High-resolution T1-weighted MRI Research Articles

Explicit verbal memory impairments associated with brain functional deficits and morphological alterations in patients with generalized anxiety disorder

BackgroundGeneralized anxiety disorder (GAD) is associated with brain function and morphological alterations. This study investigated explicit verbal memory impairment in patients with GAD in terms of brain functional deficits in combination with morphologic changes. MethodsSeventeen patients with GAD and 17 healthy controls matched for age, sex, and education level underwent high-resolution T1-weighted MRI and fMR imaging at 3 T during explicit verbal memory tasks with emotionally neutral and anxiety-inducing words. ResultsIn response to the neutral words, the patients showed significantly lower activities in the regions of the hippocampus (Hip), middle cingulate gyrus (MCG), putamen (Pu) and head of the caudate nucleus (HCd) compared with healthy controls. In response to the anxiety-inducing words, the patients showed significantly higher activities in the ventrolateral prefrontal cortex and precentral gyrus. However, they showed lower activities in the Hip, MCG, Pu and HCd. In addition, patients with GAD showed a significant reduction in gray matter volumes, especially in the regions of the Hip, midbrain, thalamus, insula and superior temporal gyrus, compared with healthy controls. LimitationsThis study examined a small sample sizes in each of the groups, and there was no consideration of a medication effect on brain activity and volume changes. ConclusionsThis study provides evidence for the association between brain functional deficits and morphometric alterations in an explicit verbal memory task for patients with GAD. This finding is helpful for understanding explicit verbal memory impairment in connection with GAD symptoms.

Functional and structural abnormalities associated with empathy in patients with schizophrenia: An fMRI and VBM study.

Empathy deficit is a core feature of schizophrenia which may lead to social dysfunction. The present study was carried out to investigate functional and structural abnormalities associated with empathy in patients with schizophrenia using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). A sample of 14 schizophrenia patients and 14 healthy control subjects matched for age, sex and education were examined with structural highresolution T1-weighted MRI; fMRI images were obtained during empathy task in the same session. The analysis was carried out using SPM8 software. On behavioural assessment, schizophrenic patients (83.00+-29.04) showed less scores for sadness compared to healthy controls (128.70+-22.26) (p less than 0.001). fMRI results also showed reduced clusters of activation in the bilateral fusiform gyrus, left lingual gyrus, left middle and inferior occipital gyrus in schizophrenic subjects as compared to controls during empathy task. In the same brain areas, VBM results also showed reduced grey and white matter volumes. The present study provides an evidence for an association between structural alterations and disturbed functional brain activation during empathy task in persons affected with schizophrenia. These findings suggest a biological basis for social cognition deficits in schizophrenics.

Neurological soft signs in recent-onset schizophrenia: Focus on the cerebellum.

Previous structural neuroimaging studies linked cerebellar deficits to neurological soft signs (NSS) in schizophrenia. However, no studies employed a methodology specifically designed to assess cerebellar morphology. In this study, we evaluated the relationship between NSS levels and abnormalities of the human cerebellum in patients with recent-onset schizophrenia and healthy individuals using an exclusive cerebellar atlas. A group of 26 patients with recent-onset schizophrenia and 26 healthy controls were included. All participants underwent a high-resolution T1-weighted MRI scan on a 3 Tesla scanner. We used a voxel-based morphometry (VBM) approach utilizing the Spatially Unbiased Infratentorial (SUIT) toolbox to provide an optimized and fine-grained exploration of cerebellar structural alterations associated with NSS. Compared with healthy controls, patients had significantly smaller cerebellar volumes for both hemispheres. In the patients' group, we identified a significant negative correlation between NSS levels and gray matter volume in the left lobule VI and the right lobule VIIa, corrected for multiple comparisons. Further, NSS performance was significantly associated with white matter volume in the left midbrain and corpus medullare and the right lobule VIIa. In contrast, no significant associations between NSS scores and cerebellar subregions in healthy subjects arose. Our results demonstrate the benefits of SUIT when investigating cerebellar correlates of NSS. These results support the view that distinct parts of sensorimotor and cognitive cerebellum play an important role in the pathogenesis of NSS in schizophrenia.

