Prospective comparative study of spiral computer tomography and magnetic resonance imaging or detection of hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is often detected at a relatively late stage when tumour size prohibits curative surgery. Screening to detect HCC at an early stage is performed for patients at risk. Aim: The aim of this study was to compare prospectively the diagnostic accuracy and classification for management of the two state of the art secondline imaging techniques: triphasic spiral computer tomography (CT) and super paramagnetic iron oxide (SPIO) enhanced magnetic resonance imaging (MRI). Patients: Sixty one patients were evaluated between January 1996 and January 1998. Patients underwent CT and MRI within a mean interval of 6.75 days. Methods: CT and MRI were evaluated blindly for the presence and number of lesions, characterisation of these lesions, and classification for management. For comparison of the data on characterisation, the CT and MRI findings were compared with histopathological studies of the surgical of specimens and/or follow up imaging. Data of patients not lost to follow up were available to January 2001. Results: SPIO enhanced MRI detected more lesions and overall smaller lesions than triphasic spiral CT (number of lesions 189 v 124; median diameter 1.0 v 1.8 cm; Spearman rank's correlation coefficient 0.63, p <0.001). There was no significant difference in accuracy between CT and MRI for lesion characterisation. The agreement in classification for management was very good (weighted kappa 0.91, 95% CI 0.83-0.99). Conclusion: SPIO enhanced MRI detects more and smaller lesions, but both techniques are comparable in terms of classification for management. SPIO enhanced MRI may be preferred as there is no exposure to ionising radiation