Probe pressure effects on human skin diffuse reflectance and fluorescence spectroscopy measurements

Abstract

Abstract. Diffuse reflectance and fluorescence spectroscopy are popular research techniques for noninvasive disease diagnostics. Most systems include an optical fiber probe that transmits and collects optical spectra in contact with the suspected lesion. The purpose of this study is to investigate probe pressure effects on human skin spectroscopic measurements. We conduct an in-vivo experiment on human skin tissue to study the short-term (<2 s) and long-term (>30 s) effects of probe pressure on diffuse reflectance and fluorescence measurements. Short-term light probe pressure (P0 < 9 mN/mm 2 ) effects are within 0 ± 10% on all physiological properties extracted from diffuse reflectance and fluorescence measurements, and less than 0 ± 5% for diagnostically significant physiological properties. Absorption decreases with site-specific variations due to blood being compressed out of the sampled volume. Reduced scattering coefficient variation is site specific. Intrinsic fluorescence shows a large standard error, although no specific pressure-related trend is observed. Differences in tissue structure and morphology contribute to site-specific probe pressure effects. Therefore, the effects of pressure can be minimized when the pressure is small and applied for a short amount of time; however, long-term and large pressures induce significant distortions in measured spectra. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

The Effect of Probe Pressure on In Vivo Single Fiber Reflectance Spectroscopy

“…13 Our results are in agreement with them. Decrease in absorption and reduced scattering coefficients with increasing the pressure is consistent with the results obtained by Lim et al 9 However, the trend of scattering was reversed after 500 nm in their study. The comparison was made in detail in Table 3.…”

“…Less effect of probe pressure on spectroscopic parameters of SFRS compared with DRS can be attributed to the smaller sampling volume. 9 While the number of illumination and collection optical fibers ranges from two 13 to seven 14 in other similar studies, SFRS uses a single fiber for both illumination and collection of the spectra. The other reason is the shorter time during which the pressure was applied.…”

“…It is consistent with the negligible short-term effect of probe pressure on tissue characteristics. 9 In order to reduce the tissue-specific variations, 9,11 the lip tissue was chosen for the experiment. It has comparable characteristics to uterine cervix which is under investigation by the authors.…”

“…7 In order to obtain clinically useful information about the measured tissue, the spectroscopy results must depend solely on the tissue characteristics rather than environmental parameters, such as probe pressure. 8 Probe pressure effect on fluorescence [9][10][11][12] and reflectance 9,11,13,14 spectroscopy has been studied by several authors. Nath et al 12 and Rivoire et al 10 investigated this effect on fluorescence spectra acquired from the human cervix.…”

Optical clearing of biological tissues: prospects of application in medical diagnostics and phototherapy

“…The mechanical compression also changes the optical properties of tissues in vivo, which is accompanied by the spectral changes both in the diffuse reflection [176][177][178][179][180][181][182][183][184][185][186] and in the fluorescence [185,[187][188][189]. The authors of [176,187] were one of the first researchers who noticed the influence of the compression on the spectra of diffuse reflection and autofluorescence of human skin in vivo.…”