Multimodal photoacoustic and optical coherence tomography scanner using an all optical detection scheme for 3D morphological skin imaging

TLDR

The scanner could be used to characterize skin conditions such as tumors, vascular lesions, burns, wounds, dermatitis, and other superficial abnormalities. The study presents a noninvasive, multimodal photoacoustic and optical coherence tomography (PAT/OCT) scanner for three‑dimensional in vivo skin imaging. It employs an integrated, all‑optical backward‑mode detection scheme with a shared 2‑D optical scanner (≈13 × 13 mm² FOV) and a transparent Fabry‑Perot polymer film ultrasound sensor that allows simultaneous 670‑680 nm photoacoustic excitation and 1050 nm OCT probing through the sensor head. The system achieves 8 µm (OCT) and 20 µm (PAT) axial, 18 µm (OCT) and 50‑100 µm (PAT) lateral resolution, greater penetration depth than prior PA/OCT devices, and produces high‑resolution 3‑D images of vasculature and tissue micro‑morphology in murine and human skin up to 5 mm depth.

Abstract

A noninvasive, multimodal photoacoustic and optical coherence tomography (PAT/OCT) scanner for three-dimensional in vivo (3D) skin imaging is described. The system employs an integrated, all optical detection scheme for both modalities in backward mode utilizing a shared 2D optical scanner with a field-of-view of ~13 × 13 mm(2). The photoacoustic waves were detected using a Fabry Perot polymer film ultrasound sensor placed on the surface of the skin. The sensor is transparent in the spectral range 590-1200 nm. This permits the photoacoustic excitation beam (670-680 nm) and the OCT probe beam (1050 nm) to be transmitted through the sensor head and into the underlying tissue thus providing a backward mode imaging configuration. The respective OCT and PAT axial resolutions were 8 and 20 µm and the lateral resolutions were 18 and 50-100 µm. The system provides greater penetration depth than previous combined PA/OCT devices due to the longer wavelength of the OCT beam (1050 nm rather than 829-870 nm) and by operating in the tomographic rather than the optical resolution mode of photoacoustic imaging. Three-dimensional in vivo images of the vasculature and the surrounding tissue micro-morphology in murine and human skin were acquired. These studies demonstrated the complementary contrast and tissue information provided by each modality for high-resolution 3D imaging of vascular structures to depths of up to 5 mm. Potential applications include characterizing skin conditions such as tumors, vascular lesions, soft tissue damage such as burns and wounds, inflammatory conditions such as dermatitis and other superficial tissue abnormalities.