Oxygen Saturation Imaging Using LED-Based Photoacoustic System

Abstract

Oxygen saturation imaging has potential in several preclinical and clinical applications. Dual-wavelength LED array-based photoacoustic oxygen saturation imaging can be an affordable solution in this case. For the translation of this technology, there is a need to improve its accuracy and validate it against ground truth methods. We propose a fluence compensated oxygen saturation imaging method, utilizing structural information from the ultrasound image, and prior knowledge of the optical properties of the tissue with a Monte-Carlo based light propagation model for the dual-wavelength LED array configuration. We then validate the proposed method with oximeter measurements in tissue-mimicking phantoms. Further, we demonstrate in vivo imaging on small animal and a human subject. We conclude that the proposed oxygen saturation imaging can be used to image tissue at a depth of 6–8 mm in both preclinical and clinical applications.

A Cost-Efficient Multiwavelength LED-Based System for Quantitative Photoacoustic Measurements

“…Considering the scattering properties of the intralipid layer in Series II phantoms, as well as the standard background noise of the system, a maximum penetration depth of ~4-5 mm can be potentially achieved. Despite the lowcost of the integrated components, the precision of the acquired data is comparable to similar studies utilizing multispectral PA measurements [33]. Considering the apparent high repeatability in phantom generation procedures and PA amplitude measurements To evaluate the performance of the PA unmixing method in tissue-mimicking samples presenting both optical scattering and absorption properties, we investigated Series II phantoms, incorporating a 1 mm thick 1% w/w intralipid layer prior to the ink-gelatin (i.e., the absorbing) medium.…”

“…Considering the scattering properties of the intralipid layer in Series II phantoms, as well as the standard background noise of the system, a maximum penetration depth of ~4–5 mm can be potentially achieved. Despite the low-cost of the integrated components, the precision of the acquired data is comparable to similar studies utilizing multispectral PA measurements [ 33 ]. Considering the apparent high repeatability in phantom generation procedures and PA amplitude measurements of single-absorber samples, we believe that the observed deviations from the reference concentration values are predominantly related to the adopted linear unmixing model, which in many cases fails to deliver accurate information [ 12 , 37 ].…”

“…However, research focusing on the spectral quantitative measurement capabilities of LD and LED-based PA systems is still relatively limited. Focusing on PA sensing using multiwavelength LED excitation, there are a few research efforts [ 32 , 33 ], based on a commercially available hybrid PA-ultrasound imaging system [ 34 , 35 ]. This imaging system utilizes two LED arrays integrated with an ultrasound transducer (UT) array for signal detection and can record co-registered ultrasound and multispectral PA images in-vivo.…”

Biomedical Photoacoustic Imaging and Sensing Using Affordable Resources

“…By illuminating tissue using two wavelengths, it is feasible to probe the oxygen saturation of tissue with microvasculature scale resolution. Bulsink et al reported fluence-compensated oxygen saturation imaging using two wavelength LED-based PA imaging [13]. In this work, the authors demonstrated real-time fluence compensated oxygen saturation imaging in phantoms, small animals, and measurements on human volunteers.…”

Organic Semiconducting Macromolecular Dyes for NIR‐II Photoacoustic Imaging and Photothermal Therapy

“…Photoacoustic techniques can visualize microvasculature, including vascular contours, [ 41 ] flow, [ 42 ] and oxygen saturation level of blood [ 43 ] with superb imaging sensitivity and spatial resolution, offering abundant information for pathological diagnosis. However, owing to the scarcity of NIR‐II light‐responsive contrast agents and the developed instruments for NIR‐II PAI, most reported PAIs of blood vessels are conducted using visible or NIR‐I light excitation.…”