Weibo Chen

Characterizing Topological Patterns in Amnestic Mild Cognitive Impairment by Quantitative Water Diffusivity

Mean diffusivity (MD) derived from diffusion tensor imaging has shown its ability to assess the microscopic structural integrity damage of gray matter in amnestic mild cognitive impairment (aMCI), a prodromal stage of Alzheimers disease (AD). However, little is known about the small world topology networks constructed by cortical MD in cognitive disease. In this work, we measured the cortical MD in the entire brain in patients with aMCI (n = 30) and AD (n = 30) compared with cognitive-normal (CNs) controls (n = 30), and then constructed the cortical diffusivity network by using graph-theoretical analysis. Compared with CNs, patients with aMCI and AD showed abnormal small-world property of cortical diffusivity networks (higher degree of clustering and longer path length), reflecting a less optimal topological organization. Moreover, the mean degree of connections of network in aMCI patients was characterized by lower than CNs but higher than AD. In addition, 11 hub regions were identified by negative correlations between MD and the score of Montreal Cognitive Assessment after multiple regression analysis, including bilateral hippocampi and related limbic system. Among those hub regions, the connectivity of the right olfactory cortex and middle orbital gyrus to the rest of brain regions were disrupted earlier than the other 9 regions in aMCI when compared to CN. In conclusion, the change of cortical diffusivity in topological network organization, mean degree of connections, and disrupted hub regions in aMCI may serve to identify patients in the prodromal stage of AD and reflect microstructural deterioration of neurodegeneration.

Reduced GABA levels correlate with cognitive impairment in patients with relapsing-remitting multiple sclerosis

ObjectivesTo investigate if brain gamma-aminobutyric acid (GABA) levels in patients with relapsing-remitting multiple sclerosis (RRMS) are abnormal compared with healthy controls, and their relationship to cognitive function in RRMS.MethodsTwenty-eight RRMS patients and twenty-six healthy controls underwent magnetic resonance spectroscopy (MRS) at 3-T to detect GABA signals from posterior cingulate cortex (PCC), medial prefrontal cortex (mPFC) and left hippocampus using the ‘MEGAPoint Resolved Spectroscopy Sequence’ (MEGA-PRESS) technique. All subjects also underwent a cognitive assessment.ResultsIn RRMS patients, GABA+ were lower in the PCC (p = 0.036) and left hippocampus (p = 0.039) compared with controls, decreased GABA+ in the PCC and left hippocampus were associated with specific cognitive functions (r = -0.452, p = 0.016 and r = 0.451, p = 0.016 respectively); GABA+ in the mPFC were not significantly decreased or related to any cognitive scores (p > 0.05).ConclusionsThis study demonstrates that abnormalities of the GABAergic system may be present in the pathogenesis of RRMS and suggests a potential link between regional GABA levels and cognitive impairment in patients with RRMS.Key points• GABA levels may decrease in patients with RRMS.• Lower GABA levels correlated with worse cognitive performance in patients with RRMS.• Dysfunctional GABAergic neurotransmission may have a role in cognitive impairment in RRMS.

Diffusional kurtosis imaging of parotid glands in Sjögren's syndrome: Initial findings: DKI of Parotid in Sjögren's Syndrome

To explore the role of diffusion kurtosis imaging (DKI) of parotid glands in diagnosing Sjögrens syndrome (SS).

Investigation of diffusion kurtosis imaging for discriminating tumors from inflammatory lesions after treatment for bladder cancer: DKI After Treatment for Bladder Cancer

The bladder wall may thicken resulting from chronic inflammation after initial treatment (transurethral resection [TUR] or neoadjuvant chemotherapy), which may mimic the feature of recurrent or residual bladder tumors (RBT). Therefore, it is critical to discriminate RBT from benign lesions after initial treatment.

Correlation between intravoxel incoherent motion MR parameters and MR nodular grade of parotid glands in patients with Sjögren’s syndrome: A pilot study

PURPOSE To explore the correlation between intravoxel incoherent motion (IVIM) magnetic resonance (MR) parameters and MR nodular grade of parotid glands in patients with Sjögrens syndrome (SS). MATERIALS AND METHODS A total of 31 consecutive patients with SS and 28 gender- and age-matched healthy volunteers underwent bilateral parotid 3.0T MR examination including the IVIM sequence (9 b values, 0-800s/mm2). The apparent diffusion coefficient (ADC), diffusion coefficient D, pseudo-diffusion coefficient D*, and perfusion fraction f of bilateral parotid glands were obtained, and the nodular grade of each parotid gland was evaluated according to the MR morphological appearance. RESULTS Sixty-two parotid glands in 31 patients with SS consisted of 32, 14, 8, and 8 parotid glands at MR nodular grades 0, 1, 2, and 3, respectively. In parotid glands of grade 0, 1, 2, 3 and healthy volunteers, the ADC values were (1.13±0.25, 1.11±0.17, 1.05±0.24, 0.89±0.04 and 1.00±0.21)×10-3mm2/s, D values were (0.92±0.13, 0.90±0.19, 0.90±0.03, 0.67±0.03, 0.81±0.03)×10-3mm2/s, f values were 0.20±0.04, 0.18±0.02, 0.15±0.01, 0.11±0.01, 0.15±0.06, and D*values were (53.89±28.26, 41.78±16.35, 51.24±18.69, 31.83±18.03, 36.83±16.14)×10-3mm2/s respectively. The ADC, D, f, and D* values of parotid glands in patients with SS at grade 0 were significantly higher than those in healthy volunteers (all P<0.05). Significant differences were observed in the D and f values of parotid glands in patients with SS among different grades (P=0.003,<0.001, respectively). The IVIM parameters (D, f) of parotid glands at early (grades 0-1) and advanced (grades 2-3) stages in patients with SS were significantly higher and lower, respectively, than those in healthy volunteers (all P<0.05). The D and f values inversely correlated with MR nodular grades significantly (r=- 0.297, P=0.019; r=- 0.653, P<0.001, respectively) CONCLUSION: The parotid glands with different MR nodular grades in patients with SS showed different IVIM parameters, reflecting different pathophysiological characteristics of parotid glands at different stages.