Increasing structural atrophy and functional isolation of the temporal lobe with duration of disease in temporal lobe epilepsy

Due to pharmacoresistant seizures and the underutilization of surgical treatments, a large number of temporal lobe epilepsy (TLE) patients experience seizures for years or decades. The goal of this study was to generate a predictive model of duration of disease with the least number of parameters possible in order to identify and quantify the significant volumetric and functional indicators of TLE progression. Two cohorts of subjects including 12 left TLE, 21 right TLE and 20 healthy controls (duration = 0) were imaged on a 3T MRI scanner using high resolution T1-weighted structural MRI and 20 min of resting functional MRI scanning. Multivariate linear regression methods were used to compute a predictive model of duration of disease using 49 predictors including functional connectivity and gray matter volumes computed from these images. No model developed from the full set of data accurately predicted the duration of disease across the entire range from 3 to 50 years. We then performed the regression on 35 subjects with durations of disease in the range 10 to 35 years. The resulting predictive model showed that longer durations were associated with reductions in functional connectivity from the ipsilateral temporal lobe to the contralateral temporal lobe, precuneus and mid cingulate, and with decreases in volume of the ipsilateral hippocampus and pallidum. Functional and volumetric parameters accurately predicted duration of disease in TLE. The findings suggest that TLE is associated with a gradual functional isolation and significant progressive structural atrophy of the ipsilateral temporal lobe over years of duration in the range of 10-35 years. Furthermore, these changes can also be detected in the contralateral hemisphere in these patients, but to a lesser degree.

The relationship between brain morphology and polysomnography in healthy good sleepers.

BackgroundNormal sleep continuity and architecture show remarkable inter-individual variability. Previous studies suggest that brain morphology may explain inter-individual differences in sleep variables.MethodThirty-eight healthy subjects spent two consecutive nights at the sleep laboratory with polysomnographic monitoring. Furthermore, high-resolution T1-weighted MRI datasets were acquired in all participants. EEG sleep recordings were analyzed using standard sleep staging criteria and power spectral analysis. Using the FreeSurfer software for automated segmentation, 174 variables were determined representing the volume and thickness of cortical segments and the volume of subcortical brain areas. Regression analyses were performed to examine the relationship with polysomnographic and spectral EEG power variables.ResultsThe analysis did not provide any support for the a-priori formulated hypotheses of an association between brain morphology and polysomnographic variables. Exploratory analyses revealed that the thickness of the left caudal anterior cingulate cortex was positively associated with EEG beta2 power (24–32 Hz) during REM sleep. The volume of the left postcentral gyrus was positively associated with periodic leg movements during sleep (PLMS).ConclusionsThe function of the anterior cingulate cortex as well as EEG beta power during REM sleep have been related to dreaming and sleep-related memory consolidation, which may explain the observed correlation. Increased volumes of the postcentral gyrus may be the result of increased sensory input associated with PLMS. However, due to the exploratory nature of the corresponding analyses, these results have to be replicated before drawing firm conclusions.

Anterior and posterior MTL networks in aging and MCI

Two neuroanatomically dissociable, large-scale cortical memory networks, referred to as the anterior and posterior medial temporal lobe (MTL) networks have recently been described in young adults using resting-state blood oxygen level–dependent (BOLD) functional magnetic resonance imaging (fMRI)–based functional connectivity (fc-BOLD). They have been hypothesized to subserve distinct mnemonic and non-memory cognitive functions and are thought to be associated with differential vulnerability in neurological disorders. In this article, we demonstrate the existence of these functional networks in an older adult population and in a cohort of patients diagnosed with amnestic mild cognitive impairment (aMCI). Anatomic subregions of interest in the MTL were defined using high-resolution T2-weighted MRI and used as seeds for defining the putative networks using fc-BOLD. Although the literature has suggested that the posterior MTL network is particularly vulnerable to early Alzheimer's disease, we show that both the networks are affected in MCI, to varying degrees, compared with the control group. Furthermore, cortical thickness in the brain regions defined by these networks was reduced in MCI.

