OCT images blood vessels that feed cancer

An optical coherence tomography (OCT) technique that noninvasively maps the network of tiny blood vessels in the epidermis could soon help doctors better diagnose, monitor and treat skin cancer.

Scientists at Medical University Vienna (MUW) are the first to use the high-resolution three-dimensional imaging method to visualize the network of blood vessels beneath the outer layer of the skin – the epidermis – that feed cancerous lesions. A laser light source developed at Ludwig Maximilian University was used to maximize image quality. It also enabled unprecedented high-speed imaging and operated at a near-infrared wavelength for better skin penetration.

“The condition of the vascular network carries important information on tissue health and its nutrition,” said Rainer Leitgeb, an MUW researcher and the study’s principal investigator. “Currently, the value of this information is not utilized to its full extent.”

Healthy versus diseased skin vasculature: (Left) A healthy network of blood vessels in the lower layer of skin on the palm of a hand. (Right) Blood vessels supplying a basal cell carcinoma on the forehead. The effects of disease on the vascular system are evidenced by the branching pattern of vessels in the image on the right, with abnormally large vessels for a depth range similar to the image on the left. Both images show a 2 x 2 mm area. Courtesy of Medical University Vienna/Biomedical Optics Express.

The device shapes the light by forming a Bessel beam, which can re-form, or heal, its shape even if portions of it are blocked. The beam enabled the researchers to keep the images in focus across a depth range of approximately 1 mm.

The system was tested on a range of different skin conditions, including a healthy human palm, dermatitis on the forehead, allergy-induced eczema on the forearm, and two cases of basal cell carcinoma – the most common type of skin cancer – on the face. The network of vessels supplying blood to the tested lesions showed significantly altered patterns in comparison to healthy skin.

Ophthalmologists have used OCT to image different parts of the eye since the 1990s, but recently it has attracted interest from dermatologists because it is noninvasive and provides high-resolution images at high speed.

“High speed is of paramount importance in order to image lesions in vivo and in situ while minimizing the effect of involuntary patient motion,” said MUW’s Cedric Blatter.

Although typically used to show tissue structure, the technique can also reveal blood vessel patterns, which carry important clues about disease, by capitalizing on the unique optical properties of flowing blood cells.

The international team’s images of basal cell carcinoma showed a dense network of unorganized blood vessels, with large vessels abnormally close to the skin surface. The larger vessels branch into secondary vessels that supply blood to energy-hungry tumor regions. The images, together with information about blood flow rates and tissue structure, could yield important insight into the metabolic demands of tumors during different growth stages.

“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,” Leitgeb said. The technique could also help assess how quickly tumors grow and spread, as well as monitor treatment effectiveness.

The research appeared in Biomedical Optics Express (doi: 10.1364/BOE.3.002636).