Common and unique alterations of functional connectivity in major depressive disorder and bipolar disorder.

OBJECTIVE: Major depressive disorder (MDD) and bipolar disorder (BD) are considered whole-brain disorders with some common clinical and neurobiological features. It is important to investigate neural mechanisms to distinguish between the two disorders. However, few studies have explored the functional dysconnectivity between the two disorders from the whole brain level. METHODS: In this study, 117 patients with MDD, 65 patients with BD, and 116 healthy controls completed resting-state functional magnetic resonance imaging (R-fMRI) scans. Both edge-based network construction and large-scale network analyses were applied. RESULTS: Results found that both the BD and MDD groups showed decreased FC in the whole brain network. The shared aberrant network across patients involves the visual network (VN), sensorimotor network (SMN), dorsal attention network (DAN), and ventral attention network (VAN), which is related to the processing of external stimuli. The default mode network (DMN) and the limbic network (LN) abnormalities were only found in patients with MDD. Furthermore, results showed the highest decrease in edges of patients with MDD in between-network FC in SMN-VN, whereas in VAN-VN of patients with BD. CONCLUSIONS: Our findings indicated that both MDD and BD are extensive abnormal brain network diseases, mainly aberrant in those brain networks correlated to the processing of external stimuli, especially the attention network. Specific altered functional connectivity also was found in MDD and BD groups, respectively. These results may provide possible trait markers to distinguish the two disorders.

Discrimination of vertebral fragility fracture with lumbar spine bone mineral density measured by quantitative computed tomography.

BACKGROUND/OBJECTIVE: This study is a case-control study to explore risk and protective factors, including clinical data and bone mineral density (BMD), affecting vertebral body fragility fracture in elderly men and postmenopausal women. In addition, we investigate the effectiveness of lumbar spine BMD by quantitative computed tomography (QCT) in discriminating vertebral fragility fracture. METHODS: In this case-control study, 52 males and 198 females with vertebral fragility fracture were compared with sex- and age-matched healthy controls to analyse the risk factors that may affect vertebral fragility fracture. The L1-L3 vertebral BMDs were measured by QCT. The difference in risk factors between fracture cases and controls were analysed using student t test and Mann-Whitney U test. The correlation between BMD, age, height and weight were analysed using univariate analysis. Multiple logistic regression analysis was used to study statistically significant indexes. The receiver operating characteristic curve was used to calculate the cut-off values for positive and negative predictive values of BMD for vertebral fracture discrimination. RESULTS: In males, body weight and BMD were significantly different between the fracture group and the control group, whereas BMD was only weakly correlated with age (r = -0.234). In females, only BMD was significantly different between the fracture and control groups. BMD was weakly correlated with height (r = 0.133) and weight (r = 0.120) and was moderately correlated with age (r = -0.387). There was no correlation between BMD and the remaining variables in this study. In both men and women, the BMD (p = 0.000) was the independent protective factor against vertebral fracture. The cut-off values of vertebral BMD for fractures were 64.16 mg/cm3 for males and 55.58 mg/cm3 for females. QCT-measured BMD has a high positive predictive value and negative predictive value for discriminating vertebral fragility fracture across a range of BMD values. CONCLUSION: This study suggests that BMD is closely related to vertebral fragility fracture and that QCT is an effective technique to accurately discriminate vertebral fragility fracture. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: The spine BMD measured by QCT is closely related to fracture, which may allow clinicians to more accurately discriminate which individuals are likely to experience vertebral fragility fracture.

Correlation between Non-Alcoholic Fatty Liver Disease and Visceral Adipose Tissue in Non-Obese Chinese Adults: A CT Evaluation.

Objective: To investigate the correlation between non-alcoholic fatty liver disease and visceral adipose tissue in non-obese Chinese adults using computed tomography (CT). Materials and Methods: The study included 454 subjects undergoing abdominal CT scan. Degree of CT attenuation in liver and spleen, and the degree of fat infiltration in liver were evaluated according to three indices: the attenuation value of liver parenchyma (CTLP), the attenuation ratio of liver and spleen (LSratio) and the attenuation difference between liver and spleen (LSdif). Visceral fat area (VFA) and total fat area (TFA) at L2/3 and L4/5 levels were measured, and the abdominal subcutaneous fat area (SFA) was calculated. Bivariate correlation analysis was carried out to determine the correlation among these factors. Results: In men, VFA, SFA and TFA at L2/3 and L4/5 levels showed significant differences in terms of the three indices to distinguish fatty liver from non-fatty liver (all, p < 0.001). In men, all the three indices showed negative correlation with TFA, SFA and VFA (all, p < 0.001). The negative correlation between the three indices and VFA at the L2/3 level was higher than at L4/5 level (r = -0.476 vs. r = -0.340 for CTLP, r = -0.502 vs. r = -0.413 for LSratio, r = -0.543 vs. r = -0.422 for LSdif, p < 0.001, respectively). The negative correlation between LSratio, LSdif and VFA at L2/3 and L4/5 levels was higher than SFA at the corresponding level. In women, all the three indices showed negative correlation with VFA and TFA at L2/3 and L4/5 levels, and the negative correlation between CTLP and VFA was higher at L2/3 level than at L4/5 level (r = -0.294 vs. r = -0.254, p < 0.001). Conclusion: In non-obese Chinese adults, the degree of hepatic fatty infiltration showed a strong correlation with abdominal fat on CT. VFA at L2/3 level was more closely related to fatty liver compared with VFA at L4/5 level.