Morphometric Changes of the Corpus Callosum in Congenital Blindness

We examined the effects of visual deprivation at birth on the development of the corpus callosum in a large group of congenitally blind individuals. We acquired high-resolution T1-weighted MRI scans in 28 congenitally blind and 28 normal sighted subjects matched for age and gender. There was no overall group effect of visual deprivation on the total surface area of the corpus callosum. However, subdividing the corpus callosum into five subdivisions revealed significant regional changes in its three most posterior parts. Compared to the sighted controls, congenitally blind individuals showed a 12% reduction in the splenium, and a 20% increase in the isthmus and the posterior part of the body. A shape analysis further revealed that the bending angle of the corpus callosum was more convex in congenitally blind compared to the sighted control subjects. The observed morphometric changes in the corpus callosum are in line with the well-described cross-modal functional and structural neuroplastic changes in congenital blindness.

Voxel-based MRI intensitometry reveals extent of cerebral white matter pathology in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is characterized by progressive loss of upper and lower motor neurons. Advanced MRI techniques such as diffusion tensor imaging have shown great potential in capturing a common white matter pathology. However the sensitivity is variable and diffusion tensor imaging is not yet applicable to the routine clinical environment. Voxel-based morphometry (VBM) has revealed grey matter changes in ALS, but the bias-reducing algorithms inherent to traditional VBM are not optimized for the assessment of the white matter changes. We have developed a novel approach to white matter analysis, namely voxel-based intensitometry (VBI). High resolution T1-weighted MRI was acquired at 1.5 Tesla in 30 ALS patients and 37 age-matched healthy controls. VBI analysis at the group level revealed widespread white matter intensity increases in the corticospinal tracts, corpus callosum, sub-central, frontal and occipital white matter tracts and cerebellum. VBI results correlated with disease severity (ALSFRS-R) and patterns of cerebral involvement differed between bulbar- and limb-onset. VBI would be easily translatable to the routine clinical environment, and once optimized for individual analysis offers significant biomarker potential in ALS.

Evaluation of a 32-channel versus a 12-channel head coil for high-resolution post-contrast MRI in giant cell arteritis (GCA) at 3 T

The aim of this study was to evaluate the diagnostic value of a 32-channel head coil for the characterization of mural inflammation patterns in the superficial cranial arteries in patients with giant cell arteritis (GCA) compared to a standard 12-channel coil at 3T MRI.55 patients with suspected GCA underwent high resolution T1-weighted post-contrast MRI at 3T to detect inflammation related vessel wall enhancement using both coils. To account for different time delays between contrast agent injection and sequence acquisition, the patients were divided into two cohorts: 27 patients were examined with the 32-channel coil first and 28 patients with the 12-channel coil first. Images were evaluated by two blinded readers with regard to image quality, artifact level and arteries’ inflammation according to a standardized ranking scale; furthermore signal-to-noise ratio (SNR) measurements were performed at three locations.Identification of arteries’ inflammation was achieved with both coils with excellent inter-observer agreement (κ=0.89 for 12-channel and κ=0.96 for 32-channel coil). Regarding image grading, the inter-observer variability was moderate for the 12-channel (κ=0.5) and substantial for the 32-channel coil (κ=0.63). Significantly higher SNR and improved image quality (p<0.01) were obtained with the 32-channel coil in either coil order.Image quality for depiction of the superficial cranial arteries was superior for the 32-channel coil. For standardized GCA diagnosis, the 12-channel coil was sufficient.

