Array Placement Research Articles

Transimpedance Matrix Measurement (TIM) Parameters Evaluation for the Assessment of Cochlear Implant Electrode Placement and Modiolar Proximity in Children

Introduction: Transimpedance matrix measurement (TIM) is an electrophysiological measurement protocol of the impedance patterns of electrode contacts within the cochlea. Several studies have reported that TIM is an effective tool for the identification of abnormal electrode array placement. However, the normative values for properly inserted electrodes, as well as correlation of the TIM patterns with the electrode position, are not completely determined. Objectives: The first aim of this study is to establish normative values of TIM measurements obtained in children with proper electrode array insertion and tip fold-over, with proper inner ear anatomy and in congenital anomalies. The second aim of this study is to compare TIM measurements in Slim Modiolar (SM) and in Contour Advance (CA) electrodes, as their position is different according to the modiolus proximity. Methods: A total of 55 pediatric patients were included in the study and underwent cochlear implantation. 62 intraoperative measurements were conducted in this group—50 in children with normal inner ear anatomy and 12 in children with inner ear malformations. After each implantation, a plain x-ray was obtained. Results: There were clear statistically significant differences in TIM patterns in patients where electrode fold-over was confirmed and between SM and CA electrodes. Conclusions: TIM is a promising technique for intraoperative analysis of electrode placement. TIM patterns differ and correlate consistently with the different models of array implanted. This study is the first to report TIM patterns observed in children with normal inner ear anatomy and in inner ear malformations.

Anatomical investigation of safety determining factors for keyhole drilling trajectories for robotic cochlear implant surgery.

Cochlear implants (CI) are the most successful bioprosthesis in medicine probably due to the tonotopic anatomy of the auditory pathway and of course the brain plasticity. Correct placement of the CI arrays, respecting the inner ear anatomy are therefore important. The ideal trajectory to insert a cochlear implant array is defined by an entrance through the round window membrane and continues as long as possible parallel to the basal turn of the cochlea. Image-guided surgery can directly drill with a robotic arm through the mastoid and execute an exact drilling of this precalculated most ideal trajectory. Here, we aim to identify critical anatomical structures determining the safest keyhole drilling trajectory by comparing easy and difficult CI surgeries performed with the HEARO Procedure: a robotic tool for image-guided surgery. Cone-beam computed tomography images of patients who underwent robot-assisted cochlear implantation surgery (RACIS) were included. Three of 25 cases had to be converted to conventional surgery because of the current safety mitigations based on anatomical distance. Radiological images in DICOM format were transferred to dedicated software (OTOPLAN® Cascination GMHB Bern Switzerland) for analyses. Surgical segmentation and previously planned trajectories were analyzed for these 25 cases by comparing cochlear sizes, facial recess sizes, round window sizes, and trajectory angles. In addition, facial recess angle, and cochlear orientation angles were measured with RadiAnt DICOM Viewer (Medixant, Pozan, Poland). Facial recess size, facial recess angle, and distance between the facial nerve and safe trajectory were smaller in patient who converted from robotic surgery to conventional. A significant positive correlation existed between basal turn angle and in-plane angle (p = 0.001, r = 0.859). In addition, there was a significant negative correlation between the basal turn length and the last electrode insertion depth degree (p = 0.007, r = 0.545). In our robotic surgery cases, we demonstrate that the limiting factors of anatomical relationships are constituted by the dimensions of the facial recess and the cochlear orientation. The findings of this study are considered to be a reference for future studies in achieving collision-free trajectory planning in robotic-assisted cochlear implant surgery.

Global Placement Exploiting Soft 2D Regularity

Cell placement is a step of paramount importance in chip physical design and requests relentless effort for continuous improvement. Recently, designs with 2D processing element arrays have become popular primarily due to their deep neural network hardware applications. The 2D array regularity is similar to but different from the regularity of conventional datapath designs. To exploit the 2D array regularity, this work develops a new global placement technique, PASOR (Placement of Arrays with SOft Regularity), built upon RePlAce, the state-of-the-art placement framework. Experimental results from various designs show that the proposed approach can reduce global routing wirelength by 11% and 6% compared to RePlAce and a previous work on datapath driven placement, respectively.

