Evaluating the severity of nonalcoholic steatohepatitis with superparamagnetic iron oxide-enhanced magnetic resonance imaging

Purpose: To evaluate the utility of noninvasive assessment of human nonalcoholic fatty liver disease (NAFLD) patients using superparamagnetic iron oxide (SPIO)-enhanced MRI. Materials and Methods: Nineteen NAFLD patients underwent SPIO-enhanced MRI. The values of τ, a time constant for an exponential approximation, were calculated using gradient-echo echo-planar imaging, and the values of %T2, a marker of the T2 relaxation effect of SPIO, were calculated using T2-weighted fast spin-echo images. Correlations between these values and the histological NAFLD activity scores were evaluated. The study protocol was approved by our Institutional Review Board and all patients gave informed consent. Results: There was a statistically significant relationship between the NAFLD activity scores and the τ values (r = 0.66, P = 0.002). The %T2 values were also significantly correlated with the NAFLD activity score (r = -0.58, P = 0.009). A cutoff τ value of 42.8 predicted "definitive NASH" (NAFLD activity score ≥5) with a specificity of 66.7% and a sensitivity of 99.9%, whereas a cutoff %T2 value of 32.5 predicted "definitive NASH" with a specificity of 72.7% and a sensitivity of 87.5%. Conclusion: Noninvasive SPIO-enhanced MRI may be helpful for identifying NASH patients among patients suspected of having NAFLD.