Susceptibility weighted imaging of multistep hepatocarcinogenesis in cirrhotic livers: correlation with pathology

Objective To investigate imaging characteristics of multistep hepatocarcinogenesis in cirrhotic livers on susceptibility-weighted imaging (SWI). Methods Seventy-three patients with 83 nodules in cirrhotic livers underwent hepatic MR imaging with SWI.Two radiologists reviewed MR images by consensus.Imaging characteristics of dysplastic nodules (DN),DN with malignant foci and hepatocellular carcinoma (HCC) were evaluated.Prussian blue staining was performed for semiquantification of hepatic iron content and above cirrhosis-associated nodules. Results Positive iron staining of background liver parenchyma was found in 69 of 73 patients and 4 HCC patients showed iron-negative staining of background liver parenchyma.Nine DNs appeared as hypointensity or isointensity with pathologically confirmed similar (n=7) or slightly decreased (n=2) iron deposition compared with background liver parenchyma.SWI detected 14 of 15 DNs with malignant foci.Seven patients appeared as homogeneous hyperintensity and 1 patient appeared as heterogeneous hyperintensity due to intratumoral hemorrhages.The remaining 6 patients demonstrated as nodule-innodule appearance with iron deposition in all background nodules,iron deposition with grade 1 in one internal HCC foci,and iron-free in 5 internal HCC foci.The remaining 50 patients with hepatic iron deposition had 55 HCC lesions.Three HCC lesions had iron deposition with grade 1 to 2 and the remaining 52 HCC lesions were pathologically iron-resistant.HCC appeared as hyperintensity compared with siderotic surrounding liver parenchyma.However,HCCs with diameter larger than 3 cm usually demonstrated heterogeneous hyperintensity due to intratumoral hemorrhage. Conclusions SWI could accurately demonstrate dynamic iron depletion on multistep hepatocarcinogenesis in cirrhotic livers.On SWI images,DNs appear as hypointensity due to siderosis and malignant nodules appear as hyperintensity due to iron depletion. Key words: Liver cirrhosis; Liver neoplasms; Magnetic resonance imaging