Laser-based gas absorption spectroscopy in decaying hip bone: water vapor as a predictor of osteonecrosis

Abstract

Affluent blood flow through a complicated net of vessels supplies skeletal bone tissue with oxygen and nutrients. Due to accidental events or physiological processes, the blood supply might be deficient or even disrupted, and the healthy bone decays in a process that, for the hip location, is denoted as osteonecrosis of the femoral head (ONFH) or avascular femoral head necrosis. Early diagnosis is important for the prognosis. X-ray-based imaging, such as CT or MRI, is not of much value for the early detection. As the decay theoretically is associated with the development of gas-filled pores, gas analysis should have diagnostic value. We have introduced gas in scattering media absorption spectroscopy, as a complementary modality. Eighteen extracted femoral joint heads, diseased as well as normal, were investigated. Diseased samples are associated with clear signals due to water vapor, whereas the normal ones largely lack such features. The results suggest that free water vapor could serve as an early indicator of pore development and thus as a promising predictor of ONFH pathological changes, once the technique has been fully refined.

Lung tissue phantom mimicking pulmonary optical properties, relative humidity, and temperature: a tool to analyze the changes in oxygen gas absorption for different inflated volumes

“…Gas in scattering media absorption spectroscopy (GASMAS) is a gas spectroscopy technique that uses tunable diode laser spectroscopy to measure the concentration of gases enclosed by diffuse media in a noninvasive way. 5 The clinical applications of GASMAS include: assessment of infection in paranasal sinuses, 6 diagnosis of otitis, 7 early diagnosis of osteonecrosis, 8 and monitoring of oxygen ( ) and water vapor ( ) in the lungs of neonates. 9 – 12 The studies advancing the clinical translation of GASMAS into respiratory healthcare have focused on neonates as the thickness of protective organs surrounding their lungs is within the limits of penetration depth for near-infrared light.…”

Anthropomorphic optical phantom of the neonatal thorax: a key tool for pulmonary studies in preterm infants

“…The printer operates with a violet light curing technique using a 405-nm laser to cure the resin layer by layer with an axial resolution of 25 μm. The biggest volume that can be printed with this printer model is 145 × 145 × 175 mm 3 . The dimensions of the thorax used in this study are below this limit, but for other applications, the build volume of the 3D printer can pose a constraint.…”

Gas in scattering media absorption spectroscopy as a potential tool in neonatal respiratory care

“…Initially, GASMAS has been employed in different commercial areas (e.g., food, 1 – 4 pharmaceutical industries 5 – 7 ) helping to detect, measure and analyse gas trapped inside diffuse materials. More recent in vitro and in vivo studies evaluated the concept of non-invasive oxygen detection inside biological tissues like sinuses, 8 – 13 middle ear, 14 , 15 femoral bone 16 and lungs. Different lung phantom models were used for GASMAS measurements, such as porcine lung samples, 17 or produced by 3D printing nylon shells filled with tissue optical phantom material and air 18 , 19 or structured sponge.…”