Conductivity-weighted ultrasound for cancer detection

DESCRIPTION (provided by applicant): Inadequate sensitivity and specificity of currently-used imaging methods for cancer screening of the breast motivates the development of new modalities capable of adding diagnostic information. EMAI (electromagnetic aco ustic imaging) is a novel imaging method which exploits tissue electrical conductivity and acoustic properties for the purposes of cancer detection. The technique relies on inducing ultrasound by electromagnetic irradiation of the tissue of interest in the radiofrequency (RF) range. This modality has advantages in the use of RF for illumination which has been well-developed in MRI, and the use of ultrasound receiving, thereby allowing for automatic image co-registration. Preliminary studies in phantoms have confirmed theoretical predictions in that the induced ultrasound signal occurs at two frequencies (the incident and twice that) and depends on conductivity gradients. In this fast-track STTR application, work is proposed to demonstrate the feasibility of EMAI as a potentially clinically useful cancer screening imaging method. The specific aims of Phase I are: 1) design and characterize conductivity phantoms, 2) build and test imager components, 3) optimize RF pulse sequence, and 4) extend previously obtain ed experimental verifications of EMAI theory. The quantitative milestones obtained during Phase I will be 1) induced ultrasound SNR as a function of conductivity gradient in phantoms at specified source-receiver distances, 2) EMAI SNR as a function of volu me of region of interest with homogeneous conductivity, 3) EMAI SNR at the RF frequency and at twice that frequency, 4) The time for signal averaging required to bring the overall SNR above 1, and 5) The temperature change in the phantom as a result of the RF power deposition. Phase II will focus on constructing a dual mode EMAI/US prototype imager with demonstration in small animals to show viability for future clinical use. Long-terms goals are to develop EMAI as a useful imaging technique for cancer scre ening, diagnosis, and monitoring. PUBLIC HEALTH RELEVANCE. The proposed project is designed to determine the feasibility of electromagnetic acoustic imaging (EMAI) for medical applications. EMAI produces conductivity-weighted ultrasound which will potentia lly improve diagnostic performance in cancer screening, and may be especially useful for screening and diagnosing breast cancer.