Changes in dopamine release and dopamine D2/3 receptor levels with the development of mild obesity

Dopamine (DA) neurotransmission is an important modulator of both homeostatic food consumption mediated by the hypothalamus, and reward-related/ hedonic food consumption mediated by the brain reward circuit (Lutter and Nestler, 2009; Schwartz et al., 2000; Wise, 2008). Although there are monogenetic mutations that affect the regulation of body weight, the majority of cases of human obesity appear to result from the interaction of polygenetic predispositions to obesity with an environment in which highly palatable foods are readily available leading to excessive consumption of such foods (Walley et al. 2009). There have been two major hypotheses regarding the role of DA neurotransmission in the development of obesity. The first postulates a rewarddeficient state leading to compensatory overeating to remedy an anhedonic state; decreased brain reward circuit DA neurotransmission is hypothesized to be a significant factor in this reward-deficient state (Blum et al., 2000; Geiger et al., 2008). The second hypothesis postulates that increased behavioral salience of food produces excessive intake of highly palatable foods leading to obesity; this increased behavioral salience is believed to be mediated by increased ventral striatal DA release (Berridge et al., 2009). Although studies of obese animals and obesity prone animals have consistently shown decreased striatal DA release and DA D2/3 receptor levels (DA D2r), to date there have been no published data in humans on changes in DA release in the evolution of obesity and varying results on changes in DA D2r with the development of obesity (Eisenstein et al., 2013; Geiger et al., 2008; Haltia et al., 2007; Johnson and Kenny, 2010; Wang et al., 2001). The purpose of this study was to evaluate the changes in DA release and DA D2r with the development of mild obesity. Baseline [F]fallypride PET studies were performed in 33 healthy subjects (M5 18, F515, mean age5 25.8, range 18–35; mean BMI5 24.8, range 19–35) as previously described to determine regional DA D2r (Kessler, 2009). To evaluate regional DA release, 16 of the 33 subjects having the baseline [F]fallypride positron emission tomography (PET) study (8M, 8F; mean age5 24.3, age range5 21–32; mean BMI5 25.2, body mass index (BMI) range of 19–35) had a second [F]fallypride PET study 3 h following oral administration of 0.43 mg/kg d-amphetamine.(Riccardi et al., 2006). Regions believed to be involved in the development of obesity including ventral striatum, ventral midbrain/substantia nigra, amygdala, caudate, and putamen were specifically examined. High-resolution T1-weighted MRI scans and PET scans of the brain were performed and coregistered to each other. Regions of interest were delineated on the coregistered MRI, and regional estimates of DA D2r (BPND’s) and amphetamine-induced DA release were calculated as previously described (Kessler, 2009; Riccardi et al., 2006). Correlations of regional DA D2r and DA release with BMI were performed using a Pearson product moment correlation covaried for age. Correlations of DA D2r with BMI covaried for age demonstrated small negative correlations in the regions examined (Table 1). Correlations in the right

Motor function deficits in schizophrenia: an fMRI and VBM study

To investigate whether the motor functional alterations in schizophrenia (SZ) are also associated with structural changes in the related brain areas using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). A sample of 14 right-handed SZ patients and 14 right-handed healthy control subjects matched for age, sex, and education were examined with structural high-resolution T1-weighted MRI; fMRI images were obtained during right index finger-tapping task in the same session. fMRI results showed reduced functional activation in the motor areas (contralateral precentral and postcentral gyrus) and ipsilateral cerebellum in SZ subjects as compared to healthy controls (n = 14). VBM analysis also revealed reduced grey matter in motor areas and white matter reduction in cerebellum of SZ subjects as compared to controls. The present study provides an evidence for a possible association between structural alterations in the motor cortex and disturbed functional activation in the motor areas in persons affected with SZ during a simple finger-tapping task.

