DOI: 10.5061/dryad.wpzgmsbxn
title: Data from: Photoacoustic imaging of rat kidney tissue oxygenation using NIR-II wavelengths

description: Significance: Conventionally, spectral photoacoustic imaging (sPAI) to
 assess tissue oxygenation (sO2) uses optical wavelengths in the first near
 infrared window (NIR-I). This limits the maximum photoacoustic imaging
 depth (~1 cm) due to the high spectral coloring of biological tissues and
 has been a major barrier to the clinical translation of the technique.
 Aim: Here, we demonstrate the second near infrared (NIR-II) tissue optical
 window (950-1400 nm) for the assessment of blood and tissue sO2. Approach:
 The NIR-II PA spectra of oxygenated and deoxygenated hemoglobin were first
 characterized using a phantom. Optimal wavelengths to minimize spectral
 coloring were identified. The resulting NIR-II PA imaging methods were
 then validated in vivo by measuring kidney sO2 in adult female rats.
 Results: sPAI of whole blood, in a phantom, and of blood in kidneys in
 vivo, produced PA spectra proportional to wavelength-dependent optical
 absorption. Using the NIR-II wavelengths for spectral unmixing resulted in
 a ~50% decrease in the error of the estimated blood sO2, compared to
 conventional NIR-I wavelengths. In vivo measurements of kidney sO2
 validated these findings, with a similar reduction in error when using
 NIR-II wavelengths versus NIR-I wavelengths. Conclusions: sPAI using
 NIR-II wavelengths improved the accuracy of tissue sO2 measurements. This
 is likely due to reduced scattering, which reduces the attenuation and
 therefore the impact of spectral coloring in this wavelength range.
 Combined with the increased safe skin exposure fluence limits in this
 wavelength range, these results demonstrate the potential to use NIR-II
 wavelengths for quantitative sPAI of sO2 from deep heterogeneous tissues..
description: # Photoacoustic imaging of rat kidney tissue oxygenation using NIR-II
 wavelengths
 [https://doi.org/10.5061/dryad.wpzgmsbxn](https://doi.org/10.5061/dryad.wpzgmsbxn) ## Description of the data and file structure The data presented in the paper titled "Photoacoustic Imaging of Rat Kidney Tissue Oxygenation using NIR-II Wavelengths"  The data in the repository has the following two files: 1. "PA_Blood_NIR2_data.xlsx" - Tabulated data of the phantom and in vivo experiments used for Figures 3 and 4, respectively, from the main manuscript.    2. "PA_Blood_NIR2_DataSets.zip" - A zip file containing all the raw photoacoustic and ultrasound images acquired as part of the results demonstrated in figures 3 & 4 of the main manuscript.  ### Files and variables #### File #1: PA\_Blood\_NIR2\_data.xlsx **Description:** Tabulated (Excel) data of the phantom and in vivo experiments with replicates 1. Sheet 1 - Photoacoustic spectra of oxygenated and deoxygenated hemoglobin recorded from the Phantom studies (A 3 mm slice of porcine muscle was placed over a blood-filled tube in a gelatin mold for photoacoustic imaging, with oxygenated and deoxygenated bovine blood and PBS sequentially injected. Images were collected across NIR-I and NIR-II wavelengths, and the experiment was repeated three times to ensure reproducibility.) 2. Sheet 2 - Photoacoustic spectra of oxygenated and deoxygenated hemoglobin recorded from the In Vivo Rat studies (In vivo photoacoustic imaging of rat kidneys at NIR-I and NIR-II wavelengths confirmed that PA signals originate from hemoglobin, with 1064 nm showing the highest contrast between oxygenation states. NIR-II imaging improved signal-to-noise ratio and reduced spectral unmixing errors in deeper tissue by up to 50% compared to NIR-I.) #### File #2: PA\_Blood\_NIR2\_DataSets.zip **Description:** A .zip file containing all the raw photoacoustic (PA) and ultrasound (B-mode) images acquired 1. Folder "InVivo_Study" - Data from the in vivo rat experiments. The folder contains subfolders that all follows the following naming scheme - "##sO2_Rat##", where "##sO2" corresponds to either 0% (post euthanasia) or 100% (pre euthanasia) oxygenated animal and "Rat##" corresponds to the rat replicate number. Additionally, a folder named "BleachedKidney" houses all the PA data corresponding to the bleached kidney.  2. Folder "Phantom_Study" - Data from the Phantom experiments. The folder contains subfolders that all follows the following naming scheme - "Phantom_##sO2_Run##", where "##sO2" corresponds to either 0% (deoxy-Hb) or 100% (oxy-Hb) oxygenated animal and "Run##" corresponds to the phantom experiment replicate number. Additionally, a folder named "PBS" houses all the PA data corresponding to the control PBS.