Dynamic contrast-enhanced MRI of implanted VX2 tumors in rabbit muscle: Comparison of Gd-DTPA and NMS60

We studied the dynamics of injected contrast enhancement in implanted VX2 tumors in rabbit thigh muscle, We compared two contrast agents Gd-DTPA and NMS60, a novel gadolinium containing trimer of molecular weight 2.1 kd, T-1-weighted spin echo images were acquired preinjection and at 5-60 min after i.v. injection of 0.1 mmol/kg of agent. Dynamic T-1-weighted SPGR images (1.9 s/image) were acquired during the bolus injection. Male NZW rabbits (n = 13) were implanted with approximately 2 x 10(6) VX2 tumor cells and grew tumors of 28 +/- 27 mL over 12 to 21 days. NMS60 showed significantly greater peak enhancement in muscle, tumor rim, and core compared to DTPA in both T-1-weighted and SPGR images. NMS60 also showed delayed peak enhancement in the dynamic scans (compared to Gb-DTPA) and significantly reduced leakage rate constant into the extravascular space for tumor rim (K-21 = 5.1 min(-1) vs, 11.5 min(-1) based on a 2 compartment kinetic model). The intermediate weight contrast agent NMS60 offers greater tumor enhancement than Gd-DTPA and may offer improved regional differentiation on the basis of vascular permeability in tumors, (C) 1999 Elsevier Science Inc.