Apparatus and methods for optical coherence tomography and two-photon luminescence imaging

Exemplary embodiments of the present disclosure include a combined catheter-based optical coherence tomography-two-photon luminescence (OCT-TPL) imaging system. Exemplary embodiments further include methods to detect, and further characterize the distribution of cellular components (e.g., macrophage, collagen/elastin fiber, lipid droplet) in thin-cap fibroatheromas with high spatial resolution in vivo.