Is 3-Tesla Gd-EOB-DTPA-enhanced MRI with diffusion-weighted imaging superior to 64-slice contrast-enhanced CT for the diagnosis of hepatocellular carcinoma?

Abstract

Objectives: To compare 64-slice contrast-enhanced computed tomography (CT) with 3-Tesla magnetic resonance imaging (MRI) using Gd-EOB-DTPA for the diagnosis of hepatocellular carcinoma (HCC) and evaluate the utility of diffusion-weighted imaging (DWI) in this setting.

Methods: 3-phase-liver-CT was performed in fifty patients (42 male, 8 female) with suspected or proven HCC. The patients were subjected to a 3-Tesla-MRI-examination with Gd-EOB-DTPA and diffusion weighted imaging (DWI) at b-values of 0, 50 and 400 s/mm2. The apparent diffusion coefficient (ADC)-value was determined for each lesion detected in DWI. The histopathological report after resection or biopsy of a lesion served as the gold standard, and a surrogate of follow-up or complementary imaging techniques in combination with clinical and paraclinical parameters was used in unresected lesions. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive values were evaluated for each technique.

Results: MRI detected slightly more lesions that were considered suspicious for HCC per patient compared to CT (2.7 versus 2.3, respectively). ADC-measurements in HCC showed notably heterogeneous values with a median of 1.2±0.5×10-3 mm2/s (range from 0.07±0.1 to 3.0±0.1×10-3 mm2/s). MRI showed similar diagnostic accuracy, sensitivity, and positive and negative predictive values compared to CT (AUC 0.837, sensitivity 92%, PPV 80% and NPV 90% for MRI vs. AUC 0.798, sensitivity 85%, PPV 79% and NPV 82% for CT; not significant). Specificity was 75% for both techniques.

Conclusions: Our study did not show a statistically significant difference in detection in detection of HCC between MRI and CT. Gd-EOB-DTPA-enhanced MRI tended to detect more lesions per patient compared to contrast-enhanced CT; therefore, we would recommend this modality as the first-choice imaging method for the detection of HCC and therapeutic decisions. However, contrast-enhanced CT was not inferior in our study, so that it can be a useful image modality for follow-up examinations.

Figure 1. A 59-year-old male patient with liver cirrhosis (Child A) and HCC (arrow) in segment 7.

Axial images: A) lesion is barely visible using unenhanced T1w-VIBE, B) marked arterial enhancement in T1w-VIBE following i.v. administration of contrast medium, C) typical washout of the lesion in the equilibrium phase (T1w-VIBE), and D) a clear hypointense lesion in the hepatobiliary phase (20 min after contrast agent injection, T1w-VIBE). Similar behaviour was observed with typical contrast medium enhancement in CT: E) early arterial phase after bolus tracking and F) washout in the portal venous phase with pseudocapsule.

Figure 2. Flow chart for identification of patients with HCC in MRI and CT.

Figure 3. A 59-year-old male patient with liver cirrhosis and HCC (arrow) in S3 was only observed using MRI: A) markedly hyperintense HCC in T2w-HASTE axial, B) typical arterial enhancement in T1w-VIBE, and C) hypointense lesion in the hepatobiliary phase.

No lesion was detected using CT: D) early arterial phase and E) portal venous phase.

Figure 4. MRI of a 53-years-old male patient with HCC (arrow) in Segment 5: no lesion was identified in the arterial (A) and equilibrium phases (B), a small hypointense lesion was only observed in the hepatobiliary phase (C) and in DWI, where it is seen as a hyperintense lesion in b 50- (D) and b 400-images (E) and hypointense in the ADC-map (F).

Figure 5. Range of ADC-values (10⁻³ mm²/s) in lesions suspicious for HCC.