T2‐weighted prostate MRI at 7 tesla using a simplified external transmit‐receive coil array: Correlation with radical prostatectomy findings in two prostate cancer patients

To report design of a simplified external transmit-receive coil array for 7 Tesla (T) prostate MRI, including demonstration of the array for tumor localization using T2-weighted imaging (T2WI) at 7T before prostatectomy. Following simulations of transmitter designs not requiring parallel transmission or radiofrequency-shimming, a coil array was constructed using loop elements, with anterior and posterior rows comprising one transmit-receive element and three receive-only elements. This coil structure was optimized using a whole-body phantom. In vivo sequence optimization was performed to optimize achieved flip angle (FA) and signal to noise ratio (SNR) in prostate. The system was evaluated in a healthy volunteer at 3T and 7T. The 7T T2WI was performed in two prostate cancer patients before prostatectomy, and localization of dominant tumors was subjectively compared with histopathological findings. Image quality was compared between 3T and 7T in these patients. Simulations of the B1(+) field in prostate using two-loop design showed good magnitude (B1(+) of 0.245 A/m/w(1/2)) and uniformity (nonuniformity [SD/mean] of 10.4%). In the volunteer, 90° FA was achieved in prostate using 225 v 1 ms hard-pulse (indicating good efficiency), FA maps confirmed good uniformity (14.1% nonuniformity), and SNR maps showed SNR gain of 2.1 at 7T versus 3T. In patients, 7T T2WI showed excellent visual correspondence with prostatectomy findings. 7T images demonstrated higher estimated SNR (eSNR) in benign peripheral zone (PZ) and tumor compared with 3T, but lower eSNR in fat and slight decreases in tumor-to-PZ contrast and PZ-homogeneity. We have demonstrated feasibility of a simplified external coil array for high-resolution T2-weighted prostate MRI at 7T.

Basal ganglia involvement in amyotrophic lateral sclerosis

To characterize the nature and extent of basal ganglia involvement in amyotrophic lateral sclerosis (ALS) genotypes in vivo. Forty-four healthy controls and 39 patients with ALS were included in the study. Thirty patients with ALS had a negative C9orf72 status and 9 patients with ALS carried the C9orf72 hexanucleotide repeat expansion. High-resolution T1-weighted MRI data were used for model-based subcortical registration and segmentation. Fifteen subcortical structures were studied with both volumetric and vertex-wise approaches. Changes in basal ganglia diffusivity parameters were also assessed. Using age as a covariate, patients with ALS who were C9orf72 repeat negative showed significant volume reductions in the left caudate nucleus (p = 0.01), left hippocampus (p = 0.007), and right accumbens nucleus (p = 0.001) compared with healthy controls. Vertex-wise shape analyses revealed changes affecting the superior and inferior aspects of the bilateral thalami, the lateral and inferior portion of the left hippocampus, and the medial and superior aspect of the left caudate. Basal ganglia pathology was more extensive in patients with ALS carrying the C9orf72 hexanucleotide repeat expansion. ALS is associated with widespread basal ganglia involvement. Caudate nucleus, hippocampus, and nucleus accumbens atrophy are key features of ALS. Dysfunction of frontostriatal networks is likely to contribute to the unique neuropsychological profile of ALS, dominated by executive dysfunction, apathy, and deficits in social cognition. Our quantitative imaging findings are consistent with postmortem studies and indicate that subcortical gray matter structures should be included in future biomarker studies of ALS.

Gray matter abnormalities in schizophrenia patients with tardive dyskinesia: a magnetic resonance imaging voxel-based morphometry study.

