Ultra Wideband-Based Imaging Technology for Stroke Detection
Medical Physics, Biomedical Technology
Final Report Abstract
Microwave signals penetrating into human head are anticipated to be severely diffracted by the high contrast head tissues. Therefore, the detection of stroke utilizing microwave technology is a more demanding task compared to other so far investigated microwave medical imaging applications (e.g. detection of tumor in breast). Through imaging a numerically realistic MRI-derived head model, it was shown that microwave imaging technology has a good potential for head imaging. Depending on the employed imaging method, however, different specification of hardware and software are required. Above all careful design of the antenna system is of great importance as it directly influences the ultimate efficiency of the imaging system. For this complicated application, single antenna elements capable of efficiently directing microwave power into human head and capturing the very weak scattered signals are critical. In this research, two antenna structures were proposed for head imaging. As an alternative to the low-efficient monopole antenna widely used so far in microwave tomography imaging systems, a miniaturized modified Bowtie antenna was proposed. The required specification of the antenna for the application in 3D microwave tomography e.g. simple structure, directional radiation, broadband performance etc. were the main consideration in the design of the antenna. The broadband planar antenna can also be used in a conformal 3D array configuration for head imaging. An alternative head imaging method that is considerably faster than full-wave 3D microwave tomography is the synthetic microwave tomography approach. The technique might also be applied prior to full-wave 3D imaging to provide a fast efficient initial imaging results to be later enhanced using full-wave approach. A second antenna structure, namely a Vivaldi antenna was proposed for this imaging technique and it was shown to outperform the Bowtie antenna regarding the estimated modeling error for application in synthetic microwave imaging. The proposed Vivaldi antenna was successfully used in a simulated imaging scenario in CST microwave studio for the detection of hemorrhagic stroke in a multilayer head model. In conclusion, the possibility of detecting a stroke using microwave technology was examined using a numerically realistic head model and 2D nonlinear iterative image reconstruction algorithms. As one very important step prior to the implementation of an imaging system for head imaging, the antenna requirements of different imaging methods were deeply studied. It turned out that there is no general optimum antenna structure for head imaging, rather the choice of the efficient antenna depends to a high extent on the employed imaging method. Two antenna structures namely a planar Bowtie antenna and a Vivaldi antenna were optimized and proposed for head imaging using microwave technology. A hemorrhagic stroke region inside a multilayer head model was successfully detected using an array of Vivaldi antenna in a simulation scenario in CST microwave studio. The integration of the developed imaging algorithms (software) to the proposed antenna array (hardware) through an implemented imaging system (laboratory version) is not yet fully accomplished mainly due to reduced project duration. The results so far obtained during this research encourage further investigation of the utilization of microwave technology for head imaging and the detection of stroke. The current state of this research at IHE & IBT involves the implementation of a laboratory version of a microwave imaging system using the proposed antennas for the detection of stroke in a headmimicking multilayer phantom.
Publications
- "A Model Approach to the Analytical Analysis of Stroke Detection Using UWB Radar," in EuCAP 2013, Gothenburg, Apr. 2013
M. Jalilvand, X. Li, and T. Zwick
- "A Compact Double-Layer On-Body Matched Bowtie Antenna for Medical Diagnosis," Antennas and Propagation, IEEE Transactions on, vol. 62, pp. 1808- 1816, Apr. 2014
X. Li, M. Jalilvand, Y.L. Sit, and T. Zwick
(See online at https://doi.org/10.1109/TAP.2013.2297158) - "Broadband miniaturized bow-tie antenna for 3D microwave tomography," Electronics Letters, vol. 50, pp. 244-246, Feb. 2014
M. Jalilvand, X. Li, J. Kowalewski, and T. Zwick
(See online at https://doi.org/10.1049/el.2013.3974) - "Implementation of Antenna Array Systems for Medical Imaging," in Microwave Conference (GeMIC), 2014 German, pp. 1-4, 2014
M. Jalilvand, C. Vasanelli, J. Kowalewski, and T. Zwick
- "On the evaluation of a proposed bowtie antenna for microwave tomography," in Antennas and Propagation (EuCAP), 2014 8th European Conference on, pp. 2790-2794, 2014
M. Jalilvand, C. Vasanelli, C. Wu, J. Kowalewski, and T. Zwick
(See online at https://doi.org/10.1109/EuCAP.2014.6902405) - "Quantitative imaging of numerically realistic human head model using microwave tomography," Electronics Letters, vol. 50, pp. 255-256, Feb. 2014
M. Jalilvand, Chuanren Wu, J. Schmid, and T. Zwick
(See online at https://doi.org/10.1049/el.2013.4078) - “Toward Radar based Stroke Imaging by Integrating a Priori Knowledge”, in IEEE Engineering in Medicine and Biology (EMBC), 2015 37th conference
J. Schmid, O. Dössel
