Laurent Barantin

Preserved subcortical volumes and cortical thickness in women with sexual abuse-related PTSD

Posttraumatic stress disorder (PTSD) has been frequently associated with volumetric reductions of grey matter structures (e.g. hippocampus and anterior cingulate), but these results remain controversial, especially in female non-combat-related samples. The present study aimed at exploring whole-brain structures in women with sexual abuse-related PTSD on the basis of cortical and subcortical structure comparisons to a matched pair sample that was well-controlled. Seventeen young women who had experienced sexual abuse and who had a diagnosis of chronic PTSD based on the Clinician Administered PTSD Scale for DSM-IV and 17 healthy controls individually matched for age and years of education were consecutively recruited. Both groups underwent structural magnetic resonance imaging and psychiatric assessment of the main disorders according to Axis I of DSM-IV. The resulting scans were analyzed using automated cortical and subcortical volumetric quantifications. Compared with controls, PTSD subjects displayed normal global and regional brain volumes and cortical thicknesses. Our results indicate preserved subcortical volumes and cortical thickness in a sample of female survivors of sexual abuse with PTSD. The authors discuss potential differences between neural mechanisms of sexual abuse-related PTSD and war-related PTSD.

FIBRASCAN: a novel method for 3D white matter tract reconstruction in MR space from cadaveric dissection.

INTRODUCTION Diffusion tractography relies on complex mathematical models that provide anatomical information indirectly, and it needs to be validated. In humans, up to now, tractography has mainly been validated by qualitative comparison with data obtained from dissection. No quantitative comparison was possible because Magnetic Resonance Imaging (MRI) and dissection data are obtained in different reference spaces, and because fiber tracts are progressively destroyed by dissection. Here, we propose a novel method and software (FIBRASCAN) that allow accurate reconstruction of fiber tracts from dissection in MRI reference space. METHOD Five human hemispheres, obtained from four formalin-fixed brains were prepared for Klinglers dissection, placed on a holder with fiducial markers, MR scanned, and then dissected to expose the main association tracts. During dissection, we performed iterative acquisitions of the surface and texture of the specimens using a laser scanner and two digital cameras. Each texture was projected onto the corresponding surface and the resulting set of textured surfaces was coregistered thanks to the fiducial holders. The identified association tracts were then interactively segmented on each textured surface and reconstructed from the pile of surface segments. Finally, the reconstructed tracts were coregistered onto ex vivo MRI space thanks to the fiducials. Each critical step of the process was assessed to measure the precision of the method. RESULTS We reconstructed six fiber tracts (long, anterior and posterior segments of the superior longitudinal fasciculus; Inferior fronto-occipital, Inferior longitudinal and uncinate fasciculi) from cadaveric dissection and ported them into ex vivo MRI reference space. The overall accuracy of the method was of the order of 1mm: surface-to-surface registration=0.138mm (standard deviation (SD)=0.058mm), deformation of the specimen during dissection=0.356mm (SD=0.231mm), and coregistration surface-MRI=0.6mm (SD=0.274mm). The spatial resolution of the method (distance between two consecutive surface acquisitions) was 0.345mm (SD=0.115mm). CONCLUSION This paper presents the robustness of a novel method, FIBRASCAN, for accurate reconstruction of fiber tracts from dissection in the ex vivo MR reference space. This is a major step toward quantitative comparison of MR tractography with dissection results.

Working memory processing of traumatic material in women with posttraumatic stress disorder

BACKGROUND Posttraumatic stress disorder (PTSD) is associated with medial frontal and amygdala functional alterations during the processing of traumatic material and frontoparietal dysfunctions during working memory tasks. This functional magnetic resonance imaging (fMRI) study investigated the effects of trauma-related words processing on working memory in patients with PTSD. METHODS We obtained fMRI scans during a 3-back task and an identity task on both neutral and trauma-related words in women with PTSD who had been sexually abused and in healthy, nonexposed pair-matched controls. RESULTS Seventeen women with PTSD and 17 controls participated in the study. We found no behavioural working memory deficit for the PTSD group. In both tasks, deactivation of posterior parietal midline regions was more pronounced in patients than controls. Additionally, patients with PTSD recruited the left dorsolateral frontal sites to a greater extent during the processing of trauma-related material than neutral material. LIMITATIONS This study included only women and did not include a trauma-exposed non-PTSD control group; the results may, therefore, have been influenced by sex or by effects specific to trauma exposure. CONCLUSION Our results broadly confirm frontal and parietal functional variations in women with PTSD and suggest a compensatory nature of these variations with regard to the retreival of traumatic memories and global attentional deficits, respectively, during cognitively challenging tasks.

