Negative emotional distraction on neural circuits for working memory in patients with posttraumatic stress disorder.

OBJECTIVE: To study the neural mechanism for the impact of negative emotional distraction on working memory in patients with posttraumatic stress disorder (PTSD) resulting from exposure to motor vehicle accidents. METHODS: Twenty PTSD patients and 20 healthy subjects were recruited. Event-related functional magnetic resonance imaging (fMRI) was used to investigate the effects of negative and neutral distractors on a delayed-response working memory task. All experiments were performed on a 3.0T MRI scanner, and the functional imaging data were analyzed using SPM8 software. RESULTS: The PTSD group showed poorer performance than the control group when the negative distractors were presented during the delay phase of working memory. The functional imaging indicated that, in the presence of negative relative to neutral distractors, the PTSD group showed higher activation in the emotion processing regions, including amygdala, precuneus and fusiform gyrus, but lower activation in the inferior frontal cortex, insula and left supramarginal gyrus than the control group. CONCLUSION: Based on the results that activation in the PTSD patients in the presence of negative distractors increased in the emotion-related brain regions but decreased in the working memory-related brain regions, we may conclude that the neural basis of working memory is impaired by negative emotion in PTSD patients.

Diffusion tensor imaging-based research on human white matter anatomy.

The aim of this study is to investigate the white matter by the diffusion tensor imaging and the Chinese visible human dataset and to provide the 3D anatomical data of the corticospinal tract for the neurosurgical planning by studying the probabilistic maps and the reproducibility of the corticospinal tract. Diffusion tensor images and high-resolution T1-weighted images of 15 healthy volunteers were acquired; the DTI data were processed using DtiStudio and FSL software. The FA and color FA maps were compared with the sectional images of the Chinese visible human dataset. The probability maps of the corticospinal tract were generated as a quantitative measure of reproducibility for each voxel of the stereotaxic space. The fibers displayed by the diffusion tensor imaging were well consistent with the sectional images of the Chinese visible human dataset and the existing anatomical knowledge. The three-dimensional architecture of the white matter fibers could be clearly visualized on the diffusion tensor tractography. The diffusion tensor tractography can establish the 3D probability maps of the corticospinal tract, in which the degree of intersubject reproducibility of the corticospinal tract is consistent with the previous architectonic report. DTI is a reliable method of studying the fiber connectivity in human brain, but it is difficult to identify the tiny fibers. The probability maps are useful for evaluating and identifying the corticospinal tract in the DTI, providing anatomical information for the preoperative planning and improving the accuracy of surgical risk assessments preoperatively.

Creation of a female and male segmentation dataset based on Chinese Visible Human (CVH).

OBJECTIVE: Segmentation is a necessary step when creating realistic three-dimensional (3D) models. In order to build 3D models of whole body structures and have a wider lateral application, the thin sectional anatomical images of the Chinese Visible Human (CVH) dataset should be segmented. The more detailed structures are segmented to provide greater potential for wider application of the segmented images. MATERIALS AND METHODS: All the images based on the CVH male and female dataset were segmented semi-automatically using PHOTOSHOP software. This research lasted about 7 years. RESULT: In this study, 869 structures of CVH male and 860 structures of CVH female were semi-automatically segmented, and the formats for the segmented color-filled image data were PSD and PNG. In these segmented structures, nearly all skeletal muscles included muscle belly and tendon, and hollow organs included their organ walls and their lumen. Most nerve trunks, small arteries, lymph nodes, and lymph ducts were also segmented. Many surface-rendering and volume-rendering organ models were created using these segmented images. CONCLUSION: The CVH male and female images represent the normal Asian population. After segmentation, the images can be reconstructed directly in 3D and greatly facilitate the biological modeling of physical and physiological information, a great help in improving medical and biological science in China.

Changes of brain structure and function in ADHD children.

To explore the changes of brain structure and function in attention-deficit/hyperactivity disorder (ADHD), fifteen ADHD patients (inattention subtype) and 15 normal control participants were recruited, the brain structure and function of these subjects were investigated by combining structural magnetic resonance imaging (MRI), diffusion tensor imaging and resting-state functional MRI. The results showed that ADHD patients had a significant decrease in the volume of the white matter (P = 0.04), and a trend toward decreased volume of brain structures except for the putamen and globus pallidus. The visualization of statistical difference maps of the cortical thickness showed that ADHD patients had focal thinning in bilateral frontal regions and the right cingulate cortex (P < 0.05 uncorrected, except for a cluster threshold of 10 voxels). Statistical analysis of the FA maps revealed that ADHD patients had significantly decreased FA in the forceps minor, the internal capsule, the corona radiata, the splenium of the corpus callosum, and the bilateral basal ganglia (P < 0.05 uncorrected as above). ADHD patients had significantly decreased functional connectivity in the anterior cingulate cortex, posterior cingulate cortex, lateral prefrontal cortex, left precuneus and thalamus, but increased functional connectivity in bilateral posterior medial frontal cortex in the default mode network (P < 0.05 uncorrected as above). Our results provide new insights into the changes of the brain structure and function in ADHD, which suggests that alterations in the brain structural and functional connectivity might implicate the pathophysiology of ADHD.

