A catheter and catheter system for treatment of a blood vessel of a patient include an elongate flexible catheter body with a radially expandable structure. A plurality of electrodes or other electrosurgical energy delivery surfaces can radially engage material to be treated when the structure expands. A material detector near the distal end of the catheter body may measure circumferential material distribution, and a power source selectively energizes the electrodes to eccentrically treat of a body lumen.