findings of the liver lesions were analyzed and correlated with pathological findings including macroscopic observation, HE staining and immunohistochemical staining for bFGF. (1) The viable tumor area showed mostly hypersignal intensity (12/15), whereas coagulative necrotic lesions showed hyposignal (8/15) or isosignal intensity (6/15). The ADC values of zones of viable tumor and necrosis in tumor were (1.42 +/- 0.16) x 10(-3) mm(2)/s and (1.58 +/- 0.18) x 10(-3) mm(2)/s, respectively. There was a significant difference of ADC values between the two zones (t = 2.618, P < 0.05). (2) There was a significant difference in ADC values of viable tumor between well and poorly differentiated tumors (t = -2.646, P < 0.05). The distinction of ADC values of the whole tumor was significant among tumors with different degree of necrosis (chi(2) = 7.236, P < 0.05). (3) A negative correlation was observed between bFGF protein expression index and ADC values of viable parts of the tumors in the study group (r = -0.552, P = 0.033). DWI shows certain characteristic features of the HCC after TACE, and can be used to distinguish viable and necrotic tumor tissues in HCC after TACE.Zhonghua zhong liu za zhi [Chinese journal of oncology] 01/2009; 30(12):914-6. -
Article: Gene expression and MR diffusion-weighted imaging after chemoembolization in rabbit liver VX-2 tumor model.
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ABSTRACT: To investigate the dynamic characteristics and the correlation between PCNA, Bax, nm23, E-cadherin expression and apparent diffusion coefficient (ADC) on MR diffusion-weighted imaging (DWI) after chemoembolization in rabbit liver VX-2 tumor model. Forty New Zealand rabbit liver VX-2 tumor models were included in the study. DWI was carried out periodically after chemoembolization. All VX-2 tumor samples in each group were examined by histopathology and Strept Avidin-Biotin Complex (SABC) immunohistochemical staining. The PCNA expression index in VX-2 tumors was higher than in the normal parenchyma around the tumor (P < 0.001). Nm23, Bax or E-caderin expression index in VX-2 tumors were lower than in the normal parenchyma around the tumor (all P < 0.001). PCNA and nm23 expression in the VX-2 tumor periphery first increased and then decreased (P < 0.001 and P = 0.03, respectively), while the expression of Bax and E-cadherin before and after chemoembolization was insignificant. When b-value was 100 s/mm(2), there was a linear correlation between PCNA expression and ADC in the area of VX-2 tumor periphery (P < 0.001), and PCNA expression in VX-2 tumor periphery influenced the ADC. The potential of VX-2 tumor infiltrating and metastasizing decreases, while its ability to proliferate increases for a short time after chemoembolization. To some degree, the ADC value indirectly reflects the proliferation of VX-2 tumor cells.World Journal of Gastroenterology 09/2008; 14(36):5557-63; discussion 5562. · 2.47 Impact Factor -
Article: Characteristics of liver on magnetic resonance diffusion-weighted imaging: dynamic and image pathological investigation in rabbit liver VX-2 tumor model.
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ABSTRACT: To investigate dynamical and image pathological characteristics of the liver on magnetic resonance (MR) diffusion-weighted imaging (DWI) in the rabbit VX-2 tumor model. Forty New Zealand rabbits were included in the study and VX-2 tumor piece was implanted intrahepatically. Fifteen animals received two intrahepatic implantations while 25 had one intrahepatical implantation. DWI, T1- and T2-weighted of magnetic resonance imaging (MRI) were carried out on the 7th and the 14th d after implantation and DWI was conducted, respectively on the 21st d. Ten VX-2 tumor samples were studied pathologically. The rate of lump detected by DWI, T1WI and T2WI was 78.7%, 10.7% and 53.5% (c2=32.61, P<0.001) on the 7th d after implantation and 95.8%, 54.3% and 82.9% (c2=21.50, P<0.001) on the 14th d. The signal of most VX-2 tumors on DWI was uniform and it was equal on the map of apparent diffusion coefficient (ADC). The signal of VX tumors did not decrease on the 7th d after implantation, most of them slowly growing during the week following implantation without significant cell dying within the tumor. VX-2 tumors grew increasingly within 14 d after implantation but the signal of most VX-2 tumors on DWI or on the map of ADC was uniform or uneven and ADC of VX tumors decreased obscurely or slightly because tumor necrosis was still not obvious. On the 21st d after implantation, the signal of most VX-2 tumors on DWI or on the map of ADC was uneven because tumor necrosis was evident and ADC of VX-2 tumor necrotic areas decreased. The areas of viable cells in VX-2 tumors manifested a high signal on DWI and a low signal on the map of ADC. The areas of dead cells or necrosis in VX-2 tumors manifested low signals on DWI and low, equal or high signals on the map of ADC but they manifested high signals on DWI and on the map of ADC at the same time when the areas of necrotic tumor became liquefied or cystic. The border of tumors on DWI appeared gradually distinct and internal signals of tumor became progressively uneven. The manifestations of viable, necrotic and liquefied or cystic areas in VX-2 tumors on DWI are typical and DWI is of significant and potential values in clinical application in both the early detection and diagnosis of liver tumors.World Journal of Gastroenterology 08/2008; 14(25):3997-4004. · 2.47 Impact Factor -
Article: Characteristics and pathological mechanism on magnetic resonance diffusion-weighted imaging after chemoembolization in rabbit liver VX-2 tumor model.
