Accurate external localization of the left frontal cortex in dogs by using pointer based frameless neuronavigation

Background. In humans, non-stereotactic frameless neuronavigation systems are used as a topographical tool for non-invasive brain stimulation methods such as Transcranial Magnetic Stimulation (TMS). TMS studies in clogs may provide treatment modalities for several neuropsychological disorders in dogs. Nevertheless, an accurate non-invasive localization of a stimulation target has not yet been performed in this species. Hypothesis. This study was primarily put forward to externally locate the left frontal cortex in 18 healthy dogs by means of a human non-stereotactic neuronavigation system. Secondly, the accuracy of the external localization was assessed. Animals. A total of 18 healthy dogs, drawn at random from the research colony present at the faculty of Veterinary Medicine (Ghent University), were used. Methods. Two sets of coordinates (X, Y, Z and X", Y", Z") were compared on each dog their tornographical dataset. Results. The non-stereotactic neuronavigation system was able to externally locate the frontal cortex in dogs with accuracy comparable with human studies. Conclusion and clinical importance. This result indicates that a non-stereotactic neuronavigation system can accurately externally locate the left frontal cortex and paves the way to use guided non-invasive brain stimulation methods as an alternative treatment procedure for neurological and behavioral disorders in dogs. This technique could, in analogy with human guided non-invasive brain stimulation, provide a better treatment outcome for dogs suffering from anxiety disorders when compared to its non-guided alternative

Image-Guided High-Intensity Focused Ultrasound, A Novel Application for Interventional Nuclear Medicine?

Image-guided high-intensity focused ultrasound (HIFU) has been increasingly used in medicine over the past few decades, and several systems for such have become commercially available. HIFU has passed regulatory approval around the world for the ablation of various solid tumors, the treatment of neurologic diseases, and the palliative management of bone metastases. The mechanical and thermal effects of focused ultrasound provide a possibility for histotripsy, supportive radiation therapy, and targeted drug delivery. The integration of imaging modalities into HIFU systems allows for precise temperature monitoring and accurate treatment planning, increasing the safety and efficiency of treatment. Preclinical and clinical results have demonstrated the potential of image-guided HIFU to reduce adverse effects and increase the quality of life postoperatively. Interventional nuclear image–guided HIFU is an attractive noninvasive option for the future

Visualization-Based Mapping of Language Function in the Brain

Cortical language maps, obtained through intraoperative electrical stimulation studies, provide a rich source of information for research on language organization. Previous studies have shown interesting correlations between the distribution of essential language sites and such behavioral indicators as verbal IQ and have provided suggestive evidence for regarding human language cortex as an organization of multiple distributed systems. Noninvasive studies using ECoG, PET, and functional MR lend support to this model; however, there as yet are no studies that integrate these two forms of information. In this paper we describe a method for mapping the stimulation data onto a 3-D MRI-based neuroanatomic model of the individual patient. The mapping is done by comparing an intraoperative photograph of the exposed cortical surface with a computer-based MR visualization of the surface, interactively indicating corresponding stimulation sites, and recording 3-D MR machine coordinates of the indicated sites. Repeatability studies were performed to validate the accuracy of the mapping technique. Six observers—a neurosurgeon, a radiologist, and four computer scientists, independently mapped 218 stimulation sites from 12 patients. The mean distance of a mapping from the mean location of each site was 2.07 mm, with a standard deviation of 1.5 mm, or within 5.07 mm with 95% confidence. Since the surgical sites are accurate within approximately 1 cm, these results show that the visualization-based approach is accurate within the limits of the stimulation maps. When incorporated within the kind of information system envisioned by the Human Brain Project, this anatomically based method will not only provide a key link between noninvasive and invasive approaches to understanding language organization, but will also provide the basis for studying the relationship between language function and anatomical variability

Extending the limits of wireless power transfer to miniaturized implantable electronic devices

