MR characterization of dysplastic nodules and hepatocarcinoma in cirrhotic liver with hepatospecific superparamagnetic contrast agents. Anatomo-pathological correlation in explanted liver.

Purpose. The authors sought to evaluate the potential of magnetic resonance (MR) imaging with superparamagnetic iron oxide (SPIO) contrast material for identifying, characterising and differentiating dysplastic nodules (DN) and hepatocellular carcinoma (HCC) in the cirrhotic liver by correlating the results with pathological findings on the explanted liver. Material and methods. MR imaging was used to study the liver of 400 cirrhotic patients awaiting liver transplantation, 31 of whom were selected to receive a liver. Of these 31 patients, we included in the study 22 patients (mean age 53 years; range 46–57 years) who underwent liver transplantation within 12–24 h after MR examination. Patients were studied with a 1.5-T device, and scans were acquired before and after the administration of paramagnetic contrast material. For every lesion, we recorded signal intensity on unenhanced baseline T1- and T2-weighted images and enhancement pattern after SPIO administration. Histological examination of the entire liver provided the definitive diagnosis of the lesions. Results. Histological examination identified 59 lesions: 14 HCC, 4 HCC–DN, 39 DN, and 2 cystoadenomas. Among the 14 HCC, three were well differentiated, eight were moderately differentiated and three were poorly differentiated. Of the 39 DN, 28 were low-grade and 11 high-grade lesions. Unenhanced baseline MR imaging correctly identified and characterised 20 lesions, equal to 33.90% of all lesions: 6 HCC, 12 DN and 2 DN with a subfocus of HCC. SPIO-enhanced MR imaging showed greater sensitivity detecting and characterising 45 lesions, equal to 76.27% of all lesions identified at histology: 14 HCC, 27 DN and 4 DN with subfocus of HCC. SPIO administration improved the sensitivity of MR imaging in lesion detection and characterisation by 42.37%. False negative results with SPIO-enhanced MR imaging occurred in 12 DN (31%), which histological examination revealed to be low-grade DN with a diameter <1 cm. Conclusions. SPIO-enhanced MR imaging proved to be of value in detecting and characterising lesions in the cirrhotic liver, allowing differentiation of DN from HCC and providing an early diagnosis of neoplastic degeneration of DN. Keywords SPIO · Dysplastic nodules · Hepatocellular carcinoma · Magnetic resonance imaging