Gd-EOB-DTPA-enhanced MRI for evaluation of liver function: Comparison between signal-intensity-based indices and T1 relaxometry

Diagnostic performance of Gd-EOB-DTPA-enhanced MRI for evaluation of liver dysfunction: a multivariable analysis of 3T MRI sequences

OBJECTIVE

The aim of this study was to evaluate the diagnostic performance of a multiparametric gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced MRI examination for the estimation of liver dysfunction classified by the Model for End-Stage Liver Disease (MELD) score.

RESULTS

Liver dysfunction can be assessed by different methods. In a logistic regression analysis, T1- and T2-weighted images were affected by impaired liver function. In the assessment of liver dysfunction, the reduction rate in T1 mapping sequences showed a significant correlation in simple and multiple logistic regression.

CONCLUSION

Changes in Gd-EOB-DTPA-enhanced MRI between plain images and images obtained during the hepatobiliary phase allowed good prediction of liver dysfunction, especially when using T1 mapping sequences.

MATERIALS AND METHODS

A total of 199 patients underwent contrast-enhanced MRI with a hepatocyte-specific contrast agent at 3T. In the multivariable analysis, the full range of available MRI sequences was used to estimate the liver dysfunction of patients with various MELD scores.

Quantitative Assessment of Liver Function by Using Gadoxetic Acid-enhanced MRI: Hepatocyte Uptake Ratio

Purpose To determine whether hepatocyte uptake ratios derived at gadoxetic acid-enhanced MRI correlate with quantitative measures of liver function and can help to identify contraindication to major hepatectomy. Materials and Methods Between August 2016 and October 2016, 50 study participants with chronic liver disease or cirrhosis underwent liver MRI at 3.0 T including T1 mapping and elastography. Liver function was quantitatively assessed by using the indocyanine green retention test (ICG R₁₅). T1 maps were obtained by using the Look-Locker sequence before and 10 minutes after gadoxetic acid administration (0.025 mmol/kg). The relationship between ICG R₁₅ and the following MRI parameters was evaluated: pre- and postcontrast T1 values of the liver, hepatocyte uptake ratio representing the amount of contrast media solely taken into hepatocytes, liver volume, and degree of enhancement at the common bile duct. Diagnostic performance of the hepatocyte uptake ratio to identify patients with ICG R₁₅ greater than 20% (ie, contraindication to hepatectomy) was compared with other parameters by using areas under the receiver operating characteristic curve. Results Hepatocyte uptake ratio showed a negative correlation with ICG R₁₅ r of -0.78 (P < .001). In participants with chronic liver disease or Child-Pugh class A, those with ICG R₁₅ of 20% or less showed higher hepatocyte uptake ratio than those with ICG R₁₅ greater than 20% (P < .001). Hepatocyte uptake ratios demonstrated better performance for helping to detect ICG R₁₅ greater than 20% than did liver volume (area under the curve, 0.96 vs 0.70; P = .01). Conclusion Hepatocyte uptake ratios are negatively correlated with liver function as measured by indocyanine green retention test and provide acceptable diagnostic performance for helping to identify participants who have contraindications to major hepatectomy. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Reeder in this issue.

Evaluation of two-point Dixon water-fat separation for liver specific contrast-enhanced assessment of liver maximum capacity

Gadoxetic acid-enhanced magnetic resonance imaging has become a useful tool for quantitative evaluation of liver capacity. We report on the importance of intrahepatic fat on gadoxetic acid-supported T1 mapping for estimation of liver maximum capacity, assessed by the realtime ¹³C-methacetin breathing test (¹³C-MBT). For T1 relaxometry, we used a respective T1-weighted sequence with two-point Dixon water-fat separation and various flip angles. Both T1 maps of the in-phase component without fat separation (T1_in) and T1 maps merely based on the water component (T1_W) were generated, and respective reduction rates of the T1 relaxation time (rrT1) were evaluated. A steady considerable decline in rrT1 with progressive reduction of liver function could be observed for both T1_in and T1_W (p < 0.001). When patients were subdivided into 3 different categories of ¹³C-MBT readouts, the groups could be significantly differentiated by their rrT1_in and rrT1_W values (p < 0.005). In a simple correlation model of ¹³C-MBT values with T1_inpost (r = 0.556; p < 0.001), T1_Wpost (r = 0.557; p < 0.001), rrT1_in (r = 0.711; p < 0.001) and rrT1_W (r = 0.751; p < 0.001), a log-linear correlation has been shown. Liver maximum capacity measured with ¹³C-MBT can be determined more precisely from gadoxetic acid-supported T1 mapping when intrahepatic fat is taken into account. Here, T1_W maps are shown to be significantly superior to T1_in maps without separation of fat.

