The characterization of an economic and portable LED-based photoacoustic imaging system to facilitate molecular imaging

• Published in: Photoacoustics (Munich) Vol. 9; pp. 10 - 20
• Main Authors: Hariri, Ali, Lemaster, Jeanne, Wang, Junxin, Jeevarathinam, AnanthaKrishnan S., Chao, Daniel L., Jokerst, Jesse V.
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 01.03.2018; Elsevier
• Subjects: LED; Molecular imaging; Optoacoustic imaging; Portable photoacoustic imaging; Molecular imaging; Portable photoacoustic imaging; LED; Optoacoustic imaging
• ISSN: 2213-5979; 2213-5979
• DOI: 10.1016/j.pacs.2017.11.001

[Display omitted] •We characterized a commercially available LED-based photoacoustic imaging system.•The LED beam profile, spatial/temporal resolution, and penetration depth were measured.•Indocyanine green and methylene blue were utilized as exogenous contrast agent, and their detection limits were calculated.•The capability for in vivo experiments was demonstrated using human mesenchymal stem cells labeled with a near-infrared dye (DiR) in living mice. Photoacoustic imaging (PAI) is a non-invasive, high-resolution hybrid imaging modality that combines optical excitation and ultrasound detection. PAI can image endogenous chromophores (melanin, hemoglobin, etc.) and exogenous contrast agents in different medical applications. However, most current equipment uses sophisticated and complicated OPO lasers with tuning and stability features inconsistent with broad clinical deployment. As the number of applications of PAI in medicine increases, there is an urgent need to make the imaging equipment more compact, portable, and affordable. Here, portable light emitting diode – based photoacoustic imaging (PLED-PAI) was introduced and characterized in terms of system specifications, light source characterizations, photoacoustic spatial/temporal resolution, and penetration. The system uses two LED arrays attached to the sides of a conventional ultrasound transducer. The LED pulse repetition rate is tunable between 1 K Hz, 2 K Hz, 3 K Hz, and 4 K Hz. The axial resolution was 0.268 mm, and the lateral resolution was between 0.55 and 0.59 mm. The system could detect optical absorber (pencil lead) at a depth of 3.2 cm and the detection limits of indocyanine green (ICG) and methylene blue (MB) were 9 μM and 0.78 mM. In vivo imaging of labeled human mesenchymal stem cells was achieved to confirm compatibility with small animal imaging. The characterization we report here may have value to other groups evaluating commercially available photoacoustic imaging equipment.