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ABSTRACT: To investigate dynamic characteristics and pathological mechanism of signal in rabbit VX-2 tumor model on diffusion-weighted imaging (DWI) after chemoembolization. Forty New Zealand rabbits were included in the study and forty-seven rabbit VX-2 tumor models were raised by implanting directly and intrahepatically after abdominal cavity opened. Forty VX-2 tumor models from them were divided into four groups. DWI was performed periodically and respectively for each group after chemoembolization. All VX-2 tumor samples of each group were studied by pathology. The distinction of VX-2 tumors on DWI was assessed by their apparent diffusion coefficient (ADC) values. The statistical significance between different time groups, different area groups or different b-value groups was calculated by using SPSS12.0 software. Under b-value of 100 s/mm(2), ADC values were lowest at 16 h after chemoembolization in area of VX-2 tumor periphery, central, and normal liver parenchyma around tumor, but turned to increase with further elongation of chemoembolization treatment. The distinction of ADC between different time groups was significant respectively (F = 7.325, P < 0.001; F = 2.496, P < 0.048; F = 6.856, P < 0.001). Cellular edema in the area of VX-2 tumor periphery or normal liver parenchyma around tumor, increased quickly in sixteen h after chemoembolization but, from the 16th h to the 48th h, cellular edema in the area of normal liver parenchyma around tumor decreased gradually and that in the area of VX-2 tumor periphery decreased lightly at, and then increased continually. After chemoembolization, Cellular necrosis in the area of VX-2 tumor periphery was more significantly high than that before chemoembolization. The areas of dead cells in VX-2 tumors manifested low signal and high ADC value, while the areas of viable cells manifested high signal and low ADC value. DWI is able to detect and differentiate tumor necrotic areas from viable cellular areas before and after chemoembolization. ADC of normal liver parenchyma and VX-2 tumor are influenced by intracellular edema, tissue cellular death and microcirculation disturbance after chemoembolization.World Journal of Gastroenterology 11/2007; 13(43):5699-706. · 2.47 Impact Factor -
Article: Reduced ventral anterior cingulate and amygdala volumes in medication-naïve females with major depressive disorder: A voxel-based morphometric magnetic resonance imaging study.
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ABSTRACT: High resolution magnetic resonance imaging and voxel-based morphometry were used to compare regional gray matter volumes between 14 medication-naïve female participants with a first episode of major depressive disorder (MDD) and 13 female healthy comparison participants (HC). Volumes of bilateral ventral anterior cingulate cortex (vACC) and right amygdala were significantly smaller in the MDD group than in the HC group. These results suggest that volume reductions in vACC and amygdala in females with MDD are present at illness onset.Psychiatry Research 11/2007; 156(1):83-6. · 2.52 Impact Factor -
Article: Prefrontal white matter abnormalities in young adult with major depressive disorder: a diffusion tensor imaging study.
