The microstructure of white matter in male to female transsexuals before cross-sex hormonal treatment. A DTI study

Background

Diffusion tensor imaging (DTI) has been shown to be sensitive in detecting white matter differences between sexes. Before cross-sex hormone treatment female to male transsexuals (FtM) differ from females but not from males in several brain fibers. The purpose of this paper is to investigate whether white matter patterns in male to female (MtF) transsexuals before commencing cross-sex hormone treatment are also more similar to those of their biological sex or whether they are more similar to those of their gender identity.

Method

DTI was performed in 18 MtF transsexuals and 19 male and 19 female controls scanned with a 3 T Trio Tim Magneton. Fractional anisotropy (FA) was performed on white matter of the whole brain, which was spatially analyzed using Tract-Based Spatial Statistics.

Results

MtF transsexuals differed from both male and female controls bilaterally in the superior longitudinal fasciculus, the right anterior cingulum, the right forceps minor, and the right corticospinal tract.

Conclusions

Our results show that the white matter microstructure pattern in untreated MtF transsexuals falls halfway between the pattern of male and female controls. The nature of these differences suggests that some fasciculi do not complete the masculinization process in MtF transsexuals during brain development.     

Effects of androgenization on the white matter microstructure of female-to-male transsexuals. A diffusion tensor imaging study

Diffusion tensor imaging (DTI) can sensitively detect white matter sex differences and the effects of pharmacological treatments. Before cross-sex hormone treatment, the white matter microstructure of several brain bundles in female-to-male transsexuals (FtMs) differs from those in females but not from that in males. The purpose of this study was to investigate whether cross-sex hormone treatment (androgenization) affects the brain white matter microstructure. Using a Siemens 3 T Trio Tim Magneton, DTI was performed twice, before and during cross-sex hormonal treatment with testosterone in 15 FtMs scanned. Fractional anisotropy (FA) was analyzed on white matter of the whole brain, and the latter was spatially analyzed using Tract-Based Spatial Statistics. Before each scan the subjects were assessed for serum testosterone, sex hormone binding globulin level (SHBG), and their free testosterone index. After at least seven months of cross-gender hormonal treatment, FA values increased in the right superior longitudinal fasciculus (SLF) and the right corticospinal tract (CST) in FtMs compared to their pre-treatment values. Hierarchical regression analyses showed that the increments in the FA values in the SLF and CST are predicted by the free testosterone index before hormonal treatment. All these observations suggest that testosterone treatment changes white matter microstructure in FtMs.     

A meta-analysis of whole-brain diffusion tensor imaging studies in bipolar disorder

Objectives

White matter abnormalities are one of the most consistently reported findings in neuroimaging studies of bipolar disorder (BD). We conducted an anatomical likelihood estimation meta-analysis of BD whole-brain diffusion tensor imaging (DTI) studies, with the aim of identifying statistically consistent fractional anisotropy (FA) changes reflecting microstructural modifications to white matter in BD.

Methods

We performed online searches of the PUBMED and EMBASE databases in January 2011. Studies were considered for inclusion if they used diffusion tensor MRI, compared a group of subjects with BD with healthy controls and involved whole-brain white matter analysis of FA. The analyses were conducted in Talairach space, using the activation likelihood estimation technique. We carried out a meta-analysis restricted to studies reporting a lower FA in patients with BD than in healthy controls.

Results

Ten studies were included. We identified two significant clusters of decreased FA on the right side of the brain. The first was located in the right white matter, close to the parahippocampal gyrus. Four of the ten studies included contributed to this cluster. The second cluster was located close to the right anterior and subgenual cingulate cortex. These two clusters of decreased FA in BD are crossed by several white matter tracts.

Conclusions

These two clusters of altered FA may underlie the abnormal emotional processing and altered functional limbic connectivity in BD. Explorations based on DTI-based tractography are required to identify the tracts involved in the pathophysiology of BD.     

