Operative Anatomy of the Skull Base: 3D Exploration with a Highly Detailed Interactive Atlas.

Objective We evaluated the usefulness of a three-dimensional (3D) interactive atlas to illustrate and teach surgical skull base anatomy in a clinical setting. Study Design A highly detailed atlas of the adult human skull base was created from multiple high-resolution magnetic resonance imaging (MRI) and computed tomography (CT) scans of a healthy Caucasian male. It includes the parcellated and labeled bony skull base, intra- and extracranial vasculature, cranial nerves, cerebrum, cerebellum, and brainstem. We are reporting retrospectively on our experiences with employing the atlas for the simulation and teaching of neurosurgical approaches and concepts in a clinical setting. Setting The study was conducted at the University Hospital Mainz, Germany, and Hirslanden Hospital, Zürich, Switzerland. Participants Medical students and neurosurgical residents participated in this study. Results Handling the layered graphical user interface of the atlas requires some training; however, navigating the detailed 3D content from intraoperative perspectives led to quick comprehension of anatomical relationships that are otherwise difficult to perceive. Students and residents appreciated the collaborative learning effect when working with the atlas on large projected screens and markedly improved their anatomical knowledge after interacting with the software. Conclusion The skull base atlas provides an effective way to study essential surgical anatomy and to teach operative strategies in this complex region. Interactive 3D computer graphical environments are highly suitable for conveying complex anatomy and to train and review surgical concepts. They remain underutilized in clinical practice.

CACNA1C genomewide supported psychosis genetic variation affects cortical brain white matter integrity in Chinese patients with schizophrenia.

OBJECTIVE: Recent genomewide association studies have implicated the calcium channel, voltage-dependent, L type, alpha 1C subunit (CACNA1C) genetic variant in schizophrenia, which is associated with functional brain changes and cognitive deficits in healthy individuals. However, the impact of CACNA1C on brain white matter integrity in schizophrenia remains unclear. On the basis of prior evidence of CACNA1C-mediated changes involving cortical brain regions, we hypothesize that CACNA1C risk variant rs1006737 is associated with reductions of white matter integrity in the frontal, parietal, and temporal regions and cingulate gyrus. METHOD: A total of 160 Chinese participants (96 DSM-IV-diagnosed patients with schizophrenia and 64 healthy controls) were genotyped by using blood samples and underwent structural magnetic resonance imaging and diffusion tensor imaging scans from 2008 to 2012. Two-way analysis of covariance was employed to examine CACNA1C-related genotype effects, diagnosis effects, and genotype × diagnosis interaction effects on fractional anisotropy (FA) of relevant brain regions. RESULTS: Significant diagnosis-genotype interactions were observed (left frontal lobe mean FA: F1,156 = 6.22, P = .014; left parietal lobe mean FA: F1,156 = 7.14, P = .008; left temporal lobe mean FA: F1,156 = 8.37, P = .004). Compared with patients who were A carriers, patients who were G homozygotes had lower mean FA in the left frontal lobe (F1,93 = 2.504, P = .014), left parietal lobe (F1,93 = 2.37, P = .020), and left temporal lobe (F1,93 = 3.01, P = .003), with standardized effect sizes of -1.43, -1.3, and -1.0, respectively. CONCLUSIONS: CACNA1C risk variant rs1006737 affects cortical white matter integrity in schizophrenia. Further imaging genetic investigations on the mediating effect of CACNA1C in schizophrenia can uncover brain circuitries involved in schizophrenia and suggest potential novel targets for intervention.

Quantification of the human cerebrovasculature: a 7Tesla and 320-row CT in vivo study.

OBJECTIVE: Human cerebrovasculature has not been quantified in volume, length, and vascular-brain relationships. We investigated this using imaging. METHODS: From 0.5-mm 7T and 320-row CT acquisitions, 6 arterial and 4 venous systems were reconstructed, measured, and analyzed. RESULTS: The ratio of the volume of arterial to venous system is approximately 1:3. The ratio of the volume of dural sinuses to vasculature is 1:2. The ratio of the posterior (PCA) to anterior (ACA) to middle cerebral artery (MCA) is 1:2:4 in volume and length. Ratios of left to right vessels are 1:1 for arteries and veins. Ratios of branching frequency for the ACA, MCA, and PCA are 1:1:1. The branching frequency ratio for superficial to deep veins is 1:2. The MCA occupies 1/2 of arterial length and 1/4 of vascular length. The ratio of the length of superficial to deep veins is 1:1 and each is equal to 1/4 of the vascular length. The ratio of cerebrovasculature to brain volume is 2.5%. CONCLUSIONS: Despite its enormous complexity, cerebrovasculature is characterized by 4 approximate proportions, 1:1, 1:2, 1:3, 1:4, and their combinations, 1:1:1 and 1:2:4.