Quantitative assessment of liver function with whole-liver T1rho mapping at 3.0T

OBJECTIVES To assess the segmental liver function in healthy subjects and liver cirrhosis (LC) patients with different Child-Pugh grades using whole-liver T1rho mapping at 3.0T. METHODS Thirty-three healthy volunteers and 33 patients with clinically diagnosed LC were examined using a three-dimensional (3D) whole-liver coverage T1rho mapping. T1rho maps were calculated from five respiratory-triggered sequences with different spin-lock durations (0, 10, 20, 40, and 60ms). The patients were classified into group A with Child-Pugh A cirrhosis and group B with Child-Pugh B or C cirrhosis. The hepatic T1rho values in different segments of the healthy volunteers and LC patients were compared, and receiver operating characteristic curves (ROC) were plotted to determine the performance of T1rho. RESULTS The median T1rho value of the patients (Child-Pugh class A: 47.07ms; Child-Pugh classes B and C: 51.09ms) was significantly higher than that of the healthy volunteers (39.37ms, P<0.001). No remarkable variations among different hepatic segments in LC patients with various Child-Pugh grades were found (P>0.05). The T1rho values of the liver parenchyma were significantly correlated with albumin (r=-0.590, P<0.001) and prothrombin time (r=0.601, P<0.001). The T1rho values in patients increased with an increase in the Child-Pugh classification (r=0.574, P<0.001). CONCLUSIONS The whole-liver coverage T1rho sequence at 3.0T was feasible for the assessment of segmental liver function. T1rho relaxation might be a potential biomarker for the estimation of liver function in LC patients.

Inhibitory motor dysfunction in parkinson's disease subtypes

Parkinsons disease (PD) is divided into postural instability gait difficulty (PIGD) and tremor‐dominant (TD) subtypes. Increasing evidence has suggested that the GABAergic neurotransmitter system is involved in the pathogenesis of PD.

Use of T1ρMR imaging in Sjögren's syndrome with normal appearing parotid glands: Initial findings

To explore the feasibility of parotid spin‐lattice relaxation time in the rotating frame (T1ρ) MR imaging in the diagnosis of Sjögrens syndrome (SS) without morphological changes of the parotid glands.

Spatial Navigation Impairment Is Associated with Alterations in Subcortical Intrinsic Activity in Mild Cognitive Impairment: A Resting-State fMRI Study

Impairment of spatial navigation (SN) skills is one of the features of the Alzheimers disease (AD) already at the stage of mild cognitive impairment (MCI). We used a computer-based battery of spatial navigation tests to measure the SN performance in 22 MCI patients as well as 21 normal controls (NC). In order to evaluate intrinsic activity in the subcortical regions that may play a role in SN, we measured ALFF, fALFF, and ReHo derived within 14 subcortical regions. We observed reductions of intrinsic activity in MCI patients. We also demonstrated that the MCI versus NC group difference can modulate activity-behavior relationship, that is, the correlation slopes between ReHo and allocentric SN task total errors were significantly different between NC and MCI groups in the right hippocampus (interaction F = 4.44, p = 0.05), pallidum (F = 8.97, p = 0.005), and thalamus (F = 5.95, p = 0.02), which were negative in NC (right hippocampus, r = −0.49; right pallidum, r = −0.50; right thalamus, r = −0.45; all p < 0.05) but absent in MCI (right hippocampus, r = 0.21; right pallidum, r = 0.32; right thalamus r = 0.28; all p > 0.2). These findings may provide a novel insight of the brain mechanism associated with SN impairment in MCI and indicated a stage specificity of brain-behavior correlation in dementia. This trial is registered with ChiCTR-BRC-17011316.

Cerebral Glioma Grading Using Bayesian Network with Features Extracted from Multiple Modalities of Magnetic Resonance Imaging

Many modalities of magnetic resonance imaging (MRI) have been confirmed to be of great diagnostic value in glioma grading. Contrast enhanced T1-weighted imaging allows the recognition of blood-brain barrier breakdown. Perfusion weighted imaging and MR spectroscopic imaging enable the quantitative measurement of perfusion parameters and metabolic alterations respectively. These modalities can potentially improve the grading process in glioma if combined properly. In this study, Bayesian Network, which is a powerful and flexible method for probabilistic analysis under uncertainty, is used to combine features extracted from contrast enhanced T1-weighted imaging, perfusion weighted imaging and MR spectroscopic imaging. The networks were constructed using K2 algorithm along with manual determination and distribution parameters learned using maximum likelihood estimation. The grading performance was evaluated in a leave-one-out analysis, achieving an overall grading accuracy of 92.86% and an area under the curve of 0.9577 in the receiver operating characteristic analysis given all available features observed in the total 56 patients. Results and discussions show that Bayesian Network is promising in combining features from multiple modalities of MRI for improved grading performance.