Proton MR spectroscopic imaging of basal ganglia and thalamus in neurofibromatosis type 1: correlation with T2 hyperintensities

IntroductionNeurofibromatosis type 1 (NF1) is frequently associated with hyperintense lesions on T2-weighted images called “unidentified bright objects” (UBO). To better characterize the functional significance of UBO, we investigate the basal ganglia and thalamus using spectroscopic imaging in children with NF1 and compare the results to anomalies observed on T2-weighted images.MethodsMagnetic resonance (MR) data of 25 children with NF1 were analyzed. On the basis of T2-weighted images analysis, two groups were identified: one with normal MR imaging (UBO− group; n = 10) and one with UBO (UBO+ group; n = 15). Within the UBO+ group, a subpopulation of patients (n = 5) only had lesions of the basal ganglia. We analyzed herein seven regions of interest (ROIs) for each side: caudate nucleus, capsulo-lenticular region, lateral and posterior thalamus, thalamus (lateral and posterior voxels combined), putamen, and striatum. For each ROI, a spectrum of the metabolites and their ratio was obtained.ResultsPatients with abnormalities on T2-weighted images had significantly lower NAA/Cr, NAA/Cho, and NAA/mI ratios in the lateral right thalamus compared with patients with normal T2. These abnormal spectroscopic findings were not observed in capsulo-lenticular regions that had UBO but in the thalamus region that was devoid of UBO.ConclusionMultivoxel spectroscopic imaging using short-time echo showed spectroscopic abnormalities in the right thalamus of NF1 patients harboring UBO, which were mainly located in the basal ganglia. This finding could reflect the anatomical and functional interactions of these regions.

Diagnosis of Sjögren-Larsson syndrome by magnetic resonance spectroscopy.

A 25-month-old girl had been born, after an uneventful pregnancy, at 36 weeks of gestation. Her weight was low for her gestational age (2025 g). She was the first child of unrelated and healthy parents. She presented with marked congenital ichthyosis. Motor retardation was later observed (i.e., stable sitting and walking at ages 12 and 22 months, respectively). Her speech was also delayed. Her first clinical evaluation at age 25 months revealed hyperkeratotic ichthyosis, especially at the main flexor folds, with mild facial involvement. The girl manifested severe pruritus. Her hair, nails, and teeth were normal. No organomegaly was evident. A neurologic examination indicated spastic quadriplegia with axial hypotonia and a left convergent strabismus. Cranial magnetic resonance imaging and proton magnetic resonance spectroscopy were performed with a 1.5 T Signa HDXt scanner (General Electric Medical Systems, Milwaukee, WI) (echo times, 35 ms and 144 ms; repetition time, 1500 ms; volume of interest, 8 mL). Cranial magnetic resonance imaging indicated abnormal, hyperintense signals on T2-weighted sequences in the subcortical white matter, predominantly in periventricular areas (Fig 1A). Magnetic resonance spectra were analyzed in the parietal subcortical white matter (Fig 1B), and at various echo times indicated two abnormal peaks compatible with lipid content: one broad and small peak at 0.9 parts per million corresponding to CH3 lipids of the methyl group, and one high and sharp peak at 1.3 parts per million corresponding to (CH2)n lipids of the methylene group (Fig 1C,D). The remaining peaks for N-acetyl aspartate, creatine, choline, and myoinositol appeared normal in shape and relative proportions. The association of congenital ichthyosis with pruritus, spastic tetraplegia, mental retardation, and white-matter hyperintensities on magnetic resonance imaging was highly suggestive of Sjogren-Larsson syndrome. Fibroblast fatty aldehyde/NADþ oxidoreductase activity was not detectable, confirming our diagnosis of Sjogren-Larsson syndrome.

