Superparamagnetic iron oxide-enhanced magnetic resonance imaging is useful in predicting malignant potential of vascular transformation of hypointense hypovascular nodules on gadoxetic acid-enhanced magnetic resonance imaging

Aim To examine whether superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) can be used to assess the malignant potential of hepatic hypovascular nodules showing hypointensity during the hepatobiliary phase (HBP) on gadoxetic acid (Gd–EOB–DTPA)-enhanced MRI. Methods The study included 42 patients with chronic liver disease who had small hypovascular nodules (5–15 mm) showing hypointensity during the HBP on Gd–EOB–DTPA-enhanced MRI. The SPIO-enhanced T2-weighted MRI analyzed whether the signal intensity of each nodule was high. Nodules were prospectively followed up until hypervascularization by periodic Gd–EOB–DTPA-enhanced MRI. Initial MRI findings and clinical variables were used to analyze predictive factors for hypervascularization. Results We analyzed 77 nodules, of which 19 (25%) showed hypervascularization during the observation period. The cumulative rates for hypervascularization were 11% and 22% at 1 and 2 years, respectively. Hyperintensity was observed in 12 nodules (16%) on SPIO-enhanced T2-weighted MRI; among these, 7 (58%) showed hypervascularization, whereas 12 (18%) of the remaining 65 nodules without hyperintensity showed hypervascularization (P = 0.007). A Cox model revealed that independent predictors of hypervascularization included hyperintense nodules on SPIO-enhanced MRI (P < 0.001). The cumulative rates for hypervascularization in hyperintense nodules on SPIO-enhanced MRI were 52% at 1 year, whereas these rates were 3% for non-hyperintense nodules. Conclusion Superparamagnetic iron oxide-enhanced MRI is useful for predicting the malignant potential of vascular transformation of hypovascular nodules with hypointensity observed in the HBP on Gd–EOB–DTPA-enhanced MRI.