Depth sensing capabilities of an interoperative impedance sensing probe.

Providing information on the depth of positive surgical margins and important underlying anatomic features would help guide surgeons to resect tissue to negative margins, while sparing healthy tissue needed to preserve function. In transoral robotic surgery, surgeons lack haptic feedback which would be used to locate tumor boundaries and underlying critical structures. An interoperative electrical impedance sensing probe has the potential to provide highly specific tissue classification and 3D imagery.

Evaluating an impedance-based smart drill system in a preliminary human cadaver model.

Dental implant placement requires a great level of accuracy given the risk of iatrogenic injury to the inferior alveolar nerve and maxillary sinus. Real-time impedance sensing of the surrounding tissues by the drill tip can provide feedback to the surgeon for improved outcomes and reduced risk of injury. Previous studies have shown impedance sensing to successfully discriminate between cortical and cancellous bone in ex vivo and in situ large animal tissue.

Evaluating EIT, hdEEG, and iPhone Electrode Localization for Stroke Applications.

This paper summarizes preliminary findings from a pilot study investigating the utility of combining electrical impedance tomography (EIT) with high-density electroencephalography (hdEEG) for aiding in the diagnosis or monitoring of stroke. A major effort in the work was developing a computational framework to produce high-fidelity subject-specific meshes with accurately registered electrode locations mapping the 256-electrode cap. Data was collected on seven acute stroke patients shortly after stabilization.

Assessing Pulmonary Function in ALS using Electrical Impedance Tomography.

This study aimed to determine an optimal model involving thoracic electrical impedance tomography (EIT) metrics and patient geometric information to best correlate to standard pulmonary function test (PFT) measures in a cohort of 32 ALS patients and 32 age-matched healthy controls. Thoracic EIT is a non-invasive technology in which an electrode belt chest allows for real-time impedance imaging of respiratory function. The optimal form of the model was determined via a genetic algorithm a novel technique for model generation in EIT applications.

Comparison of Complex Open Domain Electrical Impedance Tomography Methods.

Objective: This study evaluates the potential of complex 3D Electrical Impedance Tomography (EIT) for intraoperative surgical margin assessment (SMA) using an ex vivo bovine model.

Methods: A custom electrode array was used to collect impedance data across multiple frequencies (100 Hz - 1 MHz) from 57 tissue samples. An optimal pressure range was identified to ensure proper electrode contact with minimal tissue deformation (2 kPa to 5 kPa) and a saline calibration was used to minimize model-data mismatch.

Detection of occult hemorrhage using multivariate non-invasive technologies: a porcine study.

Occult hemorrhage (OH) can emerge subtly post-trauma, especially when internal bleeding is not yet severe enough to result in noticeable hemodynamic changes or shock. Despite normal appearances of traditional vital signs like heart rate (HR) and blood pressure (BP), clinically significant OH may be present, posing a critical diagnostic challenge. Early detection of OH, before vital signs begin to deteriorate, is vital as delays in identifying such conditions are linked to poorer patient outcomes.

Thoracic electrical impedance tomography for assessing progression of pulmonary dysfunction in ALS.

: We compared thoracic electrical impedance tomography (EIT) with slow vital capacity (SVC) to determine if EIT could monitor pulmonary function in ALS patients longitudinally. : Of 32 ALS patients and 32 age- and sex-matched healthy controls (HCs) initially enrolled in the Pulmonary Function via Impedance Tomography (PuFIT) study, 22 ALS and 20 HCs returned for a follow-up visit ∼3.9 months later.

Independent effects of transcranial direct current stimulation and social influence on pain.

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulatory technique with the potential to provide pain relief. However, tDCS effects on pain are variable across existing studies, possibly related to differences in stimulation protocols and expectancy effects. We investigated the independent and joint effects of contralateral motor cortex tDCS (anodal vs cathodal) and socially induced expectations (analgesia vs hyperalgesia) about tDCS on thermal pain.

Onward to Better Surgery - the Critical Need for Improved Ex Vivo Testing and Training Methods.

Guided surgery has demonstrated significant improvements in patient outcomes in some disease processes. Interest in this field has led to substantial growth in the technologies under investigation. Most likely no single technology will prove to be "best," and combinations of macro- and microscale guidance-using radiological imaging navigation, probes (activatable, perfusion, and molecular-targeted; large- and small-molecule), autofluorescence, tissue intrinsic optical properties, bioimpedance, and other characteristics-will offer patients and surgeons the greatest opportunity for high-success/low-morbidity medical interventions.

