Meiyun Wang

Quantitative 3-T diffusion tensor imaging in detecting optic nerve degeneration in patients with glaucoma: association with retinal nerve fiber layer thickness and clinical severity

IntroductionTo investigate the association of quantitative 3-T diffusion tensor imaging (DTI) with retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and clinical severity in detecting optic nerve degeneration in patients with primary closed-angle glaucoma.MethodsTwenty three patients (42 eyes; 9 men, 14 women) with primary closed-angle glaucoma and 20 healthy controls were enrolled in this study. Both DTI and OCT were performed on the optic nerves of all subjects. The mean diffusivity (MD), fractional anisotropy (FA), and eigenvalue maps were obtained for quantitative analysis. RNFL thickness and quantitative electrophysiology were also performed on all subjects. The association of quantitative DTI with RNFL thickness and glaucoma stage was analyzed.ResultsCompared with control nerves, the FA, λ‖, and λ⊥ values, and RNFL thickness in affected nerves decreased, while MD increased in patients with primary glaucoma (p < 0.05). There was a significant correlation between FA, MD, λ‖, and λ⊥ and the mean RNFL thickness (P < 0.01). The mean FA and λ⊥ values derived with DT MR imaging correlated well with glaucoma stage (P < 0.05), but the mean MD and λ‖ values did not correlate with glaucoma stage (P > 0.05).ConclusionDTI measurement could detect abnormality of the optic nerve in patients with glaucoma and may serve as a biomarker of disease severity.

Susceptibility Weighted Imaging: A New Tool in the Diagnosis of Prostate Cancer and Detection of Prostatic Calcification

Background Susceptibility weighted imaging (SWI) is a new MRI technique which has been proved very useful in the diagnosis of brain diseases, but few study was performed on its value in prostatic diseases. The aim of the present study was to investigate the value of SWI in distinguishing prostate cancer from benign prostatic hyperplasia and detecting prostatic calcification. Methodology/Principal Findings 23 patients with prostate cancer and 53 patients with benign prostatic hyperplasia proved by prostate biopsy were scanned on a 3.0T MR and a 16-row CT scanner. High-resolution SWI, conventional MRI and CT were performed on all patients. The MRI and CT findings, especially SWI, were analyzed and compared. The analyses revealed that 19 out of 23 patients with prostate cancer presented hemorrhage within tumor area on SWI. However, in 53 patients with benign prostatic hyperplasia, hemorrhage was detected only in 1 patient in prostate by SWI. When comparing SWI, conventional MRI and CT in detecting prostate cancer hemorrhage, out of the 19 patients with prostate cancer who had prostatic hemorrhage detected by SWI, the prostatic hemorrhage was detected in only 7 patients by using conventional MRI, and none was detected by CT. In addition, CT demonstrated calcifications in 22 patients which were all detected by SWI whereas only 3 were detected by conventional MRI. Compared to CT, SWI showed 100% in the diagnostic sensitivity, specificity, accuracy, positive predictive value(PPV) and negative predictive value(NPV) in detecting calcifications in prostate but conventional MRI demonstrated 13.6% in sensitivity, 100% in specificity, 75% in accuracy, 100% in PPV and 74% in NPV. Conclusions More apparent prostate hemorrhages were detected on SWI than on conventional MRI or CT. SWI may provide valuable information for the differential diagnosis between prostate cancer and prostatic hyperplasia. Filtered phase images can identify prostatic calcifications as well as CT.

Self-Regulation of Brain Activity in Patients with Postherpetic Neuralgia: A Double-Blind Randomized Study Using Real-Time fMRI Neurofeedback

Background A pilot study has shown that real-time fMRI (rtfMRI) neurofeedback could be an alternative approach for chronic pain treatment. Considering the relative small sample of patients recruited and not strictly controlled condition, it is desirable to perform a replication as well as a double-blinded randomized study with a different control condition in chronic pain patients. Here we conducted a rtfMRI neurofeedback study in a subgroup of pain patients – patients with postherpetic neuralgia (PHN) and used a different sham neurofeedback control. We explored the feasibility of self-regulation of the rostral anterior cingulate cortex (rACC) activation in patients with PHN through rtfMRI neurofeedback and regulation of pain perception. Methods Sixteen patients (46–71 years) with PHN were randomly allocated to a experimental group (n = 8) or a control group (n = 8). 2 patients in the control group were excluded for large head motion. The experimental group was given true feedback information from their rACC whereas the control group was given sham feedback information from their posterior cingulate cortex (PCC). All subjects were instructed to perform an imagery task to increase and decrease activation within the target region using rtfMRI neurofeedback. Results Online analysis showed 6/8 patients in the experimental group were able to increase and decrease the blood oxygen level dependent (BOLD) fMRI signal magnitude during intermittent feedback training. However, this modulation effect was not observed in the control group. Offline analysis showed that the percentage of BOLD signal change of the target region between the last and first training in the experimental group was significantly different from the control group’s and was also significantly different than 0. The changes of pain perception reflected by numerical rating scale (NRS) in the experimental group were significantly different from the control group. However, there existed no significant correlations between BOLD signal change and NRS change. Conclusion Patients with PHN could learn to voluntarily control over activation in rACC through rtfMRI neurofeedback and alter their pain perception level. The present study may provide new evidence that rtfMRI neurofeedback training may be a supplemental approach for chronic clinical pain management.

