A method is disclosed for creating and outputting a masked parametric map that reflects parameters in a first parametric map and second parametric map. First and second parametric maps are generated, and then a masked parametric map that reflects parameters in the first and second parametric maps is generated. The first parametric map may be based upon portions of two optoacoustic images created using differing wavelengths of light. The first parametric map is reflective of areas within the volume of tissue that have a differing response to the longer wavelength light event compared to the shorter one. The second parametric map is reflective of areas within the volume of tissue that have a stronger response to the longer and shorter wavelength light events than the surrounding areas. A masked parametric map is output which is reflective of a combination of information in the first and second parametric maps.