A novel technique for three-dimensional reconstruction for surgical simulation around the craniocervical junction region.

Performing surgeries on the craniocervical junction presents a technical challenge for operating surgeons. Three-dimensional (3D) reconstruction and surgical simulation have improved the efficacy and success rate of surgeries. The aim of this study was to create a 3D, digitized visible model of the craniocervical junction region to help realize accurate simulation of craniocervical surgery on a graphic workstation. Transverse sectional anatomy data for the study were chosen from the first Chinese visible human. Manual axial segmentation of the skull base, cervical spine, cerebellum, vertebral artery, internal carotid artery, sigmoid sinus, internal jugular vein, brain stem, and spinal cord were carried out by using Photoshop software. The segmented structures were reconstructed in 3 dimensions with surface and volume rendering to accurately display 3D models spatially. In contrast to conventional 3D reconstruction techniques that are based on computed tomography and magnetic resonance imaging Digital Imaging and Communications in Medicine (DICOM) inputs and provide mostly osseous details, this technique can help to illustrate the surrounding soft tissue structure and provide a realistic surgical simulation. The reconstructed 3D model was successfully used in simulating complex procedures in the virtual environment, including the transoral approach, bone drillings, and clivus resection.

Creation of the digital three-dimensional model of the prostate and its adjacent structures based on Chinese visible human.

We managed to provide three-dimensional digitized visible model of the prostate and its adjacent structures and to provide morphological data for imaging diagnosis and male urological surgery. With 3D-DOCTOR software, the contour line of prostate and its adjacent structures including rectum, bladder, male urethra, ureter, seminal vesicle, ductus deferens, ejaculatory ducts, obturator internus, levator ani, coccygeus, male pelvis, femur, prostatic nervous and venous plexus, internal and external iliac arteries were segmented from the Chinese visible human (CVH)-1 data set and the three-dimensional surfaces of intrapelvic visceras were successfully and accurately reconstructed via surface rendering, which can also be manipulated individually and interactively. Combined with AMIRA software, surface rendering reconstructed model of male urological organs and its adjacent structures via volume rendering reconstruction can be displayed together clearly and actually. It provides a learning tool of practicing virtual anatomy and virtual urological surgery for medical students and younger surgeons.

Aging changes of the angioarchitecture and arterial morphology of the spinal cord in rats.

BACKGROUND: It is well known that vascular myelopathy increases with age, however, there are no systematic reports on the quantitative capillary density in the spinal cord and no reports concerning the age-related changes of vascularity and capillary density of the spinal cord. OBJECTIVE: Age-related changes of vascularity and capillary density of the spinal cord and the morphology of the ventral spinal artery were observed and measured so as to provide reference to study the microcirculation of the spinal cord. METHODS: Three different age groups of Wistar rats (1-2, 6-7 and >22 months old) were studied by ink-gelatin injection, corrosion casts, biological stereological technique, image analysis and transmission electron microscope. RESULTS: The number of central arteries per centimeter of the spinal cord decreased significantly with age; the ventral spinal artery and central arteries often became tortuous in the >22 month group. Capillary density in the anterior horn was significantly higher than that in the posterior horn. Capillary density in the gray matter decreased significantly with age. These aging changes of the ventral spinal artery in the rat included that the folds of internal elastic membrane were reduced, the internal elastic membrane thinned and disrupted, the endothelial cells degenerated and broke away from the wall, and smooth muscle cells in the tunica media degenerated and protruded to the lumen. The relative content of the elastic fibers decreased significantly with age, while the relative content of the collagenic fibers and the ratio of the C/E increased significantly with age. CONCLUSIONS: The difference between capillary density in gray and white matter in the spinal cord has shown that the need of metabolization is adapted to the function of the neurons, and the anterior horn is more sensitive than the posterior horn to anoxia and is easily damaged during ischemia in the spinal cord. Aging changes of capillary density and arterial morphology of the spinal cord may be important contributory factors in vascular myelopathy.

[Visualization and thin sectional anatomy of the laryngeal cartilages].

