Correlations between the trigeminal nerve microstructural changes and the trigeminal-pontine angle features

BACKGROUND

Morphological and microstructural changes of the trigeminal nerve due to neurovascular compression (NVC) have been reported in primary trigeminal neuralgia (PTN) patients. This investigation was to examine the relationship between the trigeminal-pontine angle and nerve microstructural changes.

METHODS

Twenty-five patients underwent microvascular decompression (MVD) for trigeminal neuralgia, and 25 age- and sex-matched controls were studied. The two groups underwent high-resolution three-dimensional MRI and diffusion tensor imaging (DTI). Bilateral trigeminal-pontine angle, cross-sectional area of cerebellopontine angle (CPA) cistern, and the length of trigeminal nerve were evaluated. The mean values of fractional anisotropy and apparent diffusion coefficient at the site of NVC were also measured. Correlation analyses were performed for the trigeminal-pontine angle and the diffusion metrics (FA and ADC) in PTN patients.

RESULTS

The mean trigeminal-pontine angle and FA value on the affected side was significantly smaller than the unaffected side and the control group (p < 0.001), while the mean ADC value was significantly increased (p < 0.01). When taking the conflicting vessel types into consideration, the angle affected by the superior cerebellar artery (SCA) was statistically sharper than when affected by other vessels (p < 0.01). However, there were no significant changes in the area of the CPA cistern or the length of the trigeminal nerve between the groups. Correlation analyses showed that the trigeminal-pontine angle was positively correlated with FA and negatively correlated with ADC.

CONCLUSIONS

A sharp trigeminal-pontine angle may increase the chance of NVC and exacerbate nerve degeneration, which may be one of the supplementary factors that contribute to the pathogenesis of trigeminal neuralgia.

Two patterns of anterior insular cortex functional connectivity in bipolar disorder and schizophrenia

OBJECTIVES

Bipolar disorder (BD) and schizophrenia (SZ) share structural abnormalities in the anterior insula cortex (AIC). The AIC appears to have a crucial role in emotional processing and regulation and cognitive control in BD and SZ.

METHODS

Forty-six participants with BD, 68 with SZ and 66 healthy controls (HC) underwent functional magnetic resonance imaging scanning. Resting-state functional connectivity (rsFC) from AIC subregions (ventral and dorsal) was compared among the three groups.

RESULTS

Compared to HC group, both BD and SZ groups exhibited increased rsFC from the ventral AIC (vAIC) and dorsal AIC (dAIC) to bilateral frontal pole and thalamus, the left middle frontal gyrus and the hippocampus. Meanwhile, the BD group demonstrated increased rsFC from the vAIC to the perigenual anterior cingulate cortex, the SZ group presented increased rsFC from the vAIC and dAIC to the right caudate. Compared with the BD group, the SZ group showed significantly increased rsFC from the vAIC and dAIC to the left middle frontal gyrus.

CONCLUSIONS

The shared AIC rsFC abnormalities in both BD and SZ support the importance of the AIC in the common pathophysiology of BD and SZ. There were also disorder-specific features of AIC rsFC, which might implicate potential avenues for differentiating during the early stages.

Spontaneous Regional Brain Activity in Healthy Individuals is Nonlinearly Modulated by the Interaction of ZNF804A rs1344706 and COMT rs4680 Polymorphisms

ZNF804A rs1344706 has been identified as one of the risk genes for schizophrenia. However, the neural mechanisms underlying this association are unknown. Given that ZNF804A upregulates the expression of COMT, we hypothesized that ZNF804A may influence brain activity by interacting with COMT. Here, we genotyped ZNF804A rs1344706 and COMT rs4680 in 218 healthy Chinese participants. Amplitudes of low-frequency fluctuations (ALFFs) were applied to analyze the main and interaction effects of ZNF804A rs1344706 and COMT rs4680. The ALFFs of the bilateral dorsolateral prefrontal cortex showed a significant ZNF804A rs1344706 × COMT rs4680 interaction, manifesting as a U-shaped modulation, presumably by dopamine signaling. Significant main effects were also found. These findings suggest that ZNF804A affects the resting-state functional activation by interacting with COMT, and may improve our understanding of the neurobiological effects of ZNF804A and its association with schizophrenia.

