57 research outputs found
Front-End Receiver Architecture for Miniaturised Ultrasound Imaging
Abstract -The design and measured results for an I/Q synthetic aperture beamforming front-end are presented. The system targets a highly portable ultrasound imaging applications such as wearable/portable devices and capsule endoscopes. Synthetic aperture beamforming is carried out in the baseband in order to minimise the bandwidth and power consumption. A single-channel analogue front-end (AFE) demodulates RF signals into I/Q components. The FPGA-based beamformer dynamically apodises and focuses the data by interpolating and applying complex phase rotations to the I/Q samples. The entire system is pipelined using a synthetic aperture protocol through a single, multiplexed channel in order to reduce the cost and complexity of the system and minimise the area. The AFE consumes 7.8mW and occupies 1.5 mm × 1.5 mm in AMS 0.35µm CMOS. The digital beamformer is implemented on a Kintex-7 TM FPGA and consumes 262mW for a frame rate of 4Hz. Measured results using real ultrasound data reveal that comparable image quality may be attained to the case when full RF beamforming is used. Future work includes integration of analogue/digital components on a single chip
Real-Time Non-Invasive Imaging and Detection of Spreading Depolarizations through EEG: An Ultra-Light Explainable Deep Learning Approach
A core aim of neurocritical care is to prevent secondary brain injury.
Spreading depolarizations (SDs) have been identified as an important
independent cause of secondary brain injury. SDs are usually detected using
invasive electrocorticography recorded at high sampling frequency. Recent pilot
studies suggest a possible utility of scalp electrodes generated
electroencephalogram (EEG) for non-invasive SD detection. However, noise and
attenuation of EEG signals makes this detection task extremely challenging.
Previous methods focus on detecting temporal power change of EEG over a fixed
high-density map of scalp electrodes, which is not always clinically feasible.
Having a specialized spectrogram as an input to the automatic SD detection
model, this study is the first to transform SD identification problem from a
detection task on a 1-D time-series wave to a task on a sequential 2-D rendered
imaging. This study presented a novel ultra-light-weight multi-modal
deep-learning network to fuse EEG spectrogram imaging and temporal power
vectors to enhance SD identification accuracy over each single electrode,
allowing flexible EEG map and paving the way for SD detection on
ultra-low-density EEG with variable electrode positioning. Our proposed model
has an ultra-fast processing speed (<0.3 sec). Compared to the conventional
methods (2 hours), this is a huge advancement towards early SD detection and to
facilitate instant brain injury prognosis. Seeing SDs with a new dimension -
frequency on spectrograms, we demonstrated that such additional dimension could
improve SD detection accuracy, providing preliminary evidence to support the
hypothesis that SDs may show implicit features over the frequency profile
Clinical value of bioelectrical properties of cancerous tissue in advanced epithelial ovarian cancer patients
Currently, there are no valid pre-operatively established biomarkers or algorithms that can accurately predict surgical and clinical outcome for patients with advanced epithelial ovarian cancer (EOC). In this study, we suggest that profiling of tumour parameters such as bioelectrical-potential and metabolites, detectable by electronic sensors, could facilitate the future development of devices to better monitor disease and predict surgical and treatment outcomes. Biopotential was recorded, using a potentiometric measurement system, in ex vivo paired non-cancerous and cancerous omental tissues from advanced stage EOC (n = 36), and lysates collected for metabolite measurement by microdialysis. Consistently different biopotential values were detected in cancerous tissue versus non-cancerous tissue across all cases (p < 0.001). High tumour biopotential levels correlated with advanced tumour stage (p = 0.048) and tumour load, and negatively correlated with stroma. Within our EOC cohort and specifically the high-grade serous subtype, low biopotential levels associated with poorer progression-free survival (p = 0.0179, p = 0.0143 respectively). Changes in biopotential levels significantly correlated with common apoptosis related pathways. Lactate and glucose levels measured in paired tissues showed significantly higher lactate/glucose ratio in tissues with low biopotential (p < 0.01, n = 12). Our study proposes the feasibility of biopotential and metabolite monitoring as a biomarker modality profiling EOC to predict surgical and clinical outcomes
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What Should a Clinician Do When Spreading Depolarizations are Observed in a Patient?
