Focal secondary malignant liver lesions:: MnDPDP-enhanced MRT at 0.2 Tesla vs. helical CT-arterioportography

Purpose: Prospective evaluation of the efficacy of MnDPDP-enhanced MRI using an open low-field scanner for the detection of focal malignant liver lesions in comparison with helical CT-arterioportography (CT AP). Material and Methods: As part of a phase III study, 27 consecutive patients we enrolled for comparison, with seven patients later eliminated for failing the inclusion criteria. Native and MnDPDP-enhanced MRI of the liver at a field-strength of 0.2 Tesla (Siemens Magnetom Open) and DSA with helical CT AP (Siemens Somatom Plus 4) were performed within one week. The lesions were compared collectively and after categorization by size: (a) < 1 cm, (b) 1 - 2 cm, and (c) > 2 cm. For statistical evaluation, the sign test with a significance level of p < 0.05 was used. Results: CT AP depicted 114 lesions, whereas native MRI detected 62 and MnDPDP-enhanced MRI revealed 69 lesions. Significant differences were shown for collective comparison and for selective comparison of category (b), and of categories (a) and (b) combined. No significant differences were found between native and contrast-enhanced MRI. Conclusion: MnDPDP should be reserved for high-field strengths since low field strengths cannot be expected to confirm or exclude malignant liver lesions reliably.