A catheter that creates enhanced lesions uses a needle electrode assembly and employs diffuse reflectance optical spectroscopy, including optical transmissive and refractive spectroscopy before, during or after ablation to assess tissue attributes, including malignancy and/or necrosis. The catheter comprises an elongated catheter body, a control handle, and a longitudinally movable needle electrode assembly and one or more optical wave guides extending from the control handle and through the catheter body, wherein the needle electrode assembly is adapted for penetrating and ablating tissue at a distal end of the catheter and at least one optical waveguide is adapted to collect light refracted from the tissue at or near the distal end of the catheter. An integrated ablation and spectroscopy system of the present invention comprises an RF generator, a light source and a light analyzer adapted to analyze the light collected by the at least one waveguide.
