A downhole tool includes a body having a longitudinal axis and bore therethrough, an array of longitudinal electrode segments separated by electrical insulators, wherein substantially an entire cross section of said body comprises at least one electrode segment, at least one longitudinal electrode configured to emit a first electrical current into said formation and measure said first emitted current, at least one longitudinal electrode segment configured to emit a second electrical current for directing said first emitted current into said formation, and at least one longitudinal electrode segment configured to receive said first emitted current returning from said formation.