Chronic liver disease: Quantitative MRI vs CEUS-based microperfusion.

Purpose: To compare the diagnostic performance of MRI-based T1 relaxometry with dynamic contrast-enhanced ultrasound (CEUS)-based liver microcirculation for evaluation of liver function.

Materials and Methods: 22 patients underwent Gd-EOB-DTPA-enhanced MRI with T1 relaxometry and previous or consecutive CEUS examinations. A transverse 3D VIBE sequence with an inline T1 calculation was acquired and the reduction rate of T1 relaxation time (rrT1) was evaluated. For CEUS measurements (1-6 MHz), a bolus injection of 1.4 ml sulfur hexafluoride microbubbles were administered and both cine loops and single images from arterial phase up to late phase were stored.Quantification of time to peak (TTP), rise time (RT), Wash- In Area Under the Curve (WiAUC), mean transit time (mTTI), the wash- in rate (WiR) and Wash-in perfusion index (WIPI)) was performed using a novel quantification software (VueBoxTM). To compare quantification parameters, patients were classified in patients representing a healthy population (rrT1 > 50%, n = 8) and those representing patients with liver disease (rrT1 < 50%, n = 14).

Results: Comparing perfusion parameters TTP, mTTI, and WiR were higher in patients without liver disease compared to patients with impaired liver function (p = 0.10-0.21). RT, WiAUC and WIPI were significantly lower in patients with impaired liver function (RT, 14.8±1.5 s; WiAUC, 17288±6179 a.u., WIPI, 1243±423) compared to patients without liver disease (RT, 21.2±2.6 s, p = 0.032; WiAUC, 71534±25600, p = 0.034; WIPI, 4286±1748, p = 0.04). In a simple linear regression model, none of the perfusion parameters correlated significantly with rrT1 (p = 0.08-0.63).

Conclusion: Within the framework of this study, CEUS-based perfusion parameters were not able to assess severity of liver disease, however, WiAUC, RT and WIPI were significant perfusion parameters to make a rough assessment of liver function.