INNV-34. APPLICATION OF 200 KHZ TUMOR TREATING FIELDS (TTFIELDS) IN PATIENTS WITH INFRATENTORIAL HIGH-GRADE GLIOMA: CASE SERIES

Abstract BACKGROUND 200 kHz Tumor Treating Fields (TTFields) therapy is FDA-approved for supratentorial newly-diagnosed and recurrent glioblastoma. However, reports of its application in patients with infratentorial high-grade glioma (HGG) are rare. Based on computational modeling, the therapeutic field strength (~1 V/cm peak-to-peak) is thought to be achievable for infratentorial HGG. METHODS Two patients with infratentorial HGG received off-label 200 kHz TTFields therapy with the Optune® device (Novocure, Ltd.). To reduce impaired range of motion of the neck, the electrode transducer arrays were “skeletonized” by cutting a portion of the adhesive material surrounding them. Application of the electrode arrays was performed with the neck in flexion, to further promote neck range of motion. Cloth tape was used for reinforcement as necessary. Electrode arrays were changed every 2-3 days. We report the results of patient survival and adverse events. RESULTS Patient 1: 22-year-old man with high-grade diffuse pontine glioma with recurrences and prior treatments (including radiation, temozolomide, lomustine, and dopamine receptor D2 [DRD2] antagonist), tolerated TTFields combined with systemic treatment (initially with a bi-functional DNA alkylating agent; subsequently with temozolomide and bevacizumab) for 5 months with stable disease for 4 months. He experienced grade 1 rash of the neck. Patient 2: 58-year-old woman with diffuse glioma of the brainstem (H3K27M-mutated) with multiple recurrences and prior treatments (including concurrent radiation and temozolomide, and DRD2 antagonist), tolerated TTFields combined with systemic treatment (lomustine and bevacizumab). The TTFields infratentorial layout was iteratively modified with respect to placement of the electrode transducer arrays, for improved tolerability. With the TTFields+systemic combination therapy, the patient was stable for 8 months with no local TTFields-related side effects. CONCLUSIONS We provide initial post-marketing evidence that off-label use of 200 kHz TTFields in infratentorial HGG is safe and feasible. Prospective studies are necessary to validate the efficacy of this approach.

INNV-11. DELIVERY OF TTFIELDS TO THE INFRATENTORIAL BRAIN USING HFE ARRAYS

Abstract INTRODUCTION Tumor Treating Fields (TTFields) therapy is a noninvasive, locoregional treatment comprising alternating electric fields delivered to the tumor via two pairs of skin-placed transducer arrays. TTFields physically disrupt cancer cell viability through a multimodal mechanism that includes antimitotic and antitumor immune effects. TTFields therapy is FDA-approved for glioblastoma (GBM) and CE marked for WHO grade 4 glioma. While clinically approved array layouts for GBM target supratentorial tumors, TTFields distribution depends on the arrays’ locations and dedicated layouts are needed to target infratentorial tumors. To increase patient comfort, Novocure developed HFE arrays that are thinner and lighter than existing INE arrays. Here, we evaluate innovative HFE array layouts for TTFields delivery to infratentorial tumors at therapeutic intensities (~1 V/cm). METHODS TTFields delivery was simulated using Sim4Life v6.2 in a male computational model. 32 layouts of HFE arrays were placed on the model’s scalp, neck, and scapulae, with one placed at a standard cerebral location. Local Average Field Intensity (LAFI) and Local Minimum Power Density (LMiPD) were calculated in the cerebrum, cerebellum and brainstem. RESULTS Standard cerebral layout provided LAFI of 2.47 V/cm to the cerebrum, while providing 1.50 and 1.10 V/cm to the cerebellum and brainstem, respectively (LMiPD 2.22, 1.34 and 0.64 mW/cm3). Layouts comprising arrays on the scapulae (right and left) paired in cross configuration with arrays on either the temples or forehead, provided LAFI of 1.87-2.17 V/cm (LMiPD 1.05-2.20 mW/cm3) to the cerebrum, while providing 1.64-2.13 V/cm (LMiPD 1.77-2.26 mW/cm3) to the cerebellum and 1.74-1.89 V/cm (LMiPD 2.28-2.89 mW/cm3) to the brainstem. CONCLUSION Lower array placement provides higher levels of field intensity in the cerebellum and brainstem versus standard cerebral layout, while still providing adequate field intensity to the cerebrum. This simulation-based study suggests feasibility of delivering therapeutic TTFields intensities to infratentorial tumors using dedicated HFE array layouts.

