Gianluigi Vaccarino

Basal ganglia network by constrained spherical deconvolution: a possible cortico-pallidal pathway?

In the recent past, basal ganglia circuitry was simplified as represented by the direct and indirect pathways and by hyperdirect pathways. Based on data from animal studies, we hypothesized a fourth pathway, the cortico‐pallidal, pathway, that complements the hyperdirect pathway to the subthalamus. Ten normal brains were analyzed by using the high angular resolution diffusion imaging—constrained spherical deconvolution (CSD)‐based technique. The study was performed with a 3T magnetic resonance imaging (MRI) scanner (Achieva, Philips Healthcare, Best, Netherlands); by using a 32‐channel SENSE head coil. We showed that CSD is a powerful technique that allows a fine evaluation of both the long and small tracts between cortex and basal ganglia, including direct, indirect, and hyperdirect pathways. In addition, a pathway directly connecting the cortex to the globus pallidus was seen. Our results confirm that the CSD tractography is a valuable technique allowing a reliable reconstruction of small‐ and long‐fiber pathways in brain regions with multiple fiber orientations, such as basal ganglia. This could open a future scenario in which CSD could be used to focally target with deep brain stimulation (DBS) the small bundles within the basal ganglia loops.

Morphometrical and morphological analysis of lateral ventricles in schizophrenia patients versus healthy controls

The goal of this report was to highlight lateral ventricle morphology and volume differences between schizophrenia patients and matched controls. Subjects identified as suitable for analysis comprised 15 schizophrenia patients and 15 healthy subjects. The method applied is three-dimensional (3D) volume rendering starting from structural magnetic resonance imaging (MRI) studies of selected ventricular regions. Differences between groups relative to the global ventricular system and its subdivisions were found. Total lateral ventricle volume, right ventricle volume and left ventricle volume were all higher in schizophrenia patients than in controls; unilateral differences between the two groups were also outlined (right ventricle volume>left ventricle volume in schizophrenia patients vs. healthy subjects). Furthermore, occipital and frontal horn enlargement was found in schizophrenia patients compared with normal controls, but the difference in the temporal horn was not statistically significant. A substantial difference was noted in lateral ventricle morphology between the two groups. Our findings were consistent with the literature and may shed light on some of the discrepancies in previous reports on differences in lateral ventricle volume enlargement.

Three-dimensional volume rendering of the ankle based on magnetic resonance images enables the generation of images comparable to real anatomy

We have applied high‐quality medical imaging techniques to study the structure of the human ankle. Direct volume rendering, using specific algorithms, transforms conventional two‐dimensional (2D) magnetic resonance image (MRI) series into 3D volume datasets. This tool allows high‐definition visualization of single or multiple structures for diagnostic, research, and teaching purposes. No other image reformatting technique so accurately highlights each anatomic relationship and preserves soft tissue definition. Here, we used this method to study the structure of the human ankle to analyze tendon–bone–muscle relationships. We compared ankle MRI and computerized tomography (CT) images from 17 healthy volunteers, aged 18–30 years (mean 23 years). An additional subject had a partial rupture of the Achilles tendon. The MRI images demonstrated superiority in overall quality of detail compared to the CT images. The MRI series accurately rendered soft tissue and bone in simultaneous image acquisition, whereas CT required several window‐reformatting algorithms, with loss of image data quality. We obtained high‐quality digital images of the human ankle that were sufficiently accurate for surgical and clinical intervention planning, as well as for teaching human anatomy. Our approach demonstrates that complex anatomical structures such as the ankle, which is rich in articular facets and ligaments, can be easily studied non‐invasively using MRI data.

Muscle-specific integrins in masseter muscle fibers of chimpanzees: an immunohistochemical study.

