Characterization of the imaging signature of hepatocellular carcinoma with enhancement pattern mapping

Background and Aims: Limited methods exist to accurately characterize risk of malignant progression of liver lesions in patients undergoing surveillance for hepatocellular carcinoma (HCC). Enhancement pattern mapping (EPM) measures voxel-based root mean square deviation (RMSD) and improves the contrast to noise ratio (CNR) of liver lesions on standard of care imaging. This study investigates the utilization of EPM to differentiate between malignant versus non-malignant lesions. Methods: Patients with liver cirrhosis undergoing MRI surveillance at a single, tertiary-care hospital were studied prospectively. Controls (n=99) were patients without lesions during surveillance. Cases (n=48) were defined as patients with LI-RADS 3 and 4 lesions who developed HCC within the study period. RMSD measured with EPM was compared to the signal from MRI arterial and portovenous (PV) phases. EPM signals of liver parenchyma between cases and controls were quantitatively validated on an independent patient set using cross validation. Results: With EPM, RMSD of 0.37 was identified as a quantitative cutoff for distinguishing lesions that progress to HCC from background parenchyma, including non-malignant lesions, on pre-diagnostic scans with an area under the curve (AUC) of 0.83 (CI: 0.73-0.94). EPM RMSD signals of background parenchyma in cases and controls were similar (case EPM: 0.22 +/- 0.08, control EPM: 0.22 +/- 0.09, p=0.8). Conclusions: EPM differentiates between HCC and non-cancerous parenchyma in a surveillance population and helps in early detection of HCC. Future directions may involve applying EPM for risk stratification of indeterminate lesions.