Enhancing Electric Field Distribution in the Pancreas for Improved TTFields Therapy: A Computational Modeling Investigation.

Tumor treating fields (TTFields) therapy has shown effectiveness in glioblastoma treatment and holds potential for other cancers. However, its application in pancreatic cancer and the distribution of electric fields in pancreas remain unexplored. This study aims to investigate the electric field distributions in pancreatic regions using different array configurations for TTFields therapy. Computational modelling was employed to simulate electric field distributions, and quantitative analysis was conducted. Human body impedance measurements were used to optimize the electric properties of the model. Various array configurations were examined to assess their impact on the electric field distributions. The study revealed that well-positioned arrays, specifically the combination of 20-piece transducer arrays in anterior-posterior orientation and 13-piece transducer arrays in left-right orientation, consistently achieved electric fields exceeding the 1V/cm threshold in over 99.4% of the pancreas. Even with a reduced number of transducers (13 pieces for both orientations), sufficient electric field coverage was achieved, exceeding the threshold in over 92.9% of the pancreas. Additionally, different array placements within the same orientation were explored to address clinical challenges such as skin rash and patient anatomical variations. This research lays the groundwork for understanding TTFields distribution within the abdomen, offering insights into optimizing array configurations for improved electric field delivery. These results offer promises of advancing TTFields therapy for pancreatic cancer towards clinical applications, and potentially enhancing treatment efficacy and patient outcomes.

Comparing Audiological Outcomes of Conventional and AI-Upgraded Cochlear Implant Speech Processors.

In current age of technology, artificial intelligence is used in the medical field to improve the quality and accuracy in patient care and achieve better clientele satisfaction. The use of artificial intelligence in the field of hearing rehabilitation and cochlear implantation has an immense scope and it enhances the accuracy in placement of electrode array, forecasting site of surgical location and optimization of speech processing. This study aims to compare the audiological outcomes of conventional versus artificial intelligence technology enabled cochlear implant speech processors. Additionally, it compares the individual performance and satisfaction level with use of both types of speech processors. All children who underwent upgradation of their cochlear implant speech processors at a tertiary care cochlear implant centre with artificial intelligence enabled speech processors were included in the study. The comparison of audiological outcomes of conventional versus artificial intelligence integrated speech processors were assessed by using Aided Audiometry, Categories of Auditory Perception Score and Speech Intelligibility Rating scale. Children using the basic model cochlear implant speech processor which was provided at the time of implantation are referred as conventional cochlear implant speech processor user. Their speech processors were subsequently upgraded with current generation artificial intelligence integrated speech processors which is referred here as artificial intelligence upgraded cochlear implant speech processor. During the study, a total of thirty-four (34) patients underwent upgradation of cochlear implant speech processors. The mean categories of auditory perception score were 11.58 and 11.94 using conventional and artificial intelligence upgraded speech processor respectively. The mean speech intelligibility rating score was 4.5 and 4.6 respectively. The audiological outcomes of conventional speech processors are comparable with those using artificial intelligence enabled speech processors. However, the clientele satisfaction in respect to quality of sound, ease of listening in difficult listening environment, smart connectivity options for both phone and television is available and better with the artificial intelligence enabled cochlear implant speech processor. This also has the advantages of auto switching of programming with change in ambient noise, better signal to noise ratio and better 360* hearing.

