The Effect of Liver Iron Deposition on Hepatic Apparent Diffusion Coefficient Values in Cirrhosis

OBJECTIVE. The purpose of this study was to assess the effect of hepatic iron deposition on apparent diffusion coefficient (ADC) values measured with single-shot echo-planar imaging (EPI) diffusion-weighted MRI (DWI) in patients with liver cirrhosis and in vitro. MATERIALS AND METHODS. Fifty-two patients with liver cirrhosis who underwent breath-hold single-shot EPI DWI at 1.5 T before liver transplantation were retrospectively assessed. Estimated signal-to-noise ratio (SNRest) and ADC were measured in the right hepatic lobe (for b values of 50 and 500 s/mm(2)). SNRest and ADC were compared between patients stratified by pathologic iron grade using the Mann-Whitney test. Hepatic ADC values were correlated to T2* values using the Spearman correlation test in a subset of patients. In addition, a phantom consisting of solutions of varying iron concentrations was imaged with single-shot EPI DWI and T2* imaging, and iron concentration was correlated with ADC and T2*. RESULTS. In phantoms, there was a decrease in ADC and T2* with increasing iron concentration (r = -0.95 and -0.92, respectively; p < 0.05). Patients with hepatic siderosis had significantly lower SNRest and ADC compared with patients without siderosis (p < 0.0001). SNRest at b = 50 s/mm(2) and b = 500 s/mm(2) and ADC had a significant negative correlation with pathologic iron grade (r = -0.67 to 0.77, p < 0.0001). There was a significant correlation between liver T2* and ADC (r = 0.83, p < 0.0001). CONCLUSION. Hepatic siderosis lowers liver ADC and should be taken into account when using ADC for diagnosing liver cirrhosis.