Gd HP-DO3A--experimental evaluation in brain and renal MR

GD HP-DO3A, a neutral (nonionic) IV MR contrast agent presently in clinical trials, was evaluated with respect to imaging characteristics in rats. Following administration of 0.25 mmol/kg I.V., 58 +/- 19%, i.e. (n = 6) enhancement was noted in a brain gliosarcoma model. Meningeal spread of neoplasia could be identified due to its enhancement (69 +/- 26%) in nine animals. The time course of renal enhancement was quantitated at two dosages, 0.05 (n = 4) and 0.25 mmol/kg (n = 8). At the higher dose, enhancement of both cortex and medulla plateaued between 9 and 23 min postinjection. At the lower dose, enhancement of renal medulla was maximum at 2 min postinjection. These enhancement characteristics (both brain and kidney), at equivalent contrast dosages, are comparable to that previously published for Gd-DTPA. However, Gd HP-DO3A has the potential to be utilized clinically at higher doses than Gd-DTPA, with no reported adverse effects in initial trials employing up to 0.3 mmol/kg.