Resting heart rate (RHR) is considered an important biomedical indicator to evaluate cardiovascular function. High RHR is an important prognostic factor for sudden cardiac death and heart failure in the general population, and especially among patients with known cardiac disease. The imaging photoplethysmography (IPPG) technology is used to achieve the accurate detection of RHR signal, which has the advantages of low cost, simple operation, fast acquisition speed etc. In this paper, we propose a new simple, inexpensive and easy-to-use method to measure the RHR in vivo. The result shows that Fast Fourier Transform with Hamming window filters, band-pass filter gives more accurate results. The color change of the fingertip is enlarged by using the mobile phone camera. From the distribution of color change of the fingertip, the RHR is estimated with the primary calibration result of the relationship between color variation and the blood volume change.
An optical method of surface-enhanced Raman spectroscopy (SERS) was developed for non-invasive detection of hepatitis B surface virus (HBV). Hepatitis B virus surface antigen (HBsAg) is an established serological marker that is routinely used for the diagnosis of acute or chronic hepatitis B virus(HBV) infection. Utilizing SERS to analyze blood serum for detecting HBV has not been reported in previous literature. SERS measurements were performed on two groups of serum samples: one group for 50 HBV patients and the other group for 50 healthy volunteers. Blood serum samples are collected from healthy control subjects and patients diagnosed with HBV. Furthermore, principal components analysis (PCA) combined with linear discriminant analysis (LDA) were employed to differentiate HBV patients from healthy volunteer and achieved sensitivity of 80.0% and specificity of 74.0%. This exploratory work demonstrates that SERS serum analysis combined with PCA-LDA has tremendous potential for the non-invasive detection of HBV.
Two sets of in vivo female cheek skin epidermis images were analyzed through gray level co-occurrence matrix (GLCM) and fast fourier transform (FFT). One set was derived from women in their 20s and the other from women more than 60 years of age. GLCM was used to evaluate the texture features of the regions of interest within the cheek epidermis, and texture classification was subsequently performed. During texture classification, 25 images (320×240 pixels) in each age set were randomly selected. Three texture features, i.e., energy, contrast, and correlation, were obtained from the skin images and analyzed at four orientations (0°, 45°,90°, and 135°), accompanied by different distances between two pixels. The textures of the different aging skins were characterized by FFT, which provides the dermatoglyph orientation index. The differences in the textures between the young and old skin samples can be well described by the FFT dermatoglyph orientation index. The texture features varied among the different aging skins, which provide a versatile platform for differentiating the statuses of aging skins.
The 632nm wavelength low intensity He-Ne laser was used to irradiated on 15 mice which had skin wound. The
dynamic changes and wound healing processes were observed with nonlinear spectral imaging technology. We observed
that:(1)The wound healing process was accelerated by the low-level laser therapy(LLLT);(2)The new tissues produced
second harmonic generation (SHG) signals. Collagen content and microstructure differed dramatically at different time
pointed along the wound healing. Our observation shows that the low intensity He-Ne laser irradiation can accelerate the
healing process of skin wound in mice, and SHG imaging technique can be used to observe wound healing process,
which is useful for quantitative characterization of wound status during wound healing process.
In this presentation, several ultrasound-modulated optical phenomena in a tissue phantom were observed by a pulsed
ultrasound transducer. Some factors affected the modulated signal value were studied including the changing of the
experimental conditions such as the distance between the focused volume of ultrasound beam and the detector as well as
the frequency of ultrasound transducer. The experimental results and the analysis suggest that a compositive parameter
concerning the intensity of the modulated signal, namely the modulation depth which is a key parameter to measure the
scattering property even as a sensor to indicate the glucose concentration.
Ultrasound-modulated optical tomography is a promising and noninvasive method for biomedical imaging. The
advantage of this technology is its combination of optical contrast and ultrasonic resolution. In order to reconstruct the
tissue imaging effectively and reliably, the propagation of the light modulated by ultrasound in the tissue should be
understood extensively. In our opinion, there are three light transport processes in tissue as follows: Firstly, the incident
light goes from the surface to the focused region. If the distance, tagged as Iis long enough (Z>>mfp, mean free path).
the light transport obeys diffuse theory. Secondly, the diffuse light can be modulated in the focused region at Z due to the
light-sound interaction. Finally, the modulation light from the Z can be regarded as a spot light source which emits the
ballistic or snake photons to reach the surface and so as to be collected by a detector outside of tissue in the third process.
the propagation of the diffused light modulated by ultrasound play an important role in particularly because it reflects
some information about the optical and ultrasonic properties of tissue. Based on the Monte Carlo simulation, the relations
to the modulation light intensity and its modulation depth contributed by the tissue thickness, optical properties, etc. are
figured out and supported by an equivalent experiment and at an extended condition also agree with the diffuse theory.
A non-invasive method to determine the optical property of biological tissue by the combination with ultrasound modulation and diffuse reflection light is firstly presented. A focused ultrasound beam through tissue has the modulated diffuse light located within the focal spot and so that the diffuse fluence distribution is easily detected from out of tissue. Based on the diffuse reflectance fitted formula concluded from Monte Carlo simulation by authors, the optical property including absorption coefficient, scattering coefficient, average scattering cosine, and even the refractive index can be rebuild. In addition, this new method is very significant to measure a light dose in vivo in laser medicine and surgery.
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