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Non-invasive mapping of the network of tiny blood vessels beneath the skin is now possible thanks to an advanced optics system and near-infrared imaging. The new technique could one day be used to quickly and efficiently reveal the latent signs of skin disorders, such as psoriasis or even skin cancer.
Teams based at the Medical University Vienna in Austria and the Ludwig-Maximilians University in Munich, Germany worked together on optical coherence tomography (OCT), which they say allows them to get under a patient's skin. "The condition of the vascular network carries important information on tissue health and its nutrition," explains team leader Rainer Leitgeb. "Currently, the value of this information is not utilized to its full extent." Of course, ophthalmologists have been using OCT since the 1990s to image different parts of the eye but it is only that the technology is finding application in dermatology.
The MUW team have now used OCT to look at the network of blood vessels in human skin that feeds cancerous skin lesions. They used a laser source developed by their collaborators at LMU to optimise the imaging. Importantly, the laser allowed them to obtain unprecedented high-speed images in the near-infrared which allowed for better penetration of the skin tissue overlying the blood vessels. The researchers tested the approach on various skin conditions, as well as imaging a healthy human palm. They looked at allergy-induced eczema on the forearm, dermatitis on the forehead, and two cases of basal cell carcinoma, which is the most common form of skin cancer. The OCT revealed very different patterns of blood vessels supplying the areas of skin with lesions compared to healthy skin.
The researchers explain that in the basal cell carcinoma study they see a dense network of unorganized blood vessels, with many larger vessels closer to the skin surface than normal. They can also see that the larger vessels branch into secondary vessels supplying tumour cells which are fast growing and have high oxygen and nutritional demands. Taken together with independent information about blood flow rates and tissue structure, it should be possible to use near-infrared OCT to obtain important insights into the metabolic demands of tumours during different growth stages. This would not only allow medical research to progress in this area but also provide oncologists with an additional means to "stage" a skin cancer and so offer appropriate and hopefully more effective treatment in a timely manner for their patients.
While the technique could have many uses in dermatology, the team suggests that it will likely have the widest use in the diagnosis and treatment of skin cancer. "We hope that improved in-depth diagnosis of tissue alterations due to disease might help to reduce the number of biopsies by providing better guidance," explains Leitgeb.
Of course, before it can become a valid clinical test, it will require fully controlled trials on many more patients to demonstrate efficacy. Nevertheless, OCT has many advantages over other imaging techniques primarily in that is non-invasive but it can also produce high-resolution images as well as doing that quickly. "High speed is of paramount importance in order to image lesions in vivo and in situ while minimizing the effect of involuntary patient motion," explains team member Cedric Blatter of MUW. An extra advantage is that the device shapes the light to form a Bessel beam, which is unhindered even if the beam is partially blocked as it is by the skin. It is therefore possible to ensure focus is maintained even to a depth of 1 millimetre, the team says.
Teams based at the Medical University Vienna in Austria and the Ludwig-Maximilians University in Munich, Germany worked together on optical coherence tomography (OCT), which they say allows them to get under a patient's skin. "The condition of the vascular network carries important information on tissue health and its nutrition," explains team leader Rainer Leitgeb. "Currently, the value of this information is not utilized to its full extent." Of course, ophthalmologists have been using OCT since the 1990s to image different parts of the eye but it is only that the technology is finding application in dermatology.
The MUW team have now used OCT to look at the network of blood vessels in human skin that feeds cancerous skin lesions. They used a laser source developed by their collaborators at LMU to optimise the imaging. Importantly, the laser allowed them to obtain unprecedented high-speed images in the near-infrared which allowed for better penetration of the skin tissue overlying the blood vessels. The researchers tested the approach on various skin conditions, as well as imaging a healthy human palm. They looked at allergy-induced eczema on the forearm, dermatitis on the forehead, and two cases of basal cell carcinoma, which is the most common form of skin cancer. The OCT revealed very different patterns of blood vessels supplying the areas of skin with lesions compared to healthy skin.
The researchers explain that in the basal cell carcinoma study they see a dense network of unorganized blood vessels, with many larger vessels closer to the skin surface than normal. They can also see that the larger vessels branch into secondary vessels supplying tumour cells which are fast growing and have high oxygen and nutritional demands. Taken together with independent information about blood flow rates and tissue structure, it should be possible to use near-infrared OCT to obtain important insights into the metabolic demands of tumours during different growth stages. This would not only allow medical research to progress in this area but also provide oncologists with an additional means to "stage" a skin cancer and so offer appropriate and hopefully more effective treatment in a timely manner for their patients.
While the technique could have many uses in dermatology, the team suggests that it will likely have the widest use in the diagnosis and treatment of skin cancer. "We hope that improved in-depth diagnosis of tissue alterations due to disease might help to reduce the number of biopsies by providing better guidance," explains Leitgeb.
Of course, before it can become a valid clinical test, it will require fully controlled trials on many more patients to demonstrate efficacy. Nevertheless, OCT has many advantages over other imaging techniques primarily in that is non-invasive but it can also produce high-resolution images as well as doing that quickly. "High speed is of paramount importance in order to image lesions in vivo and in situ while minimizing the effect of involuntary patient motion," explains team member Cedric Blatter of MUW. An extra advantage is that the device shapes the light to form a Bessel beam, which is unhindered even if the beam is partially blocked as it is by the skin. It is therefore possible to ensure focus is maintained even to a depth of 1 millimetre, the team says.