A primary study of diffusion tensor imaging-based histogram analysis in vascular cognitive impairment with no dementia

Purpose

This study performed diffusion tensor imaging (DTI) histogram analysis and voxel-based analysis (VBA) to detect white matter (WM) damage in patients with vascular cognitive impairment with no dementia (VCIND) and to determine correlations between DTI histogram-derived measures and cognitive dysfunction in these patients.

Materials and methods

Among patients with subcortical ischemic vascular disease, 18 patients with VCIND were selected along with 18 age- and sex-matched cognitive-normal subjects. Both groups underwent magnetic resonance and DTI scans, and fractional anisotropy (FA) changes in VBA between the two groups were assessed. Further, mean diffusivity (MD) and FA histograms of WM and normal-appearing WM (NAWM) in each subject were evaluated.

Results

Compared to control, the VCIND group showed lower FA values throughout the brain. FA and MD histogram patterns of WM and NAWM were significantly different between the groups. Significant differences were found in all DTI histogram-derived measures, except in the mean FA peak height of WM and mean MD peak location of NAWM. Neuropsychological results (z-scores) were found to be significantly correlated with mean FA peak location, average MD, mean MD peak location of WM, and mean FA peak height, average MD, mean MD peak location of NAWM.

Conclusions

Results of VBA and diffusion tensor imaging-based histogram analysis suggest that VCIND patients have more severe damage in WM and NAWM than the control. Thus, the severity of damage in WM and NAWM may be related with cognitive dysfunction in VCIND patients, and DTI histogram analysis can help in further understanding VCIND.     

Diffusion tensor imaging patterns differ in bulbar and limb onset amyotrophic lateral sclerosis

Background

Amyotrophic lateral sclerosis (ALS) is characterized by pronounced clinical heterogeneity in terms of onset and disease progression. Widespread changes in white matter fibres could be observed by diffusion tensor imaging (DTI), which detects alterations in the degree (diffusivity, ADC) and directedness (fractional anisotropy, FA) of proton movement. The aim of the current study was to determine whether different ALS onset types were reflected in different DTI brain patterns.

Methods

Seventeen patients with a diagnosis of ALS (6 bulbar, 11 limb onset) and seventeen age-matched controls received 1.5T DTI, where FA and ADC were analyzed using statistical parametric mapping.

Results

In ALS patients, an increased diffusivity in the white matter was found below the precentral gyrus and along the corticospinal tract (CST) right into the internal capsule. The FA was decreased in the posterior limb of internal capsule and in the subcortical white matter in the precentral gyrus. In bulbar onset increased diffusivity was found in the CST, whilst in limb onset, frontal subcortical areas displayed an increased diffusivity.

Conclusion

DTI changes can be regarded as prominent features in ALS. Herein we were able to demonstrate discriminating brain DTI patterns due to bulbar or limb onset.     

Association of White Matter Integrity With Executive Function and Antidepressant Treatment Outcome in Patients With Late-Life Depression

ObjectiveWhile patients with late-life depression (LLD) often exhibit microstructural white matter alterations that can be identified with diffusion tensor imaging (DTI), there is a dearth of information concerning the links between DTI findings and specific cognitive performance, as well as between DTI measures and antidepressant treatment outcomes.DesignNeuroimaging and cognitive tests were conducted at baseline in 71 older adults participating in a larger, 8-week duration antidepressant randomized controlled trial. Correlations between DTI measures of white matter integrity evaluated with tract-based spatial statistics, baseline neurocognitive performance, and prospective antidepressant treatment outcome were evaluated.ResultsFractional anisotropy (FA), an index of white matter integrity, was significantly positively associated with better cognitive function as measured by the Initiation/Perseveration subscale of the Dementia Rating Scale in the bilateral superior longitudinal fasciculus (SLF), bilateral SLF-temporal, and right corticospinal tract (CST). An exploratory analysis limited to these tracts revealed that increased FA in the right CST, right SLF, and right SLF-temporal tracts was correlated with a greater decrease in depressive symptoms. Increased FA in the right CST predicted a greater chance of remission, while increased FA in the right CST and the right SLF predicted a greater chance of treatment response.ConclusionIn late-life depression LLD subjects, white matter integrity was positively associated with executive function in white matter tracts which act as key connecting structures underlying the cognitive control network. These tracts may play a role as a positive prognostic factor in antidepressant treatment outcome.     