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ABSTRACT: Prefrontal impairments have been hypothesized to be most strongly associated with the cognitive and emotional dysfunction in depression. Recently, white matter microstructural abnormalities in prefrontal lobe have been reported in elderly patients with major depressive disorder (MDD) using diffusion tensor imaging (DTI). However, it is still unclear whether the same changes exist in younger patients. In the present study, we first utilized DTI to detect prefrontal white matter in young adults with MDD. Nineteen first-episode, untreated young adults with MDD and twenty age- and gender-matched healthy controls were recruited. DTI and localizing anatomic data were acquired. Then, the regions of interest (ROIs) were located in prefrontal white matter at 4 mm inferior, and 0, 4, 8, 12, 16 and 20 mm superior to the anterior commissure-posterior commissure (AC-PC) plane, respectively. Compared with healthy controls, patients with MDD showed significantly lower fractional anisotropy (FA) values in prefrontal white matter at bilateral 20 mm, right 16 mm and right 12 mm above the AC-PC. Furthermore, there was no significant correlation between the FA value of any ROI and illness course as well as severity of depression. Together with previous findings, the present results suggest that microstructural abnormalities in prefrontal white matter may occur early in the course of MDD and may be related to the neuropathology of depression throughout adulthood from young to elderly.Brain Research 10/2007; 1168:124-8. · 2.73 Impact Factor -
Article: Brain responses to symptom provocation and trauma-related short-term memory recall in coal mining accident survivors with acute severe PTSD.
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ABSTRACT: Functional neuroimaging studies have largely been performed in patients with longstanding chronic posttraumatic stress disorder (PTSD). Additionally, memory function of PTSD patients has been proved to be impaired. We sought to characterize the brain responses of patients with acute PTSD and implemented a trauma-related short-term memory recall paradigm. Individuals with acute severe PTSD (n=10) resulting from a mining accident and 7 men exposed to the mining accident without PTSD underwent functional magnetic resonance imaging (fMRI) while performing the symptom provocation and trauma-related short-term memory recall paradigms. During symptom provocation paradigm, PTSD subjects showed diminished responses in right anterior cingulate gyrus, left inferior frontal gyrus and bilateral middle frontal gyrus and enhanced left parahippocampal gyrus response compared with controls. During the short-term memory recall paradigm, PTSD group showed diminished responses in right inferior frontal gyrus, right middle frontal and left middle occipital gyrus in comparison with controls. PTSD group exhibited diminished right parahippocampal gyrus response during the memory recall task as compared to the symptom provocation task. Our findings suggest that neurophysiological alterations and memory performance deficit have developed in acute severe PTSD.Brain Research 06/2007; 1144:165-74. · 2.73 Impact Factor -
Article: White matter abnormalities in first-episode, treatment-naive young adults with major depressive disorder.
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ABSTRACT: The aim of this study was to explore the microstructural integrity of whole-brain white matter by diffusion tensor imaging in first-episode, treatment-naive young adults with major depressive disorder. Diffusion tensor imaging scans were obtained from 14 first-episode, treatment-naive young adult patients with major depressive disorder and 14 healthy comparison subjects. A voxel-based method was used to analyze the scans. The patient group exhibited significantly lower fractional anisotropy values than healthy comparison subjects in the white matter of the right middle frontal gyrus, the left lateral occipitotemporal gyrus, and the subgyral and angular gyri of the right parietal lobe. There were no regions of significantly higher fractional anisotropy values in patients compared with healthy comparison subjects. These findings suggest that abnormalities of brain white matter may be present early in the course of major depressive disorder. They also support the idea that white matter lesions may disrupt the neural circuits involved in mood regulation and thus contribute to the neuropathology of major depressive disorder.American Journal of Psychiatry 06/2007; 164(5):823-6. · 12.54 Impact Factor -
Article: Second-order moments representation of nonparaxial TM flattened Gaussian beams
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ABSTRACT: By using the angular spectrum representation of the Hertz vector and the theory of nonparaxial vectorial moments of light beam propagation, expressions for the width matrix, curvature and divergence matrices and M 2 factor of nonparaxial TM flattened Gausssian beams (FGBs) are derived and their matrix elements are expressed in terms of a series sum. Generally, nonparaxial TM FGBs possess different beam widths, divergence angles and M 2 factors in the x and y directions, which are dependent on the beam order N and f parameter. For 1/f → 0 the divergence angles θ x and θ y in the x and y directions approach their maximum values θ x = 54.736° and θ y = 63.435°, respectively. The M 2 factor can be less than 1 and take arbitrarily small values if 1/f is small enough.Journal of Modern Optics 08/2006; 53(12):1727-1737. · 1.17 Impact Factor -
Article: Magnetic resonance imaging and magnetic resonance spectroscopy study of deficits in hippocampal structure in fire victims with recent-onset posttraumatic stress disorder.