Abnormalities of diffusional kurtosis imaging and regional homogeneity in idiopathic generalized epilepsy with generalized tonic-clonic seizures

Neuroimaging techniques have been used to investigate idiopathic generalized epilepsy with generalized tonic-clonic seizures (IGE-GTCS) and different studies employing these methods have produced varying results. However, there have been few studies exploring diffusional kurtosis imaging (DKI) and regional homogeneity (ReHo) techniques in patients with IGE-GTCS. In the current study, resting-state functional magnetic resonance imaging (fMRI) and DKI data were collected from 28 patients with IGE-GTCS and 28 healthy controls. The ReHo method and tract-based spatial statistical (TBSS) analysis were performed to compare differences between the groups. Compared with healthy controls, patients with IGE-GTCS exhibited markedly increased ReHo in the bilateral putamen, the thalamus, right pallidum, right supplementary motor area and the bilateral paracentral lobules. Compared with healthy controls, patients with IGE-GTCS also exhibited markedly decreased ReHo in the posterior cingulate/precuneus, left angular gyrus and dorsolateral prefrontal cortex. In patients with IGE-GTCS, DKI revealed lower fractional anisotropy in the left anterior/superior corona radiata, left superior longitudinal fasciculus and genu/body of the corpus callosum. Higher mean diffusivity was detected in the bilateral anterior corona radiata, left superior corona radiata, left cingulum, and genu/body/splenium of the corpus callosum. Furthermore, reduced mean kurtosis values were identified over the bilateral superior/posterior corona radiate, left anterior corona radiata, right superior longitudinal fasciculus, left posterior thalamic radiation and the genu/body/splenium of the corpus callosum. Therefore, the results of the current study revealed abnormalities in spontaneous activity in the gray and white matter tracts in patients with IGE-GTCS. These results suggest that novel MRI technology may be useful to help determine the pathogenesis of IGE-GTCS.

Impaired Frontolimbic Connectivity and Depressive Symptoms in Patients with Alzheimer's Disease

BACKGROUND/AIMS

Depressive symptoms are commonly observed in Alzheimer's disease (AD). The underlying mechanisms of depressive symptoms in AD remain unclear; frontolimbic circuitry dysfunction may play a role. We aimed to investigate the microstructural integrity of frontolimbic connectivity of specific fiber tracts in AD patients with and without depressive symptoms using diffusion tensor imaging (DTI).

METHODS

Eleven AD patients with depressive symptoms (dep-AD), 18 AD patients without depressive symptoms (nondep-AD), and 18 normal control (NC) subjects were included. The cingulum bundle (CB), uncinate fasciculus (UF), and fornix, mainly frontolimbic connectivity, were measured by DTI tractography and the metrics of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity, and radial diffusivity (RD) were calculated.

RESULTS

Compared with NC subjects, both dep-AD and nondep-AD patients showed significant differences for all indices in the fornix and significantly decreased FA and increased MD and RD in the bilateral CB and UF. When compared to nondep-AD patients, dep-AD patients showed significantly increased MD and RD in the bilateral CB and right UF.

CONCLUSION

Depressive symptoms in AD patients may be involved in greater microstructural abnormalities of frontolimbic connectivity and myelin injury in the bilateral CB and right UF might contribute to the pathophysiology of depressive symptoms in AD.

Trait-Related Cortical-Subcortical Dissociation in Bipolar Disorder: Analysis of Network Degree Centrality

BACKGROUND

Bipolar disorder is a systemic brain disorder. Accumulated evidence suggested that cortical-subcortical imbalance could be a trait-related pathogenic factor of bipolar disorder. Degree centrality, a robust index of focal connectivity in which the number of direct connections from one node to all nodes is counted, has not previously been studied in bipolar disorder as a whole.

METHODS

Resting state functional magnetic resonance imaging was performed on 52 patients with DSM-IV bipolar I disorder and 70 healthy controls recruited between September 2009 and July 2014. Degree centrality was calculated within cerebral gray matter for each subject and compared between patients with bipolar disorder and healthy controls. Hub distributions of both groups were explored. Effects of medication exposure and mood state on degree centrality, as well as cortical-subcortical degree centrality correlations, were explored.

RESULTS

Compared to healthy controls, patients with bipolar disorder exhibited significant decrease in degree centrality in cortical regions, including the middle temporal pole, inferior temporal gyrus, and ventral prefrontal cortex, but showed significant increase in degree centrality mainly in subcortical regions, including caudate, thalamus, parahippocampal gyrus, hippocampi, anterior cingulate, insula, and amygdala, and a small portion of cortical regions, such as superior and middle frontal gyrus (P < .05, corrected). Spatial distributions of the 2 groups were very similar. No significant effects of medication exposure or mood state on degree centrality were found. Patients with bipolar disorder also showed significant decrease in cortical-subcortical degree centrality correlation (P = .003).

