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Background/aims: Increasing signal-to-noise ratio for skin spectroscopy means increasing area, but increased area usually means resorting to Fourier window techniques to prevent overwhelming muscle contamination. The aim of this work was to develop a simple coil that would allow large areas of skin to be sampled while limiting muscle contamination simply by the coil's geometry. Methods: The coil design was arrived at by using simulations that were calibrated by phantom tests with prototype units. It was then fabricated by using an etched circuitboard technique and tested on three volunteers for comparison with predicted performance. Results: The new coil acquires magnetic resonance signals from a 140 cm2 contoured layer of surface tissue with sufficient selectivity that 81% of the signal comes from tissue less than 1.9 mm deep. For skin and fat thicknesses of 1.1 and 3.1 mm, respectively, tending toward a worst case in-vivo situation, muscle contamination is only 3.3%. With the new coil, in 1 h, it was possible to directly acquire 31P skin spectra comparable to those formerly obtained in 4 h in two separate acquistions that then had to be subtracted to obtain the desired skin spectra. Conclusion: Increasing the area of skin sampled while maintaining selectivity to limit muscle contamination, relying simply on coil geometry, is practical using a parallel configuration of long narrow strip coils.

Background/aims: 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. Methods: Human skin was examined in vivo on nine healthy volunteers, both male and female. Localized 1H 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. Results: 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. Conclusions: 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.

With the help of ESR study it is shown that localized impurity dipole moment in strongly polarizable crystal represents the host lattice region polarized by the impurity, with effective dipole moment d* determined by the dielectric constant of pure crystal. Characteristic size of such region is connected with lattice correlation length and cannot be determined from magnitude d* contrary to statement of authors2.The possibility of ferroelectric phase transition in KTaO3:Li follows from the performed theoretical analysis.