Quantitative characterization of hepatocellular carcinoma and metastatic liver tumor by CT perfusion

Abstract

Purpose: To evaluate the diagnostic value of computed tomography perfusion (CTP) in the distinction of hepatocellular carcinomas (HCCs) from metastatic liver tumors.

Materials and methods: CTP data from 90 liver tumors (HCC 38, metastasis 52) in 31 patients (16 men and 15 women; mean age 60.3 years) were studied. CTP was performed on a 16/64 multidetector-row CT scanner using a 30-s duration cine acquisition after rapid bolus injection (5-7 ml/s) of 50-70 ml of iodinated contrast medium. The CTP data were analyzed using a deconvolution model. Metastatic tumors were grouped into hypovascular (n = 36) and hypervascular (n = 16) tumors.

Results and conclusion: The hypovascular metastases showed a significantly lower blood flow (BF) and blood volume (BV), and higher mean transit time (MTT) than HCC (all P < 0.0001). BF, BV, and MTT of HCCs were substantially lower than those of hypervascular metastases (P = 0.02, P < 0.0001, P = 0.03, respectively). A receiver-operating characteristic analysis showed that BV was a useful marker to distinguish HCCs from hypervascular metastases.

Figure 1

Transverse CT perfusion functional map of BF, BV, and MTT in a 65-year-old woman. A region of interest was drawn freehand around the peripheral boundary of the visible tumor.

Figure 2

Arterial phase CECT images. Metastatic liver tumors were grouped into hypervascular tumors (A) and hypovascular tumors (B).

Figure 3

The diagnostic values of CTP parameters in distinguishing HCCs from hypervascular metastases were also evaluated by ROC analysis. The areas under the ROC curves of BF, BV, and MTT were 0.70, 0.95, and 0.69, respectively.

Figure 4

Differentiation of HCC from other hypervascular metastasis in the liver is occasionally difficult. However, we observed clear differences in their BV value. (A) HCC (BV = 6.9). (B) Metastases of a pancreatic endocrine tumor (BV = 10.4).