Three-Tesla magnetic resonance elastography for hepatic fibrosis: comparison with diffusion-weighted imaging and gadoxetic acid-enhanced magnetic resonance imaging

Abstract

Aim: To evaluate the feasibility of 3-Tesla magnetic resonance elastography (MRE) for hepatic fibrosis and to compare that with diffusion-weighted imaging (DWI) and gadoxetic acid-enhanced magnetic resonance (MR) imaging.

Methods: Forty-two patients were included in the study. On MRE, mean stiffness values were measured on the elastograms in kilopascals. The apparent diffusion coefficient (ADC) of the liver was measured using DWI. On gadoxetic acid enhanced MR, the contrast enhancement index (CEI) was calculated as signal intensity (SI)post/SIpre, where SIpost is liver-to-muscle SI ratio on hepatobiliary phase images and SIpre is that on nonenhanced images. Correlation between aspartate aminotransferase to the platelet ratio index (APRI) and three MR parameters was assessed. Each MR parameter was compared between a hepatic fibrosis (HF) group and non-hepatic fibrosis (nHF) group.

Results: Liver stiffness showed strong positive correlation with APRI [Spearman correlation coeffiecient (r) = 0.773, P < 0.0001], while ADC and CEI showed weak or prominent negative correlation (r = -0.28 and -0.321, respectively). In the HF group, only liver stiffness showed strong correlation with APRI (r = 0.731, P < 0.0001). Liver stiffness, ADC, and APRI were significantly different between the HF group and nHF group.

Conclusion: MRE at 3-Tesla could be a feasible method for the assessment of hepatic fibrosis.

Keywords: Diffusion weighted imaging; Gadoxetic acid enhanced magnetic resonance imaging; Hepatic fibrosis; Magnetic resonance elastography; Serum markers.

Figure 1

Flow chart of the study profile based on recommended standards for reporting diagnostic accuracy. MR: Magnetic resonance; MRE: Magnetic resonance elastography; HBV: Hepatitis B virus; HCV: Hepatitis C virus; NAFLD: Non-alcoholic fatty liver disease.

Figure 2

Graphs showing scattergrams and lines of correlation between aspartate aminotransferase to the platelet ratio index score and three magnetic resonance parameters, which are liver stiffness (A), apparent diffusion coefficient (B), and contrast enhancement ratio (C). Dotted curved lines represent 95%CIs. ADC: Apparent diffusion coefficient; CEI: Contrast enhancement ratio; APRI: Aspartate aminotransferase to the platelet ratio index.

Figure 3

A 58-year-old man in the hepatic fibrosis group, who had hepatitis B virus-associated liver cirrhosis. A: T2-weighted reference image on which the measurement of three MR parameters were performed; B: MRE (95% confidence map) shows increased stiffness value of 11.64 kPa (asterisk) in the right lobe of the liver; C: Wave image shows elongated wavelength of the corresponding liver parenchyma; D: ADC map of the DWI image with b = 400 at the same level as A. Measured ADC value was 1.011 × 10^-3 mm²/s; E: Hepatobiliary phase image of gadoxetic acid-enhanced MR at the same level as A. Measured CEI was 1.701. MR: Magnetic resonance; MRE: Magnetic resonance elastography; DWI: Diffusion weighted image; ADC: Apparent diffusion coefficient; CEI: Contrast enhancement ratio.

Figure 4

A 20-year-old woman in the non-hepatic fibrosis group, with incidental hepatic mass (biopsy proven focal nodular hyperplasia later) on screening. A: T2-weighted reference image on which the measurement of three MR parameters were performed; B: MRE (95% confidence map) shows normal range stiffness value of 1.88 kPa (asterisk) in the right lobe of the liver; C: Wave image shows normal range (not elongated) wavelength of the corresponding liver parenchyma; D: ADC map of the DWI image with b = 400 at the same level as A. Measured ADC value was 1.119 × 10^-3 mm²/s; E: Hepatobiliary phase image of gadoxetic acid-enhanced MR at the same level as A. Measured CEI was 1.826. MR: Magnetic resonance; MRE: Magnetic resonance elastography; DWI: Diffusion weighted image; ADC: Apparent diffusion coefficient; CEI: Contrast enhancement ratio.