Rapid liver tissue characterization using simultaneous multi-relaxation-time imaging: a comparative study with...

With the increasing need for accurate liver disease diagnostics, non-invasive imaging techniques with rapid and precise quantitative measurements need to be established. This study introduced and validated the application of simultaneous multi-relaxation-time imaging (TXI) for the quantitative assessment of liver tissue by simultaneously acquiring proton density fat fraction (PDFF), lateral relaxation rate (R2*), and longitudinal relaxation time (T1) maps. It aimed to compare the accuracy and consistency of TXI with established quantitative magnetic resonance imaging (MRI) techniques, such as three-dimensional variable flip angle (VFA) T1 mapping, and multi-point quantitative Dixon (qDixon), in healthy volunteers and patients diagnosed with non-alcoholic fatty liver disease (NAFLD).

A prospective cohort of 35 healthy volunteers (mean age: 52±13 years, 21 women) and nine NAFLD patients (mean age: 48±13 years, 6 women) underwent liver MRI using TXI, VFA T1 mapping, and qDixon sequences. Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to assess inter-observer agreement and measurement consistency. Paired T-tests and Pearson correlation coefficients were used to compare the TXI measurements with those from conventional MRI techniques. Differences between the healthy volunteers and NAFLD patients were evaluated using the independent sample T-test.

The ICCs for the TXI-derived T1, R2*, and PDFF in healthy volunteers were 0.985 [95% confidence interval (CI): 0.971-0.993], 0.999 (95% CI: 0.998-1.000), and 0.995 (95% CI: 0.990-0.997), respectively, indicating excellent agreement. The regression analysis revealed strong correlations between the TXI and reference MRI measurements for the T1 (R²=0.895), R2* (R²=0.984), and PDFF (R²=0.894) values with no significant differences (P=0.713, 0.090, and 0.072, respectively). Statistically significant differences were observed in the R2* (P=0.045) and PDFF (P<0.001) values between the NAFLD patients and healthy volunteers, but no significant difference was observed in the T1 values (P=0.965). Multiparametric imaging showed that TXI provides comprehensive liver tissue characterization, consistent with conventional MRI techniques.

TXI offers a rapid and reliable method for the simultaneous acquisition of T1, R2*, and PDFF maps, and has high consistency with established quantitative MRI techniques. This approach has significant potential for non-invasive liver tissue characterization in clinical settings, particularly in the diagnosis and monitoring of conditions such as NAFLD.