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.
The incidence of skin cancer, including melanoma, has been steadily increasing over the past decades. Early-stage melanoma often exhibits minimal symptoms, making it challenging to detect. However, when it progresses to later stages and spreads to the lymph nodes, the chances of survival significantly decrease. The current diagnostic gold standard involves invasive and time-consuming procedures, such as visual examination, excision, and histological examination of tissue samples. As an alternative, we developed a new multimodal optical system that addresses these challenges by integrating ultrasound (US), photoacoustic tomography (PAT), optical coherence tomography (OCT) and Raman spectroscopy (RS) into a single measurement unit. The optical coherence tomography OCT delivers detailed structural and depth information for thin skin lesions, while US and PAT enable the assessment of penetration depth in thicker lesions, and Raman spectroscopy analyzes the chemical composition of skin lesions, aiding in the differentiation between benign and malignant cases. The US and PAT are seamlessly integrated using an acoustical reflector inside a custom-made water tank, enabling C-mode measurements at the same position as OCT and RS without the need to switch scanning heads. Our system offers a fast and non-invasive approach to measure the dignity and maximal depth of skin lesions, which can help the dermatologists to make informed decisions regarding excision margins. The exemplary imaging capabilities of the presented multimodal setup are demonstrated in vivo on human nevus, which was excised after the measurement. The obtained results are compared with corresponding histological images for comprehensive evaluation.
Cutaneous melanoma is one of the most lethal types of skin cancer. Non-invasively distinguishing malignant melanoma from benign tumours has always been a challenge. In this paper, an OCT and co-localized Raman spectroscopic system was built and Raman spectroscopy was used to measure skin samples of suspected melanoma lesions and their surrounding healthy areas non-invasively and in vivo. The Raman spectral signal intensities of the lesions increased at 1320 cm-1 and 1650 cm-1, while the content of carotenoids decreased, compared to that of the healthy skin samples. The results of the Shapley analysis values showed that the spectral peaks at 1320 cm-1 and 1650 cm-1 had a more significant effect on the differentiation of lesions from normal skin. This result can be used to guide the diagnosis of melanoma based on Raman spectroscopy.
KEYWORDS: Image fusion, Skin, Image segmentation, Machine learning, Melanoma, Data acquisition, Cancer detection, Digital imaging, Skin cancer, Medical imaging
We propose a method for digital hair removal from dermoscopic images that involves a new scheme for the acquisition of dermoscopic images to uncover hidden information by employing image fusion of multiple images of lesions. Classical approaches for the removal of hair from dermoscopic images are usually based on interpolation, pattern propagation or machine learning. These replace the hair pixels with calculated data aiming to reduce the impairment of the medical diagnostics. While these approaches are well established, the problem of information loss is not addressed. We show that our approach can lead to improved skin lesion assessment in dermoscopy.
The rate of skin cancer incidence including melanoma has been steadily increasing in the last decades. While melanoma often show little to no symptoms in the early stages, they can spread to the lymph nodes and drastically reduce survival chances in the later stages. The current gold standard for diagnosis is visual examination, excision, and histological examination of the sample tissue, which is an invasive, costly and time-consuming process. As an alternative to this procedure, we introduce a novel multimodal optical system that integrates ultrasound (US), photoacoustic tomography (PAT), and optical coherence tomography (OCT) with Raman spectroscopy (RS). The setup allows quick and non-invasive skin lesion diagnosis and the determination of 3D lesion depth, helping the dermatologists make a decision on the excision margins. The OCT delivers structural and depth information of thin skin lesions, while the US and PAT measure the penetration depth of thicker lesions and the RS analyzes the chemical composition that can be used to distinguish between benign and malignant skin lesions. In our setup, the RS and OCT share the optical path and the scanning elements, which allows colocalized measurements. The US and PAT are integrated with an acoustical reflector, which enables B-mode measurements at the same position as OCT and RS without switching the scanning head. We demonstrate the imaging capabilities of the multimodal setup on custom made agar phantoms and present first measurements on ex vivo mouse and in vivo human skin samples. We compare the results with the corresponding histological images.
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