ObjectiveThe pathophysiological mechanism of TD remains unknown. All previous studies, using the region-of-interest method, focused on basal ganglion areas, were with inconsistent results. This whole-brain voxel-based morphometry (VBM) study investigate the grey matter abnormality of TD and its correlates with clinical ratings.MethodHigh resolution T1-weighted brain volumetric MRI from 25 schizophrenia patients with TD (TD group), 25 age-, gender-, and handedness-matched schizophrenia patients without TD (non-TD group), and 25 matched healthy subjects (NC group) were analyzed using a VBM approach. Clinical ratings included the Positive and Negative Symptom Scale (PANSS), Abnormal Involuntary Movement Scale (AIMS), and the Simpson-Angus Scale (SAS).ResultsThe TD group had significantly smaller total gray matter volumes than the NC group (p = 0.05). Compared to the non-TD group, the TD group had significantly higher PANSS negative (p<0.001), SAS (p<0.001), and AIMS (p<0.001) scores; and smaller bilateral inferior frontal gyrus, which correlated negatively with the PANSS negative scores (r = −0.366, p<0.05); and smaller right superior frontal gyrus, which correlated negatively with AIMS scores (r = −0.399, p<0.001), and PANSS general score (r = −0.338, p<0.05).LimitationsThe cross-section design can’t separate the gray matter change to TD from the context of the illness of schizophrenia, although TD with more severe clinical psychopathology could be a phenotype.ConclusionsThe schizophrenia patients with TD had significantly reduced gray matter, mostly at the bilateral inferior frontal gyrus and the right superior frontal gyrus, which correlated with severity of clinical symptoms and involuntary movement, respectively.

Utility of diffusion-weighted MRI in the diagnosis of bladder carcinoma

BackgroundThe purposes of our study were to investigate the feasibility of diffusion-weighted imaging in the detection of malignant bladder tumors, with comparison to the high-resolution thin-section fast spin-echo (FSE) T2-weighted MRI, and also to compare the apparent diffusion coefficient (ADC) values of the bladder tumors with the surrounding structures. Material and MethodsFifty-three consecutive patients consisting of 44 males and 9 females who presented with a bladder mass were prospectively enrolled in this study. Mean age was 62.53±12.03 (age range, 33–86 years). These patients were evaluated by high-resolution thin-section FSE T2-weighted and diffusion-weighted MRI for the detection of bladder masses. Following MRI, within 2 weeks, all patients were subjected to either surgery or cystoscopic biopsy, and the obtained histopathological proofs were used as the reference standard. Furthermore, ADC values of the bladder tumors, urine, the normal bladder wall, the central and peripheral zones of the prostate, the seminal vesicule, and the uterus outer myometrium were also calculated. ADC values of the bladder carcinomas and the related surrounding structures were compared as to whether a statistically significant difference was present or not. ResultsIn a total of 47 patients, consisting of 39 males and 8 females, bladder carcinomas were clearly shown as having conspicuous high and intermediate signal intensity masses, relative to the surrounding structures on diffusion-weighted and T2-weighted images, respectively. An 89% sensitivity and a 100% positive predictive value were obtained for both FSE T2-weighted and diffusion-weighted MRI in the diagnosis of bladder carcinoma. Mean ADC values and standard deviations of the bladder tumors and the surrounding structures were as follows: bladder carcinomas (n=47): 1.28±0.31, normal bladder wall (n=47): 1.98±0.41, urine (n=47): 3.12±0.24, seminal vesicle (n=39): 1.82±0.33, peripheral zone of prostate (n=39): 1.80±0.29, central zone of prostate (n=39): 1.55±0.33, and uterus outer myometrium (n=8): 1.53±0.19. It can be clearly seen that the mean ADC values of the bladder carcinomas were significantly lower than the surrounding structures (P<.05). ConclusıonHigh-resolution thin-section FSE T2 and diffusion-weighted MRI show high diagnostic performance and are comparable in the detection of bladder tumors. Diffusion-weighted MRI provides high quality images of the malignant bladder tumors against a suppressed background signal. Diffusion-weighted MRI using ADC measurements may be useful in the evaluation of tumor invasion to the adjacent organs.

