Fluid Skin Imaging for Better Resolution

By: Katie Schaefer, Cosmetics & Toiletries magazine

Posted: April 6, 2011, from the April 2011 issue of Cosmetics & Toiletries.

Noninvasive subcutaneous skin imaging is a tool sought for use by the medical, pharmaceutical and personal care industries, but techniques have been lacking due to resolution and speed constraints. However, these obstacles may have been overcome by Jannick Rolland, PhD, and her team at the University of Rochester who developed a probe with a custom liquid lens microscope that can noninvasively image skin up to 2 mm deep with lateral resolution.

Skin Imaging Challenges

Lateral resolution is an important aspect of skin imaging, according to Rolland. “Previous capabilities have allowed the imaging of tissue under the skin, but that imaging showed only the layers and not the cells as there was no lateral resolution across the depths,” she explained. Rolland furthered that lateral resolution could be obtained by moving the slide on a stage and measuring point by point, e.g., in time-domain optical coherance tomography, but that this technique could not be applied in an in vivo clinical setting.

Rolland noted that in vivo skin imaging must be conducted quickly to ensure that the subjects’ breathing and motion do not affect the results. She added that while the recently developed Fourier domain optical coherence tomography technique allows for a quick, entire depth scan with one measurement followed by a lateral scan to obtain a 3-D image, the lateral resolution remains unclear.

“The idea was that either speed or resolution could be achieved, but not both,” Rolland said. Her team thus sought to develop a noninvasive technique to image the layers of skin with depth and lateral resolution.

Resolving Lateral Resolution

The key to obtaining lateral resolution, according to Rolland, is to open the numerical aperture of the lens to make it larger, referred to as Fourier domain optical coherance microscopy (FDOCM). “The problem is that lateral resolution can only be obtained when the lens is focused in one spot,” Rolland explained. She furthered that depending on the angle of the lens light, a wider cone would provide more lateral resolution but result in less clarity around that point, whereas a narrower cone would provide clearer depth but with little resolution.