A Clinically Feasible Electrode Array for 3D Intraoperative Electrical Impedance Tomography-Based Surgical Margin Assessment in Robot-Assisted Radical Prostatectomy.

Objective: A novel small form factor circular electrode array was designed specifically for electrical impedance tomography (EIT) based assessment of surgical margins during robot assisted radical prostatectomy (RARP).

Methods: The electrode array consists of 33 gold-plated electrodes arranged within a 9.5 mm diameter circular footprint on the end of a surgical probe that can be introduced through a standard 12 mm laparoscopic port used during RARP.

An Imaging-Compatible Oral Retractor System for Transoral Robotic Surgery.

This study aimed to develop and validate a Computed Tomography (CT)/Magnetic Resonance Imaging (MRI)-compatible polymer oral retractor system to enable intraoperative image guidance for transoral robotic surgery (TORS). The retractor was designed based on standard-of-care metallic retractors and 3D (three-dimensional) printed with carbon fiber composite and nylon. The system was comprehensively evaluated in bench-top and cadaveric experiments in terms of its ability to enable intraoperative CT/MR images during TORS, functionality including surgical exposure and working volume, usability, compatibility with da Vinci surgical systems, feasibility for disinfection or sterilization, and robustness over an extended period of time.

Non-invasive biomarkers for detecting progression toward hypovolemic cardiovascular instability in a lower body negative pressure model.

Occult hemorrhages after trauma can be present insidiously, and if not detected early enough can result in patient death. This study evaluated a hemorrhage model on 18 human subjects, comparing the performance of traditional vital signs to multiple off-the-shelf non-invasive biomarkers. A validated lower body negative pressure (LBNP) model was used to induce progression towards hypovolemic cardiovascular instability.

Assessing pulmonary function in ALS using electrical impedance tomography.

Objective: We sought to determine whether thoracic electrical impedance tomography (EIT) could characterize pulmonary function in amyotrophic lateral sclerosis (ALS) patients, including those with facial weakness. Thoracic EIT is a noninvasive, technology in which a multi-electrode belt is placed across the chest, producing real-time impedance imaging of the chest during breathing.

Methods: We enrolled 32 ALS patients and 32 age- and sex-matched healthy controls (HCs) without underlying lung disease.

Prediction of Occult Hemorrhage in the Lower Body Negative Pressure Model: Initial Validation of Machine Learning Approaches.

Introduction: Detection of occult hemorrhage (OH) before progression to clinically apparent changes in vital signs remains an important clinical problem in managing trauma patients. The resource-intensiveness associated with continuous clinical patient monitoring and rescue from frank shock makes accurate early detection and prediction with noninvasive measurement technology a desirable innovation. Despite significant efforts directed toward the development of innovative noninvasive diagnostics, the implementation and performance of the newest bedside technologies remain inadequate.

Rapid patient-specific FEM meshes from 3D smart-phone based scans.

The objective of this study was to describe and evaluate a smart-phone based method to rapidly generate subject-specific finite element method (FEM) meshes. More accurate FEM meshes should lead to more accurate thoracic electrical impedance tomography (EIT) images.The method was evaluated on an iPhonethat utilized an app called Heges, to obtain 3D scans (colored, surface triangulations), a custom belt, and custom open-source software developed to produce the subject-specific meshes.

Estimating tongue deformation during laryngoscopy using a hybrid FEM-multibody model and intraoperative tracking - a cadaver study.

Throat tumour margin control remains difficult due to the tight, enclosed space of the oral and throat regions and the tissue deformation resulting from placement of retractors and scopes during surgery. Intraoperative imaging can help with better localization but is hindered by non-image-compatible surgical instruments, cost, and unavailability. We propose a novel method of using instrument tracking and FEM-multibody modelling to simulate soft tissue deformation in the intraoperative setting, without requiring intraoperative imaging, to improve surgical guidance accuracy.

Towards intraoperative surgical margin assessment: Validation of an electrical impedance-based probe with ex vivo bovine tissue.

Radical prostatectomy (RP) is a common surgical therapy to treat prostate cancer. The procedure has a high positive surgical margin (PSM) rate ranging from 4-48%. Patients with PSMs have a higher rate of cancer recurrence and often undergo noxious adjuvant therapy.