GW-MUSIC focusing algorithm with high accuracy for composite damage diagnosis

The Guided Wave (GW)-based Multiple Signal Classification (MUSIC) method for damage imaging in composite structures offers high-resolution and flexible sensor array placement, demonstrating considerable potential for precise damage localization. However, the application to real aircraft composite structures, characterized by complex structural features, presents substantial challenges. These include complex boundary reflections, pronounced anisotropy, and diminished scattered signals from damage sites. This paper presents a novel single-peak anisotropy-compensated MUSIC method for damage imaging of complex composites. This method, designed for improved localization accuracy, combines a self-excited calibration strategy to mitigate anisotropy with single wave peak focusing to amplify signals and reduce boundary reflections. Experimental validation on a complex composite wing structure demonstrated significant enhancements in localization precision, affirming the method's efficacy.

A Performance Assessment on Rotor Noise-Informed Active Multidrone Sound Source Tracking Methods

This study evaluates and assesses the performance of recent developments in sound source tracking using microphone arrays from multiple drones. Stemming from a baseline study, which triangulates the spatial spectrum calculated from the MUltiple SIgnal Classification (MUSIC) for each drone, otherwise known as Particle Filtering with MUSIC (PAFIM), recent studies extended the method by introducing methods to improve the method’s effectiveness. This includes a method to optimise the placement of the drone while tracking the sound source and methods to reduce the influence of high levels of drone rotor noise in the audio recordings. This study evaluates each of the recently proposed methods under a detailed set of simulation settings that are more challenging and realistic than those from previous studies and progressively evaluates each component of the extensions. Results show that applying the rotor noise reduction method and array placement planning algorithm improves tracking accuracy significantly. However, under more realistic input conditions and representations of the problem setting, these methods struggle to achieve decent performance due to factors not considered in their respective studies. As such, based on the performance assessment results, this study summarises a list of recommendations to resolve these shortcomings, with the prospect of further developments or modifications to PAFIM for improved robustness against more realistic settings.

Surgical Treatment of Calcified Thoracic Herniated Disc Disease via the Transthoracic Approach with the Use of Intraoperative Computed Tomography (iCT) and Microscope-Based Augmented Reality (AR).

Background and Objectives: The aim of this study is to present our experience in the surgical treatment of calcified thoracic herniated disc disease via a transthoracic approach in the lateral position with the use of intraoperative computed tomography (iCT) and augmented reality (AR). Materials and Methods: All patients who underwent surgery for calcified thoracic herniated disc via a transthoracic transpleural approach at our Department using iCT and microscope-based AR were included in the study. Results: Six consecutive patients (five female, median age 53.2 ± 6.4 years) with calcified herniated thoracic discs (two patients Th 10-11 level, two patients Th 7-8, one patient Th 9-10, one patient Th 11-12) were included in this case series. Indication for surgery included evidence of a calcified thoracic disc on magnet resonance imaging (MRI) and CT with spinal canal stenosis of >50% of diameter, intractable pain, and neurological deficits, as well as MRI-signs of myelopathy. Five patients had paraparesis and ataxia, and one patient had no deficit. All surgeries were performed in the lateral position via a transthoracic transpleural approach (Five from left side). CT for automatic registration was performed following the placement of the reference array, with a high registration accuracy. Microscope-based AR was used, with segmented structures of interest such as vertebral bodies, disc space, herniated disc, and dural sac. Mean operative time was 277.5 ± 156 min. The use of AR improved orientation in the operative field for identification, and tailored the resection of the herniated disc and the identification of the course of dural sac. A control-iCT scan confirmed the complete resection in five patients and incomplete resection of the herniated disc in one patient. In one patient, complications occurred, such as postoperative hematoma, and wound healing deficit occurred. Mean follow-up was 22.9 ± 16.5 months. Five patients improved following surgery, and one patient who had no deficits remained unchanged. Conclusions: Optimal surgical therapy in patients with calcified thoracic disc disease with compression of dural sac and myelopathy was resectioned via a transthoracic transpleural approach. The use of iCT-based registration and microscope-based AR significantly improved orientation in the operative field and facilitated safe resection of these lesions.

Hampshire Sheep as a Large-Animal Model for Cochlear Implantation.

