Abstract: Objective To evaluate the value of long-time delayed contrast-enhanced scan of magnetic resonance imaging （MRI） in the diagnosis of patients with solitary necrotic nodules of the liver （SNNL）. Methods 17 patients with SNNL and 15 patients with malignant liver tumors（including 10 with hepatocellular carcinomas and 5 with hepatic metastases） were admitted to our hospital between May 2013 and May 2018,and all patients underwent conventional CT/MRI enhanced scan and multi-phase long-delayed to 120 minute MRI scanning. The imaging characteristics,such as density and enhancement type of the lesions were compared between the two groups. Result Out of 17 patients with SNNL,17 single foci were found by CT and MRI scan,all localized in right lobe with the diameters of（2.1±0.4） cm;out of 10 patients with HCC,MRI scan demonstrated 11 foci,8 localized in right and 3 in left lobe with the diameters of（5.4±1.6） cm;out of 5 patients with metastases,12 foci were found,9 localized in right,and 3 in left lobe,with the diameters of （3.1±0.9） cm;four SNNL lesions showed “target sign” on T2WI and the imaging manifestation of liver metastases were similar to those of SNNL;at delayed phase （DP）3/5 min,the edge of HCC and liver metastasis foci showed moderate to severe circular enhancement,and the enhancement in SNNL was intensified as the scan time prolonged;at DP 1 hour,17 SNNL foci showed moderate to severe circular enhancement and no enhancement in the centre of each lesion,while all enhancement in tumors disappeared. Conclusion Long-time delayed contrast-enhanced MRI might effectively distinguish SNNL from malignant hepatic tumors,which needs further investigation.

Key words: Solitary necrotic nodules, liver, Delayed MRI scanning, Diagnosis