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Project: Non-invasive RF 4D Thorax Hemodynamic Characterization

Acronym: CHARF
Main Objective:
The project hereby presented aims the development of a non-invasive, portable, operator independent electromagnetic centimeter-wave 4D high-resolution hemodynamic characterization system for the thorax.
There are four vectors that define the inception of this project: scientific, entrepreneurial, academic, social.
Scientifically it is a new challenge to spatially and temporally map the hemodynamics within the thorax accurately in an supervised environment.
Our approach to this challenge is also scientifically new: the use of centimeter-wave RF pulses combined with traditional electric impedance tomography. The use of pulsed RF waves with frequencies in the range between 500 MHz and 1.5 GHz will allow the assessment of the velocity of blood cells by reverse reconstitution of the Doppler distortion of the pulses as well as the scatter observed by the pulses on the blood cells in a dispersive medium. This velocity assessment can take place simultaneously at several points within the thorax. The electrical impedance tomography, a technique typically used for the spatial mapping of passive electric properties (PEP) of materials through near-field paradigm, will be used here essentially to measure instantaneous blood volume changes. Simultaneous assessment of blood volumes and velocities allows for the inference of blood pressures using the Bernoulli equation. These provide for a full hemodynamic characterization with both spatial and temporal assessment
allowing the determination and temporal evolution of some cardio-physiologic variables like the right atrial pressure (RAP), the pulmonary artery pressure (PAP), pulse pressure variation (PPV), stroke volume variation (SVV), cardiac output (CO) and the pre-ejection period (PEP). Moreover, some of these variables, specially when associated with autonomic maneuvers, should be carried out for a period of between 30 and 60 minutes which existing solutions fail to achieve. This project will allow us to accomplish several scientific goals: design the experimental prototype (antennas, switching elements, filter tuning,
instrumentation); create the finite element model that aggregates both the far-field pulsed and the near-field harmonic paradigms and solve the inverse problem associated with the velocity and volume estimation within a dispersive medium.
From an entrepreneurial perspective, the use of very low power electromagnetic radiation for automatic wide body area scanning of fluxes, pressures and volumes is innovative and should give rise to a high-valued product. The prototype to be built, together with the simulation models, will provide a proof-of-concept that can pave the way for further private equity funding directed towards the technological development to market.
The academic goals are quite different. This project should help fund the addition of more elements to the team and bring awareness of its importance to students while instilling in them a liking for electromagnetism with an open desire to promote PhD enrollments in these subjects.
Socially, the importance of this project is directly linked with the clinical relevance and impact in the welfare of the population the outcome of this project can bring in the long haul. Cardiovascular and respiratory diseases clearly standout as some of the most relevant health issues to be addressed by modern societies.
This technology has potentially several advantages over traditional methods that rely on MRI, ultrasound or thoracic electrical impedance measurement: lower cost, higher portability, longer period assessment, higher reliability, better coverage. The main expected disadvantage would be lower spatial resolution when compared with MRI which should be more than compensated by an increase in temporal resolution.
Reference: PTDC/EEI-ELC/5811/2014
Funding: FCT/PTDC
Start Date: 01-07-2016
End Date: 01-08-2019
Team: Helena Maria dos Santos Geirinhas Ramos, Artur Fernando Delgado Lopes Ribeiro
Groups: Instrumentation and Measurements – Lx
Partners: Associação para a Investigação e Desenvolvimento da Faculdade de Medicina (AIDFM/FM/ULisboa)
Local Coordinator: Helena Maria dos Santos Geirinhas Ramos

Associated Publications