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ABSTRACT: To explore hippocampal structural abnormalities in fire victims with recent-onset posttraumatic stress disorder (PTSD). We compared 12 patients with recent-onset PTSD diagnosed according to DSM-IV criteria 6 to 8 months after a major fire with 12 individuals without PTSD who were victims of the same fire accident. Voxel-based morphometry (VBM) and magnetic resonance spectroscopy (MRS) were combined to examine hippocampal structural abnormalities in patients with recent-onset PTSD. Results of VBM showed that the grey matter density of the left hippocampus was lower in the group with PTSD than it was in the group without PTSD. Results of MRS showed that the ratio of N-acetyl asparate and creatine in the left hippocampus was significantly lower in patients with PTSD than in control subjects. Patients with recent-onset PTSD had hippocampal structural abnormalities.Canadian journal of psychiatry. Revue canadienne de psychiatrie 07/2006; 51(7):431-7. · 2.42 Impact Factor -
Article: Gray matter density reduction in the insula in fire survivors with posttraumatic stress disorder: a voxel-based morphometric study.
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ABSTRACT: Voxel-based morphometry (VBM) is an objective whole-brain technique for characterizing regional cerebral volume and tissue concentration differences in structural magnetic resonance images. In the current study, we used VBM to examine possible cerebral gray matter abnormalities in patients with posttraumatic stress disorder (PTSD) due to fire. The subjects included 12 victims of a fire disaster with PTSD and 12 matched victims of the same fire without PTSD. Magnetic resonance images were obtained on a 1.5-Tesla General Electric scanner at Central South University, and an entire brain volume of 248 contiguous slices was obtained for each subject. Then, gray matter density in patients with PTSD and control groups was compared by using a VBM approach in SPM2. Group analysis was thresholded at P<0.001, uncorrected, at the voxel level. The following three regions of reduced gray matter volume were found in patients with PTSD compared with controls: left hippocampus, left anterior cingulate cortex (ACC), and bilateral insular cortex. It was concluded that there are structural abnormalities of the hippocampus, the ACC and the insular cortex in patients with PTSD due to fire.Psychiatry Research 02/2006; 146(1):65-72. · 2.52 Impact Factor -
Article: MR diffusion-weighed imaging of rabbit liver.
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ABSTRACT: To study the techniques of MR diffusion-weighed imaging (DWI) for normal rabbit liver. After 15 normal New Zealand white rabbits and one New Zealand white rabbit implanted with VX-2 tumor were anesthetized with 3% soluble pentobarbitone, DWI was performed respectively for different b values, repetition times (TR) or thicknesses, when other parameters were the same and magnetic resonance imaging (MRI) was performed respectively, or with different field of views (FOV) or coil when other parameters were the same. The distinction between groups was analyzed by SPSS10.0 with apparent diffusion coefficient (ADC), quality index (QI) or signal-noise ratio (SNR). As b value increased, liver ADC, QI and SNR of DWI became smaller and simultaneously (F = 292.87, 156.1, 88.23, P<0.01). QI of DWI was high, when b value was 10, 50 or 100 respectively, but the distinction between them was insignificant; when b value was 800, QI and SNR of DWI were low. QI and SNR of DWI had no significant difference between TR = 4 000, 6 000 and 8 000. QI of DWI with 2 mm thickness was bigger than that with 5 mm thickness (t = 3.04, P<0.01), but SNR of DWI with 2 mm thickness was significantly smaller (t = -17.86, P<0.01). SNR of MRI with knee joint coil was obviously bigger than that with cranium coil (t = -5.77 (T1WI) or -4.02 (T2WI), P<0.01), but QI of MRI was smaller on the contrary (t = 7.10 (T1WI) or 3.97 (T2WI), P<0.01). When FOV was enlarged gradually, SNR of MRI increased (F = 85.81 (T1WI) or 221.96 (T2WI), P<0.01), but QI firstly increased, then decreased (F = 68.67 (T1WI) or 69.46 (T2WI), P<0.01) and QI of MRI was the biggest when FOV was 20 cm x 15 cm. The scanning technique is very important in DWI of rabbit liver and the overall quality of DWI with b (100 s/mm2), thickness (2 mm), cranium coils and FOV (20 cm x 15 cm) was best in our study, when other parameters were the same.World Journal of Gastroenterology 10/2005; 11(35):5506-11. · 2.47 Impact Factor -
Article: MR diffusion-weighted imaging of rabbit liver VX-2 tumor.
