Fig. 3.

In vivo noninvasive photoacoustic imaging of sentinel lymph nodes in rat (λ = 767 nm). (A–J, M–N) Scale bar is 5 mm. 150 µL of nanobeacons were injected intradermally in all the cases.

GNB₁₆₀: A. Control PA image. B. 5 min post-injection image of GNB₁₆₀s (5 µM).

P-GNB₂₉₀: C. Control PA image. D. Lymph node is not visible in a 60 min post-injection image of P-GNB₂₉₀s (680 nM).

L-GNB₉₀: E. Sagittal maximum amplitude projection (MAP) [8] pre-injection control image: Bright parts represent optical absorption from blood vessels, marked with red arrows. F. PA image (MAP) acquired 5 min after L-GNB₉₀ injection (10 nM). SLNs are clearly visible, marked with green arrow. Lymphatic vessel is also visible, marked with blue arrow. G. 20 min post-injection PA image. H. Same as G with two different color spaces showing the blood vessel as well as the SLNs. I. Control PA image. J. 5 min post-injection image of 4 times diluted L-GNB₉₀s (2.5 nM). K. Digital optical photograph of the rat with the skin removed after PA imaging. Lymph node area is shown with green arrow. L. Excised lymph node. Smallest tick: 1 mm. M. Control PA image. N. 5 min post-injection image of 10 times diluted L-GNB₉₀s (1 nM). O. Average PA signal from the ROI (marked as yellow dotted square in all the pre-injection or control images, 3A, C, E, I, M). Blue represents pre-injection and brown represents post-injection. Images are normalized by pre-injection signal.