CONCLUSIONS

These findings further contribute to the mounting evidence of cortical-subcortical dissociation in bipolar disorder pathophysiology. In addition, this study supports the continued development and implementation of graph-based techniques to enhance our understanding of the underlying neural mechanisms in mental disorders such as bipolar disorder, which are increasingly viewed as systemic brain disorders rather than disorders arising from disruption within a single structure or a limited number of structures. Due to the heterogeneity of our sample, as well as the small sample size of each medication and mood state subgroups, further investigation is needed to support our findings.

Morphologic changes within the cerebellar cortex in the unilateral 6-hydroxydopamine lesioned rat model for Parkinson disease

Parkinson's disease (PD) is a common neurodegenerative disorder caused by the progressive loss of dopaminergic neurons in the substantia nigra. Most investigations have focused on the cerebral regions such as the basal ganglia, thalamus, or the substantia nigra, but whether there is pathologic impairment within the cerebellum has rarely been assessed. Synapsin and neurofilament as the inner markers of neurons and synapses reflect the functional state by their distribution or expression. Significant morphologic changes at the cellular level have been demonstrated directly or indirectly in multiple neurodegenerative diseases. The purpose of this study was to determine whether the behavioral abnormalities that accompany PD are associated with the cerebellum using an in vivo 6-hydroxydopamine lesioned rat model. Forty-two rats were divided into three groups, the Parkinsonian group (N=22), sham group (N=10) and control group (N=10). The dopaminergic lesion was determined by immunohistochemical analysis for tyrosine hydroxylase-immunopositive cells. Immunohistochemical studies showed that the density of synapsin I in the granular layer of the cerebellum on both sides of the Parkinsonian -model was not statistically significantly different compared to the control and sham groups. However, expression of neurofilament H in the cortex within bilateral paramedian lobule (PML) and Crus 2 of the ansiform lobule (C2AL) in cerebellum posterior lobe of Parkinsonian rats was decreased compared with controls (P<0.05), especially in the loss of Purkinje cells and the presence of morphologic abnormalities in the cell nucleus. The study suggested that loss of neurons and synapses may take place in the cerebellar cortex of Parkinson's disease, and might play an important role in the pathologic mechanism of PD.

The papez circuit in first-episode, treatment-naive adults with major depressive disorder: combined atlas-based tract-specific quantification analysis and voxel-based analysis

Previous findings suggest that the Papez Circuit may have a role in major depressive disorders. We used atlas-based tract-specific quantification analysis and voxel-based analysis to examine the integrity of white matter tracts involved in mood regulation (including tracts in the Papez Circuit). Diffusion tensor imaging acquired from 35 first-episode, treatment-naive adults with major depressive disorders and 34 healthy adult controls were compared. Our statistical approach compared structural integrity of 11 major white matter tracts between the major depressive disorder and adult controls, as well as illness duration influence in patients. Fractional anisotropy was decreased in the hippocampal cingulum and in the anterior thalamic radiation according to both analytical approaches, all of which were important tracts included in the Papez Circuit. Our results support the role of the Papez Circuit in major depressive disorders with the minimal probability of false positive due to similar findings in both analyses that have complementary advantages. Dysfunction of the Papez Circuit may be a potential marker for studying the pathogenesis of major depressive disorders.

Alterations in amplitude of low frequency fluctuation in treatment-naïve major depressive disorder measured with resting-state fMRI

There are limited resting-state functional magnetic resonance imaging (fMRI) studies in major depressive disorder (MDD). Of these studies, functional connectivity analyses are mostly used. However, a new method based on the magnitude of low frequency fluctuation (LFF) during resting-state fMRI may provide important insight into MDD. In this study, we examined the amplitude of LFF (ALFF) within the whole brain during resting-state fMRI in 30 treatment-naïve MDD subjects and 30 healthy control (HC) subjects. When compared with HC, MDD subjects showed increased ALFF in the frontal cortex (including the bilateral ventral/dorsal anterior cingulate cortex, orbitofrontal cortex, premotor cortex, ventral prefrontal cortex, left dorsal lateral frontal cortex, left superior frontal cortex), basal ganglia (including the right putamen and left caudate nucleus), left insular cortex, right anterior entorhinal cortex and left inferior parietal cortex, together with decreased ALFF in the bilateral occipital cortex, cerebellum hemisphere, and right superior temporal cortex. These findings may relate to characteristics of MDD, such as excessive self-referential processing and deficits in cognitive control of emotional processing, which may contribute to the persistent and recurrent nature of the disorder.

Differentiating patterns of amygdala-frontal functional connectivity in schizophrenia and bipolar disorder

BACKGROUND

Insight into the neural mechanisms underlying the shared and disparate features of schizophrenia (SZ) and bipolar disorder (BD) is limited. The amygdala and prefrontal cortex (PFC) appear to have crucial roles in SZ and BD, yet abnormalities appear to manifest differently in the 2 disorders.

