  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 HCC
versus benign cirrhotic tissue. 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 or progression to HCC. 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 on
pre-diagnostic scans with an area under the curve (AUC) of 0.83 (CI: 0.73-0.94)
and a sensitivity, specificity, and accuracy of 0.65, 0.97, and 0.89,
respectively. At the time of diagnostic scans, a sensitivity, specificity, and
accuracy of 0.79, 0.93, and 0.88 was achieved with an AUC of 0.89 (CI:
0.82-0.96). 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 may aid in early detection of HCC. Future
directions involve applying EPM for risk stratification of indeterminate
lesions.
