The value of hepatic diffusion-weighted MR imaging in demonstrating hepatic congestion secondary to pulmonary hypertension

Abstract

Background: Congestive hepatomegaly might be the first sign for pulmonary hypertension. Apparent diffusion coefficient (ADC) value obtained with quantitative diffusion-weighted magnetic resonance imaging (DW-MRI) is affected by liver fibrosis and perfusion. We aimed to evaluate the diagnostic value of DW-MRI in cooperation with biochemical markers, ultrasonography (US) and echocardiography (TTE) in determining the degree of hepatic congestion secondary to pulmonary hypertension (PHT).

Methods: 35 patients with PHT and 26 control subjects were included in the study. PHT was diagnosed if pulmonary artery systolic pressure (PASP) was measured above 35 mmHg with TTE. Study group was classified into mild and moderate PHT. DW-MRI was performed with b-factors of 0, 500 and 1000 sec/mm(2). Mean ADC, ADC-II (Average of the ADC values of right lobe anterior and posterior segments), US, TTE and blood biochemical parameters of both groups were compared.

Results: There exists a positive correlation between liver size and the diameters of vena cava inferior, right atrium, right hepatic vein(RHV), mid-hepatic vein(MHV), left hepatic vein(LHV) (p < 0.01). There was a positive correlation between PASP and RHV, MHV, LHV. The patients had lower ejection fractions (p < 0.01) and higher LDH (p < 0.01) and ALP (p < 0.05) levels than the control group. The ADC values of the patients with moderate PASP were higher than those with a mild PASP (p < 0.05). Mean ADC was higher in patients with moderate PHT compared to control group (p = 0.009). There was a positive correlation between PASP and ADC values of right lobe posterior segment of the liver (p < 0.05). The ADC-II and mean ADC values of the patients with moderate PASP were higher than those of the control group (p < 0.01).

Conclusions: Congestion due to moderate PHT might be diagnosed with DW-MRI. As PASP increase; mean ADC and ADC-II values increase.

Figure 1

Bar graphic of the distribution of mean ADC by the degree of PHT. Abb: ADC; Apparent diffusion coefficient, PHT; Pulmonary arterial hypertension.

Figure 2

MRI sequences of a patient with moderate PHT (43 year old female). There is slight enlargement of IVC and hepatic veins. A Coronal T2-weighted sequence, B Axial T2-weighted sequence C Axial diffusion-weighted image (b = 1000 s/mm²), D ADC map of the same patient; calculated ADC was 1.86 × 10ˉ³ mm²/s (increased diffusion due to intercellular fluid accumulation that is not apparent visually, however detectable with ADC calculation).