Sheep have been proposed as a large-animal model for studying cochlear implantation. However, prior sheep studies report that the facial nerve (FN) obscures the round window membrane (RWM), requiring FN sacrifice or a retrofacial opening to access the middle-ear cavity posterior to the FN for cochlear implantation. We investigated surgical access to the RWM in Hampshire sheep compared to Suffolk-Dorset sheep and the feasibility of Hampshire sheep for cochlear implantation via a facial recess approach. Sixteen temporal bones from cadaveric sheep heads (ten Hampshire and six Suffolk-Dorset) were dissected to gain surgical access to the RWM via an extended facial recess approach. RWM visibility was graded using St. Thomas' Hospital (STH) classification. Cochlear implant (CI) electrode array insertion was performed in two Hampshire specimens. Micro-CT scans were obtained for each temporal bone, with confirmation of appropriate electrode array placement and segmentation of the inner ear structures. Visibility of the RWM on average was 83% in Hampshire specimens and 59% in Suffolk-Dorset specimens (p = 0.0262). Hampshire RWM visibility was Type I (100% visibility) for three specimens and Type IIa (> 50% visibility) for seven specimens. Suffolk-Dorset RWM visibility was Type IIa for four specimens and Type IIb (< 50% visibility) for two specimens. FN appeared to course more anterolaterally in Suffolk-Dorset specimens. Micro-CT confirmed appropriate CI electrode array placement in the scala tympani without apparent basilar membrane rupture. Hampshire sheep appear to be a suitable large-animal model for CI electrode insertion via an extended facial recess approach without sacrificing the FN. In this small sample, Hampshire specimens had improved RWM visibility compared to Suffolk-Dorset. Thus, Hampshire sheep may be superior to other breeds for ease of cochlear implantation, with FN and facial recess anatomy more similar to humans.

Optimal Microphone Array Placement Design Using the Bayesian Optimization Method.

In addition to the filter coefficients, the location of the microphone array is a crucial factor in improving the overall performance of a beamformer. The optimal microphone array placement can considerably enhance speech quality. However, the optimization problem with microphone configuration variables is non-convex and highly non-linear. Heuristic algorithms that are frequently employed take a long time and have a chance of missing the optimal microphone array placement design. We extend the Bayesian optimization method to solve the microphone array configuration design problem. The proposed Bayesian optimization method does not depend on gradient and Hessian approximations and makes use of all the information available from prior evaluations. Furthermore, Gaussian process regression and acquisition functions make up the Bayesian optimization method. The objective function is given a prior probabilistic model through Gaussian process regression, which exploits this model while integrating out uncertainty. The acquisition function is adopted to decide the next placement point based upon the incumbent optimum with the posterior distribution. Numerical experiments have demonstrated that the Bayesian optimization method could find a similar or better microphone array placement compared with the hybrid descent method and computational time is significantly reduced. Our proposed method is at least four times faster than the hybrid descent method to find the optimal microphone array configuration from the numerical results.

Absent Intraoperative Electrically Evoked Compound Action Potential Results during Cochlear Implant Surgery: Our Experience

Intraoperative electrically evoked compound action potential (ECAP) testing during cochlear implant surgery is used to assess the integrity of implant, proper placement of electrode array, auditory nerve stimulation and to use as a preliminary tool to start a map, especially for difficult-to-test population. Sometimes, irrespective of normal or abnormal anatomical structure of the inner ear, ECAP response can be absent in one or more recording electrodes intraoperatively due to many factors. This report presents four pediatric cases who underwent cochlear implantation at our center. One of the cases had a hypoplastic auditory nerve and the rest had normal inner ear anatomy. Intraoperatively, two of the cases had absent neural responses in all the electrodes whereas in the remaining two absent neural response was found in single and in three basal electrodes. Postoperatively, in all the cases, neural response had recovered, except the one with hypoplastic nerve, which recovered only in few electrodes.

Exploring Trauma Patterns and Contributing Factors With Slim Straight Electrode Array After Cochlear Implantation.

