Rapid estimation of conductivity and permittivity using Bloch-Siegert B1 mapping at 3.0T

Introduction: Tissue conductivity and permittivity are critical to estimating local RF power deposition during MR imaging. These electrical properties may also have diagnostic value as malignant tissue types have been shown to have higher permittivity and conductivity than surrounding healthy tissue . In this work, we explore rapid estimation of electrical properties that will prove to be useful in real time estimation of local RF power deposition or in conjunction with images, prove to be of diagnostic value in identifying tissue abnormality. The target time for estimation is time acceptable for routine clinical use. Methods: The spatial distribution of transmit RF field (B1+) is related to the electrical properties of the imaging object. This relationship is used to obtain expressions for conductivity and permittivity in terms of complex B1+ .