Gadolinium(III)-gold nanorods for MRI and photoacoustic imaging dual-modality detection of macrophages in atherosclerotic inflammation

Aim: One of the features of high-risk atherosclerotic plaques is the preponderance of macrophages. Gadolinium(III)-gold nanorods (Gd-III-GNRs) have been developed as a dual-modality probe for MRI and photoacoustic imaging (PAI) to trace macrophages for determining the degree of inflammation. Materials & methods: Gd-III-GNRs were utilized for MRI and PAI dual-modality detection of macrophages in living mice and ex vivo simulated macrophage-rich plaque. Results: Gd-III-GNRs were shown to be endocytosed by macrophages in vitro. Macrophages labeled with Gd-III-GNRs were detected by both PAI and MRI. With Gd-III-GNRs, it is possible to institute a multiscale complementary imaging protocol: MRI can screen to identify the location of the probe-phagocytosed macrophages, and intravascular PAI provides a subsequent precise morphology to quantify the infiltration area and invasion depth of macrophages in the arterial wall. Conclusion: This new dual-modality nanoparticle approach has promise for enabling quantitative detection of macrophages in atherosclerotic plaques.