Most notably, recent comparative genomic analyses strongly indicate that the marked differences between modern human and chimpanzees are likely due more to changes in gene regulation than to modifications of the genes. The most peculiar aspect of hominoid karyotypes is that human have 46 chromosomes whereas gorillas and chimpanzees have 48. Interestingly, human and chimpanzees do share identical inversions on chromosome 7 and 9 that are not evident in the gorilla karyotype. Thus, the general phylogeny suggests that humans and chimpanzees are sister taxa; based on this, it seems that human-chimpanzee sequence similarity is an astonishing 99%. At this purpose, of particular interest is the inactivation of the myosin heavy chain 16 (MYH16) gene, most prominently expressed in the masticatory muscle of mammals. It has been showed that the loss of this gene in humans may have resulted in smaller masticatory muscle and consequential changes to cranio-facial morphology and expansion of the human brain case. Powerful masticatory muscles are found in most primates; contrarily, in both modern and fossil member Homo, these muscles are considerably smaller. The evolving hominid masticatory apparatus shifted towards a pattern of gracilization nearly simultaneously with accelerated encephalization in early Homo. To better comprehend the real role of the MYH16 gene, we studied the primary proteins present in the muscle fibers of humans and non-humans, in order to understand if they really can be influenced by MYH16 gene. At this aim we examined the muscle-specific integrins, alpha 7B and beta 1D-integrins, and their relative fetal isoforms, alpha 7A and beta 1A-integrins, analyzing, by immunohistochemistry, muscle biopsies of two components of a chimpanzees group in captivity, an alpha male and a non-alpha male subjects; all these integrins participate in vital biological processes such as maintenance of tissue integrity, embryonic development, cell differentiation, and cell-extracellular matrix interactions. Our results demonstrated a different quantitative composition of integrins, in alpha male in respect to human and non-alpha male, hypothesizing that the MYH16 gene could modify the expression of integrins, influencing, in turn, the phenotype of muscle. In this way, alpha 7A-and beta 1A-integrin could determine the presence of type II fibers and then they could play a key role in the determination of contraction force. Then, MYH16 gene could be a common interactor of signalling between sarcoglycans and integrins in chimpanzee muscles.

Advances from probabilistic tractography in connections of the limbic system with the cerebellum

The limbic system is a complex set of brain structures located on both sides of the thalamus, right under the cerebrum. It is not a separate system but a collection of structures from the telencephalon, diencephalon, and mesencephalon, including the hippocampus, amygdala, anterior thalamic nuclei, fornix, columns of fornix, mammillary body, septum pellucidum, habenular commissure, cingulate gyrus, parahippocampal gyrus, limbic cortex, pars of olfactory system and limbic midbrain areas. Nevertheless, recent studies showed that the definition of anatomical structures considered part of the limbic system is a controversial subject. Although the role of the cerebellum was traditionally considered mainly associated to motion control, it has been recently suggested a cerebellar involvement in emotions control, cognitive processes and social behavior. In this regard, we have previously demonstrated that the cerebellum is interconnected with the hippocampus [1]. In this work, a wider sample of normal subjects was examined by using probabilistic Constrained Spherical Deconvolution (CSD) tractography, which represents a method able to overcome many limitations of other Diffusion Tensor Imaging (DTI) techniques, providing more accurate data [2]. We found evidences in the human brain that the cerebellum is widely linked with limbic-related structures and provided a more reliable demonstration of direct cerebello-limbic pathways. In addition, we further extendend our analysis to the other limbic connections including uncinated fasciculus, cingulate fasciculus, inferior longitudinal fasciculus, anterior thalamic connections and fornix. Although these pathways have been already described in the tractographic literature we provided reconstruction and quantitative analysis, which could be potentially useful to explore pathological conditions damaging this system. Finally, the demonstration of the existence of cerebello-limbic connections could constitute an important step in the knowledge of the anatomic substrate of non-motor cerebellar functions.

Three-dimensional analysis for the evaluation of left ventricular aneurysm and pseudo-aneurysm after myocardial infarction

Myocardial Infarction (MI) is an ischemic heart disease representing one of the main causes of death for acute cardiac pathologies. Two important consequences of MI are left ventricular (LV) aneurysm and pseudo-aneurysm. The aim of the present study is to highlight anatomical and functional changes in LV undergoing post-ischemic remodeling by means of three dimensional-Magnetic Resonance Imaging (MRI) and three dimensional-Computed Tomography (CT), which are useful techniques for the diagnosis and evaluation of accurate clinical and surgical approaches. In this way the surgeon can evaluate pro and counter of the classical approach or the parachute implant with possible promotion of mininvasive surgery [1]. Although to date MI consequences can be assessed with bidimensional technique (e.g. echocardiography and ventriculography), we want to suggest the use of three dimensional Direct Volume Rendering (DVR), which is a direct technique for visualizing primitive volumes without any intermediate conversion of the volume data to surface presentation [2]. DVR allows to better discriminate between aneurysm and pseudoaneurysm and to do a better evaluation of inclusion and exclusion criteria for the implant of a parachute device.

