Fig. 1. Schematic of the CVN-PAM. ACL, achromatic lens; AL, acoustic lens; CL, convex lens; BPF, bandpass filter; CP, coupler; DM, dichroic mirror; HWP, half-wave plate; MR, mirror; NDF, neutral density filter; PBS, polarization beam splitter; UT, ultrasonic transducer.

Fig. 2. (a) Measured and fitted edge spread function (ESF) and derived line spread function (LSF) at 532 nm, 558 nm, and 1064 nm; acoustic axial resolution. (b) Penetration depths, 0.95 mm for 532 nm and 1.45 mm for 1064 nm with a 6 dB SNR. (c) Depth-encoded vascular image of the mouse ear at 532 nm. (d) Depth-encoded vascular image of the mouse ear at 1064 nm. (e) sO2 image of the mouse ear computed from 532 nm and 558 nm wavelengths.

Fig. 3. (a) PA image of SPNs at 532 nm. (b) PA image of SPNs at 1064 nm. (c) PA image of blood at 1064 nm. (d) PA image of water at 1064 nm. (e) PA image of blood at 532 nm. (f) Comparison of average PA amplitudes of these samples. Error bars are standard deviations.

Fig. 4. (a) Mouse ear before injecting tumor cells (day 0). The black dotted box is the region of interest. (b) Microvasculature image of the mouse ear at 532 nm on day 0. (c) The color-coded depth microvasculature image of the mouse ear at 532 nm on day 0. (d) The mouse ear on day 6 (before injecting SNPs). (e) Microvasculature image of the mouse ear at 532 nm on day 6. (f) The color-coded depth microvasculature image of the mouse ear at 532 nm on day 6. (g) The mouse ear on day 7 (24 h after SPN injection). (h) Microvasculature image of the mouse ear at 532 nm on day 7. (i) The color-coded depth microvasculature image of the mouse ear at 532 nm on day 7.

Fig. 5. (a) The sO2 of the mouse ear before injecting cancer cells (day 0). (b) The sO2 of the mouse ear on day 7. (c) Extracted sO2 of the tumor region. The feeding vessels and draining vessels are pointed out. (d) Imaging of the mouse ear at 1064 nm on day 0 and day 7. (e) The combined image of sO2 and 1064 nm image. (f) The sO2 pixels percentage in the mouse ear on day 0 and day 7. The vertical axis is the percentage ratio of the pixel number at an sO2 value to the total pixel number of the blood vessels in the image. The sO2 value interval on the x axis is 0.001. (g) The sO2 pixels percentage of R1 and R2 in the mouse ear on day 7. (h) The sO2 change of the feeding vessels and draining vessels. The OEFs of the tumor region are extracted from the sO2 values.

Fig. 6. (a) Color-coded vessel tortuosity of the microstructure on day 0 and day 7. The extracted blood vessels are overlaid with the vessel centerlines. (b) Color-coded vessel diameter on day 0 and day 7. The extracted blood vessels are overlaid with the vessel centerlines. (c) Color-coded vessel density on day 0 and day 7. The image is divided into 40×34 subareas.

Table 1. Vessel Parameters in Tumor and Non-Tumor Regions