METHODS

Eighteen participants with SZ, 18 participants with BD, and 18 healthy controls (HC) underwent resting-state functional magnetic resonance imaging. Resting-state functional connectivity (rsFC) between the PFC and the amygdala divided into 3 subregions (the laterobasal, centromedial, and superficial amygdala) was examined using probabilistic anatomic maps. For each participant, rsFC maps of the 3 amygdala subregions were computed and compared across the 3 groups.

RESULTS

Compared with the HC group, we found significant differences in rsFC between the amygdala and PFC in the SZ and BD groups. In direct comparison between the SZ and BD groups, distinct patterns of rsFC between the amygdala and PFC were observed, particularly in the superficial amygdala. RsFC between the amygdala and the dorsal lateral PFC was significantly decreased in the SZ group, whereas rsFC between the amygdyala and the ventral PFC was significantly decreased in the BD group.

CONCLUSIONS

These results strongly suggest dorsal vs ventral PFC differentiation in amygdala-PFC neural system abnormalities between SZ and BD. These regional differences in SZ and BD may give rise to the differences in clinical characteristics observed in SZ and BD, and may implicate potential avenues for differentiating the 2 disorders during early stages of illness.

A comparative diffusion tensor imaging study of corpus callosum subregion integrity in bipolar disorder and schizophrenia

Structural magnetic resonance imaging (MRI) studies have provided evidence for corpus callosum (CC) white matter abnormalities in bipolar disorder (BD) and schizophrenia (SZ). These findings include alterations in shape, volume, white matter intensity and structural integrity compared to healthy control populations. Although CC alterations are implicated in both SZ and BD, no study of which we are aware has investigated callosal subregion differences between these two patient populations. We used diffusion tensor imaging (DTI) to assess CC integrity in patients with BD (n=16), SZ (n=19) and healthy controls (HC) (n=24). Fractional anisotropy (FA) of CC subregions was measured using region of interest (ROI) analysis and compared in the three groups. Significant group differences of FA values were revealed in five CC subregions, including the anterior genu, middle genu, posterior genu, posterior body and anterior splenium. FA values of the same subregions were significantly reduced in patients with SZ compared with HC. FA values were also significantly reduced in patients with BD compared to the HC group in the same subregions, excepting the middle genu. No significant difference was found between patient groups in any region. Most of the alterations in CC subregions were present in both the BD and SZ groups. These results imply an overlap in potential pathology, possibly relating to risk factors common to both disorders. The one region that differed between patient groups, the middle genu area, may serve as an illness marker and is perhaps involved in the different cognitive impairments observed in BD and SZ.

Development of intraspinal ectopic endometrial tissue in connection with tethered cord syndrome

We herein report a rare case of intraspinal ectopic endometrial tissue associated with tethered cord syndrome. The patient underwent MR imaging of the lumbar spine and CT spinal angiography. Asymptomatic dysraphism was also detected, including spinal bifida, low-lying conus medullaris, spinal meningocele and a lumbosacral lipoma. Venous reflux obstruction was also suggested. The patient underwent L2-S1 laminectomy and microdecompression of the lesion. The histological and immunohistochemical features were characteristic of ectopic endometrial tissue. Since the surgery, no neurological signs have been noted, either during or outside the patient's menstrual periods. The two-month follow-up MRI scans showed a regression of the lesion.

Amplitude of low-frequency fluctuations in bipolar disorder: a resting state fMRI study

OBJECTIVES

The spontaneous low frequency fluctuations (LFF) of blood oxygenation level-dependent (BOLD) signal in resting state have been identified as a biological measure of baseline spontaneous activity in the brain. Increasingly, studies of spontaneous resting state functional connectivity have demonstrated neural network abnormalities in bipolar disorder (BD). This study used the amplitude of low frequency fluctuations (ALFF) to explore the regional functional changes in BD during resting state.

METHODS

Twenty-nine BD participants and 29 matched healthy controls (HC) were recruited to undergo resting-state functional magnetic resonance imaging scan on a 3.0T magnetic resonance imaging system. The ALFF of BOLD signal in gray matter for each participant was calculated, and then was compared between BD and HC using ALFF maps.

RESULTS

Compared to the HC group, the BD group showed increased ALFF in ventral prefrontal cortex, dorsal lateral prefrontal cortex, frontal eye field, insula, and putamen with extension into the ventral striatum, as well as decreased ALFF in the lingual gyrus (p<0.05, corrected).