To assess trauma patterns associated with the insertion of lateral wall electrode arrays. The study focused on 3 categories-scala tympani (ST), intermediate, and scala vestibuli (SV)-to identify traumatic patterns and contributing factors. Retrospective study. Data from 106 cochlear implant recipients at a tertiary otologic center. Demographic and surgical data were collected from recipients who underwent cochlear implantation manually and with RobOtol®. Measurements included cochlear dimensions, angular depth of insertion, and position of the first electrode. Three-dimensional reconstructions were used to analyze the electrode array location relative to the basilar membrane, categorized into ST, intermediate, and SV electrodes. Nontraumatic insertion was defined as all electrodes in the ST, while traumatic insertions had 1 or more electrodes in intermediate or SV locations. Out of 106 cases, 44% had nontraumatic and 56% had traumatic insertions. Demographic and surgical characteristics showed no association with traumatic insertions. A deeper position of the first electrode, relative to the round window, was associated with traumatic insertions (P = .03). Three trauma patterns were observed: distal (facing the apical electrodes), proximal (facing the middle electrodes around 180°), and distal/proximal. This study considers the intermediate position which could be associated with basilar membrane lesions. Risk zones for intracochlear trauma with lateral wall arrays were identified distally and proximally. Traumatic insertions were independently linked to deeper array placement. Future studies should explore whether gentler insertion, without insisting on further electrode array insertion depth, could reduce the trauma during cochlear implantation.

Intraoperative Handheld Digital X-ray for Assessment of Intracochlear Positioning of Electrode Arrays in Recipients of Cochlear Implants.

Objectives: This study aims to evaluate the practicality of handheld digital X-ray in determining the position of the electrode array following Cochlear implantation (CI). Methods: A retrospective study was conducted involving 11 patients (12 ears) who underwent intraoperative imaging via handheld X-ray (MINE ALNU®, OTOM, Gwangju, South Korea) post-CI between December 2021 and January 2023. Immediate confirmation of the correct electrode array placement in the cochlea was achieved, with subsequent comparisons made to C-arm image and postoperative transorbital view X-ray. Results: Rapid intraoperative imaging was achieved in all instances. The electrode types used included 9 Nucleus slim modiolar electrodes, 1 Nucleus contour electrode, and 2 Medel flex26 electrodes. A malpositioned electrode array was detected in one patient. The handheld digital X-ray also adeptly visualized the electrodes implanted in pediatric patients. Conclusions: The use of intraoperative handheld digital X-ray using MINE ALNU® proves to be a safe, efficient, straightforward, and reliable method for immediate identification of an inserted electrode array. It has potential to replace the traditional C-arm X-ray for verifying electrode positioning in the operating room.

Robot-Assisted Patellofemoral Arthroplasty.

Patellofemoral arthroplasty is indicated in patients with isolated patellofemoral arthritis in whom nonoperative treatment has failed2. The goal of the presently described procedure is to provide relief from patellofemoral arthritis pain while maintaining native knee kinematics2. Patient radiographs are carefully reviewed for isolated patellofemoral arthritis in order to determine the appropriateness of robotic-assisted patellofemoral arthroplasty. Magnetic resonance imaging can be performed preoperatively to help confirm isolated patellofemoral arthritis. We perform this procedure with use of the MAKO Surgical Robot (Stryker). Preoperative computed tomography is performed to plan the bone resection, the size of the implant, and the positioning of the device. The steps of the procedure include (1) medial parapatellar arthrotomy, (2) intraoperative inspection to confirm isolated patellofemoral arthritis, (3) patellar resurfacing, (4) placement of optical arrays and trochlear registration, (5) trochlear resection, (6) trialing of implants, (7) removal of the optical array, (8) impaction of final implants, (9) confirmation of appropriate patellar tracking, and (10) closure. Alternatives to patellofemoral arthroplasty include standard nonoperative treatment, bicompartmental arthroplasty, total knee arthroplasty, tibial tubercle osteotomy, partial lateral facetectomy, and arthroscopy2. Patellofemoral arthroplasty is indicated in patients with isolated patellofemoral arthritis in whom nonoperative treatment has failed2. Patellofemoral arthroplasty may be superior to total knee arthroplasty because it helps treat pain that affects patient quality of life and activities of daily living while also preserving greater tibiofemoral bone stock2. We recommend against performing patellofemoral arthroplasty in patients with arthritis of the tibiofemoral joints2. In properly selected patients, outcomes include improvement in patient pain and function1. One study found that robotic-assisted patellofemoral arthroplasty may result in improved patellar tracking compared with non-robotic-assisted patellofemoral arthroplasty1; however, functional outcomes were found to be similar between procedures, and data for all non-robotic-assisted controls were retrospectively captured1. Confirm isolated patellofemoral arthritis on radiographs and/or magnetic resonance imaging.Review the preoperative plan for appropriate positioning of the trochlear implant.○ Confirm coverage of the trochlear groove.○ Avoid medial overhang.○ Avoid lateral overhang.○ Avoid anterior femoral notching.○ Avoid impingement of the trochlear component into the notch.○ Avoid excessive prominence of the trochlear component on the anterior femoral cortex.○ General principles are to place the trochlear component in 0° to 6° of flexion and 0° to 2° of external rotation.Robotic-assisted trochlear resurfacing is accurate and efficient. CT = computed tomography.