Crossed cerebellar diaschisis detected by arterial spin-labeled perfusion magnetic resonance imaging in subacute ischemic stroke.

BACKGROUND Crossed cerebellar diaschisis (CCD) was a common radiological phenomenon manifested as reduced blood flow and metabolism in the cerebellar hemisphere contralateral to a supratentorial cerebral lesion. The hypoperfusion and hypometabolism in the contralateral cerebellum in CCD was traditionally detected by positron emission tomography (PET) and single-photon emission computed tomography (SPECT). The present prospective study aimed to assess the detection of CCD in subacute stage ischemic stroke by arterial spin-labeling (ASL) perfusion technique with a 3.0-T magnetic resonance imaging (MRI) scanner. METHODS ASL images were obtained from 46 patients with supratentorial ischemic stroke at subacute stage. Regional cerebral blood flow values in the cerebellar hemispheres were measured on a region of interest basis. RESULTS Twenty-four of 46 (52%) patients showed CCD phenomenon by ASL-MRI method, which was in line with the PET/SPECT series. Infarctions in basal ganglia areas are prone to cause CCD. CONCLUSIONS With advantages in easy acquisition and no radiation, ASL-MRI seems to be an ideal tool for the detection and follow-up of CCD.

Measurement of tumor size in adult glioblastoma: Classical cross-sectional criteria on 2D MRI or volumetric criteria on high resolution 3D MRI?

OBJECTIVE To investigate the added value of volume on post-contrast three dimensional (3D) T1-weighted image (T1WI) over classical cross-sectional area on two dimensional (2D) T1WI in evaluating tumor response in glioblastoma multiforme (GBM). METHODS Tumor cross-sectional area and volume measurements were performed on 104 MRI studies from 42 adult patients with GBM on post-contrast 5 mm 2D T1WI and isotropic high resolution 3D T1WI, respectively. 52 pairs of MRI scans were analyzed for relative change. Radiographic responses were determined based on change in either area or volume. RESULTS A high correlation was revealed between tumor size measured by area on thick 2D and volume on high resolution 3D MRI in 104 scans (r=0.82, p<0.001). When four tumor response criteria were used according to the percentage changes (complete response/partial response/stable disease/progression), the kappa coefficient between the area on 2D and volume on 3D was 0.68 (p<0.05) with an overall agreement of 81%. CONCLUSIONS Tumor cross-sectional area on post-contrast 2D T1WI appears comparable to volume on 3D T1WI and should still be a practical alternate of volume on 3D for evaluating tumor response.

Cortical Structural Connectivity Alterations in Primary Insomnia: Insights from MRI-Based Morphometric Correlation Analysis

The etiology and maintenance of insomnia are proposed to be associated with increased cognitive and physiological arousal caused by acute stressors and associated cognitive rumination. A core feature of such hyperarousal theory of insomnia involves increased sensory processing that interferes with the onset and maintenance of sleep. In this work, we collected structural magnetic resonance imaging data from 35 patients with primary insomnia and 35 normal sleepers and applied structural covariance analysis to investigate whether insomnia is associated with disruptions in structural brain networks centered at the sensory regions (primary visual, primary auditory, and olfactory cortex). As expected, insomnia patients showed increased structural covariance in cortical thickness between sensory and motor regions. We also observed trends of increased covariance between sensory regions and the default-mode network, and the salience network regions, and trends of decreased covariance between sensory regions and the frontoparietal working memory network regions, in insomnia patients. The observed changes in structural covariance tended to correlated with poor sleep quality. Our findings support previous functional neuroimaging studies and provide novel insights into variations in brain network configuration that may be involved in the pathophysiology of insomnia.