LIMITATIONS

Although we observed differences in ALFF between BD and HC, we cannot conclusively state that these differences are caused by the pathophysiology of BD since most of BD participants were being treated with medications at the time of scanning.

CONCLUSIONS

Our results revealed altered regional brain activity in BD during resting state. The affected regions have been associated with BD pathophysiology. This suggests that methods using ALFF method may potentially be useful in further studies of this disorder.

Functional connectivity between the amygdala and prefrontal cortex in medication-naive individuals with major depressive disorder

BACKGROUND

Convergent evidence suggests dysfunction within the prefrontal cortex (PFC) and amygdala, important components of a neural system that subserves emotional processing, in individuals with major depressive disorder (MDD). Abnormalities in this system in the left hemisphere and during processing of negative emotional stimuli are especially implicated. In this study, we used functional magnetic resonance imaging (fMRI) to investigate amygdala-PFC functional connectivity during emotional face processing in medication-naive individuals with MDD.

METHODS

Individuals with MDD and healthy controls underwent fMRI scanning while processing 3 types of emotional face stimuli. We compared the strength of functional connectivity from the amygdala between the MDD and control groups.

RESULTS

Our study included 28 individuals with MDD and 30 controls. Decreased amygdala-left rostral PFC (rPFC) functional connectivity was observed in the MDD group compared with controls for the fear condition (p < 0.05, corrected). No significant differences were found in amygdala connectivity to any cerebral regions between the MDD and control groups for the happy or neutral conditions.

LIMITATIONS

All participants with MDD were experiencing acute episodes, therefore the findings could not be generalized to the entire MDD population.

CONCLUSION

Medication-naive individuals with MDD showed decreased amygdala-left rPFC functional connectivity in response to negative emotional stimuli, suggesting that abnormalities in amygdala-left rPFC neural circuitry responses to negative emotional stimuli might play an important role in the pathophysiology of MDD.

Altered resting-state functional connectivity of the dentate nucleus in Parkinson's disease

We used functional magnetic resonance imaging (fMRI) to measure functional connectivity of the dentate nucleus (DN) between patients with Parkinson's disease (PD) and normal controls who were studied in a resting state. Images were acquired in 18 PD patients and in age- and sex-matched normal controls. Connectivity of the bilateral DN was calculated and compared between patients and controls, connectivity of the bilateral DN within the cerebellum was compared between rigidity and bradykinesia-dominant patients (PD(AR)) and tremor-dominant patients (PD(T)), and correlation analysis was performed between the connectivity strength and behavioral measures within the cerebellum. Some regions in the cerebellum showed enhanced connectivity with the bilateral DN in PD patients, and decreased connectivity of the DN with the bilateral cerebellar posterior lobe was observed in PD(T) as compared to PD(AR). A set of regions consistent with the default mode network showed disrupted connectivity with the DN. Decreased connectivity between the inferior parietal lobule and the DN was also observed in PD patients. Additional analyses did not show any significant correlations between functional connectivity within the cerebellum and Unified Parkinson's Disease Rating Scale-III scores. Our findings suggest that connectivity of the DN in the resting state is disrupted in PD, and there may be a compensatory cerebellar connectivity mechanism in the resting state in PD. Further study of the cerebellum may clarify the pathophysiology of PD.

Changes in cerebellar functional connectivity and anatomical connectivity in schizophrenia: a combined resting-state functional MRI and diffusion tensor imaging study

PURPOSE

To examine the functional and anatomical connectivity of the cerebellum and their relationship in schizophrenia through resting-state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI).

MATERIALS AND METHODS

Ten subjects with schizophrenia and 10 healthy controls underwent resting-state fMRI and DTI. Left and right cerebellar seed regions were used in a voxel-wise functional connectivity analysis of the cerebellum. Fractional anisotropy (FA) was measured to assess white matter integrity of the middle cerebellar peduncle (MCP) and superior cerebellar peduncle (SCP). Differences in functional connectivity and FA values between the two groups were determined by two-sample t-tests. The relationship between functional connectivity and FA values in both groups were assessed using Pearson s correlation.

RESULTS

Decreased functional connectivity to the left middle temporal gyrus, bilateral middle cingulate cortex, right paracentral lobule, right thalamus, and bilateral cerebellum were found in subjects with schizophrenia when compared to healthy controls; while decreased FA values in the left SCP were found in subjects with schizophrenia compared to healthy controls. Significant correlation was observed between the functional connectivity of the left cerebellum-right paracentral lobule and right cerebellum-right thalamus and the FA values of the MCP in healthy controls.

