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

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 I-124 (PET) radiolabeled tri-gadolinium endohedral metallofullerene Gd3N@C-80 (MRI) nanoprobe platform. The outer surface of the fullerene cage of the Gd3N@C-80 metallofullerenes was surface functionalized with carboxyl and hydroxyl groups (f-Gd3N@C-80) using previously developed procedures and subsequently iodinated with I-124 to produce I-124-f-Gd3N@C-80 nanoprobe. Orthotopic tumor-bearing rats were infused intratumorally by convection-enhanced delivery (CED) with the I-124-f-Gd3N@C-80 agent and imaged by MRI or micro PET. The anatomical positioning and distribution of the I-124-f-Gd3N@C-80 agent were comparable between the MRI and PET scans. The I-124-f-Gd3N@C-80 dual-agent distribution and infusion site within the tumor was clearly evident in both T-1- and T-2-weighted MR images. The results demonstrate the successful preparation of a dual-modality imaging agent, I-124-f-Gd3N@C-80, which could ultimately be used for simultaneous PET/MR imaging.