Structural insights into aberrant cortical morphometry and network organization in psychogenic erectile dysfunction

Functional neuroimaging studies have revealed abnormal brain dynamics of male sexual arousal (SA) in psychogenic erectile dysfunction (pED). However, the neuroanatomical correlates of pED are still unclear. In this work, we obtained cortical thickness (CTh) measurements from structural magnetic resonance images of 40 pED patients and 39 healthy control subjects. Abnormalities in CTh related to pED were explored using a scale space search based brain morphometric analysis. Organizations of brain structural covariance networks were analyzed as well. Compared with healthy men, pED patients showed significantly decreased CTh in widespread cortical regions, most of which were previously reported to show abnormal dynamics of male SA in pED, such as the medial prefrontal, orbitofrontal, cingulate, inferotemporal, and insular cortices. CTh reductions in these areas were found to be significantly correlated with male sexual functioning degradation. Moreover, pED patients showed decreased interregional CTh correlations from the right lateral orbitofrontal cortex to the right supramarginal gyrus and the left angular cortex, implying disassociations between the cognitive, motivational, and inhibitory networks of male SA in pED. This work provides structural insights on the complex phenomenon of psychogenic sexual dysfunction in men, and suggests a specific vulnerability factor, possibly as an extra “organic” factor, that may play an important role in pED. Hum Brain Mapp 36:4469–4482, 2015.

Noninvasive amide proton transfer magnetic resonance imaging in evaluating the grading and cellularity of gliomas

Using noninvasive magnetic resonance imaging techniques to accurately evaluate the grading and cellularity of gliomas is beneficial for improving the patient outcomes. Amide proton transfer imaging is a noninvasive molecular magnetic resonance imaging technique based on chemical exchange saturation transfer mechanism that detects endogenous mobile proteins and peptides in biological tissues. Between August 2012 and November 2015, a total number of 44 patients with pathologically proven gliomas were included in this study. We compared the capability of amide proton transfer magnetic resonance imaging with that of noninvasive diffusion-weighted imaging and noninvasive 3-dimensional pseudo-continuous arterial spin imaging in evaluating the grading and cellularity of gliomas. Our results reveal that amide proton transfer magnetic resonance imaging is a superior imaging technique to diffusion-weighted imaging and 3-dimensional pseudo-continuous arterial spin imaging in the grading of gliomas. In addition, our results showed that the Ki-67 index correlated better with the amide proton transfer-weighted signal intensity than with the apparent diffusion coefficient value or the cerebral blood flow value in the gliomas. Amide proton transfer magnetic resonance imaging is a promising method for predicting the grading and cellularity of gliomas.

2D and 3D CT Radiomics Features Prognostic Performance Comparison in Non-Small Cell Lung Cancer

OBJECTIVE: To compare 2D and 3D radiomics features prognostic performance differences in CT images of non-small cell lung cancer (NSCLC). METHOD: We enrolled 588 NSCLC patients from three independent cohorts. Two sets of 463 patients from two different institutes were used as the training cohort. The remaining cohort with 125 patients was set as the validation cohort. A total of 1014 radiomics features (507 2D features and 507 3D features correspondingly) were assessed. Based on the dichotomized survival data, 2D and 3D radiomics indicators were calculated for each patient by trained classifiers. We used the area under the receiver operating characteristic curve (AUC) to assess the prediction performance of trained classifiers (the support vector machine and logistic regression). Kaplan–Meier and Cox hazard survival analyses were also employed. Harrells concordance index (C-Index) and Akaikes information criteria (AIC) were applied to assess the trained models. RESULTS: Radiomics indicators were built and compared by AUCs. In the training cohort, 2D_AUC = 0.653, 3D_AUC = 0.671. In the validation cohort, 2D_AUC = 0.755, 3D_AUC = 0.663. Both 2D and 3D trained indicators achieved significant results (P < .05) in the Kaplan-Meier analysis and Cox regression. In the validation cohort, 2D Cox model had a C-Index = 0.683 and AIC = 789.047; 3D Cox model obtained a C-Index = 0.632 and AIC = 799.409. CONCLUSION: Both 2D and 3D CT radiomics features have a certain prognostic ability in NSCLC, but 2D features showed better performance in our tests. Considering the cost of the radiomics features calculation, 2D features are more recommended for use in the current study.

Disrupted brain network topology in chronic insomnia disorder: A resting-state fMRI study

This study investigated the topological characteristics of brain functional networks in chronic insomnia disorder (CID) patients. The resting-state functional magnetic resonance imaging and graph theory analysis method were applied to investigate the brain functional connectome patterns among 45 CID patients and 32 healthy controls. The brain functional connectome was constructed by thresholding partial correlation matrices of 90 brain regions from an automated anatomical labeling atlas. The topologic properties of brain functional connectomes at both global and nodal levels were tested. The CID patients had decreased number of module (p = .014) and hierarchy (p = .038), and increased assortativity (p = .035). Furthermore, some brain regions located in the default mode network, dorsal attention network, and sensory-motor network in these patients showed altered nodal centralities. Within these areas, the node betweenness of right central paracentral lobule had positive correlation with the Pittsburgh Sleep Quality Index score (R = 0.319, p = .039). The results imply that functional disruptions of CID patients may be related to disruptions in global and regional topological organization of the brain functional connectome, and provide new and important insights to understand the pathophysiological mechanisms of CID.