Small (≤3cm) Hepatocellular Carcinoma in Cirrhosis: the Role of Double Contrast Agents MR Imaging vs. Multi-Detector Row CT

Purpose: We prospectively compared gadoliniumenhanced magnetic resonance imaging (dynamic MRI), superparamagnetic iron oxide (SPIO) (ferucarbotran) MRI and multidetector-row computed tomography (MDCT) and the combination of dynamic MRI plus MDCT vs. dynamic MRI plus SPIO-MRI (double-contrast MRI: DC-MRI) for the detection of small (≤3 cm) hepatocellular carcinomas (HCCs). Materials and Methods: Sixty-three patients with liver cirrhosis and suspicious nodules detected during ultrasound (US) surveillance underwent DC-MRI in the same imaging session and MDCT within 15 days. The final diagnosis was established at pathology on the explanted liver (n=10), resection (n=6) and biopsy (n=38) specimens or at 2-years’ follow-up (n=9). Results: One hundred and twenty-three nodules were detected: 87 were confirmed HCCs in 54 patients. The accuracy of SPIO-MRI and dynamic MRI were similar, both being superior to MDCT. Dynamic MRI demonstrated the highest sensitivity (83.9%; p<0.001) especially for lesions <1 cm (90.6%) – coupled with a lower specificity (36.1%) than SPIO-MRI, particularly in subcentimeter lesions (28.6%). SPIO-MRI demonstrated the highest sensitivity for nodules >1 cm and the highest specificity (83.3%) superior to dynamic MRI (p<0.0001). In the per-lesion analysis, SPIO-MRI demonstrated a positive predictive value higher than dynamic MRI (p=0.0059) and than both the combinations dynamic MRI/MDCT and DC-MRI (p=0.0021 and p=0.0087, respectively). DC-MRI showed the highest sensitivity (97.7%) and accuracy (78.9%), detecting hypovascular and atypical HCCs >1 cm. Furthermore its per-patient negative predictive value was the highest (100%), and significantly higher than all the other methods. Conclusions: DC-MRI is the most sensitive and accurate method and can be confidently used as a single-step procedure for the detection of small HCCs, with the exception of lesions <1 cm.