Imaging of Temporomandibular Joint: Approach by Direct Volume Rendering

BACKGROUND The purpose of this study was to conduct a morphological analysis of the temporomandibular joint, a highly specialized synovial joint that permits movement and function of the mandible. MATERIALS AND METHODS We have studied the temporom-andibular joint anatomy, directly on the living, from 3D images obtained by medical imaging Computed Tomography and Nuclear Magnetic Resonance acquisition, and subsequent re-engineering techniques 3D Surface Rendering and Volume Rendering. Data were analysed with the goal of being able to isolate, identify and distinguish the anatomical structures of the joint, and get the largest possible number of information utilizing software for post-processing work. RESULTS It was possible to reproduce anatomy of the skeletal structures, as well as through acquisitions of Magnetic Resonance Imaging; it was also possible to visualize the vascular, muscular, ligamentous and tendinous components of the articular complex, and also the capsule and the fibrous cartilaginous disc. We managed the Surface Rendering and Volume Rendering, not only to obtain three-dimensional images for colour and for resolution comparable to the usual anatomical preparations, but also a considerable number of anatomical, minuter details, zooming, rotating and cutting the same images with linking, graduating the colour, transparency and opacity from time to time. CONCLUSION These results are encouraging to stimulate further studies in other anatomical districts.

A study of the olfactory tract with 3D rendering, f-MRI and CSD fiber tractography in healty and PD subjects

In this study we report an optimized single-shot diffusion-weighted echo planar imaging sequence that can visualize the olfactory tracts with CSD fiber tracking, 3D volume rendering and f-MRI. The olfactory tracts are localized in the olfactory grooves of the ethmoidal bone, running posteriorly through the olfactory sulci connecting to the inferior surfaces of the frontal lobes. Distally the tracts are enlarged into the olfactory bulbs and proximally they split into medial, intermediate and lateral striae and from here the axon projecting to the olfactory cortex, divided into five main areas: the anterior olfactory nucleus, which connects the two olfactory bulbs through a portion of the anterior commissure; the piriform cortex; parts of the amigdala, the olfactory tubercle and entorinal cortex; not all of these connections through the thalamus. Moreover, olfactory information is transmitted from the amygdala to the hypothalamus and from the entorinal area to the hippocampus.The olfactory tracts are difficult to depict with MRI diffusion-weighted imaging due to the high sensitivity to susceptibility artifacts at the base of the skull (Duprez and Rombaux, 2010). Ten subjects were examined; in five healthy subjects the olfactory tracts could be fiber tracked with the diffusion-weighted sequence, while in five anosmic PD patients, altered olfactory tracts were visualized. Furthermore, olfactory stimuli were applied during fMRI scanning to show the area BOLD activation to advance our understanding of olfactory dysfunction in PD patients compared to control. Olfactory function was established using the “Sniffin’ Sticks” test battery.This study of the olfactory tracts promise to visualize the anatomic organization and to facilitate the identification of different hyposmic and anosmic entities caused by neurodegenerative disorders or post-traumatic and congenital disfunctions.

The anatomy as the basis of new ways for the dissemination of clinical information. Implementation of a system of anatomical data related to the mastication within the technology of cloud computing

Chewing is one of the most important functional movement of the stomatognathic system. It ‘a highly coordinated neuromuscular motor function, characterized by mandibular movements with a fast and continuous adaptation of the modulation strength. The information resulting from the masticatory pattern, in fact, are important to diagnose the functional status of the patient, such as repeatability and variability of the mandibular movement, neuromuscular coordination between the right and left side, or the ability to adapt to the load during chewing a hard bolus. In the context of scientific research, there is a constant demand for new applications to take advantage of the more technologically advanced clinical information. In this perspective the anatomy is presented as a basis for the study and the ‘integration of medical imaging techniques aimed at creating a system of Cloud Computing, able to process and store data. In our study, we found patients with craniomandibular disorders and chewing. Patients underwent an MRI Philips Achieva 3T, at IRCSS “Neurolesi”. The protocol included a MRI, fMRI and DTI, then the data obtained were processed processed and finally stored. On this basis we observe as the multimodal integration of different imaging modalities allows for numerous clinical data that favor a proper diagnosis, which is useful for the planning of an effective therapy. In addition, the cloud computing system allows the sharin

fMRI study in human brain during chewing

The mastication is a rhythmic motor act involving peripheral effector organs and sensory inputs and it is attended by intense activity of brain stem. The prefrontal cortex has long been suspected to play an important role during mastication, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery (Ono Y. et al. 2010). We selected a sample of 10 healthy right-handed subjects who underwent fMRI during mastication as forced as free with soft and hard bolus. Results showed, during free mastication with hard or soft bole, in “left” cerebral cortex the activation of the primary (area 4) supplementary (area 6) motor areas and somesthesic primary area (area 3), with maximum activation during hard bole. At same time, in forced mastication, besides the previous areas, are activated also, in “right” cerebral cortex, area 10 and 11 and omolateral neostriatum. In conclusion, in the light of recent studies, we observed the significant role of basal ganglia in planning and execution of motor gesture process.