Performance benchmarks of an array-based hand-held photoacoustic probe adapted from a clinical ultrasound system for non-invasive sentinel lymph node imaging

Clinical translation of photoacoustic (PA) imaging can be facilitated by integration with commercial ultrasound (US) scanners to enable dual-modality imaging. An array-based US scanner was modified for hand-held PA imaging. The performance was benchmarked in terms of signal-to-noise ratio (SNR), axial spatial resolution and sensitivity. PA images of a tube, filled with methylene blue (MB; approx. 30 mM) and placed at various depths in chicken tissue, were acquired. A 5 cm penetration depth was achieved with an 18.6 dB SNR using a laser fluence of 3 mJ cm −2 , only one-seventh of the safety limit (20 mJ cm −2 ). An axial resolution of approximately 400 μm was maintained at all imaging depths. The PA sensitivity to MB placed 2.3 cm deep in chicken tissue was less than 100 μM. Further, after intradermal injection of MB (approx. 30 mM), a rat sentinel lymph node was clearly identified in vivo , beneath a 3.8 cm thick layer of chicken breast. The accumulated concentration of MB in the node was estimated to be approximately 7 mM. The noise-equivalent sensitivities (approx. 2 cm depth) were 17 and 85 μM, ex vivo and in vivo , respectively. These results support the use of this PA system for non-invasive mapping and image-guided needle biopsy of sentinel nodes in breast cancer patients.

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In vivo biodistribution studies and ex vivo lymph node imaging using heavy metal-free quantum dots

Biomaterials ◽

10.1016/j.biomaterials.2016.07.014 ◽

2016 ◽

Vol 104 ◽

pp. 182-191 ◽

Cited By ~ 34

Author(s):

Elnaz Yaghini ◽

Helen D. Turner ◽

Alix M. Le Marois ◽

Klaus Suhling ◽

Imad Naasani ◽

...

Keyword(s):

Heavy Metal ◽

Quantum Dots ◽

Lymph Node ◽

Ex Vivo ◽

Metal Free ◽

Lymph Node Imaging ◽

In Vivo Biodistribution ◽

Biodistribution Studies

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In Vivo Dual-Modal Photoacoustic and Ultrasound Imaging of Sentinel Lymph Nodes Using a Solid-State Dye Laser System

Sensors ◽

10.3390/s20133714 ◽

2020 ◽

Vol 20 (13) ◽

pp. 3714

Author(s):

Moongyu Han ◽

Wonseok Choi ◽

Joongho Ahn ◽

Hanyoung Ryu ◽

Youngseok Seo ◽

...

Keyword(s):

Solid State ◽

Ultrasound Imaging ◽

Imaging System ◽

Laser System ◽

Thick Layer ◽

Dye Laser ◽

Chicken Breast ◽

Breast Cancer Patients ◽

Solid State Dye Laser

Photoacoustic imaging (PAI) is being actively investigated as a non-invasive and non-radioactive imaging technique for sentinel lymph node (SLN) biopsy. By taking advantage of optical and ultrasound imaging, PAI probes SLNs non-invasively with methylene blue (MB) in both live animals and breast cancer patients. However, these PAI systems have limitations for widespread use in clinics and commercial marketplaces because the lasers used by the PAI systems, e.g., tunable liquid dye laser systems and optical parametric oscillator (OPO) lasers, are bulky in size, not economical, and use risky flammable and toxic liquid dyes. To overcome these limitations, we are proposing a novel dual-modal photoacoustic and ultrasound imaging system based on a solid-state dye laser (SD-PAUSI), which is compact, convenient, and carries far less risk of flammability and toxicity. Using a solid-state dye handpiece that generates 650-nm wavelength, we successfully imaged the MB tube positioned deeply (~3.9 cm) in chicken breast tissue. The SLNs were also photoacoustically detected in the in vivo rats beneath a 2.2-cm-thick layer of chicken breast, which is deeper than the typical depth of SLNs in humans (1.2 ± 0.5 cm). Furthermore, we showed the multispectral capability of the PAI by switching the dye handpiece, in which the MB-dyed SLN was selectively highlighted from the surrounding vasculature. These results demonstrated the great potential of the SD-PAUSI as an easy but effective modality for SLN detection.

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