Aslinur Sircan-Kucuksayan

Diagnosis of Testicular Torsion by Measuring Attenuation of Dual Wavelengths in Transmission Geometry Across the Testis: An Experimental Study in a Rat Model

OBJECTIVE To develop a noninvasive and real-time dual-wavelengths optic system to detect testicular torsion in an animal model. Diagnosis of testicular torsion is challenging in emergency conditions and frequently ends with surgical exploration. MATERIALS AND METHODS In this study, 9 male 8-month-old Wistar albino rats weighing an average of 400 g were used. A transverse incision on the upper scrotum was done and the right testis was torsed with a 720° medial rotation. The other testis of each rat was used as the control or sham group. In the sham group, the testicle was moved out of the body but no torsion was applied before repositioning into the scrotum. Transmission of continuous-wave light through all testes at wavelengths of 660 nm and 940 nm were measured. RESULTS The ratio of the average intensities of the transmitted light of both wavelengths--660 nm to 940 nm--was used as a parameter to diagnose testis torsion. The ratios were significantly different (P = .001) between the torsion group and control group. CONCLUSION Our noninvasive technique measuring attenuation of dual wavelengths in transmission geometry across the testis has the ability to distinguish between the testis with and without torsion on the basis of a threshold value of the ratio.

Diffuse reflectance spectroscopy for the measurement of tissue oxygen saturation

Tissue oxygen saturation (StO2) is a useful parameter for medical applications. A spectroscopic method has been developed to detect pathologic tissues, due to a lack of normal blood circulation, by measuring StO2. In this study, human blood samples with different levels of oxygen saturation have been prepared and spectra were acquired using an optical fiber probe to investigate the correlation between the oxygen saturation levels and the spectra. A linear correlation between the oxygen saturation and ratio of the intensities (760 nm to 790 nm) of the spectra acquired from blood samples has been found. In a validation study, oxygen saturations of the blood samples were estimated from the spectroscopic measurements with an error of 2.9%. It has also been shown that the linear dependence between the ratio and the oxygen saturation of the blood samples was valid for the blood samples with different hematocrits. Spectra were acquired from the forearms of 30 healthy volunteers to estimate StO2 prior to, at the beginning of, after 2 min, and at the release of total vascular occlusion. The average StO2 of a forearm before and after the two minutes occlusion was significantly different. The results suggested that optical reflectance spectroscopy is a sensitive method to estimate the StO2 levels of human tissue. The technique developed to measure StO2 has potential to detect ischemia in real time.

Differentiating cancerous tissues from noncancerous tissues using single-fiber reflectance spectroscopy with different fiber diameters

Abstract. Elastic light-scattering spectra acquired with single-fiber optical probes with diameters of 100, 200, 400, 600, 800, 1000, 1200, and 1500  μm were used to differentiate cancerous from noncancerous prostate tissues. The spectra were acquired ex vivo on 24 excised prostate tissue samples collected from four patients. For each probe, the spectra and histopathology results were compared in order to investigate the correlation between the core diameters of the single-fiber optical probe and successful differentiation between cancerous and noncancerous prostate tissues. The spectra acquired using probes with a fiber core diameter of 400  μm or smaller successfully differentiated cancerous from noncancerous prostate tissues. Next, the spectra were acquired from monosized polystyrene microspheres with a diameter of 5.00±0.01  μm to investigate the correlation between the core diameters of the probes and the Mie oscillations on the spectra. Monte Carlo simulations of the light distribution of the tissue phantoms were run to interrogate whether the light detected by the probes with different fiber core diameters was in the ballistic or diffusive regime. If the single-fiber optical probes detect light in the ballistic regime, the spectra can be used to differentiate between cancerous and noncancerous tissues.

Intraoperative assessment of laryngeal malignancy using elastic light single‐scattering spectroscopy: A pilot study

The elastic light single‐scattering spectroscopy (ELSSS) system is a new tool for the real‐time diagnosis of cancerous lesions. In the current study, we have employed ELSSS to investigate its ability in differentiation between normal and cancerous larynx tissues ex vivo.

Measuring tissue oxygen saturation using NIR spectroscopy

Tissue oxygen saturation (StO2) is known quite useful parameter for medical applications. A spectroscopic method has been developed to diagnose pathologic tissues due to lack of normal blood circulation by measuring tissue oxygen saturation. In the study, human blood samples with different level of oxygen saturations have been prepared and spectra were taken using an optical fiber probe to investigate correlation between the oxygen saturations and the spectra. The experimental set up for the spectroscopic measurements was consists of a miniature NIR light spectrometer, an optical fiber probe, a halogen-tungsten light source and a laptop. A linear correlation between the oxygen saturation of the blood samples and the ratio of the light of wavelengths 660 nm to 790 nm has been found from the spectra. Then, oxygen saturations of the blood samples were estimated from the spectroscopic measurements within an error of 2.9%. Furthermore, it has been shown that the linear dependence between the ratio and the oxygen saturation of the blood samples was valid for the blood samples with different hematocrits. Tissue oxygen saturation has been estimated from the spectroscopic measurements were taken from the fingers of healthy volunteers using the correlation between the spectra and blood oxygen saturation. The tissue StO2 measured was 80% as expected. The technique developed to measure tissue oxygen saturation has potential to diagnose premalignant tissues, follow up prognosis of cancerous tissues, and evaluation of ischemia reperfusion tissues.

Retrieval of chromophore concentration in a tissue phantom by diffuse reflectance spectroscopy

This study describes a method for analysis of back reflectance spectroscopic data to estimate the concentration of endogenous or exogenous chromophores of tissue, noninvasively and in real time. In the study, tissue phantoms were prepared using intralipid and two chromophores, indocyanine green and methylene blue. Reduced scattering and absorption coefficients ranges of tissue phantoms were kept in the range of biological tissues. Spectroscopic measurements on the tissue phantoms were carried out using a miniature spectrometer, an optical fiber probe, a halogen tungsten light source and a laptop. Monte Carlo simulations of the experiments were run, and an average optical path lengths of the detected photons were obtained for different absorption and scattering coefficients. The average optical path lengths of the photons were used to estimate concentrations of the chromophores in the tissue phantoms. Scattering and absorption coefficients were estimated with an average error of 4.7 and 5.4%, respectively. The developed method has the potential to be used in diagnosis of pathologic tissues based on the variation of biochemical composition of tissues and in photodynamic therapy to estimate the concentration of photosensitizers.

Measuring chromophore’s concentration and scattering coefficient in a turbid medium using back reflection spectroscopy

Scattering and absorption coefficients were estimated within an error of 4.8% and 13.3% respectively using the back reflection spectral measurements and Monte Carlo simulations results from tissue phantoms consist of Intralipid and methylene blue.