Low-frequency Conductivity Tensor Images of Rat Brain Tumor Using a 9.4T MRI.

Cell proliferation, invasion, and ionic aggregation are critical features of cancer cells. The electrical conductivity of biological tissues at low frequencies is determined by cel lularity, ionic concentration, and their mobility. Anisotropic conductivity imaging of tumors has the potential to give useful information in terms of heterogenei ty and invasive nature. This study reports tumor development in relation to changes in the ionic environment using a low-frequency Conductivi ty Tensor Imaging (CTI) technique. B1 mapping for electrical conductivity distribution at Larmor frequency and mul ti-b-value diffusion imaging to differentiate extracellular and intracellular tissue compartments and their diffusion coefficients have been used to develop conductivity tensor imaging. Applying to a F98 cerebral tumor-bearing rat, a longitudinally following tumor cell inoculation on days 8, 11, and 14 was performed. Changes in the concentration of ions and cellular states of tumor growth are reflected in both high and low-frequency. Anisotropic conductivities of tumoral tissues were significantly lower (p<0.01) than the normal regions of the brain and progressive with growth (p<0.01). In conclusion, we demonstrate a novel contrast mechanism based on ionic concentration and mobility, which may aid in providing useful information about tumor heterogeneity in probing the microenvironment of brain tumors for devising better treatment therapy. [ABSTRACT FROM AUTHOR]