Optimizing Sensor Placement for Temperature Mapping during Ablation Procedures.

Accurately mapping the temperature during ablation is crucial for improving clinical outcomes. While various sensor configurations have been suggested in the literature, depending on the sensors' type, number, and size, a comprehensive understanding of optimizing these parameters for precise temperature reconstruction is still lacking. This study addresses this gap by introducing a tool based on a theoretical model to optimize the placement of fiber Bragg grating sensors (FBG) within the organ undergoing ablation. The theoretical model serves as a general framework, allowing for adaptation to various situations. In practical application, the model provides a foundational structure, with the flexibility to tailor specific optimal solutions by adjusting problem-specific data. We propose a nonlinear and nonconvex (and, thus, only solvable in an approximated manner) optimization formulation to determine the optimal distribution and three-dimensional placement of FBG arrays. The optimization aims to find a trade-off among two objectives: maximizing the variance of the expected temperatures measured by the sensors, which can be obtained from a predictive simulation that considers both the type of applicator used and the specific organ involved, and maximizing the squared sum of the distances between the sensor pairs. The proposed approach provides a trade-off between collecting diverse temperatures and not having all the sensors concentrated in a single area. We address the optimization problem through the utilization of approximation schemes in programming. We then substantiate the efficacy of this approach through simulations. This study tackles optimizing the FBGs' sensor placement for precise temperature monitoring during tumor ablation. Optimizing the FBG placement enhances temperature mapping, aiding in tumor cell eradication while minimizing damage to surrounding tissues.

Covert system for detecting nuclear dirty bombs in public venues

Background In the past two decades, the potential threat of a radiological dispersal device (RDD) or “dirty bomb,” which combines conventional explosives with radioactive material, has been a concern for counterterrorism efforts. The accessibility of radioactive materials used in various applications, such as medicine, industry, and research, makes RDDs a viable weapon of choice for terrorists. While the radiation released from an RDD is generally not lethal beyond a short range, the long-term health, environmental, and psychological effects of radiation release will have an impact on the future of a society. Providing proactive security measures will aid in the deterrence of potential radiological terrorist threats. Methods The use of commercial off-the-shelf detectors and GPS modules can be integrated with software to provide the approximate location of a radioactive anomaly. With the strategic placement of a circular array of 4-inch × 4-inch Thallium dopped Sodium-Iodide (NaI) in a façade of a full trashcan, it is possible to determine if, when, and the general direction of a hand- carried threat entering a venue. A supplemental detector containing a Cesium-Iodide (CsI) crystal and a GPS module fitted to a plate carrier vest can further refine the location of a threat. In tandem, these two designs are capable of providing the RDD screening that is currently lacking in public. Conclusions While a true threat may contain a radiation source well in the hundreds of Curies, the designs selected are tested and calibrated to 1-microcurie button sources. Which provides scaled results that indicate the possibility for the deployment of such a detection scheme in a venue. Although the devices tested are limited by commercial GPS resolution, the ability for both designs to determine the presence and approximate location of a button source within 10 feet is promising for further larger scale tests.