Brain Tissue Volumes and Perfusion Change with the Number of Optic Neuritis Attacks in Relapsing Neuromyelitis Optica: A Voxel-Based Correlation Study

Recent neuroimaging studies show that brain abnormalities in neuromyelitis optica (NMO) are more frequent than earlier described. Yet, more research considering multiple aspects of NMO is necessary to better understand these abnormalities. A clinical feature of relapsing NMO (RNMO) is that the incremental disability is attack-related. Therefore, association between the attack-related process and neuroimaging might be expected. On the other hand, the immunopathological analysis of NMO lesions has suggested that CNS microvasculature could be an early disease target, which could alter brain perfusion. Brain tissue volume changes accompanying perfusion alteration could also be expected throughout the attack-related process. The aim of this study was to investigate in RNMO patients, by voxel-based correlation analysis, the assumed associations between regional brain white (WMV) and grey matter volumes (GMV) and/or perfusion on one side, and the number of optic neuritis (ON) attacks, myelitis attacks and/or total attacks on the other side. For this purpose, high resolution T1-weighted MRI and perfusion SPECT imaging were obtained in 15 RNMO patients. The results showed negative regional correlations of WMV, GMV and perfusion with the number of ON attacks, involving important components of the visual system, which could be relevant for the comprehension of incremental visual disability in RNMO. We also found positive regional correlation of perfusion with the number of ON attacks, mostly overlapping the brain area where the WMV showed negative correlation. This provides evidence that brain microvasculature is an early disease target and suggests that perfusion alteration could be important in the development of brain structural abnormalities in RNMO.

Sensorimotor and Pain Modulation Brain Abnormalities in Trigeminal Neuralgia: A Paroxysmal, Sensory-Triggered Neuropathic Pain

ObjectiveIdiopathic trigeminal neuralgia (TN) is characterized by paroxysms of severe facial pain but without the major sensory loss that commonly accompanies neuropathic pain. Since neurovascular compression of the trigeminal nerve root entry zone does not fully explain the pathogenesis of TN, we determined whether there were brain gray matter abnormalities in a cohort of idiopathic TN patients. We used structural MRI to test the hypothesis that TN is associated with altered gray matter (GM) in brain areas involved in the sensory and affective aspects of pain, pain modulation, and motor function. We further determined the contribution of long-term TN on GM plasticity.MethodsCortical thickness and subcortical GM volume were measured from high-resolution 3T T1-weighted MRI scans in 24 patients with right-sided TN and 24 healthy control participants.ResultsTN patients had increased GM volume in the sensory thalamus, amygdala, periaqueductal gray, and basal ganglia (putamen, caudate, nucleus accumbens) compared to healthy controls. The patients also had greater cortical thickness in the contralateral primary somatosensory cortex and frontal pole compared to controls. In contrast, patients had thinner cortex in the pregenual anterior cingulate cortex, the insula and the orbitofrontal cortex. No relationship was observed between GM abnormalities and TN pain duration.ConclusionsTN is associated with GM abnormalities in areas involved in pain perception, pain modulation and motor function. These findings may reflect increased nociceptive input to the brain, an impaired descending modulation system that does not adequately inhibit pain, and increased motor output to control facial movements to limit pain attacks.

Tissue localization during resective epilepsy surgery

Imaging-guided surgery (IGS) systems are widely used in neurosurgical practice. During epilepsy surgery, the authors routinely use IGS landmarks to localize intracranial electrodes and/or specific brain regions. The authors have developed a technique to coregister these landmarks with pre- and postoperative scans and the Montreal Neurological Institute (MNI) standard space brain MRI to allow 1) localization and identification of tissue anatomy; and 2) identification of Brodmann areas (BAs) of the tissue resected during epilepsy surgery. Tracking tissue in this fashion allows for better correlation of patient outcome to clinical factors, functional neuroimaging findings, and pathological characteristics and molecular studies of resected tissue. Tissue samples were collected in 21 patients. Coordinates from intraoperative tissue localization were downloaded from the IGS system and transformed into patient space, as defined by preoperative high-resolution T1-weighted MRI volume. Tissue landmarks in patient space were then transformed into MNI standard space for identification of the BAs of the tissue samples. Anatomical locations of resected tissue were identified from the intraoperative resection landmarks. The BAs were identified for 17 of the 21 patients. The remaining patients had abnormal brain anatomy that could not be meaningfully coregistered with the MNI standard brain without causing extensive distortion. This coregistration and landmark tracking technique allows localization of tissue that is resected from patients with epilepsy and identification of the BAs for each resected region. The ability to perform tissue localization allows investigators to relate preoperative, intraoperative, and postoperative functional and anatomical brain imaging to better understand patient outcomes, improve patient safety, and aid in research.