Hepatobiliary MRI: Signal intensity based assessment of liver function correlated to 13C-Methacetin breath test

Gadoxetic acid (Gd-EOB-DTPA) is a paramagnetic MRI contrast agent with raising popularity and has been used for evaluation of imaging-based liver function in recent years. In order to verify whether liver function as determined by real-time breath analysis using the intravenous administration of ¹³C-methacetin can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using signal intensity (SI) values. 110 patients underwent Gd-EOB-DTPA-enhanced 3-T MRI and, for the evaluation of liver function, a ¹³C-methacetin breath test (¹³C-MBT). SI values from before (SI_pre) and 20 min after (SI_post) contrast media injection were acquired by T1-weighted volume-interpolated breath-hold examination (VIBE) sequences with fat suppression. The relative enhancement (RE) between the plain and contrast-enhanced SI values was calculated and evaluated in a correlation analysis of ¹³C-MBT values to SI_post and RE to obtain a SI-based estimation of ¹³C-MBT values. The simple regression model showed a log-linear correlation of ¹³C-MBT values with SI_post and RE (p < 0.001). Stratified by 3 different categories of ¹³C-MBT readouts, there was a constant significant decrease in both SI_post (p ≤ 0.002) and RE (p ≤ 0.033) with increasing liver disease progression as assessed by the ¹³C-MBT. Liver function as determined using real-time ¹³C-methacetin breath analysis can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using SI-based indices.

Basic MRI for the liver oncologists and surgeons

Magnetic resonance imaging (MRI) is the modality of choice for liver imaging due to its superior contrast resolution in comparison with computer tomography and the ability to provide both morphologic and physiologic information. The physics of MR are complex, and a detailed understanding is not required to appreciate findings on an MRI exam. Here, we attempt to introduce the basic principles of MRI with respect to hepatic imaging focusing on various commonly encountered hepatic diseases. The purpose is to facilitate an appreciation of the various diagnostic capabilities of MR among hepatic oncologists and surgeons and to foster an understanding of when MR studies may be appropriate in the care of their patients.

Quantification of hepatic perfusion and hepatocyte function with dynamic gadoxetic acid-enhanced MRI in patients with chronic liver disease

The purpose of the present study was to develop and perform initial validation of dynamic MRI enhanced with gadoxetic acid as hepatobiliary contrast agent to quantify hepatic perfusion and hepatocyte function in patients with chronic liver disease. Free-breathing, dynamic gadoxetic acid-enhanced MRI was performed at 3.0 T using a 3D time-resolved angiography sequence with stochastic trajectories during 38 min. A dual-input three-compartment model was developed to derive hepatic perfusion and hepatocyte function parameters. Method feasibility was assessed in 23 patients with biopsy-proven chronic liver disease. Parameter analysis could be performed in 21 patients (91%). The hepatocyte function parameters were more discriminant than the perfusion parameters to differentiate between patients with minimal fibrosis (METAVIR F0-F1), intermediate fibrosis (F2-F3) and cirrhosis (F4). The areas under the receiver operating characteristic curves (ROCs) to diagnose significant fibrosis (METAVIR F ≥ 2) were: 0.95 (95% CI: 0.87-1; P<0.001) for biliary efflux, 0.88 (95% CI: 0.73-1; P<0.01) for sinusoidal backflux, 0.81 (95% CI: 0.61-1; P<0.05) for hepatocyte uptake fraction and 0.75 (95% CI: 0.54-1; P<0.05) for hepatic perfusion index (HPI), respectively. These initial results in patients with chronic liver diseases show that simultaneous quantification of hepatic perfusion and hepatocyte function is feasible with free breathing dynamic gadoxetic acid-enhanced MRI. Hepatocyte function parameters may be relevant to assess liver fibrosis severity.

T1 mapping on gadoxetic acid-enhanced MR imaging predicts recurrence of hepatocellular carcinoma after hepatectomy

PURPOSE

Our purpose was to demonstrate the prognostic significance of T₁ mapping on gadoxetic acid-enhanced MR imaging in prediction of recurrence of single HCC after hepatectomy.

MATERIALS AND METHODS

One hundred and seven patients with single nodular HCC (≤3 cm) who underwent preoperative gadoxetic acid-enhanced MRI were included in the study. T₁ mapping with syngo MapIt was obtained on a 1.5 T scanner. Radiological features and reduction rate of T₁ relaxation time (Δ%) of tumors were assessed by two radiologists. Cumulative recurrence rates were compared between groups of low and high reduction rate of T₁ relaxation time. A further classified cumulative recurrence rate of the overall cohort was based on the numbers of independent predictive factors.

RESULTS

Reduction rate of T₁ relaxation time (P = 0.001) and non-hypervascular hypointense nodules (P = 0.042) in preoperative gadoxetic acid-enhanced MRI were independently related to recurrence of HCC after hepatectomy. Patients of lower reduction rates group had higher cumulative recurrence rates (P < 0.0001) than patients of higher reduction rates group. A combination of the two risk factors in patients with single HCC had significantly higher recurrence rates compared to those with either or none of the two risk factors.

CONCLUSIONS

Reduction rate of T₁ relaxation time combined with non-hypervascular hypointense nodules can be reliable biomarkers in the preoperative prediction of recurrence of HCC after hepatectomy.