Assessment of small hepatocellular carcinoma: perfusion quantification and time-concentration curve evaluation using color-coded and quantitative digital subtraction angiography

Abstract

To explore the role of quantitative digital subtraction angiography (QDSA) in the diagnosis of small hepatocellular carcinoma (HCC).Between November 2015 and November 2017, all patients who underwent chemoembolization for HCC were retrospectively reviewed. Patients with tumors measuring more than 5 cm or evident post-processing imaging artifacts were excluded. Images were post-processed using the QDSA technique. Regions of interest were manually drawn on proper hepatic artery (as a reference), target HCC and peritumoral liver. Time-concentration curves and flow parameters of the peak ratio, subtracted time-to-peak (TTP), and area under the curve (AUC) ratio was obtained and analyzed.A total of 146 HCCs (mean diameter, 1.6 cm) of 71 cirrhotic patients (54 men, 17 women; mean age, 67.7 years) were enrolled. Compared with liver parenchyma, HCCs showed an increased and more rapid flow (peak ratio, AUC ratio, subtracted TTP, and wash-in slope; all P <.001). Compared with untreated HCCs, chemoembolized HCCs showed a slower flow (subtracted TTP and wash-in slope, P = .004 and .002, respectively). HCCs with a typical enhancement pattern on computed tomography (CT) or magnetic resonance imaging (MRI) had a trend toward Type III (washout pattern) time-concentration curves (P <.001). Chemoembolized HCCs had a trend toward Type II (plateau pattern) time-concentration curves (P = .005).QDSA technology can be used to quantify perfusion measurements of HCC and hepatic parenchyma and to assess perfusion changes after HCC chemoembolization.

Figure 1

Five regions of interest [ROIs; 1 on the proper hepatic artery as a reference, 2 on the target HCC, and the other 2 on the peritumoral liver parenchyma for average measurements] were manually drawn. Time-concentration curves were obtained for each ROI, along with 3 parameters: the peak ratio, TTP attenuation, and AUC ratio. AUC = area under the curve, HCC = hepatocellular carcinoma, ROI = regions of interest, TTP = time-to-peak.

Figure 2

Time-concentration curves were obtained for each ROI and divided into 3 types. The Type I curve (progressive pattern) shows slowly progressive enhancement over time. The Type II curve (plateau pattern) shows relatively rapid enhancement followed by the plateau phase. The Type III curve (washout pattern) shows rapid enhancement followed by the early washout pattern. In this case, cirrhotic liver parenchyma showed a Type I curve and the HCC showed a Type III curve. Angiography also showed a hypervascular lesion in segment 6, which had a Type II curve. Arterioportal shunt was suspected because the follow-up images showed no retention of the embolized fragment after transarterial chemoembolization. HCC = hepatocellular carcinoma.