Luca Frullano, Ciprian Catana, Thomas Benner, A. Dean Sherry, and Peter Caravan* The extent to which magnetic resonance (MR) contrast agents can enhance the nuclear relaxation (1/T1) of water is termed relaxivity. Activatable or smart contrast agents have relaxivities that depend on environmental factors, such as pH or enzymatic activity, but the MR signal depends on relaxivity and agent concentration, which are two unknowns. A bimodal approach that incorporates a positron emitter such as F-18 solves this problem. Simultaneous positron emission tomography (PET) and MR imaging with the biomodal, pH-responsive MR-PET agent GdDOTA-4AMP-F allows direct determination of both concentration (PET) and T1 (MRI), and thus pH. Erscheint demnächst. |
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