D2 receptor imaging in neonates using I-123 iodobenzamide brain SPECT.

Purpose Hypoxic–ischemic injury induces early changes in cerebral energy that later lead to the presence and extension of brain damage and subsequently to severe neurodevelopmental impairments such as the dyskinetic form of cerebral palsy, which is associated with damage to the striatum. The purpose of the current study was to evaluate the viability of D2 receptors in the perinatal period using I-123 iodobenzamide brain SPECT and to correlate this with early neurologic status. Methods After obtaining informed parental consent, 12 full-term neonates with hypoxic–ischemic events were included. I-123 iodobenzamide brain SPECT was performed 1 week after birth, corresponding to a gestational age of 39.2 ± 1.7 weeks. Images were acquired using a brain-dedicated gamma camera 1 hour after intravenous injection of 30 MBq (0.8 mCi) I-123 iodobenzamide. Magnetic resonance images (T2 weighted sequence: repetition time/echo time: 2,000/30 to 150) of the brains of the same neonates were acquired on the same day. Results The right and left striatum:cerebellum activity ratios were between 1.28 and 2.25, with the greatest concentration of I-123 iodobenzamide occurring in the striatum area. A tendency of the striatum:cerebellum ratio to decrease was observed as the severity of the perinatal hypoxic–ischemic event increased despite striatal hypersignal on magnetic resonance imaging in only two neonates. Conclusions This study, which confirms that I-123 iodobenzamide could be used in the neonatal period, shows the biochemical maturation of D2 receptors as early as 1 week after birth and also suggests the deleterious effect of perinatal hypoxic–ischemic events on D2 receptors.

Neurocognitive, emotional and neuroendocrine correlates of exposure to sexual assault in women

BACKGROUND Survivors of sexual assault are vulnerable to long-term negative psychological and physical health outcomes, but few studies have investigated changes in cognition, emotional processing and brain function in the early stages after sexual assault. We used a multimodal approach to identify the cognitive and emotional correlates associated with sexual assault in women. METHODS Twenty-seven female survivors of sexual assault were included within 4 weeks of the traumatic event, and they were compared with 20 age-matched controls. Participants underwent functional MRI while performing cognitive/emotional tasks (n-back, emotional go/no-go, mental imagery). We also measured diurnal salivary cortisol and conducted neuropsychological assessments of attention and memory abilities. RESULTS Relative to the control group, the survivors group had lower levels of morning cortisol and showed attentional deficits. We observed no between-group differences in brain activation during the n-back or mental imagery tasks. During the emotional go/no-go task, however, the survivors group showed a lack of deactivation in the dorsal anterior cingulate cortex when processing emotional material, relative to neutral material. Exploratory analyses in the survivors group indicated that symptom severity was negatively associated with cerebellar activation when positive emotional (happy) content interfered with response inhibition, and positively associated with cerebellar activation when thinking of positive (happy) memories. LIMITATIONS The small sample size was the main limitation of this study. CONCLUSION Dysfunctions in the dorsal anterior cingulate cortex and the cerebellum may represent early functional brain modifications that alter higher cognitive processes when emotional material is involved.

A cocktail of 165Er(III) and Gd(III) complexes for quantitative detection of zinc using SPECT and MRI

We propose quantitative assessment of zinc by combining nuclear and MR imaging. We use a cocktail of a Gd3+-complex providing a Zn2+-dependent MRI response and its 165Er3+ analogue allowing for concentration assessment. 165Er is readily obtained in a cyclotron and purified, which is indispensable for successful quantification of metal ions.

Quantitative assessment of metabolic changes during brain development with 1H Magnetic Resonance Spectroscopy (MRS) in vivo in two animal models † 957

Quantitative assessment of metabolic changes during brain development with 1H Magnetic Resonance Spectroscopy (MRS) in vivo in two animal models † 957