Mn-DPDP-enhanced MR imaging of malignant liver lesions: efficacy and safety in 20 patients.

Twenty patients with malignant liver lesions underwent magnetic resonance (MR) imaging with manganese (II) DPDP [N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate)] to evaluate the safety and efficacy of the contrast agent. In two groups of 10 patients each, 5 mumol/kg Mn-DPDP was administered intravenously (3 mL/min) at a concentration of either 50 or 10 mumol/mL. T1- and T2-weighted images were obtained with a 1.5-T imager. Six patients reported a total of eight instances of side effects (flush, feeling of warmth, metallic taste) of which seven occurred at the 50 mumol/mL concentration. A significant decrease in alkaline phosphatase levels 2 hours after injection was recorded. On T1-weighted images, the 10 mumol/mL formulation yielded significantly greater increases in contrast-to-noise ratio (79.8%-137.5%) than the 50 mumol/mL formulation (46.2%-86.6%). In a blinded reader study of 10 patients with one to five lesions each, no lesion was missed on Mn-DPDP--enhanced T1-weighted images; however, four false-positive foci were identified. The authors conclude that slow administration of 5 mumol/kg Mn-DPDP at a concentration of 10 mumol/mL is safe and efficient enough to proceed to further clinical trials.