Magnetic resonance chemical shift microimaging of aging human skin in vivo: initial findings

In recent decades, interest has increased in the chronological and environmental factors governing the aging of skin. Various methods have been used for determining water and lipid content of human skin as a function of subject age. Magnetic resonance chemical shift imaging (CSI) offers a noninvasive technique for observing detailed distributions of water, lipids and other chemicals in the skin, and thus may be useful in dermatogerontology.

Human skin was examined in vivo on nine healthy volunteers, both male and female. Localized (1) H spectra of the skin were obtained from voxels 78 μm thick and parallel to the skin surface. Unique water and lipid profiles were observed for different individuals, showing the composition and microstructure of epidermis, dermis and hypodermis in each subject. These allowed the quantification of skin thickness in vivo by the first appearance of triacylglyceride olefinic protons at the dermal-hy-podermal junction, or alternatively by the degree of lipid infiltration into dermis.

The relative concentration of free water in the skin, normalized to skin thickness, was observed to be slightly greater in older subjects and also in tanned subjects. More significantly, a microstructural feature common to every subject, i.e., the position of a possible capillary plexus in the dermis, showed migration toward the skin surface with advancing age.

Such observations are consistent with previous studies of skin aging by other techniques and show promise for CSI in dermatogerontology as a non-invasive means for determination of skin water in vivo.