Vector Network Analyzer for Medical Imaging Research

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Our research focuses on new medical diagnostic modalities using RF and microwave technologies. In support of this research, we request funding for a vector network analyzer (VNA) with a frequency range up to 40 GHz. It provides frequency-sweep measurements of the scattering parameters of high-frequency devices and circuits along with two additional functionalities: frequency-conversion measurements and time-domain measurements. The requested instrument will replace two VNAs that are now malfunctioning and obsolete. The problems with our old VNAs brought to a halt experimental work, which is critical to the progress of our trainees and the success of our research projects.    There are three research programs that depend critically on the requested instrument. First, we are in the advanced stages of developing a microwave-imaging prototype for breast-cancer screening. It will provide a much needed non-ionizing alternative to mammography with equivalent or better diagnostic accuracy, wider accessibility, reduced cost, increased check-up frequency, and improved patient safety. Its modules have been undergoing tests with breast-tissue phantoms in preparation for trials with patients but these tests are now on hold. This also includes the development of a new ultra-wideband (UWB) receiver chip, to be integrated within each antenna in the breast-imaging sensor array. The chip tape-out is expected in 2022 and its characterization will require frequency-conversion measurements with a VNA.    Second, we are working on novel coil designs for a 7T magnetic resonance imaging (MRI) scanner and in vivo nuclear magnetic resonance (NMR) spectroscopy. 7T MR spectroscopy will significantly enhance the diagnostic accuracy for brain and peripheral nerve tumors, epilepsy, multiple sclerosis and other neurodegenerative diseases. MRI coil testing requires measurements with a VNA for coil tuning and to validate the coil impedance match and coupling. We also pursue the biomedical applications of electron spin resonance (ESR) spectroscopy, which requires measurements at the X-band (10 GHz, 0.33 T) and the Q-band (35 GHz, 1.25 T).    Third, we work on new radiometers to overcome the current limitations of poor linearity and limited accuracy. Medical radiometers are attractive due to their passive nature - they do not irradiate the patient; they only sense the natural thermal radiation from the body. They are used to monitor the deep-body temperature during hyperthermia and thermal-ablation therapies. High-sensitivity radiometers are used in the emerging thermographic imaging of tissue for the detection of malignancies.    Experiment-based research is critical in achieving high-impact innovation through the projects described above. It is needed not only for the development of hardware with new functionalities but also to support the development of new methods for image reconstruction and processing, anomaly detection, and automated diagnostics exploiting machine learning.