Associations of Diffusion-Tensor Fractional Anisotropy and FIM Outcome Assessments After Intracerebral Hemorrhage

Aim

This study aimed to clarify the associations between fiber tract degeneration evaluated by diffusion-tensor imaging (DTI) and outcomes following intracerebral hemorrhage (ICH).

White Matter Development in Adolescence: Diffusion Tensor Imaging and Meta-Analytic Results

Background

In light of the evidence for brain white matter (WM) abnormalities in schizophrenia, study of normal WM maturation in adolescence may provide critical insights relevant to the neurodevelopment of the disorder. Voxel-wise diffusion tensor imaging (DTI) studies have consistently demonstrated increases in fractional anisotropy (FA), a putative measure of WM integrity, from childhood into adolescence. However, the WM tracts that show FA increases have been variable across studies. Here, we aimed to assess which WM tracts show the most pronounced changes across adolescence.

Methods

DTI was performed in 78 healthy subjects aged 8–21 years, and voxel-wise analysis conducted using tract-based spatial statistics (TBSS). In addition, we performed the first meta-analysis of TBSS studies on WM development in adolescence.

Results

In our sample, we observed bilateral increases in FA with age, which were most significant in the left superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and anterior thalamic radiation. These findings were confirmed by the meta-analysis, and FA increase in the bilateral SLF was the most consistent finding across studies. Moreover, in our sample, FA of the bilateral SLF showed a positive association with verbal working memory performance and partially mediated increases in verbal fluency as a function of increasing age.

Conclusions

These data highlight increasing connectivity in the SLF during adolescence. In light of evidence for compromised SLF integrity in high-risk and first-episode patients, these data suggest that abnormal maturation of the SLF during adolescence may be a key target in the neurodevelopment of schizophrenia.     

Disruption of brain white matter microstructure in women with anorexia nervosa

Background

The etiology of anorexia nervosa is still unknown. Multiple and distributed brain regions have been implicated in its pathophysiology, implying a dysfunction of connected neural circuits. Despite these findings, the role of white matter in anorexia nervosa has been rarely assessed. In this study, we used diffusion tensor imaging (DTI) to characterize alterations of white matter microstructure in a clinically homogeneous sample of patients with anorexia nervosa.

Methods

Women with anorexia nervosa (restricting subtype) and healthy controls underwent brain DTI. We used tract-based spatial statistics to compare fractional anisotropy (FA) and mean diffusivity (MD) maps between the groups. Furthermore, axial (AD) and radial diffusivity (RD) measures were extracted from regions showing group differences in either FA or MD.

Results

We enrolled 19 women with anorexia nervosa and 19 healthy controls in our study. Patients with anorexia nervosa showed significant FA decreases in the parietal part of the left superior longitudinal fasciculus (SLF; p_FWE < 0.05), with increased MD and RD but no differences in AD. Patients with anorexia nervosa also showed significantly increased MD in the fornix (p_FWE < 0.05), accompanied by decreased FA and increased RD and AD.

Limitations

Limitations include our modest sample size and cross-sectional design.

Conclusion

Our findings support the presence of white matter pathology in patients with anorexia nervosa. Alterations in the SLF and fornix might be relevant to key symptoms of anorexia nervosa, such as body image distortion or impairments in body–energy–balance and reward processes. The differences found in both areas replicate those found in previous DTI studies and support a role for white matter pathology of specific neural circuits in individuals with anorexia nervosa.     

White matter tractography in early psychosis: clinical and neurocognitive associations

Background

While many diffusion tensor imaging (DTI) investigations have noted disruptions to white matter integrity in individuals with chronic psychotic disorders, fewer studies have been conducted in young people at the early stages of disease onset. Using whole tract reconstruction techniques, the aim of this study was to identify the white matter pathology associated with the common clinical symptoms and executive function impairments observed in young people with psychosis.