EEG electrode localization with 3D iPhone scanning using point-cloud electrode selection (PC-ES).

Electroencephalography source imaging (ESI) is a valuable tool in clinical evaluation for epilepsy patients but is underutilized in part due to sensitivity to anatomical modeling errors. Accurate localization of scalp electrodes is instrumental to ESI, but existing localization devices are expensive and not portable. As a result, electrode localization challenges further impede access to ESI, particularly in inpatient and intensive care settings.

Development of an Electrical Impedance Tomography Coupled Surgical Stapler for Tissue Characterization.

Objective: This study explores the feasibility of coupling Electrical Impedance Tomography (EIT) to a standard-of-care laparoscopic surgical stapler, stapler+EIT, with the long-term goal of enabling intraoperative tissue differentiation for tumor margin detection.

Methods: Two custom printed-circuit-board-based electrode arrays with 60 and 8 electrodes, respectively, matching the stapler geometry, served as the jaws of an electrode-integrated surrogate stapler+EIT device. The device was evaluated through a series of simulations and bench-top imaging experiments of agar-gel phantoms and bovine tissue samples to evaluate the technique and determine optimal imaging parameters.

Brain responses to food viewing in women during pregnancy and post partum and their relationship with metabolic health: study protocol for the FOODY Brain Study, a prospective observational study.

Introduction: Food cravings are common in pregnancy and along with emotional eating and eating in the absence of hunger, they are associated with excessive weight gain and adverse effects on metabolic health including gestational diabetes mellitus (GDM). Women with GDM also show poorer mental health, which further can contribute to dysregulated eating behaviour. Food cravings can lead to greater activity in brain centres known to be involved in food 'wanting' and reward valuation as well as emotional eating.

Bioimpedance Sensing Surgical Drill - In Vivo Porcine Model.

Surgical drilling to place dental implants in the mandible and maxilla is associated high risk of iatrogenic injuries to inferior alveolar nerve and maxillary sinus. Real-time tissue margin sensing at the drill-tip using electrical impedance spectroscopy (EIS) could reduce this risk by providing feedback to surgeons. Studies with saline analogues, ex-vivo tissues, in-situ tissues and computer models have been previously conducted to evaluate these impedance sensors.

A particle filter approach to dynamic kidney pose estimation in robotic surgical exposure.

Purpose: Traditional soft tissue registration methods require direct intraoperative visualization of a significant portion of the target anatomy in order to produce acceptable surface alignment. Image guidance is therefore generally not available during the robotic exposure of structures like the kidneys which are not immediately visualized upon entry into the abdomen. This paper proposes guiding surgical exposure with an iterative state estimator that assimilates small visual cues into an a priori anatomical model as exposure progresses, thereby evolving pose estimates for the occluded structures of interest.

Detection of subclinical hemorrhage using electrical impedance: a porcine study.

Analyze the performance of electrical impedance tomography (EIT) in an innovative porcine model of subclinical hemorrhage and investigate associations between EIT and hemodynamic trends.. Twenty-five swine were bled at slow rates to create an extended period of subclinical hemorrhage during which the animal's heart rate (HR) and blood pressure (BP) remained stable from before hemodynamic deterioration, where stable was defined as <15% decrease in BP and <20% increase in HRi.

Quantifying Tumor and Vasculature Deformations during Laryngoscopy.

Retractors and scopes used in head and neck surgery to provide adequate surgical exposure also deform critical structures in the region. Surgeons typically use preoperative imaging to plan and guide their tumor resections, however the large tissue deformation resulting from placement of retractors and scopes reduces the utility of preoperative imaging as a reliable roadmap. We quantify the extent of tumor and vasculature deformation in patients with tumors of the larynx and pharynx undergoing diagnostic laryngoscopy.

Novel Electrode Placement in Electrical Bioimpedance-Based Stroke Detection: Effects on Current Penetration and Injury Characterization in a Finite Element Model.

Objective: Reducing time-to-treatment and providing acute management in stroke are essential for patient recovery. Electrical bioimpedance (EBI) is an inexpensive and non-invasive tissue measurement approach that has the potential to provide novel continuous intracranial monitoring-something not possible in current standard-of-care. While extensive previous work has evaluated the feasibility of EBI in diagnosing stroke, high-impedance anatomical features in the head have limited clinical translation.