Figure 1.
(A) Structural formula of the contrast agent Oxo63, tris[8-carboxy-2,2,6,6-tetrakis(2-hydroxymethyl)benzo[1,2-d:4,5-d′]bis(1,3)dithio-4-yl]methyl radical, trisodium salt. (B) OMRI pulse-sequence diagram showing B0 field cycling and radiofrequency (RF) and field-gradient waveforms. (C) Interleaved (“EPR off” and “EPR on”) OMRI images (coronal) of a female C3H mouse, bearing SCC tumor on the right hind leg, demonstrating the Overhauser enhancement (OE) and the diagnostic quality achievable at this low magnetic field of 15 mT. The mouse was administered 3.8 mmol/kg Oxo63 by tail vein cannulation. Both images were acquired in the presence of the contrast agent. The image acquisition parameters are given in Materials and Methods.