Radar based technology for non-contact monitoring of accumulation of blood in the head: A numerical study

Abstract

BackgroundThis theoretical study examines the use of radar to continuously monitor “accumulation of blood in the head” (ACBH) non-invasively and from a distance, after the location of a hematoma or hemorrhage in the brain was initially identified with conventional medical imaging. Current clinical practice is to monitor ABCH with multiple, subsequent, conventional medical imaging. The radar technology introduced in this study could provide a lower cost and safe alternative to multiple conventional medical imaging monitoring for ACBH.Materials and methodsThe goal of this study is to evaluate the feasibility of using radar to monitor changes in blood volume in the brain through a numerical simulation of ACBH monitoring from remote, with a directional spiral slot antennae, in 3-D models of the brain. The focus of this study is on evaluating the effect of frequencies on the antennae reading. To that end we performed the calculations for frequencies of 100 MHz, 500 MHz and 1 GHz.Results and discussionThe analysis shows that the ACBH can be monitored with radar and the monitoring resolution improves with an increase in frequency, in the range studied. However, it also appears that when typical clinical dimensions of hematoma and hemorrhage are used, the variable ratio of blood volume radius and radar wavelength can bring the measurements into the Mie and Rayleigh regions of the radar cross section. In these regions there is an oscillatory change in signal with blood volume size. For some frequencies there is an increase in signal with an increase in volume while in others there is a decrease.ConclusionsWhile radar can be used to monitor ACBH non-invasively and from a distance, the observed Mie region dependent oscillatory relation between blood volume size and wavelength requires further investigation. Classifiers, multifrequency algorithms or ultra-wide band radar are possible solutions that should be explored in the future.

Peer Review #1 of "Detection and estimating the blood accumulation volume of brain hemorrhage in a human anatomical skull using a RF single coil (v0.1)"

“…We have obtained a complete record of the changes in amplitude and phase measured across the RF coil in response to injection of blood in our experimental model of intracranial hemorrhages, throughout the frequency range of 100 MHz to 1 GHz. The results are qualitatively similar to those presented in our previous theoretical studies (Oziel et al, 2017;Oziel et al, 2018). We find that the change in amplitude and phase across the RF coil upon an injection of blood, is a complex function of frequency, of the injected blood volume and of the location.…”

“…Our previous studies of monitoring the brain by a single coil began with mathematical modeling. We used numerical simulations to analyze the performances of a spiral antenna (Oziel et al, 2017) and a single inductive coil surrounding the head (Oziel et al, 2018). These feasibility studies evaluated the sensitivity of the radar-based measurements to small changes in the blood/tissue volume ratio in the case of a brain hemorrhage.…”

Peer Review #2 of "Detection and estimating the blood accumulation volume of brain hemorrhage in a human anatomical skull using a RF single coil (v0.1)"

“…This algorithm was also able to roughly estimate the injection volume. In the present study, we validate the single-coil based technology of detection internal head bleeding conceived first in previous study (Oziel et al, 2017), on a phantom as close as possible to a real human head. This is an experimental study on a human anatomical shape skull with real blood and brain tissue.…”

Noninvasive and portable stroke type discrimination and progress monitoring based on a multichannel microwave transmitting–receiving system

“…In addition to the microwave imaging, microwave scattering parameters are used in stroke diagnosis 24 – 31 . These studies focus on computer simulations 24 , 28 , 29 or phantoms 25 – 27 and rarely on in vivo experiments. In 2014, Persson et al have performed a clinical study on 25 patients with acute stroke 31 .…”