Although several intraoperative methods to localize parathyroid gland(PG) were introduced, their clinical application has been limited. Thus, the current solution has been based on visual inspection of the surgeon. Recently, we reported excellent results (PPV = 100%, n=16) of Near infrared and infrared imaging technique for identifying surgically exposed PGs (JCEM, 2016). However, it is more important to predict the location of PGs before they are exposed to the naked eye. We investigated the feasibility of PG mapping (navigation) with NIR autofluorescence imaging to localize unexposed PGs. Seventy PGs from 38 thyroidectomy patients were enrolled in this prospective study. NIR imaging was taken at the areas where PGs were predicted to exist. We named the procedure as Parathyroid Navigation. The parathyroid navigation was photographed in three stages. Stage P1, taking images at pre-identification by the naked eye, step P2, at post-identification, and step P3, at removed specimens. Of 69 PGs identified, 64 (92.8%) were found at P1, 4 (5.8%) at P2, and 1 (1.4%) at P3. Even when PGs were covered by connective or fat tissues, NIR navigation at step P1 showed the sensitivity (92.75 %), specificity (100 %), PPV (100 %), NPV (16.66 %), accuracy (92.85 %). Five PGs of step P1 negative were identified at step P2 and P3 revealing 100% of total accuracy rate. The average parathyroid/background ratio was 4.78. These results suggest the concept of parathyroid navigation is feasible. We believe surgeons can get benefits of preserving parathyroid gland with the use of our NIR imaging method.
Polarization-sensitive optical coherence tomography (PS-OCT) is capable of measuring tissue birefringence. It has been widely applied to access the birefringence in tissues such as skin and cartilage. The vocal cord tissue consists of three anatomical layers from the surface to deep inside, the epithelium that contains almost no collagen, the lamina propria that is composed with abundant collagen, and the vocalis muscle layer. Due to the variation in the organization of collagen fibers, the different tissue layers show different tissue birefringence, which can be evaluated by PS-OCT phase retardation measurement. Furthermore, collagen fibers in healthy connective tissues are usually well organized, which provides relatively high birefringence. When the collagen organization is destroyed by diseases such as tumor, the birefringence of the tissue will decrease. In this study, a rabbit laryngeal tumor model with different stages of tumor progression is investigated ex-vivo by PS-OCT. The PS-OCT images show a gradual decrease in birefringence from normal tissue to severe tumor tissue. A phase retardation slope-based analysis is conducted to distinguish the epithelium, lamina propria, and muscle layers, respectively. The phase retardation slope quantifies the birefringence in different layers. The quantitative study provides a more detailed comparison among different stages of the rabbit laryngeal tumor model. The PS-OCT result is validated by the corresponding histology images of the same samples.
This experiment was conducted by using the diffuse optical spectroscopy based on near-infrared light. The near-infrared light in the water window was used to see the change of molecular concentration in the living tissue. The experiment subject was New Zealand rabbits weighing 3 ± 0.3 kg. VX2 tumor cells were injected into the inside of the chest wall of rabbits. The concentration of indocyanine green (ICG) has been observed once every three days, after the size of the pleural tumor grew up over 1cm. We used five different wavelengths (732, 758, 805, 840, and 880 nm) with known ICG spectrum. The distance between light source and detector probes was fixed by 1 cm. The probes were placed on the skin right above the tumor with an aid of laparoscope. ICG was injected into rabbits via ear vein. The diffused light was measured through the tumor with time course using a spectrometer. These measured data enabled us to observe the change of ICG concentration in real time with respect to the baseline without ICG. ICG was present longer in tumor compared to normal tissue. This phenomenon is thought to be due to the excessive angiogenesis in the tumor tissue. Since this method can be applied to other cases easily, it is thought that there is a possibility of cancer screening with less cost and simple equipment.
(alpha) -LiIO3 crystal is grown by the constant temperature evaporation method. Brillouin scattering experiment is carried out to study the elastic properties of the crystal (alpha) -LiIO3. We obtain all of six elastic constants of the crystal (alpha) -LiIO3 by using two cubic samples. As a result the obtained elastic constants are similar to the others' results. From the obtained elastic constants it is possible to construct slowness curves.
We have combined Brillouin scattering experiments with a single Fabry-Perot interferometer and a fundamental optics theory to determine the birefringence of single crystals. Double refraction in anisotropic materials give rise to doublet peaks in Brillouin spectra. With the incident plane orthogonal to the optic axis, the birefringence of the materials can be determined from one spectrum. We present the Brillouin spectra to confirm this fact for a single crystal (alpha) -LiIO3. The birefringence of (alpha) -LiIO3 is no - ne equals 0.149 at 514.5 nm.
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