CONCLUSION

Findings of this multi-modal imaging study support functional and anatomical connectivity abnormalities and the role of the cerebellum in schizophrenia. They also indicate the need for further investigation regarding the relationship between functional and anatomical connectivity and its role in neuropathophysiology.

Assessment of cortical visual impairment in infants with periventricular leukomalacia: a pilot event-related FMRI study

Objective

We wanted to investigate the usefulness of event-related (ER) functional MRI (fMRI) for the assessment of cortical visual impairment in infants with periventricular leukomalacia (PVL).

Materials and Methods

FMRI data were collected from 24 infants who suffered from PVL and from 12 age-matched normal controls. Slow ER fMRI was performed using a 3.0T MR scanner while visual stimuli were being presented. Data analysis was performed using Statistical Parametric Mapping software (SPM2), the SPM toolbox MarsBar was used to analyze the region of interest data, and the time to peak (TTP) of hemodynamic response functions (HRFs) was estimated for the surviving voxels. The number of activated voxels and the TTP values of HRFs were compared. Pearson correlation analysis was performed to compare visual impairment evaluated by using Teller Acuity Cards (TAC) with the number of activated voxels in the occipital lobes in all patients.

Results

In all 12 control infants, the blood oxygenation level-dependent (BOLD) signal was negative and the maximum response was located in the anterior and superior part of the calcarine fissure, and this might correspond to the anterior region of the primary visual cortex (PVC). In contrast, for the 24 cases of PVL, there were no activated pixels in the PVC in four subjects, small and weak activations in six subjects, deviated activations in seven subjects and both small and deviated activations in three subjects. The number of active voxels in the occipital lobe was significantly correlated with the TAC-evaluated visual impairment (p < 0.001). The mean TTP of the HRFs was significantly delayed in the cases of PVL as compared with that of the normal controls.

Conclusion

Determining the characteristics of both the BOLD response and the ER fMRI activation may play an important role in the cortical visual assessment of infants with PVL.

Evaluation of working memory impairment in children with primary nocturnal enuresis: evidence from event-related functional magnetic resonance imaging

AIM

To assess the working memory and explore the differential activations of brain areas in children with primary nocturnal enuresis (PNE) by performing functional magnetic resonance imaging (fMRI) scans using the categorical N-Back task.

METHODS

  Thirteen right-handed PNE children (M/F = 7:6, average age 11.4 ± 0.8 years) and 15 age-matched, right-handed, healthy controls (M/F = 9:6, 11.3 ± 1.0 years) were recruited for the study. First, intelligence tests were performed using Chinese Wechsler Young Children Scales of Intelligence in PNE children and controls. The full intelligence quotient (FIQ), verbal IQ (VIQ), performance IQ (PIQ) and memory/caution (M/C) factor were measured. After intelligence tests, event-related fMRI scans were performed using the categorical N-Back working memory task on a 3.0T MR scanner. The percent of correct responses (PCR) and the mean reaction time to correct response (mRT) were recorded and compared; fMRI data were analysed using SPM2, the differences in activation were compared with the single subject and between-group levels.

RESULTS

The FIQ, VIQ and PIQ in the PNE group were within the normal range and did not significantly differ from the control group (P > 0.05). The M/C factor was statistically significantly lower in the PNE group (P < 0.05). In the N-Back test, PNE children had lower PCR and longer mRT than controls (P < 0.05). A between-group analysis of fMRI data revealed significant attenuation in the left posterior cerebellar lobes of PNE children.

CONCLUSION

PNE children had deficits in working memory, and dysfunction in the left cerebella might be associated with their working memory deficits.

Diffusion-weighted MR imaging allows monitoring the effect of combretastatin A4 phosphate on rabbit implanted VX2 tumor model: 12-day dynamic results

OBJECTIVES

To investigate the 12-day dynamic characteristics of tumor response to intravenous administration of CA4P in rabbit VX2 tumor models.

METHODS

Study protocol was approved by local ethical committee for animal care and use. Sixteen rabbits with 32 tumors on bilateral legs were randomly divided into treated and control groups. Conventional and DWI images were acquired before and 24 h, 4 days, 8 days and 12 days after treatment. The dynamic changes of tumor on images were correlated with histological results. ADCs were compared among and between groups at different time points.

RESULTS

The tumors in treated group grew slower than those in control group. In treaded group, the mean ADC decreased slightly at 24 h point due to cell edema caused by ischemia. Then, it increased significantly at 4 days and 8 days because of progressive central necrosis. Finally, peripheral tumor proliferation caused a second decrease of ADC at 12 days. The significant difference of ΔADC% between the two groups at 24 h, 4 days and 8 days indicated that the change of ADC in treated group was really caused by CA4P.

