Hand-Held Optoacoustic System for the Localization of Mid-Depth Blood Vessels.

Photonics 2022, 9(12), 907

Zohar Or,  Ahiad R.Levi,  Yoav Hazan and Amir Rosenthal

The ability to rapidly locate blood vessels in patients is important in many clinical applications, e.g., in catheterization procedures. Optical techniques, including visual inspection, generally suffer from a reduced performance at depths below 1 mm, while ultrasound and optoacoustic tomography are better suited to a typical depth on the scale of 1 cm and require an additional spacer between the tissue and transducer in order to image the superficial structures at the focus plane. For this work, we developed a hand-held optoacoustic probe, designed for localizing blood vessels from the contact point down to a depth of 1 cm, without the use of a spacer. The probe employs a flat lens-free ultrasound array, enabling a largely depth-independent response down to a depth of 1 cm, at the expense of low elevational resolution. Specifically, while in lens-based probes, the acoustic signals from outside the focal region suffer from distortion, in our probe, only the amplitude of the signal varies with depth, thus leading to an imaging quality that is largely depth-independent in the imaged region. To facilitate miniaturization, dark-field illumination is used, whereby light scattering from the tissue is exploited to homogenize the sensitivity field.

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Optoacoustic images of the blood vessels in a human wrist.

Figure-Optoacoustic images of the blood vessels in a human wrist, at different depths and orientations. A cross-section of the radial artery can be seen clearly in real time at depths up to 7 mm, as in (a,c). A deep vein can be seen in (b) at a depth of 8 mm. In (d), we can see a vein diving from 3 to 7 mm in a longitudinal cross-section. The scale bar in subfigure (a) applies to all subfigures.

Zohar Or, Ahiad R.Levi, Yoav Hazan and Amir Rosenthal

Photonics 2022, 9(12), 907; https://doi.org/10.3390/photonics9120907