Concurrent functional ultrasound imaging with graphene-based DC-coupled electrophysiology as a platform to study slow brain signals and cerebral blood flow under control and pathophysiological brain states.

Current methodology used to investigate how shifts in brain states associated with regional cerebral blood volume (CBV) change in deep brain areas, are limited by either the spatiotemporal resolution of the CBV techniques, and/or compatibility with electrophysiological recordings; particularly in relation to spontaneous brain activity and the study of individual events. Additionally, infraslow brain signals (<0.1 Hz), including spreading depolarisations, DC-shifts and infraslow oscillations (ISO), are poorly captured by traditional AC-coupled electrographic recordings; yet these very slow brain signals can profoundly change CBV. To gain an improved understanding of how infraslow brain signals couple to CBV we present a new method for concurrent CBV with wide bandwidth electrophysiological mapping using simultaneous functional ultrasound imaging (fUS) and graphene-based field effect transistor (gFET) DC-coupled electrophysiological acquisitions. To validate the feasibility of this methodology visually-evoked neurovascular coupling (NVC) responses were examined. gFET recordings are not affected by concurrent fUS imaging, and epidural placement of gFET arrays within the imaging window did not deteriorate fUS signal quality. To examine directly the impact of infra-slow potential shifts on CBV, cortical spreading depolarisations (CSDs) were induced. A biphasic pattern of decreased, followed by increased CBV, propagating throughout the ipsilateral cortex, and a delayed decrease in deeper subcortical brain regions was observed. In a model of acute seizures, CBV oscillations were observed prior to seizure initiation. Individual seizures occurred on the rising phase of both infraslow brain signal and CBV oscillations. When seizures co-occurred with CSDs, CBV responses were larger in amplitude, with delayed CBV decreases in subcortical structures. Overall, our data demonstrate that gFETs are highly compatible with fUS and allow concurrent examination of wide bandwidth electrophysiology and CBV. This graphene-enabled technological advance has the potential to improve our understanding of how infraslow brain signals relate to CBV changes in control and pathological brain states.

10269-ET-10 ARRAYS FOR DELIVERING TUMOR TREATING FIELDS (TTFIELDS) TO THE MOUSE HEAD

Abstract INTRODUCTION Tumor Treating Fields (TTFields) therapy is an approved treatment for glioblastoma (GBM), the most common malignant brain tumor. TTFields therapy is delivered continuously by two pairs of arrays placed orthogonally on the skin surrounding the tumor region. Investigational in vivo work in the field of GBM currently utilizes mouse models. To expand the possibility for TTFields-GBM in vivo studies, TTFields arrays for the mouse head are needed. The small dimensions and specific geometries of the mouse head make the development of such arrays challenging. METHODS We tested a variety of layouts for the arrays to identify one that will be suited to the geometries of the mouse head, and that will minimally restrict head movement. Efficient treatment delivery requires good adherence to the skin; hence, we investigated different skin attachment adhesive tapes. To validate the ability of the selected arrays to deliver therapeutic field intensity to the desired region, we performed direct fields measurements and simulations. RESULTS We employed 2 strategies to overcome the small size and confining geometries of the mouse head: (1) only two of the four arrays were situated on the head – opposing arrays were placed on the mouse torso; (2) the arrays on the head were each divided into two small disks instead of just one large disk. We identified an adhesive tape for securing the arrays to the skin that was thin and transparent, facilitating correct positioning of the arrays on the mouse head. The tape also offered good tackiness, and allowed for easy removal without leaving residual adhesive on the skin, facilitating repeated array placement. The arrays met the requirements for efficient treatment: field intensity ≥ 1 V/cm RMS, current ≥ 50 mA, usage ≥ 75%. CONCLUSIONS We were able to develop flexible mouse head arrays, that adheres strongly to the skin, enabling efficient electric field delivery with minimal animal discomfort. These arrays provide means to expand TTFields-GBM treatment research, and will contribute to advance this field.