Abstract: The International Conference on Spreading Depolarizations (iCSD) held in Boca Raton, Florida, in the September of 2018 devoted a section to address the question, “What should a clinician do when spreading depolarizations are observed in a patient?” Discussants represented a wide range of expertise, including neurologists, neurointensivists, neuroradiologists, neurosurgeons, and pre-clinical neuroscientists, to provide both clinical and basic pathophysiology perspectives. A draft summary of viewpoints offered was then written by a multidisciplinary writing group of iCSD members, based on a transcript of the session. Feedback of all discussants was formally collated, reviewed, and incorporated into the final document which was subsequently approved by all authors
Evaluation of a minimally invasive glucose biosensor for continuous tissue monitoring
We describe here a minimally invasive glucose biosensor based on a microneedle array electrode fabricated from an epoxy-based negative photoresist (SU8 50) and designed for continuous measurement in the dermal compartment with minimal pain. These minimally invasive, continuous monitoring sensor devices (MICoMS) were produced by casting the structures in SU8 50, crosslinking and then metallising them with platinum or silver to obtain the working and reference electrodes, respectively. The metallised microneedle array electrodes were subsequently functionalised by entrapping glucose oxidase in electropolymerised polyphenol (PP) film. Sensor performance in vitro showed that glucose concentrations down to 0.5 mM could be measured with a response times (T90) of 15 s. The effect of sterilisation by Co60 irradiation was evaluated. In preparation for further clinical studies, these sensors were tested in vivo in a healthy volunteer for a period of 3–6 h. The sensor currents were compared against point measurements obtained with a commercial capillary blood glucometer. The epoxy MICoMS devices showed currents values that could be correlated with these
Consensus statement from the 2014 International Microdialysis Forum.
Microdialysis enables the chemistry of the extracellular interstitial space to be monitored. Use of this technique in patients with acute brain injury has increased our understanding of the pathophysiology of several acute neurological disorders. In 2004, a consensus document on the clinical application of cerebral microdialysis was published. Since then, there have been significant advances in the clinical use of microdialysis in neurocritical care. The objective of this review is to report on the International Microdialysis Forum held in Cambridge, UK, in April 2014 and to produce a revised and updated consensus statement about its clinical use including technique, data interpretation, relationship with outcome, role in guiding therapy in neurocritical care and research applications.We gratefully acknowledge financial support for participants as follows: P.J.H. - National Institute for Health Research (NIHR) Professorship and the NIHR Biomedical Research Centre, Cambridge; I.J. – Medical Research Council (G1002277 ID 98489); A. H. - Medical Research Council, Royal College of Surgeons of England; K.L.H.C. - NIHR Biomedical Research Centre, Cambridge (Neuroscience Theme; Brain Injury and Repair Theme); M.G.B. - Wellcome Trust Dept Health Healthcare Innovation Challenge Fund (HICF-0510-080); L. H. - The Swedish Research Council, VINNOVA and Uppsala Berzelii Technology Centre for Neurodiagnostics; S. M. - Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico; D.K.M. - NIHR Senior Investigator Award to D.K.M., NIHR Cambridge Biomedical Research Centre (Neuroscience Theme), FP7 Program of the European Union; M. O. - Swiss National Science Foundation and the Novartis Foundation for Biomedical Research; J.S. - Fondo de Investigación Sanitaria (Instituto de Salud Carlos III) (PI11/00700) co-financed by the European Regional Development; M.S. – NIHR University College London Hospitals Biomedical Research Centre; N. S. - Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico.This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s00134-015-3930-
Consensus statement from the 2014 International Microdialysis Forum
This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s00134-015-3930-yMicrodialysis enables the chemistry of the extracellular interstitial space to be measured. Use of this technique in patients with acute brain injury has increased our understanding of the pathophysiology of several acute neurological disorders. In 2004 a consensus document on the clinical application of cerebral microdialysis was published. Since then there have been significant advances in the clinical use of microdialysis in neurocritical care. The objective of this review is to report on the International Microdialysis Forum held in Cambridge, UK, in April 2014 and to produce a revised and updated consensus statement about its clinical use including technique, data interpretation, relationship with outcome, role in guiding therapy in neurocritical care and research applications.We gratefully acknowledge financial support for participants as follows: P.J.H. - National Institute for Health Research (NIHR) Professorship and the NIHR Biomedical Research Centre, Cambridge; I.J. ? Medical