Methods

We obtained MRI scans from young people with psychosis and healthy controls. Eighteen major white matter tracts were reconstructed to determine group differences in fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD) and then were subsequently correlated with symptomatology and neurocognitive performance.

Results

Our study included 42 young people with psychosis (mean age 23 yr) and 45 healthy controls (mean age 25 yr). Compared with the control group, the psychosis group had reduced FA and AD in the left inferior longitudinal fasciculus (ILF) and forceps major indicative of axonal disorganization, reduction and/or loss. These changes were associated with worse overall psychiatric symptom severity, increases in positive and negative symptoms, and worse current levels of depression. The psychosis group also showed FA reductions in the left superior longitudinal fasciculus that were associated with impaired neurocognitive performance in attention and semantic fluency.

Limitations

Our analysis grouped 4 subcategories of psychosis together, and a larger follow-up study comparing affective and nonaffective psychoses is warranted.

Conclusion

Our findings suggest that impaired axonal coherence in the left ILF and forceps major underpin psychiatric symptoms in young people in the early stages of psychosis.     

Dose-dependent frontal hypometabolism on FDG-PET in methamphetamine abusers

Objective

Although a lot of evidence from neuropsychological and neuroimaging studies supports the view that patients with substance dependence have abnormalities in the prefrontal cortex, functional deficits in the prefrontal cortex have not been fully investigated in methamphetamine (MA) dependent patients. This study was prepared to examine whether MA abusers have cerebral metabolic abnormalities and executive dysfunction.

Method

Twenty-four abstinent MA dependent patients and 21 age-matched control subjects underwent resting brain FDG-PET and completed computerized versions of the Wisconsin card sorting test (WCST). Resting brain PET images were obtained 30 min after an intravenous injection of 370 MBq of ¹⁸F-FDG. Significant differences in glucose metabolism were estimated for every voxel using t-statistics on SPM2 implemented in Matlab.

Results

Resting brain FDG-PET revealed significant hypometabolism in the left inferior frontal white matter (Talairach coordinates (x, y, z): −34, 7, 31) in MA dependent patients compared to the control subjects (corrected p = 0.001, peak Z = 5.37, voxel number 201). The nearest gray matter region was the left inferior frontal cortex (Brodmann area 9). There were negative correlations between the relative regional cerebral metabolism for glucose (rCMRglc) in the left inferior frontal white matter and the total cumulative dose of MA (r = −0.57, p < 0.01). MA dependent patients completed significantly fewer categories (3.8 ± 2.2) and made more perseveration errors (21.3 ± 11.8) and total errors (43.5 ± 19.5) on the WCST when compared to the control subjects (p < 0.01).

Conclusions

These data suggest that MA dependent patients have dose-dependent frontal hypometabolism and frontal executive dysfunction.     

Métamémoire, remémoration et familiarité dans la maladie d’Alzheimer

Introduction

The main objective of this review is to present a new approach to the memory deficit in Alzheimer's disease. Recent memory models suggest that information is recovered either on the basis of recollection or on the basis on familiarity. Recollection, unlike familiarity, requires the retrieval of contextual details related to the encoded information.

State of the art

This review suggests that recollection is particularly affected in Alzheimer's disease. In contrast, familiarity seems to be relatively preserved. A related deficit in metamemory is observed when recollection is required; a decrease in recollection in Alzheimer's disease could explain the pattern of metamemory problems. The deficit in recollection could be explained by a disconnection between medial temporal areas and frontal areas.

Perspectives

This novel approach to memory gives research perspectives concerning both early diagnosis and rehabilitation strategies of Alzheimer disease.

Conclusion

This overview showed deficits in conscious memory processes conceived of as recollection. These novel insights should provide new explanations for the deficits observed in Alzheimer's disease, particularly metamemory.     