CONCLUSION

The dynamic histological changes of tumor caused by CA4P as reflected exactly by diffusion-weighted MR imaging indicate a noninvasive measure for monitoring tumor vascular targeting treatment.

[Early diagnosis of lingual thyroglossal duct cyst in newborns: analysis of 10 cases previously misdiagnosed as laryngomalacia]

OBJECTIVE

To distinguish lingual thyroglossal duct cyst (LTDC) from laryngomalacia in newborn infants.

METHODS

Data of 10 newborn infants with laryngeal stridor and dyspnea, admitted to the department of neonatology in our hospital during December, 2004 to August, 2007, who were finally diagnosed with LTDC though previously diagnosed as congenital laryngeal stridor in other hospitals, were summarized and analyzed.

RESULTS

Inspiratory stridor with chest wall retractions was cardinal symptom of newborn with LTDC. A slightly gray and round cyst with smooth surface at the base of the tongue was found with laryngoscopy. On computed tomography examination of larynx, a well-circumscribed lesion with low intensity was detected at the base of the tongue protruding into the air passage. Pathological examination demonstrated that the cyst wall was composed of tabular and columnar epithelium.

CONCLUSIONS

LTDC is a common disease in newborns, which is similar to laryngomalacia. For neonates suspected of LTDC, laryngoscopic examination should be performed first, while laryngeal CT scan is an important diagnostic basis. Cyst puncture can ameliorate the symptoms of the patients, while surgical removal is the method of radical cure.

[Progress in the study of the chemical synapse in glioma-associated epileptogenesis]

Seizures may be the first or sometimes the only manifestation of patients with glioma in clinics. The aim of operation is to eliminate epilepsy far beyond mere resection of tumor mass. The underlying mechanisms of glioma-associated epileptogenesis are poorly understood. Recently the theory of amino-acid like neurotransmitters in chemical synapse is gradually accepted. However, the molecular mechanisms remain to be further investigated on how glutamate release is regulated and how synaptic homeostasis in peripheral neurons is kept or disturbed. So detailed studies are needed to clarify specific molecular target and provide proper evidence for optimal antiepileptic drugs in glioma-associated epileptogenesis.

[Values of diffusion-weighted magnetic resonance imaging in the early detection of periventricular leukomalacia in preterm infants]

OBJECTIVE

Periventricular leukomalacia (PVL), the principal form of brain injury in the premature infant, is characterized by overt focal necrotic lesions in periventricular white matter and diffuse cerebral white matter injury. The early detection of the disease is not consistently possible with cranial ultrasonography or conventional magnetic resonance imaging (MRI). Recently, diffusion-weighted imaging (DWI) has been shown to be highly sensitive in detecting acute ischemic cerebral injury. This study aimed to evaluate possible role of DWI in early diagnosis of PVL.

METHODS

Images and clinical data from 12 preterm infants with PVL diagnosed in our NICU from August, 2005 to April, 2007 were reviewed. MRI using conventional and diffusion-weighted imaging, as well as the assays of blood routine test, serum bilirubin, C-reactive protein (CRP), blood culture, blood gas analysis, blood sugar and serum ions were performed in these preterm infants. All examinations were performed on a 3.0-T MRI system (Philips Intera Acheva Magnetom Vision) with echo-planar imaging capability with the use of a standard protocol. The imaging protocol for all the patients contained diffuse weighted images (EPI-SE, TR = 2144 ms, TE = 56 ms), T1-weighted images (TR = 389 ms; TE = 15 ms; slice thickness = 4 mm) as well as T2-weighted images (TR = 3035 ms; TE = 100 ms; slice thickness = 4 mm). The first MR examinations were performed in all these twelve preterm infants (mean age 4.5 days, range 2 - 7 days). Conventional MRI and DWI sequences obtained in the acute phase were compared. All the neonates underwent another two MRI examinations up to 2 and 4 weeks after delivery; five subjects also underwent MRI follow-up for up to 4 - 8 months (in 3 for 4 months, in 1 for 7 months, and in another for 8 months). Qualitative evaluations were performed to assess the presence of DWI changes compatible with PVL.