Implantable electronic devices have been evolving at an astonishing pace, due to the development of fabrication techniques and consequent miniaturization, and a higher efficiency of sensors, actuators, processors and packaging. Implantable devices, with sensing, communication, actuation, and wireless power are of high demand, as they pave the way for new applications and therapies. Long-term and reliable powering of such devices has been a challenge since they were first introduced. This paper presents a review of representative state of the art implantable electronic devices, with wireless power capabilities, ranging from inductive coupling to ultrasounds. The different power transmission mechanisms are compared, to show that, without new methodologies, the power that can be safely transmitted to an implant is reaching its limit. Consequently, a new approach, capable of multiplying the available power inside a brain phantom for the same specific absorption rate (SAR) value, is proposed. In this paper, a setup was implemented to quadruple the power available in the implant, without breaking the SAR limits. A brain phantom was used for concept verification, with both simulation and measurement data.This work is supported by FCT with the reference project PTDC/EEI-TEL/5250/2014, by FEDER funds through Projecto 3599-Promover a Produção Científica e Desenvolvimento Tecnológico e a Constituição de Redes Temáticas (3599-PPCDT) and by grant SFRH/BD/116554/2016.info:eu-repo/semantics/publishedVersio

Design of Beam Steering Electronic Circuits for Medical Applications

This thesis deals with the theory and design of a hemispherical antenna array circuit that is capable to operate in the intermediate zones. By doing that, this array can be used in Hyperthermia Treatment for Brain Cancer in which the aim is to noninvasively focus the fields at microwave frequencies to the location of the tumor cells in the brain. Another possible application of the array is to offer an alternative means of sustaining Deep Brain Stimulation other than using the traditional (surgical) approach. The new noninvasive technique is accomplished by the use of a hemispherical antenna array placed on the human's head. The array uses a new beamforming technique that achieves 3 dimensional beamforming or focusing of the magnetic field of antennas to desired points in the brain to achieve either cell death by temperature rise (Hyperthermia Application) or to cause brain stimulation and hopefully alleviate the affects of Parkinson's Disease (Deep Brain Stimulation). The main obstacle in this design was that the far field approximation that is usually used when designing antenna arrays does not apply in this case since the hemispherical array is in close proximity to where the magnetic field is desired to be focused. The antenna array problem is approached as a boundary-valued problem with the human head being modeled as a three layered hemisphere. The exact expressions for electromagnetic fields are derived. Health issues such as electric field exposure and specific absorption rate (SAR) are considered. After developing the main antenna and beamforming theory, a neural network is designed to accomplish the beamforming technique used. The radio-frequency (RF) transmitter was designed to transmit the fields at a frequency of 1.8 GHz. The antenna array can also be used as a receiver. The antenna and beamforming theory is presented. A new reception technique is shown which enables the array to receive multiple magnetic field sources from within the hemispherical surface. The receiver is designed to operate at 500 kHz with the RF receiver circuit designed to receive any signal from within the hemispherical surface at a frequency of 500 kHz

Design of a Small, Affordable Low Intensity Focused Ultrasound Device for Vagus Nerve Stimulation

Depression is a serious public health issue that affects more than 300 million people worldwide. While there are antidepressant drugs to alleviate depressive symptoms, 10 – 30% of patients either do not respond or develop a tolerance to these drugs. Researchers have found a correlation between the inflammatory response and treatment-resistant depression (TRD). Blocking this inflammatory pathway with electrical vagus nerve stimulation (VNS) can reduce cytokine levels and depressive symptoms. However, placing an electrical VNS device is invasive, costly, and poses a risk to the vagus nerve. Low intensity focused ultrasound (LIFU) is a novel therapy that is able to both excite and suppress neuronal activity in neurological disorders. However, progression of this research area has been impeded by the size and price of these devices. I designed a 50 x 57 x 76 mm LIFU device that consists of a transducer, matching network, and amplification network. Next, I characterized my LIFU device with 2D intensity maps of the focused ultrasound (FUS) field. My device produced an instantaneous intensity up to 350 mW/cm2. My colleagues and I applied the LIFU device on Sprague-Dawley rats (n=12) for VNS with the primary goal of reducing the inflammatory response. Five out of the eight rats that we analyzed showed a decrease in the cytokine TNF-α. Future work will involve design improvements and more animal studies with varying stimulation parameters. As FUS technology becomes smaller we move closer to wearable devices. As FUS technology becomes more affordable more research groups will have the opportunity to employ this novel therapy to investigate the pathophysiology of neurological disorders