The objective of this study was to determine the incidence of typical and
atypical enhancement patterns of hepatocellular carcinomas (HCCs)
on multiphasic multidetector row CT (MDCT) and to correlate the
enhancement patterns and morphological image findings of HCC with the degree
of tumour differentiation.
MDCT images of 217 patients with 243 surgically proven HCCs were evaluated
through consensus reading by two radiologists. Our MDCT protocol was composed
of precontrast, arterial, portal and delayed phases. The reviewers analysed
the CT images for degree of attenuation; relative timing of washout; presence
of dysmorphic intratumoral vessels, aneurysms and necrosis; tumour size; tumour
margin; presence of pseudocapsule; intratumoral heterogeneity; and determined
enhancement pattern. The imaging features were correlated with tumour differentiation
using Fisher's exact test or the χ2
Among 243 HCCs, 137 (56.4%) showed the typical enhancement
pattern of HCC, which is arterial enhancement and washout on portal or equilibrium
phase images. In the arterial phase, 190 of 243 (78.2%) HCCs
showed hypervascularity, with approximately three quarters of poorly differentiated (PD) (34
of 45, 75.6%) and moderately differentiated (MD) HCCs (92
of 123, 74.8%) showing washout during the portal or delayed phases, vs
only 50% of well-differentiated (WD) HCCs (11 of 22; p<0.048).
The presence of intratumoral vessels and aneurysms, tumour necrosis, attenuation
of precontrast, the relative timing of washout, intratumoral attenuation heterogeneity,
tumour margin and tumour size were correlated with the pathological differentiation
of HCCs (p<0.05).
A typical enhancement of HCCs on MDCT was not unusual (43.6%)
and WD and PD HCCs account for most of the atypical enhancement patterns.
Early washout favoured MD and PD HCCs rather than WD HCCs, whereas in our
study the presence of intratumoral aneurysm was a highly specific finding
for PD HCC.