An apparatus and method for the evaluation of tissue ablation is provided. Theapparatus comprises a broadband (white multiple wavelengths) light and/orlaser light (single wavelength) illumination source that delivers light to thesite where a lesion is being formed. Scattered light is collected from theablated tissue and evaluated to obtain qualitative information regarding thenewly formed lesion. The apparatus allows assessment of such parameters as,for example, catheter- tissue proximity, lesion formation, depth ofpenetration of the lesion, cross-sectional area of the lesion in the tissue,formation of char during the ablation, recognition of char from non-charredtissue, formation of coagulum around the ablation site, differentiation ofcoagulated from non-coagulated blood, differentiation of ablated from healthytissue, and recognition of steam formation in the tissue for prevention ofsteam pop. These assessments are accomplished by measuring the intensity andspectrum of diffusely reflected light at one or more wavelengths.