OBJECTIVE: To establish digitized visible model of the laryngeal cartilages of the visible human, providing morphological data for image diagnosis and laryngectomy. METHODS: Cross-sectional images of fresh tissues from the Chinese visible human data set were reviewed, and the laryngeal cartilages structures data were used, the data was on a section-by-section basis. Three-dimensional computer reconstructions of the laryngeal cartilages were generated from these data by surface rendering on a SGI workstation. RESULTS: The digital images from the visible human offer unique insights into the complex anatomy and ossification of the laryngeal cartilages, the quality of the computerized 3D-reconstructed images was distinct and perfect. CONCLUSIONS: The visible human data set can provide complete and accurate data The digitized model of the laryngeal cartilages offer unique insights into the laryngeal anatomy, could be used for resident education, rehearsal of an unfamiliar surgery and for developing a new surgical approach.

Three-dimensional computational reconstruction of lateral skull base with plastinated slices.

The goals of this study were to build the 3D reconstructed model of lateral skull base and to explore the spatial relationships of the important structures for providing the morphological basis for lateral skull base surgery and clinical image diagnosis. Blocks with edges of about 80 mm containing the lateral skull base region and adjacent structures were sawn out from both sides of the heads and sectioned on transverse plane at a thickness of 700 microm using a plastination technique. On an SGI workstation, a Contours-Marching cubes algorithm was selected to reconstruct the 3D model of the lateral skull base. Accurate alignment of the structures in the serial macroscopic sections was obtained by the employment of the plastination technique. The quality of the reconstructed images was distinct and perfect, specifically, the spatial positions and complicated adjacent relationships of various structures of the lateral skull base can be shown in direct viewing when they are displayed in background of the cranial bony substance. The time spent in displaying or rotating one image including 50 sections was 1.5 sec; all reconstructed structures can be represented individually or jointly and rotated in any plane. The plastination technique and computer-aided 3D reconstruction have an obvious advantage in the study of the complex anatomy of the lateral skull base. Plastination technique provides cross-section images of a higher resolution than those obtained from CT scanning. The computerized 3D reconstruction is important in studying the spatial anatomy of the lateral skull base and can serve as a standard for models created with other techniques.

The Chinese Visible Human (CVH) datasets incorporate technical and imaging advances on earlier digital humans.

We report the availability of a digitized Chinese male and a digitzed Chinese female typical of the population and with no obvious abnormalities. The embalming and milling procedures incorporate three technical improvements over earlier digitized cadavers. Vascular perfusion with coloured gelatin was performed to facilitate blood vessel identification. Embalmed cadavers were embedded in gelatin and cryosectioned whole so as to avoid section loss resulting from cutting the body into smaller pieces. Milling performed at -25 degrees C prevented small structures (e.g. teeth, concha nasalis and articular cartilage) from falling off from the milling surface. The male image set (.tiff images each of 36 Mb) has a section resolution of 3072 x 2048 pixels ( approximately 170 micro m, the accompanying magnetic resonance imaging and computer tomography data have a resolution of 512 x 512, i.e. approximately 440 micro m). The Chinese Visible Human male and female datasets are available at http://www.chinesevisiblehuman.com. (The male is 90.65 Gb and female 131.04 Gb). MPEG videos of direct records of real-time volume rendering are at: http://www.cse.cuhk.edu.hk/~crc

Creation of the Chinese visible human data set.

The United States Visible Human Project (VHP) created a digital image data set of complete human male (data acquisition finished in November 1994) and female (data acquisition finished in December 1995) cadavers in magnetic resonance imaging (MRI), computed tomography (CT), and anatomical (anatomic serial section) modes. VHP aroused worldwide enthusiasm for Visible Human Research (VHR), and the data set is being used in a variety of research and educational domains. The Visible Korean Human (VKH) male was produced in March 2001. To accelerate worldwide VHR and to promote virtual anatomy as a revolutionary break with conventional anatomy, more visible human data sets representative of different populations of the world are in demand. The Chinese Visible Human (CVH) male (created in October 2002) and female (created in February 2003) project achieved greater integrity of images, easier blood vessel identification, and were free of organic lesion (unlike the other visible human projects). We performed data acquisition, three-dimensional (3D) reconstruction, and visualization with improved technology to create CVH male and female. CVH is the first volumetric data representing a complete normal adult human male and female of an Asian population. This article presents the history of Chinese Visible Human cadavers and the methods and technology used to produce the data set.

Plastination and computerized 3D reconstruction of the temporal bone.

The purpose of this study was to generate a computerized 3D reconstruction of the temporal bone and intratemporal structures. A plastination technique was used to obtain equidistant serial thin sections of 1.2 mm thickness and, on an SGI workstation, a Contour-Marching Cubes algorithm was selected to reconstruct the temporal bone and intratemporal structures in three dimensions. All reconstructed structures can be represented individually or jointly and rotated in any plane. Any diameter and angle of a structure can be conveniently measured. The capability of reconstructing individual and combined images of intratemporal structures, viewing them from all surgical angles, and accurately measuring their spatial relationships gives skull base and otologic surgeons important guidance. The reconstructed model can also be used for resident education, rehearsal of an unfamiliar surgery, and for developing a new surgical approach.