GRIN2B gene and associated brain cortical white matter changes in bipolar disorder: a preliminary combined platform investigation.

Abnormalities in glutamate signaling and glutamate toxicity are thought to be important in the pathophysiology of bipolar disorder (BD). Whilst previous studies have found brain white matter changes in BD, there is paucity of data about how glutamatergic genes affect brain white matter integrity in BD. Based on extant neuroimaging data, we hypothesized that GRIN2B risk allele is associated with reductions of brain white matter integrity in the frontal, parietal, temporal, and occipital regions and cingulate gyrus in BD. Fourteen patients with BD and 22 healthy controls matched in terms of age, gender and handedness were genotyped using blood samples and underwent diffusion tensor imaging. Compared to G allele, brain FA values were significantly lower in BD patients with risk T allele in left frontal region (P = 0.001), right frontal region (P = 0.002), left parietal region (P = 0.001), left occipital region (P = 0.001), right occipital region (P < 0.001), and left cingulate gyrus (P = 0.001). Further elucidation of the interactions between different glutamate genes and their relationships with such structural, functional brain substrates will enhance our understanding of the link between dysregulated glutamatergic neurotransmission and neuroimaging endophenotypes in BD.

ARVCF genetic influences on neurocognitive and neuroanatomical intermediate phenotypes in Chinese patients with schizophrenia.

OBJECTIVE: There are notable similarities between velocardiofacial syndrome and schizophrenia in terms of neurocognitive deficits and brain structural abnormalities. These similarities have supported the role of the armadillo repeat gene deleted in velocardiofacial syndrome (ARVCF) as a susceptibility gene in schizophrenia. This study investigated the relationships between haplotypes of the ARVCF gene and specific intermediate phenotypes in schizophrenia. We hypothesized that ARVCF gene haplotypes influence caudate nucleus volume, fractional anisotropy, and neurocognitive functioning in schizophrenia. METHOD: Between May 2006 and November 2009, 200 Chinese participants (125 patients with DSM-IV diagnosis of schizophrenia and 75 controls) were genotyped using blood samples, and a subset of 166 participants (99 patients with DSM-IV diagnosis of schizophrenia and 67 controls) underwent structural magnetic resonance imaging, diffusion tensor imaging, and completed neuropsychological testing. RESULTS: The haplotype T-G-A-T-T-G-G-C-T-G-T (ARVCF-Hap1) was significantly associated with fractional anisotropy of the caudate nucleus and executive functioning in patients. Specifically, patients with more copies of ARVCF-Hap1 have lower white matter integrity in caudate nucleus (P = .0008) and greater perseverative errors (P = .00003) on the Wisconsin Card Sorting Test. A trend of lower caudate volume (P = .015) in patients with more copies of ARVCF-Hap1 was also observed. CONCLUSIONS: These findings are consistent with known ARVCF gene effects on neurodevelopment in terms of cellular arrangement, migration, and intracellular signaling involving the striatum and may involve interactions with other brain networks such as prefrontal cortex, and they underscore the importance of imaging-genetic studies to elucidate the genetic influences underlying intermediate phenotypes in complex neurobehavioral disorders.

Cortical and subcortical white matter abnormalities in adults with remitted first-episode mania revealed by Tract-Based Spatial Statistics.

