Integrated ultrasound and photoacoustic tomography for 3D imaging of human skin lesions

The rising incidence of skin cancer, in particular melanoma, highlights the need for improved detection techniques. Determining the maximal depth of a lesion is crucial for planning excision margins and optimizing treatment outcomes. However, the current gold standard diagnostics, such as excision and histological examination, are invasive, time-consuming, and may not accurately measure the deepest position of the lesion. Preoperative knowledge of lesion size and depth would greatly assist surgical planning and enhance the likelihood of achieving tumor-free excision margins. In this work, we report on an integrated imaging system that combines ultrasound (US) and photoacoustic tomography (PAT) into a single scanning unit, enabling fast and non-invasive co-localized measurements. Our system facilitates C-mode imaging, providing visualization of lesion depth across its entire size. The design of the setup offers a clear optical window, allowing for integration with other optical modalities. We conducted in vivo measurements on suspicious human skin nevi promptly followed by excision. The combined US/PAT imaging technique demonstrated a strong correlation with histological Breslow thickness, a key parameter for lesion depth. These results highlight the potential of combined US and PAT as a promising non-invasive 3D imaging approach for evaluating human nevi and other skin lesions. By correlating our imaging data with corresponding histological findings, we aim to increase the accuracy and demonstrate the clinical utility of the integrated ultrasound and photoacoustic tomography approach in non-invasive 3D imaging of human melanocytic and other skin lesions.