A Dual PET/MR Imaging Nanoprobe: 124I Labeled Gd3N@C80

Abstract

The current report describes the development of a dual modality tomographic agent for both positron emission tomography and magnetic resonance imaging (PET/MRI). The dual-modality agent in this study was based on a ¹²⁴I (PET) radiolabeled tri-gadolinium endohedral metallofullerene Gd₃N@C₈₀ (MRI) nanoprobe platform. The outer surface of the fullerene cage of the Gd₃N@C₈₀ metallofullerenes was surface functionalized with carboxyl and hydroxyl groups (f-Gd₃N@C₈₀) using previously developed procedures and subsequently iodinated with ¹²⁴I to produce ¹²⁴I-f-Gd₃N@C₈₀ nanoprobe. Orthotopic tumor-bearing rats were infused intratumorally by convection-enhanced delivery (CED) with the ¹²⁴I-f-Gd₃N@C₈₀ agent and imaged by MRI or micro PET. The anatomical positioning and distribution of the ¹²⁴I-f-Gd₃N@C₈₀ agent were comparable between the MRI and PET scans. The ¹²⁴I-f-Gd₃N@C_80­ dual-agent distribution and infusion site within the tumor was clearly evident in both T₁- and T₂-weighted MR images. The results demonstrate the successful preparation of a dual-modality imaging agent, ¹²⁴I-f-Gd₃N@C₈₀, which could ultimately be used for simultaneous PET/MR imaging.