Portable Diffuse Reflectance Spectroscopy for Non-invasive and Quantitative Assessment of the Parathyroid Glands Viability During Surgery

Portable Diffuse Reflectance Spectroscopy for Non-invasive and Quantitative Assessment of the Parathyroid Glands Viability During Surgery Mark Romine, Linh Luong, Alex Moazzen, Katie Cho and Paul Lee The parathyroid glands (PTGs) are responsible for the regulation of calcium levels in the blood by secreting a parathyroid hormone. This parathyroid hormone then regulates the body’s absorption, storage, and secretion of calcium, which can directly affect the way muscles and nerves operate. PTGs are often at risk of damage, or accidental removal during thyroid surgeries, because it is challenging to identify PTGs and to determine their viability. Current methods of visual inspections are often subjective and blood panels have long processing times. Diffuse Reflectance Spectroscopy (DRS) may provide a solution for the noninvasive, rapid, and quantitative assessment of the viability of PTGs. DRS is a non-invasive technique that uses the reflectance properties of tissue to quantify the hemoglobin (Hb) and concentrations and tissue oxygenation. DRS consists of a white LED (wavelength 400nm – 700nm) for a light source, a compact spectrometer that records tissue reflectance and a fiber optic probe. In this project, we have built a portable DRS system and verified the performance of the prototyped DRS system. We have characterized a signal-to-noise ratio (SNR) on tissue simulating optical phantom and the computed SNR is around 40 dB as expected. Also, we have demonstrated that DRS can measure the change in oxygenation values in our blood phantom testing. These bench-top tests show that our protype is ready for human study during a thyroid surgery

Wearable Near Infrared Spectroscopy for Noninvasive Assessment of Cerebral Oxygenation in Pediatric Sickle Cell Disease

About 1 out of every 13 African American infants are born with the Sickle Cell Trait. Sickle Cell Disease (SCD) has a profound effect on the brain due to chronic anemia and abnormal perfusion. Indeed, the risk of stroke is 300 times higher than the general population. Assessment of cerebral oxygenation in SCD is important to screen the risk of stroke and monitoring of therapeutic effects. To address this need, the technical solution that we propose is a photonic device using functional Near Infrared Spectroscopy (fNIRS) that noninvasively measures oxyhemoglobin (oxy-Hb) and deoxyhemoglobin (deoxy-Hb) levels in the bloodstream. We have built our prototype fNIRS device that consists of an ESP-32 microcontroller with a built-in Digital to Analog and Analog to Digital converter channels (DAC and ADC), three Operational Amplifiers (two AD8655 and one OPA363), two LEDs for emitting light into the skin tissue, and a Photodiode for measuring the remitted light intensity. Oxy-Hb has a higher absorption rate at lower wavelengths, while deoxy-Hb has a higher absorption rate at higher wavelengths. Thus, we use 650 nm and 950nm wavelengths to accurately measure oxy-Hb and deoxy-Hb. Using the Beer-Lambert law, we can determine the changes in oxygenation between the two. We are currently conducting performance tests on a set of optical phantoms mimicking biological tissue optical properties. This bench-top verification demonstrates that our prototype can noninvasively track the changes of tissue oxygenation level and will be ready for further validation on human subjects in the future

Wireless, Handheld Diffuse Reflectance Spectroscopy to Quantify Tissue Microvascular Hemodynamics

Diffuse Reflectance Spectroscopy (DRS) is a non-invasive optical method to characterize tissue optical properties for disease diagnosis and health monitoring. Two optical fibers are often used in a DRS system: one to deliver light to the tissue and the other to gather diffuse reflectance spectra, which provide quantitative details about the structure and composition of the tissue. The conventional DRS system, however, is expensive, bulky, and composed of fragile optical fibers and multiple electrical connections. Here we propose to build a wireless, handheld, and fiber-less diffuse optical spectroscopy system. Unfortunately, the diffusion approximation utilized for data analysis of the conventional DRS is no longer valid due to the non-contact configuration of the fiber-less DRS system. To analyze the collected diffuse reflectance spectra using the handheld spectrometer, we have built a reflectance lookup table (LUT) using Monte Carlo simulation. Also, we have conducted some tests using a blood liquid phantom that is made of water, intralipid, and bovine blood, simulating human tissues to evaluate our DRS system with our LUT to extract the phantom\u27s oxygen saturation (SO2). The results show that portable spectrometer estimated SO2 values agree with the traditional DRS system. These results demonstrate that our handheld equipment can accurately estimate tissue oxygenation and hemoglobin levels, thus providing a mean of rapid quantitative tools assessing microvascular hemodynamics

An Ethnographic Study of Students' Views of Group Work

Poster with the results of a collaborative ethnographic study of students' views of group work. The study was conducted within the framework of the anthropology course 810.21: Research Design and Ethnographic Methods (Spring 2011) taught by Dr. Mark Moritz

Possible physical and thermodynamical evidence for liquid water at the Phoenix landing site

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95444/1/jgre2665.pd