Dysembryoplastic neuroepithelial tumors: magnetic resonance imaging and magnetic resonance spectroscopy evaluation.

BACKGROUND: Dysembryoplastic neuroepithelial tumor (DNT) is a rare benign neoplasm of the central nervous system affecting young people. A correct preoperative diagnosis is helpful for planning surgical strategies and improving prognosis. The purpose of this study was to characterize DNTs using magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) and to analyze the value of these two techniques in the diagnosis of DNTs. METHODS: MR images of 13 patients with DNTs were reviewed retrospectively; and five of the patients also underwent MRS. Tumors were confirmed by surgery. The distribution, extension and signal features of the lesions were assessed, and the MRS results were analyzed. RESULTS: All tumors were supratentorial. The cortex was the main area involved, with nine tumors located in the temporal lobe, three in the frontal lobe, and one on the boundary between the temporal and occipital lobes. All cases had decreased signal intensity on T1-weighted MR images and increased signal intensity on T2-weighted images. On fluid attenuated inversion recovery weighted images, the hyperintense "ring sign" and internal septation of the lesion were seen in 9 cases. Eight tumors had well-demarcated borders. Peritumoral edema or mass effect was absent in all cases. A contrast enhancement examination was performed in 9 cases. Contrast enhancement was absent in five cases, and four cases showed significant enhancement. The MRS showed a low N-acetylaspartate peak and a lack of elevated choline-containing component (Cho) or Cho-Cr ratio (Cho/Cr) in five patients. CONCLUSIONS: The MRI findings of DNTs were stereotypical. The combination of MRI and MRS techniques were helpful in making a correct presurgical diagnosis.

Diffusion tensor imaging in medial temporal lobe epilepsy.

BACKGROUND: Diffusion tensor imaging (DTI) is a noninvasive imaging technique for the assessment of the integrity of cerebral tissues. This study was undertaken to assess the changes of diffusion indices of hippocampal formation (HF) in patients with medial temporal lobe epilepsy (MTLE). METHODS: Fourteen patients with MTLE and 14 healthy subjects were evaluated. Mean diffusivity (MD) and fractional anisotropy (FA) from the symmetrical-voxel sampling regions of the anterior HF were calculated in all subjects. The MD and FA values were compared across the groups. RESULTS: No significant differences of MD and FA values were noted between right and left HF in the controls. In the patient group, MD significantly increased in the HF ipsilateral to the lesioned side [(9.27 +/- 1.09) x 10(-4) mm(2)/s], compared with the values in the contralateral HF [(8.20 +/- 0.59) x 10(-4) mm(2)/s] (t = 4.479, P = 0.001) and healthy subjects [(7.58 +/- 0.51) x 10(-4) mm(2)/s] (P < 0.001), but no significant differences were found in FA. When compared with the controls, patients had a significantly higher MD in the contralateral HF (P < 0.05), but the difference in FA was not statistically significant. CONCLUSIONS: DTI could detect hippocampal abnormality in patients with MTLE. This technique may be helpful for preoperative evaluation of such patients.

Application of functional MRI in epilepsy.

OBJECTIVE: To review the recent development of functional MRI application in epilepsy. DATA SOURCES: Both Chinese and English language literatures were researched using MEDLINE/CD ROM (1996 - 2005) and the Chinese Biomedical Literature Disk (1996 - 2005). STUDY SELECTION: Published articles about functional MRI application and epilepsy were selected. DATA EXTRACTION: Data were mainly extracted from 38 articles which are listed in the reference section of this review. RESULTS: fMRI can be used to localize seizure foci through detecting these cerebral hemodynamic changes produced by epileptiform discharges. EEG-triggered fMRI, which has higher spatial and temporal resolution, helps to detect the spatiotemporal pattern of spike origin and propagation, and define localization of the epileptogenic focus. fMRI is also useful in language and memory cognitive function assessment and presurgical assessment of refractory epilepsy. Atypically distributed cognitive function areas can be detected by fMRI, because of cortical language and memory areas reorganization during long-term epileptic activity in patients with epilepsy. CONCLUSIONS: fMRI technique plays a very important role in cognitive function and presurgical assessment of patients with epilepsy. It is meaningful for understanding pathogenesis of epilepsy.