Fig. 4

Different Imaging patterns of [⁶⁸Ga]Ga-MSA nanoparticle in responders and non-responders to anti-PD1 treatment. a Schematic illustration of MSA. b Flow cytometry for the frequency of CD206⁺ cells in non-responder and responder tumors (n = 4/group). c Quantification of CD206 immunohistochemistry-stained tumor tissues from non-responders and responders. d Overview of experimental representative PET images of B16F10-Luc tumor-bearing mice according to the response to anti-PD1 treatment. Panels below the coronal whole-body PET images are cropped sagittal sections of the tumors. The scale bar of the image was adjusted for the image of the tumor site. e Measurement of Lesion to Blood pool (LBP) ratio at day 15 in the anti-PD1 treated tumor (non-responders, n = 14; responders, n = 10). f Representative flow cytometric dot plot (left) and percentages of MSA⁺ cells as determined by flow cytometry (right) (non-responders, n = 9; responders, n = 7). g [⁶⁸Ga]Ga-MSA uptake measured by LBP at the early phase of anti-PD1 treatment (day 15) was negatively correlated with the tumor volume at late phase (day 24) (non-responders, n = 14, responders n = 10). Scale bar = 1 mm for upper images and 300 μm for magnified images. Data are presented as mean ± SEM. Statistical significance was determined using the two-tailed Student’s t-test. *p < 0.05; **p < 0.01; ***p < 0.001.