HCC is a major health problem worldwide. Chronic infection by the hepatitis B virus is the most common cause of this disease. The peak age of incidence is 50–70 years, with a male predominance [12, 16]. There are several treatment strategies available for HCC. Resection is the first-line of therapy in patients with HCCs and well-preserved liver function. However, the recurrence rate after surgery is high [2, 12]. In our study, the recurrence or metastases rate was 58.93% within 2 years after surgery. HCC recurrence after hepatic resection is divided into early recurrence (within 1 or 2 years after surgery) and late recurrence (greater than these temporal end-points) [17,18]. Early recurrences are considered to result from metastasis of the primary HCC and are mainly affected by adverse tumor features, whereas late recurrences should be considered as de novo HCCs and are mainly affected by the underlying liver status [17,18]. In this study, we retrospectively reviewed various CT findings of 112 patients with primary HCCs to assess the association between CT features and early clinical outcome after surgery.
Multiphasic helical CT is often used as the first-line diagnostic modality for detection of HCC. The sensitivity of CT for HCC of all size is 63%-76% [6]. The accuracy of CT in the diagnosis of HCC was 94.29%, and that of lesion with a diameter ≤1 cm was 84.00% [5]. Hepatic artery is the primary feeder to the HCC. The hallmark diagnostic CT features of HCC are arterial phase hyperenhancement followed by portal venous or delayed phase washout appearance [3-6]. The arterial phase hyperenhancement is characteristic but nonspecific to radiological diagnosis of HCC, as it can also be observed in focal nodular hyperplasia, hemangiomas, hypervascular metastases and hepatic adenoma. While the combination of arterial phase hyperenhancement and washout appearance is highly specific for HCC in patients with risk factors for HCC [19, 20]. In our series, the combination of them was found in 66.07% patients. Capsule appearance is another important imaging feature for HCC, and is observed in about 42% of cases [19]. Consistently, in our study, capsule appearance was found in 47 patients (42.0%). According to the diagnostic systems [21], a mass 2 cm or larger with arterial phase hyperenhancement and capsule appearance can be diagnosed definitively as HCC even in the absence of washout appearance; for 10- to 19- mm masses with arterial phase hyperenhancement, both capsule appearance and washout appearance are required.
Previously, many factors concluding tumor size >5 cm, presence satellite lesions, vascular invasion, KIF3B expression, α-fetoprotein level have been described as important prognostic factors for poor clinical outcome [10-12, 22], but tumor capsule has been described as a protect effect for clinical outcome [12]. Other than these clinical and histological factors, Baek et al. reported that increased 18F-FDG uptake of HCCs, especially high tumor-to-muscle might be correlated with microvascular invasion and poor differentiation, and tends to have a risk for recurrence in HCC [23]. Kitao et al. reported that hypervascular HCCs that hyperintensity relative to the surrounding liver on hepatobiliary phase gadoxetic acid-enhanced MR images demonstrate a significantly higher grade of differentiation, rarer portal vein invasion and lower recurrence rate than those of hypointense HCCs [24]. In addition, Honda et al. reported that the combination of normal hepatic arterial degeneration and preserved portal veins results in low attenuation on CT arteriography and isoattenuation on CT arterioportography in well differentiated lesions, and the combination of neoplastic (abnormal) arterial development by angiogenesis and obliteration of portal veins results in high attenuation on CT arteriography and low attenuation on CT arterioportography in advanced HCC [25].
Recently, some studies have reported that gross vascular invasion, irregular tumour margin and peripheral ragged enhancement, location in the liver and nodule size on CT/MRI for HCC undergoing chemoembolization were independently associated with poor overall survival [13, 14]. Moreover, there is reported that lobular configurations on CT was important independent factor for long-term survival after resection [15]. Li et al. reported that corona enhancement on CT for patients with a single HCC>5cm without extrahepatic metastasis was a significant factor for overall survival [16]. As more prognostic CT features of patients with HCCs undergoing hepatic resection are need to determined, we reviewed various CT findings including tumour size, margin, shape, VI, arterial phase hyperenhancement, washout appearance, capsule appearance, satellite lesion, involvement segment, cirrhosis, peritumoral enhancement and necrosis, and used logistic regression analysis to identify the predictive CT features and set up a prediction model. Univariate analysis showed that CT features including tumor size, margin, shape, VI, washout appearance, satellite lesion, involvement segment, peritumoral enhancement and necrosis were associated with clinical outcome, but only tumor margin and VI of the primary HCC remained independent predictors of clinical outcome in logistic regression analysis. Hence, patients with ill-defined HCCs were more likely to have local relapse or metastases within 2 years after surgery than those with well-defined HCCs, with OR of 6.41. Meanwhile, patients with VI of HCCs were more likely to have local relapse or metastases within 2 years after surgery than those without VI, with OR of 10.92. The logistic regression model was logit(p)= -1.55+1.86 margin +2.39 VI. Further ROC curve analysis showed that the area under curve (AUC) of the obtained logistic regression model was 0.887(95% CI:0.827-0.947)., which indicated that the prediction model was a good predictor of the clinical outcomes.
There were several limitations in our study. First, as a large number of patients are needed for logistic regression analysis, we enrolled patients using 4 or 64-slice spiral CT. Second, no state-of-art CT was used in our study, which might represent more valuable parameters for HCC. It is well known that dual-energy CT is an excellent qualitative as well as a quantitative tool for assessing and predicting hepatocellular carcinoma [26,27]. Further prospective study using state-of-art CT may provide additional information of radiologic risk predictors.