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Updated: Aug 17, 2026

Computed Tomography-guided Time-domain Diffuse Fluorescence Tomography in Small Animals for Localization of Cancer Biomarkers
Published on: July 17, 2012
Development of a tumor-targeting MR contrast agent using the high-affinity folate receptor: work in progress
S D Konda1, M Aref, M Brechbiel
1Biomedical Magnetic Resonance Laboratory, College of Medicine, and the Beckman Institute, University of Illinois, Urbana-Champaign, USA.
Rationale And Objectives:
Macromolecular contrast agents enhance tumors by means of active or passive targeting. Active targeting requires surface receptors. Many tumors of epithelial origin express the high-affinity folate receptor (hFR), including ovarian tumors. The objective of this research was to enhance tumors that express hFR using macromolecular contrast agents conjugated to folic acid.
Methods:
The authors prepared a folate-conjugated dendrimer polychelate by attaching folic acid to a fourth-generation ammonia-core polyamidoamine dendrimer. The remaining amines were reacted with 2-(4-isothiocyanatobenzyl)-6-methyldiethylenetriamine pentaacetic acid. Relaxivity measurements (r1 and r2) and MRI were conducted at 4.7 T.
Results:
The dendrimer r2 exceeded that of Gd-HP-DO3A by 8.2 times at 4.7 T. It increased the tumor percentage contrast enhancement, 24 hours after injection, of T2-weighted images by 33%.
Conclusions:
This new agent accumulates in tumors expressing hFR. These results do not differentiate between active and passive targeting mechanisms. Receptor-negative tumors suggest a mechanism other than a nonspecific blood pool effect.

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