Correlating 3T MRI and histopathology in patients undergoing epilepsy surgery

Purpose

To investigate whether specific semi-quantitative 3T MRI parameters are associated with particular histological features in temporal lobe specimens in epilepsy surgery patients whose conventional MRI scan appeared normal. These MRI techniques have the potential to visualise subtle structural abnormalities currently undetected on conventional MRI; but correlation between pre-operative in vivo MRI and histopathology is needed to understand the basis of these MRI abnormalities. Predicting subtle histopathology with semi-quantitative MRI techniques could contribute to pre-surgical evaluation of epilepsy patients.

Materials and methods

MRI techniques: normalised FLAIR signal intensity (nFSI), grey matter probability and diffusion tensor imaging (DTI) were correlated with quantitative histopathological measures: NeuN (neuronal nuclear antigen); GFAP (glial fibrillary acidic protein) and MBP (myelin basic protein) field fractions and stereological neuronal densities obtained in grey and white matter regions in twenty-four patients who underwent anterior temporal lobe resections.

Results

There were no significant correlations between the histopathological measurements and MRI values in grey or white matter in macroscopically normal appearing tissue.

Conclusion

Findings suggest that in macroscopically normal appearing tissue, the studied semiquantitative MRI measurements are not significantly related to the measures of gliosis, neuronal loss/gain and myelin used in the current study. Studies of macroscopically abnormal tissue as well as improvements to the MRI techniques may increase the sensitivity of future correlative studies to improve our understanding of the histopathological basis of MRI signal characteristics.     

Impasse de la rivalité maternelle et féminine chez les transsexuelles

Objectives

The projective protocols are due for analysing one type of gender dysphoria, a kind from transsexual females, looking for an anatomical sexual status to prove their one's identity. This psychogenesis feeling comes directly from their maternal imago. The female identity and these derived experiences, through transsexuals, are the fundamentals of this article.

Patients and methods

From five cases submitted to the multi-clinical exams protocol, we can observe three charts from Murray's Thematic Aperception Test (TAT). In chart 5, 7 GF, 9 GF, we can see the saturation level of the latent attraction from the maternal and female identity question. According to a psycho-dynamical clinical conception to intervene on the body, the deadlock in the conflict between the transsexual female and the mother lead to less fantasy. From the TAT results, one could notice a clash to the facts, a difference in perception, an unmarked or avoiding the reality (type C on the analysis rates, originated by Shentoub).

Results

The analysis of the observed individual indicates a shortage of the narrative ability as well as the inter-personal one. It comes to stories overstepping the external reality. The dramatic effect does not exist and the perception fulfils a non-significant internal reality. In that case the perception takes the place of the representation and the affect is therefore plaid down. At the end of the narration, it occurs that the psychodynamic test of personality of the candidates to a sexual reassignment is more important and reinforced.

Conclusion

Some questions are pending due to the non conflictual relationship from the transsexuals to their mothers and about the sexual post-reassignment. Once reconciled with her own look, how should the transsexual female deal with her own mother, and in the future how should her be in love or having sexual relations with other females?     

Association of the ZNF804A gene polymorphism rs1344706 with white matter density changes in Chinese schizophrenia

Background

ZNF804A gene polymorphism rs1344706, the first genetic risk variant to achieve genome wide significance for schizophrenia, has been linked to neural functional connectivity. Dysconnectivity of WM may be the primary pathological mechanism of schizophrenia. Association of this variant with regional WM density has not been investigated in schizophrenic patients.

Methods

69 healthy controls and 80 patients with schizophrenia underwent genotyping of rs1344706 SNPs, and were examined for WM density (T1-weighted MRI). The association of rs1344706 with WM changes in schizophrenia patients and healthy controls was analyzed using a full-factorial 2 × 2 analysis of variance.

Results

1. There was an interaction on WM density in the left prefrontal lobe between the rs1344706 genotype and schizophrenic diagnosis, where the risk T allele carriers presented higher WM density in the schizophrenia patients and lower WM density in healthy controls in comparison with the non-risk allele carriers.2. The risk allele was associated with an increased WM density of the bilateral hippocampus in both the patients and the healthy group.

