Intraindividual Comparison of Hepatocellular Carcinoma Washout between MRIs with Hepatobiliary and Extracellular Contrast Agents

Abstract

Objective: To intraindividually compare hepatocellular carcinoma (HCC) washout between MRIs using hepatobiliary agent (HBA) and extracellular agent (ECA).

Materials and methods: This study included 114 prospectively enrolled patients with chronic liver disease (mean age, 55 ± 9 years; 94 men) who underwent both HBA-MRI and ECA-MRI before surgical resection for HCC between November 2016 and May 2019. For 114 HCCs, the lesion-to-liver visual signal intensity ratio (SIR) using a 5-point scale (-2 to +2) was evaluated in each phase. Washout was defined as negative visual SIR with temporal reduction of visual SIR from the arterial phase. Illusional washout (IW) was defined as a visual SIR of 0 with an enhancing capsule. The frequency of washout and MRI sensitivity for HCC using LR-5 or its modifications were compared between HBA-MRI and ECA-MRI. Subgroup analysis was performed according to lesion size (< 20 mm or ≥ 20 mm).

Results: The frequency of portal venous phase (PP) washout with HBA-MRI was comparable to that of delayed phase (DP) washout with ECA-MRI (77.2% [88/114] vs. 68.4% [78/114]; p = 0.134). The frequencies were also comparable when IW was allowed (79.8% [91/114] for HBA-MRI vs. 81.6% [93/114] for ECA-MRI; p = 0.845). The sensitivities for HCC of LR-5 (using PP or DP washout) were comparable between HBA-MRI and ECA-MRI (78.1% [89/114] vs. 73.7% [84/114]; p = 0.458). In HCCs < 20 mm, the sensitivity of LR-5 was higher on HBA-MRI than on ECA-MRI (70.8% [34/48] vs. 50.0% [24/48]; p = 0.034). The sensitivity was similar to each other if IW was added to LR-5 (72.9% [35/48] for HBA-MRI vs. 70.8% [34/48] for ECA-MRI; p > 0.999).

Conclusion: Extracellular phase washout for HCC diagnosis was comparable between MRIs with both contrast agents, except for tumors < 20 mm. Adding IW could improve the sensitivity for HCC on ECA-MRI in tumors < 20 mm.

Keywords: Extracellular contrast; Gadoxetic acid; Hepatocellular carcinoma; Magnetic resonance imaging; Washout.

Fig. 1. Flowchart of study participants.

ECA = extracellular agent, HBA = hepatobiliary agent, HCC = hepatocellular carcinoma

Fig. 2. A 46-year-old man with hepatitis B-related liver cirrhosis and hepatocellular carcinoma.

A–C. On the axial T1-weighted 3D turbo field-echo images obtained after gadoxetic acid injection, a 35 mm mass at hepatic segment VII shows (A) non-rim APHE (lesion-to-liver visual SIR, +2), (B) PP washout (visual SIR, −2; temporal reduction in enhancement from AP, −4), and (C) transitional phase washout (visual SIR, −2). D–F. On the axial T1-weighted 3D turbo field-echo images obtained after gadoterate meglumine administration, the mass reveals (D) non-rim APHE (visual SIR, +2), (E) mild hyperintensity (visual SIR, +1) and an enhancing capsule in PP, and (F) delayed phase washout (visual SIR, −2; temporal reduction in enhancement from AP, −4). LR-5 category was assigned on both MRIs by both readers using extracellular phase washout. AP = arterial phase, APHE = arterial phase hyperenhancement, LR-5 = Liver Imaging Reporting and Data System category 5, PP = portal venous phase, SIR = signal intensity ratio, 3D = three-dimensional

Fig. 3. A 60-year-old man with hepatitis B-related liver cirrhosis and hepatocellular carcinoma.

A–C. On the axial T1-weighted 3D turbo field-echo images obtained after gadoxetic acid injection, a 30-mm mass at hepatic segment VII shows (A) non-rim APHE (visual SIR, +2), (B) PP washout (visual SIR, −1; temporal reduction in enhancement from AP, −3) as well as an enhancing capsule, and (C) transitional phase washout (visual SIR, −2; a temporal reduction from AP, −4). D–F. On the axial T1-weighted 3D turbo field-echo images obtained after gadoterate meglumine administration, the mass reveals (D) non-rim APHE (visual SIR, +2). Isointensities in (E) PP (visual SIR, 0) and (F) delayed phase (visual SIR, 0) and an enhancing capsule indicate IW. LR-5 category was assigned on both MRIs by both readers. However, true washout is present only with hepatobiliary agent-enhanced MRI, while IW is observed with extracellular agent-enhanced MRI. AP = arterial phase, APHE = arterial phase hyperenhancement, IW = illusional washout, LR-5 = Liver Imaging Reporting and Data System category 5, PP = portal venous phase, SIR = signal intensity ratio, 3D = three-dimensional

Fig. 4. Frequency of washout according to MRI contrast media.

TP indicates washout assessed in TP. IW indicates incorporating IW in the washout definition. DP = delayed phase, ECA = extracellular agent, HBA = hepatobiliary agent, IW = illusional washout, PP = portal venous phase, TP = transitional phase

Fig. 5. Sensitivity of LR-5 criteria for hepatocellular carcinoma according to washout definition.

As modified LR-5 criteria, TP indicates using washout assessed in TP, and IW indicates allowing IW as washout. DP = delayed phase, ECA = extracellular agent, HBA = hepatobiliary agent, IW = illusional washout, LR-5 = Liver Imaging Reporting and Data System category 5, PP = portal venous phase, TP = transitional phase