Research Council (G1002277 ID 98489); A. H. - Medical Research Council, Royal College of Surgeons of England; K.L.H.C. - NIHR Biomedical Research Centre, Cambridge (Neuroscience Theme; Brain Injury and Repair Theme); M.G.B. - Wellcome Trust Dept Health Healthcare Innovation Challenge Fund (HICF-0510-080); L. H. - The Swedish Research Council, VINNOVA and Uppsala Berzelii Technology Centre for Neurodiagnostics; S. M. - Fondazione IRCCS C? Granda Ospedale Maggiore Policlinico; D.K.M. - NIHR Senior Investigator Award to D.K.M., NIHR Cambridge Biomedical Research Centre (Neuroscience Theme), FP7 Program of the European Union; M. O. - Swiss National Science Foundation and the Novartis Foundation for Biomedical Research; J.S. - Fondo de Investigaci?n Sanitaria (Instituto de Salud Carlos III) (PI11/00700) co-financed by the European Regional Development; M.S. ? NIHR University College London Hospitals Biomedical Research Centre; N. S. - Fondazione IRCCS C? Granda Ospedale Maggiore Policlinico
Development and use of bioanalytical instrumentation and signal analysis methods for rapid sampling microdialysis monitoring of neuro-intensive care patients
This thesis focuses on the development and use of analysis tools to monitor brain injury patients. For this purpose, an online amperometric analyzer of cerebral microdialysis samples for glucose and lactate has been developed and optimized within the Boutelle group. The initial aim of this thesis was to significantly improve the signal-to-noise ratio and limit of detection of the assay to allow reliable quantification of the analytical data. The first approach was to re-design the electronic instrumentation of the assay. Printed-circuit boards were fabricated and proved very low noise, stable and much smaller than the previous potentiostats. The second approach was to develop generic data processing algorithms to remove three complex types of noise that commonly contaminate analytical signals: spikes, non-stationary ripples and baseline drift. The general strategy consisted in identifying the types of noise, characterising them, and subsequently subtracting them from the otherwise unprocessed data set. Spikes were effectively removed with 96.8% success and ripples were removed with minimal distortion of the signal resulting in an increased signal-to-noise ratio by up to 250%. This allowed reliable quantification of traces from ten patients monitored with the online microdialysis assay. Ninety-six spontaneous metabolic events in response to spreading depolarizations were resolved. These were characterized by a fall in glucose by -32.0 ÎĽM and a rise in lactate by +23.1 ÎĽM (median values) for over a 20-minute time-period. With frequently repeating events, this led to a progressive depletion of brain glucose. Finally, to improve the temporal coupling between the metabolic data and the electro-cortical signals, a flow-cell was engineered to integrate a potassium selective electrode into the microdialysate flow stream. With good stability over hours of continuous use and a 90% response time of 65 seconds, this flow cell was used for preliminary in vivo experiments the Max Planck Institute in Cologne.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Use of online rapid sampling microdialysis electrochemical biosensor for bowel anastomosis monitoring in swine model
Bowel anastomosis ischemia carries a significant rise in morbidity and mortality after bowel surgery. Clinical measures of bowel ischemia are often non-specific and only become evident at a late stage. There is currently no method to continuously monitor, in real time, metabolic impairment at the anastomosis site. Our online rapid sampling microdialysis biosensor system has proved its efficacy in monitoring ischemia in the bowel. Selective glucose and lactate biosensors are coupled online to the microdialysis probe through a flow injection analysis (FIA) system, which performs in vivo bowel monitoring at high time resolution, typically every 30 seconds. The enzymatic reactors containing substrate oxidase (SOx) and horseradish peroxidase (IIRP) are coupled to flow cell electrodes. The system was used to monitor ischemia at the bowel anastomosis level, by monitoring in vivo changes in the metabolic substrates, like glucose and lactate in the colon of swine models. The rapid decrease in glucose and increase in lactate 5 minutes post-clamping of the artery feeding the anastomosis highlights the vulnerability of the bowel to damage with surgical stress and previous ischemic insults
Biosensors and invasive monitoring in clinical applications
This volume examines the advances of invasive monitoring by means of biosensors and microdialysis. Physical and physiological parameters are commonly monitored in clinical settings using invasive techniques due to their positive outcome in patients’ diagnosis and treatment. Biochemical parameters, however, still rely on off-line measurements and require large pieces of equipment. Biosensing and sampling devices present excellent capabilities for their use in continuous monitoring of patients’ biochemical parameters. However, certain issues remain to be solved in order to ensure a more widespread use of these techniques in today’s medical practices
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