title: In vivo measurement of the water content in the dermis by confocal Raman spectroscopy.
abstract: OBJECTIVE
  Dermal water plays an important role in the physical properties of the skin. Recently, researchers have attempted to directly measure the dermal water content in vivo using magnetic resonance imaging, near infrared spectroscopy, and Raman spectroscopy. However, these methods have limitations. Although confocal Raman spectroscopy has been developed to measure the water content in the skin, no reports have suggested that this instrument can measure the dermal water content. This report describes a method for measuring the dermal water content in vivo using confocal Raman spectroscopy.
  
  
  METHODS
  We used a confocal Raman spectrometer and adjusted the laser exposure time and depth increments according to the skin depth. Age-related changes in the dermal water content of the forearm were examined in 30 young and 30 elderly male subjects. Diurnal changes in the dermal water content of the forearm were examined in 12 elderly male subjects.
  
  
  RESULTS
  Adjusting the exposure time and depth increment dramatically improved the signal-to-noise ratios of the Raman spectra. Elderly dermis had significantly higher water content than young dermis. Moreover, the dermal water content displayed a diurnal change.
  
  
  CONCLUSIONS
  This study demonstrates that the dermal water content can be measured in vivo using confocal Raman spectroscopy.
authors.affiliation: Kanebo Cosmetics Inc., Basic Research Laboratory, Kanagawa, Japan. nakagawa.noriaki@kanebocos.co.jp
authors.forename: Noriaki
authors.initials: N
authors.lastname: Nakagawa
authors.forename: Masayuki
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Shingo
authors.initials: S
authors.lastname: Sakai
mesh_terms: D000368:Aged; D000375:Aging / Q000378:metabolism*; D001834:Body Water / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology*; D020405:Dermis / Q000378:metabolism*; D005542:Forearm; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged; D013059:Spectrum Analysis, Raman / Q000379:methods*; D055815:Young Adult