OBJECTIVES: Abnormalities of brain white matter have been noted in structural magnetic resonance imaging and diffusion tensor imaging (DTI) studies of bipolar disorder, but there are fewer investigations specifically examining white matter integrity early in the course of illness. In this study, we employed DTI to elucidate white matter changes in adult patients with remitted first-episode mania and hypothesized that first-episode mania was associated with decreased fractional anisotropy in cortical (frontal) and subcortical (thalamus, striatum) white matter as well as white matter tracts (cingulum, corpus callosum). METHODS: Diffusion tensor images were acquired from 16 patients with remitted first-episode mania and 16 healthy controls matched for age, gender, handedness, and years of education. Fractional anisotropy and radial and axial diffusivities were analyzed using Tract-Based Spatial Statistics. RESULTS: Patients had lower fractional anisotropy and higher radial diffusivity in the left anterior frontal white matter, right posterior thalamic radiation, left cingulum, and bilateral sagittal striatum. In addition, increased radial diffusivity was found in the left corpus callosum. CONCLUSION: Our findings highlighted that white matter abnormalities were present by the time of remission of first-episode mania. The widespread occurrence of these white matter abnormalities both in first-episode mania and chronic bipolar disorder suggested that disruption of white matter cortical-subcortical networks as well as projection, associative, and commissural tracts is a hallmark of the illness.

White matter abnormalities in first-episode schizophrenia: a combined structural MRI and DTI study.

This study examined white matter volume change and integrity jointly in patients with first-episode schizophrenia using an empirically derived region of interest approach and novel Diffusion Tensor Imaging (DTI) geometric indices. Structural images from 103 individuals comprising of 39 patients with first-episode schizophrenia and 64 healthy controls were examined for regions of white matter volume change using voxel-based morphometry (VBM). These regions were then further interrogated for group differences employing geometric indices in addition to fractional anisotropy (FA).VBM analyses revealed that patients with first-episode schizophrenia had lower white matter volume in the right temporal-occipital region (p<0.005) corresponding to the inferior longitudinal fasciculus. Further analyses of diffusion anisotropy in the right temporal-occipital region revealed lower planar anisotropy, and higher linear anisotropy (p=0.012) in patients. FA in the implicated region was also found to be correlated with severity of delusions (r=0.47, p=0.004).We confirmed previous findings of lower white matter volume in the region of inferior longitudinal fasciculus. The presence of changes in geometric diffusion indices in the implicated white matter region suggested that pathophysiological processes which underlie cerebral white matter volume reduction may not be reflected by changes in FA. Further research is needed to better understand the nature of these white matter changes and its progression in schizophrenia over time.

Duration of illness, regional brain morphology and neurocognitive correlates in schizophrenia.

INTRODUCTION: Previous studies examining brain effects of duration of illness in schizophrenia have focused on either cortical or subcortical structures. Hence this study sought to elucidate the regional grey matter changes (both cortical and subcortical) and neurocognitive correlates with increased duration of illness in a large sample of patients with schizophrenia using voxel-based morphometry. MATERIALS AND METHODS: Ninety patients (72 males and 18 females) with DSM-IV diagnosis of schizophrenia were recruited and assessed using magnetic resonance imaging and a battery of neuropsychological tests. RESULTS: A longer duration of illness was associated with smaller grey matter volumes in the left superior frontal gyrus, bilateral putamen, right superior temporal gyrus, right superior occipital gyrus as well as the right thalamus. No region showed increased grey matter volume above threshold with longer duration of illness. Longer duration of illness was correlated with poorer attention. CONCLUSIONS: The grey matter reductions in different brain regions highlighted that a distributed network of cortical and subcortical regions was associated with duration of illness. This is consistent with neural models that implicate involvement of thalamo-cortical circuitry as the disruption in these neural pathways can result in specific deficits such as poorer attention. The results have implications for the understanding of brain changes in schizophrenia, and with further studies, may guide better tailored and targeted clinical management in terms of reducing the impact of duration of illness on neural substrates in schizophrenia in the future.

Informatics in radiology (infoRAD): multimedia extension of medical imaging resource center teaching files.

A new method has been developed for multimedia enhancement of electronic teaching files created by using the standard protocols and formats offered by the Medical Imaging Resource Center (MIRC) project of the Radiological Society of North America. The typical MIRC electronic teaching file consists of static pages only; with the new method, audio and visual content may be added to the MIRC electronic teaching file so that the entire image interpretation process can be recorded for teaching purposes. With an efficient system for encoding the audiovisual record of on-screen manipulation of radiologic images, the multimedia teaching files generated are small enough to be transmitted via the Internet with acceptable resolution. Students may respond with the addition of new audio and visual content and thereby participate in a discussion about a particular case. MIRC electronic teaching files with multimedia enhancement have the potential to augment the effectiveness of diagnostic radiology teaching.