Assessment of cutaneous melanoma and pigmented skin lesions with photoacoustic imaging

Melanoma is the most dangerous form of skin cancer and is the most difficult to diagnose and stage. Knowing the thickness of melanoma and its level of invasion into cutaneous tissue is the most important factor [1, 2] in determining a patient's prognosis [3, 4]. Detection of melanoma is typically done by clinical inspection of lesion morphology, followed by lesion excision and histological assessment of the resected specimen. To improve assessment and diagnosis of melanoma and other pigmented lesions, various non-invasive imaging techniques, including photoacoustic (PA) imaging, have been investigated. PA imaging is a non-invasive imaging modality which combines laser light with ultrasound, and can be used to image pigmented skin lesion morphology [5-7] due the high absorption of melanin in the visible and near-infrared wavelength rage. In this study we investigate the clinical usefulness of PA imaging in diagnosing and assessing pigmented skin lesions such as melanoma and melanocytic nevi. Pre-operative PA images of patients with suspected cases of cutaneous melanoma were taken with the Vevo Lazr® 2100 PA imaging system at several wavelengths. The distribution and maximum thickness of suspect lesions was determined by imaging at 700 nm, and the surrounding vasculature was imaged at 900 nm. Information obtained from the PA images was compared with histological examination of resected surgical specimens.