RESULTS

The gestational ages of these twelve patients were from 31 to 35 weeks. None of them had intrauterine distress or birth asphyxia. None of the patients had localized neurological signs in the early course except for abnormal muscular tone of some extent, but seizure and apnea were their major symptoms. No other positive signs of nervous system was found in these preterm infants with PVL. First DWI detection (on the average of 4.5 days) in all these infants showed bilateral, symmetric, diffuse high signal intensity (including genu and plenum of corpus callosum), while conventional MRI showed normal images on both T1- and T2-weighted imaging; two weeks later, DWI showed irregularly high, low mixed signals while conventional MRI showed punctate high signal intensity on T1-weighted imaging and slightly lower signal on T2-weighted imaging. Four weeks later, DWI showed cystic low signal intensity where conventional MRI showed low signal intensity on T1-weighted imaging and high signal intensity on T2-weighted imaging (cystic PVL). Four months later, DWI showed that the cystic cava became diminished and disappeared, while conventional MRI showed reduced cerebral white matter and dilation of ventricle.

CONCLUSION

Bilateral, symmetric, diffuse high signal intensity on DWI seems to be the earliest evidence of PVL; diffusion-weighted imaging performed in the acute phase of the disease may have a higher correlation with later evidence of PVL than does conventional MR imaging. DWI is likely to be a considerable technique in the early assessment of white matter injury and later PVL in preterm infants.

Studies on the value of diffusion-weighted MR imaging in the early prediction of periventricular leukomalacia

OBJECTIVE

Periventricular leukomalacia (PVL) is the most common cerebral injury in premature infants. While cranial ultrasonography and conventional magnetic resonance imaging (MRI) offer little for its early diagnosis, still they are much favored at present. Based on the pathologic mechanism of ischemic cerebral injury in PVL, we attempt to elucidate the effects of diffusion-weighted MR imaging (DWI) for the early diagnosis of PVL.

METHODS

Twelve cases of PVL in premature infants confirmed by MRI examinations were included in the current study. All cases underwent DWI in addition to conventional MR imaging (T1-weighted [T1W] and T2-weighted [T2W]) 7 days, 2 weeks, and 4 approximately 8 weeks after birth, respectively.

RESULTS

Initial DWI examination (carried out at an average of 4.5 days after birth) revealed symmetrical and diffuse high signal in bilateral periventricular areas in all cases, while conventional MRI demonstrated normal signal. DWI examination of 2 weeks later showed irregular inhomogeneous signals in cerebral white matter, while conventional MRI revealed hyperintensity on T1WI and slight hypointensity on T2WI in corresponding areas. Four weeks later, DWI revealed various intensities of cystic low signals beside lateral ventricles, while conventional MRI showed hypointensity on T1WI and hyperintensity on T2WI in corresponding lesion, ie, change in cystic PVL. Four months later, conventional MRI evidenced gradual shrink and disappearance of cystic cavity, reduction in cerebral white matter, and ventricle enlargement.

CONCLUSIONS

Symmetrical, diffuse hyperintensity in both lateral periventricular white matter on DWI was the earliest sign of PVL in premature infants. Imaging abnormalities provided by DWI had a close correlation with the results obtained by conventional MRI performed at the advanced stage of PVL, which suggests that DWI may be an important sequence for the early evaluation of cerebral white matter injury as well as for the prediction of PVL occurrence in premature infants.

Lingual thyroglossal duct cyst in newborns: previously misdiagnosed as laryngomalacia

OBJECTIVE

To distinguish lingual thyroglossal duct cyst (LTDC) from laryngomalacia in newborn.

METHODS

The clinical data of five newborns who were diagnosed as LTDC were retrospectively analyzed.

RESULTS

Inspiratory stridor with chest wall retraction was cardinal symptom of newborn with LTDC. A slightly gray and round cyst with smooth surface at the base of the tongue was found with laryngoscopy. In computed tomography examination of larynx, a well-circumscribed lesion with low intensity was detected at the base of the tongue protruding into the air passage. Pathological examination demonstrated the cyst wall was composed of tabular and columnar epithelium.

CONCLUSIONS

LTDC is a common disease in newborns, which is similar with laryngomalacia. For neonate suspected of LTDC, laryngoscopy examination should be taken first, while laryngeal CT scan is an important diagnosis basis to be reg. Cyst puncture can ameliorate the symptoms of LTDC, while surgical removal serves as a radical cure for LTDC.

Comments and controversies: magnetic resonance spectroscopy and gliomas

In vivo proton magnetic resonance spectroscopy (1HMRS) can substantially improve the non-invasive categorization of human brain tumors, especially for gliomas. It provides greater information concerning tumor activity and characterization of the tumor tissue than is possible with MRI techniques alone. Moreover, 1HMRS may ultimately prove to be a highly beneficial modality in the post-irradiation care of patients with brain gliomas. This paper reviews the current status of 1HMRS with the emphasis on its clinical utility in the diagnosis of active tumor processes of gliomas, and its use in planning surgical and radiation therapy interventions and monitoring tumor treatment paradigms.