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ABSTRACT: To investigate the implanting method of rabbit liver VX-2 tumor and its MR diffusion-weighted imaging (DWI) characteristics. Thirty-five New Zealand rabbits were included in the study. VX-2 tumor was implanted subcutaneously in 14 rabbits and intrahepatically in 6 for pre-experiments. VX-2 tumor was implanted intrahepatically in 12 rabbits for experiment and three were used as the control group. DWI, T1- and T2-weighted of MRI were performed periodically in 15 rabbits for experiment before and after implantation. The distinction of VX-2 tumors on DWI was assessed by their apparent diffusion coefficient (ADC) values. The statistical significance was calculated by analysis of variance (ANOVA) of the randomized block design using SPSS10.0 software. The successful rate of subcutaneous implantation of VX-2 tumor was 29% (4/14) while that of intrahepatic implantation of it was 33% (2/6) in the pre-experiment. The successful rate of intrahepatic implantation of VX-2 tumor in the experiment was 83% (10/12) and 15 tumors grew in 10 successfully implanted rabbits. The DWI signal of VX-2 tumor was high and became lower when the b value increased step by step. The signal of VX-2 tumor on the map of ADC was low. When the b value was 100 or 300 s/mm2, the ADC value of normal group and VX-2 tumor group was respectively 2.57+/-0.26, 1.73+/-0.31, 1.87+/-0.25 and 1.57+/-0.23 mm2/s. Their distinction was significant (F = 43.26, P<0.01), the tumor ADC value between b values 100 and 300 s/mm2 was significant (Tukey HSP, P<0.05) and the ADC value between VX-2 tumor and normal liver was also significant (Tukey HSP, P<0.01). VX-2 tumor developed quickly and metastasized early to all body, especially to the lung, liver, lymph nodes of mediastinum, etc. The DWI signal of rabbit VX-2 tumor has its characteristics on MR DWI and DWI plays an important role in diagnosing and discovering VX-2 tumor.World Journal of Gastroenterology 06/2005; 11(20):3070-4. · 2.47 Impact Factor -
Article: [Motor cortex by real-time imaging process functional MRI during finger movements].
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ABSTRACT: To explore the techniques of RTIP-fMRI scanning and the correspondence between structure and functional changes of motor cortex during self-paced finger movements by RTIP-fMRI in normal volunteers. The 15 healthy volunteers were studied by RTIP-fMRI, and the activation tasks consisted of self-paced finger movements performed with the right and the left hands. Image postprocessing was done on the workstation by "correlation coefficient" algorithm analysis method, IAC and SPM software. There was a good correspondence between the anatomical landmarks of the somatotopical organization of primary motor areas in the 15 volunteers; during the finger tasks, the functional changes occurred in the contralateral primary motor-somatosensory cortex (M1/S1), the supplementary motor area (SMA), and the ipsilateral primary motor cortex. RTIP, a promising new technique, can localize the motor cortex accurately. It is superior to any other fMRI techniques, and may be used widely in the function research of the brain.Zhong nan da xue xue bao. Yi xue ban = Journal of Central South University. Medical sciences 09/2004; 29(4):397-400. -
Article: Far-field properties and beam quality of vectorial Hermite–Laguerre–Gaussian beams beyond the paraxial approximation
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ABSTRACT: The far-field properties and beam quality of vectorial nonparaxial Hermite–Laguerre–Gaussian (HLG) beams are studied in detail, where, instead of the second-order-moments-based M2 factor, the extended power in the bucket (PIB) and βparameter are used to characterize the beam quality in the far field and the intensity in the formulae is replaced by the z component of the time-averaged Poynting vector 〈Sz〉. It is found that the 〈Sz〉 PIB and βparameter of vectorial nonparaxial HLG beams depend on the mode indices n, m, αparameter and waist-width-to-wavelength ratio w0/λ and the PIB and βparameter are additionally dependent on the bucket's size taken.Optics & Laser Technology. -
Article: Characteristics of depth-sensing coplanar grid CdZnTe detectors
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ABSTRACT: The latest depth-sensing coplanar grid CdZnTe detectors have been tested. Two of these have dimensions 1.5×1.5×1.0 cm3 and one is a cylindrical detector with 1.5 cm diameter and 1.0 cm length, all of them using the third-generation coplanar anode design. Energy resolutions of 2.0% and 2.4% FWHM at 662 keV γ-ray energies were obtained. Detector performance has been observed experimentally as a function of depth of the γ-ray interaction, and as a function of radial position near the anode surface. The measured results show the improvement of the third-generation anode design. Material uniformity of CdZnTe crystals manufactured by eV Products have been directly observed and compared on two 1.5×1.5×1.0 cm3 detectors.Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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2012
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Central South University
Changsha, Hunan, China
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