Abstract: Objective To investigate the features and differential diagnosis of liver solitary necrotic nodules (SNNs) in both plain and dynamic contrast-enhanced magnetic resonance imaging (MRI) scan in order to improve the diagnosis of SNN. Methods Thirty-four patients with biopsy confirmed SNN from 2012 to 2017 in our hospital were analyzed retrospectively. The lesions in both plain and enhanced MRI scan were evaluated. Results A total of 34 lesions were found, whose maximum diameter ranged from 0.7 to 4.9 cm. There were 7 lesions distributed in the left lobe, 24 in the right lobe and 3 in the tail lobe. In diffusion weighted imaging (DWI), 7 lesions showed hypointense signals, 8 showed isointense signals, and 19 showed hyperintense signals. On T1WI, 25 lesions showed slightly hypointense signals, 6 showed isointense signals, and 3 showed lightly hyperintense signals. On T2WI, 19 lesions showed slightly hypointense signals, 9 showed isointense signals, and 5 showed slightly hyperintense signals. The dynamic contrast-enhanced scan of 28 lesions showed no enhancement inside nodules but peripherally circular enhancement with clear edge in the portal phase and delayed phase. However, 3 lesions showed no enhancement in all phases. Besides, the other 3 lesions show mild patchy enhancement in arterial phase, and peripheral enhancement with separation-like enhancement in the delayed phase. Conclusion The characteristic features of SNNs in dynamic contrast-enhanced MRI scan are peripherally circular enhancement with clear edge, which is valuable in the diagnosis of SNN.

Key words: Liver, Solitary necrotic nodule, MRI