Limitation

The influence of antipsychotics to the white matter in schizophrenic patients was not fully eliminated.

Conclusions

The ZNF804A variant may confer risk for schizophrenia by exerting its effects on the WM in the left prefrontal lobe together with other risk factors for schizophrenia.     

Microstructural Changes of Anterior Corona Radiata in Bipolar Depression

Objective

In bipolar disorder, dysregulation of mood may result from white matter abnormalities that change fiber tract length and fiber density. There are few studies evaluating the white matter microstructural changes in bipolar I patients (BD) with depressive episodes. The present study aimed to evaluate anterior corona radiata in BD patients with depressive episode using Diffusion Tensor Imaging (DTI).

Methods

Twenty-one patients with bipolar depression and 19 healthy controls were investigated and groups were matched for age and gender. Diffusion-weighted echoplanar brain images (DW-EPI) were obtained using a 1.5 T MRI scanner. Regions of interest (ROIs) were manually placed on directional maps based on principal anisotropy. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of white matter were measured in the anterior corona radiata (ACR) bilaterally by diffusion tensor imaging.

Results

There was not a significant difference between groups of age and gender (p>0.05). Significantly lower FA was observed in bilateral ACR in bipolar patients with depression compared with healthy individuals. And there is significantly higher ADC values in the left frontal corona radiate in bipolar patients.

Conclusion

White matter abnormalities can be detected in patients with BD using DTI. The neuropathology of these abnormalities is unclear, but neuronal and axonal loss, myelin abnormalities and reduced white matter fiber density are likely to be relevant.     

Dynamic changes in corticospinal tracts after stroke detected by fibretracking

Background and aims

The integrity of motor pathways and functional connectivity patterns are important in assessing plastic changes related to successful recovery, to obtain prognostic information and to monitor future therapeutic strategies of stroke patients. We tested the following hypotheses: (1) that changes in axonal integrity along the corticospinal tract after stroke can be detected as a reduction in fractional anisotropy; and (2) that sustained low fractional anisotropy is indicative of axonal loss and therefore is correlated with poor motor outcome, as measured by specific neurological motor scores.

Methods

We developed a segmentation tool based on magnetic resonance diffusion tensor imaging in conjunction with three dimensional fibretracking for longitudinal studies of the corticospinal tract, and used specific neurological motor scores to test the hypotheses in five stroke patients within the first week and 30 and 90 days after the stroke.

Results

Reduction in fractional anisotropy within the first weeks after stroke reflected a decline in axonal integrity, leading to Wallerian degeneration, and demonstrated a correlation between the temporal evolution of fractional anisotropy and motor function in patients with poor motor outcome.

Conclusion

The study demonstrated the feasibility of fibretracking as a segmentation tool for mapping distal parts of the corticospinal motor pathways and showed that fractional anisotropy in the segmented corticospinal tract is a sensitive measure of structural changes after stroke.Studies on the recovery of cerebral grey matter after stroke with positron emission tomography,^1,2,3 functional MRI^4,5,6 or transcranial magnetic stimulation^7,8 demonstrate that the adult brain is capable of regeneration and compensation for motor deficits after ischaemia. However, the integrity of the underlying motor pathways is crucial in understanding the dynamics of cortical activation patterns and qualitatively the substrate of successful recovery in individual patients. The recent introduction of magnetic resonance diffusion tensor imaging (DTI) allows the characterisation of the integrity of the white matter tract by recording the diffusion characteristics of water molecules in the highly organised environment of hydrophobic myelin sheets. White matter fibre orientation can be inferred by measuring the preferred direction of water movements and the course of fibre tracts subsequently visualised by so called “fibretracking”. The extent to which myelin sheets directs water diffusion along a specific direction is parameterised by the fractional anisotropy (FA) index. FA values have been measured in studies of both healthy subjects and chronic stroke patients.^9,10,11 In the latter, reduced FA values measured distally to the infarct were low, interpreted as evidence of axonal loss and Wallerian degeneration (WD). In stroke patients,^12,13,14 DTI tracks the pyramidal fibres in their craniocaudal course and delineates lesions to motor fibres in relation to existing neurological deficits. A recent study demonstrated a clear prognostic value of the procedure by showing that the degree of corticospinal involvement in the infarcts is related directly to stroke severity, and inversely to functional recovery.¹⁵ Furthermore, DTI revealed changes consistent with WD within the first 2 weeks of the insult, thus proving that this technique detects structural changes earlier than conventional T2 and proton density magnetic resonance images.^16,17In the present study, we developed a fibretracking based technique to segment the corticospinal tract on initial DTI images and, using this volume as a template and in a longitudinal setting, to monitor FA from the early phase in stroke patients. Using specific neurological scores, we then studied patients, testing the hypothesis that sustained low FA values associate with poor motor outcome.     

