The usefulness of contrast-enhanced ultrasonography in the early detection of hepatocellular carcinoma viability after transarterial chemoembolization: pilot study

Abstract

Background/aims: The therapeutic effect of transarterial chemoembolization (TACE) against hepatocellular carcinoma (HCC) is usually assessed using multidetector computed tomography (MDCT). However, dense lipiodol depositions can mask the enhancement of viable HCC tissue in MDCT. Contrast-enhanced ultrasonography (CEUS) could be effective in detecting small areas of viability and patency in vessels. We investigated whether arterial enhancement in CEUS after treatment with TACE can be used to detect HCC viability earlier than when using MDCT.

Methods: Twelve patients received CEUS, MDCT, and gadoxetic-acid-enhanced dynamic magnetic resonance imaging (MRI) at baseline and 4 and 12 weeks after TACE. The definition of viable HCC was defined as MRI positivity after 4 or 12 weeks.

Results: Eight of the 12 patients showed MRI positivity at 4 or 12 weeks. All patients with positive CEUS findings at 4 weeks (n=8) showed MRI positivity and residual viable HCC at 4 or 12 weeks. Five of the eight patients with positive CEUS findings at 4 weeks had negative results on the 4-week MDCT scan. Four (50%) of these eight patients did not have MRI positivity at 4 weeks and were ultimately confirmed as having residual HCC tissue at the 12-week MRI. Kappa statistics revealed near-perfect agreement between CEUS and MRI (κ=1.00) and substantial agreement between MDCT and MRI (κ=0.67).

Conclusions: In the assessment of the response to TACE, CEUS at 4 weeks showed excellent results for detecting residual viable HCC, which suggests that CEUS can be used as an early additive diagnosis tool when deciding early additional treatment with TACE.

Keywords: Computed tomography; Contrast-enhanced ultrasonography; Hepatocellular carcinoma; Magnetic resonance imaging; Transarterial chemoembolization.

Figure 1. Flow chart of the study. CEUS, contrast-enhanced ultrasonography; MDCT, multidetector computer tomography; MRI, magnetic resonance imaging; TACE, transarterial chemoembolization.

Figure 2. A typical hepatocellular carcinoma showing the characteristic arterial-phase hypervascularity and late-phase washout. (A) multidetector computed tomography (MDCT) finding, arterial phase (B) grey-scale ultrasonography, (C) contrast-enhanced ultrasonography (CEUS), arterial phase, (D) CEUS, late phase.

Figure 3. A 76-year-old patient with an hepatocellular carcinoma (HCC) on segment 5 at 4 weeks after transarterial chemoembolization (TACE). The image shows positivity for viable tissue in contrast-enhanced ultrasonography (CEUS) and gadoxetic-acid-enhanced dynamic magnetic resonance imaging (MRI) without evidence of viable tissue on multidetector computed tomography (MDCT). (A) Arterial phase and (B) late phase of CEUS. These showed slight enhancements (arrow) of peripheral portions of HCC in the arterial phase and wash-out in the late phase of CEUS. (C) Arterial and (D) delayed phase of MDCT. These showed compact lipiodol retention without viable tissue. (E) Arterial phase and (F) hepatobiliary phase of T1 weighted-MRI. The MRI shows intratumoral enhancement in the posterior aspect of the lesion (arrow: same aspect of CEUS enhancements) in the arterial phase and more defi nite hypointensity in the hepatobiliary phase image, which suggests an incomplete tumor response.