Transcriptomics of cortical gray matter thickness decline during normal aging

IntroductionWe performed a whole-transcriptome correlation analysis, followed by the pathway enrichment and testing of innate immune response pathway analyses to evaluate the hypothesis that transcriptional activity can predict cortical gray matter thickness (GMT) variability during normal cerebral aging. MethodsTranscriptome and GMT data were available for 379 individuals (age range=28–85) community-dwelling members of large extended Mexican American families. Collection of transcriptome data preceded that of neuroimaging data by 17years. Genome-wide gene transcriptome data consisted of 20,413 heritable lymphocytes-based transcripts. GMT measurements were performed from high-resolution (isotropic 800μm) T1-weighted MRI. Transcriptome-wide and pathway enrichment analysis was used to classify genes correlated with GMT. Transcripts for sixty genes from seven innate immune pathways were tested as specific predictors of GMT variability. ResultsTranscripts for eight genes (IGFBP3, LRRN3, CRIP2, SCD, IDS, TCF4, GATA3, and HN1) passed the transcriptome-wide significance threshold. Four orthogonal factors extracted from this set predicted 31.9% of the variability in the whole-brain and between 23.4 and 35% of regional GMT measurements. Pathway enrichment analysis identified six functional categories including cellular proliferation, aggregation, differentiation, viral infection, and metabolism. The integrin signaling pathway was significantly (p<10−6) enriched with GMT. Finally, three innate immune pathways (complement signaling, toll-receptors and scavenger and immunoglobulins) were significantly associated with GMT. ConclusionExpression activity for the genes that regulate cellular proliferation, adhesion, differentiation and inflammation can explain a significant proportion of individual variability in cortical GMT. Our findings suggest that normal cerebral aging is the product of a progressive decline in regenerative capacity and increased neuroinflammation.

Impairments of thalamic nuclei in idiopathic generalized epilepsy revealed by a study combining morphological and functional connectivity MRI.

ObjectiveNeuroimaging evidence suggested that the thalamic nuclei may play different roles in the progress of idiopathic generalized epilepsy (IGE). This study aimed to demonstrate the alterations in morphometry and functional connectivity in the thalamic nuclei in IGE.MethodsFifty-two patients with IGE characterized by generalized tonic-clonic seizures and 67 healthy controls were involved in the study. The three-dimensional high-resolution T1-weighted MRI data were acquired for voxel-based morphometry (VBM) analysis, and resting-state blood-oxygenation level functional MRI data were acquired for functional connectivity analysis. The thalamic nuclei of bilateral medial dorsal nucleus (MDN) and pulvinar, as detected with decreased gray matter volumes in patients with IGE through VBM analysis, were selected as seed regions for functional connectivity analysis.ResultsDifferent alteration patterns were found in functional connectivity of the thalamic nuclei with decreased gray matter volumes in IGE. Seeding at the MDN, decreased connectivity in the bilateral orbital frontal cortex, caudate nucleus, putamen and amygdala were found in the patients (P<0.05 with correction). However, seeding at the pulvinar, no significant alteration of functional connectivity was found in the patients (P<0.05 with correction).ConclusionsSome specific impairment of thalamic nuclei in IGE was identified using morphological and functional connectivity MRI approaches. These findings may strongly support the different involvement of the thalamocortical networks in IGE.