Differential diagnosis of intracranial ring enhancing cystic mass lesions—Role of diffusion-weighted imaging (DWI) and diffusion-tensor imaging (DTI)

Objective

To evaluate the contribution of DWI and DTI to the differential diagnosis of cerebral ring enhancing lesions by describing DWI and ADC (apparent diffusion coefficient) findings and measuring the two DTI parameters mean diffusivity (MD) and fractional anisotropy (FA).

Materials and methods

A total of 17 patients presenting with 26 rim enhancing cysts were investigated with DWI and DTI. Parameter maps of the DTI metrics MD and FA were calculated and quantified using regions of interest (ROIs).

Results

Five patients suffered from abscesses with a total of 10 cysts, 9 from glioblastomas with 10 cysts, and 3 from metastases with 6 cysts. All abscess cavities showed hyperintense DWI signal intensity compared to normal appearing white matter (NAWM), low ADC, low MD and high FA. Eight out of 10 glioblastoma cysts and all 6 metastatic cysts revealed hypointensity on DWI, high ADC, high MD and low FA (p < 0.0001 compared to abscess group). DWI findings of 2/10 glioblastoma cysts overlapped with those of abscesses showing hyperintensity on DWI, low ADC and low MD and hence mimicked abscesses. FA of these 2 glioblastoma cysts was significantly lower than in abscess cavities (p = 0.032).

Conclusion

The findings of reduced diffusion compared to NAWM and increased FA within a ring enhancing cyst strongly indicate a cerebral abscess. In contrast, the majority of neoplastic cysts revealed high diffusion and low FA. Reduced diffusion is also found in a very small number of tumour cysts, but in these low FA refers to a non-infectious origin and thus helps distinguishing from infectious abscess.     

Preoperative Weakness and Demyelination of the Corticospinal Tract in Meningioma Patients : Changes in Diffusion Parameters Using Diffusion Tensor Imaging

Objective

Differentiation of demyelination in white matter from axonal damage can be determined using diffusion tensor imaging (DTI). In this study using meningioma patients an attempt was made to evaluate the relationship between preoperative weakness and the changes of diffusion parameters in the corticospinal tract (CST) using DTI.

Methods

Twenty-six patients with meningioma were enrolled in this study. Eleven of them suffered from objective motor weakness and were classified as Group 1. The remaining 15 patients did not present motor weakness and were classified as Group 2. Fiber tractography and CST diffusion parameters were obtained using DTIStudio. The ratios (lesion side mean value/contralateral side mean value) of CST diffusion parameters were compared with 1.0 as a test value using a one-sample t-test.

Results

In Group 1, fractional anisotropy (FA), tensor trace (TT), and radial diffusivity (RD, λ2 and λ3) of the CST were significantly different between two hemispheres, but axial diffusivity (AD, λ1) of the CST was not significantly different between two hemispheres. In Group 2, FA and λ3 of CST did not differ significantly between the hemispheres. In Group 2, TT, λ1, and λ2 of CST in the ipsilateral hemisphere were significantly higher than those of the unaffected hemisphere. However, the differences were small.

Conclusion

Motor weakness was related to a low FA and high TT resulting from increased RD of the CST fibers. CST diffusion changes in patients with weakness are similar to those for demyelination.