Hypervascular Transformation of Hypovascular Hypointense Nodules in the Hepatobiliary Phase of Gadoxetic Acid-Enhanced MRI: A Systematic Review and Meta-Analysis.

OBJECTIVE: The purpose of this study is to evaluate the outcomes of hypovascular hypointense nodules in the hepatobiliary phase of gadoxetic acid-enhanced MRI and the risk factors for the hypervascular transformation of the nodules through a systematic review and meta-analysis.

MATERIALS AND METHODS: We searched the Ovid-MEDLINE and EMBASE databases for published studies of hypovascular hypointense nodules in patients with chronic liver disease. The pooled proportions of the overall and cumulative incidence rates at 1, 2, and 3 years for the transformation of hypovascular hypointense nodules into hypervascular hepatocellular carcinomas (HCCs) were assessed by using random-effects modeling. Metaregression analysis was performed.

RESULTS: Sixteen eligible studies with 944 patients and 1819 hypovascular hypointense nodules in total were included. The pooled overall rate of hypervascular transformation was 28.2% (95% CI, 22.7-33.6%; I2 = 87.46%). The pooled 1-, 2-, and 3-year cumulative incidence rates were 18.3% (95% CI, 9.2-27.4%), 25.2% (95% CI, 12.2-38.2%), and 30.3% (95% CI, 18.8-41.9%), respectively. The metaregression analysis revealed that the mean initial nodule size (cutoff value, 9 mm) was a significant factor affecting the heterogeneity of malignant transformation.

CONCLUSION: Hypovascular hypointense nodules detected in the hepatobiliary phase of gadoxetic acid-enhanced MRI carry a significant potential of transforming into hypervascular HCCs. The size of nodules is a significant risk factor for hypervascular transformation.