Liver T1 relaxation time of the 'normal liver' in healthy Asians: measurement with MOLLI and B1-corrected VFA methods at 3T

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

Background

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).

Methods

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.

Results

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.

Conclusions

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.

Sex-specific associations in multiparametric 3 T MRI measurements in adult livers

BACKGROUND

MRI relaxometry mapping and proton density fat fraction (PDFF) have been proposed for the evaluation of hepatic fibrosis. However, sex-specific relationships of age and body fat with these MRI parameters have not been studied in detail among adults without clinically manifest hepatic disease. We aimed to determine the sex-specific correlation of multiparametric MRI parameters with age and body fat and to evaluate their interplay associations.

METHODS

147 study participants (84 women, mean age 48±14 years, range 19-85 years) were prospectively enrolled. 3 T MRI including T1, T2 and T1ρ mapping and PDFF and R2* map were acquired. Visceral and subcutaneous fat were measured on the fat images from Dixon water-fat separation sequence.

RESULTS

All MRI parameters demonstrated sex difference except for T1ρ. PDFF was more related to visceral than subcutaneous fat. Per 100 ml gain of visceral or subcutaneous fat is associated with 1 or 0.4% accretion of liver fat, respectively. PDFF and R2* were higher in men (both P = 0.01) while T1 and T2 were higher in women (both P < 0.01). R2* was positively but T1 and T2 were negatively associated with age in women (all P < 0.01), while T1ρ was positively related to age in men (P < 0.05). In all studies, R2* was positively and T1ρ was negatively associated with PDFF (both P <0.0001).

CONCLUSION

Visceral fat plays an essential role in the elevated liver fat. When using MRI parametric measures for liver disease evaluation, the interplay between these parameters should be considered.

3D variable flip angle T1 mapping for differentiating benign and malignant liver lesions at 3T: comparison with diffusion weighted imaging

BACKGROUND

Different methods have been used to improve the imaging diagnosis of focal liver lesions (FLL). Among them, magnetic resonance imaging (MRI) has received more attention since it provides significant amount of information without radiation exposure. However, atypical imaging characteristics of FLL on MRI may complicate the differential diagnosis between benign and malignant FLL. This study aimed to compare the diagnostic value of T1 mapping and diffusion-weighted imaging (DWI) for differentiating of benign and malignant FLLs.

METHODS

This retrospective study enrolled 294 FLLs, including 150 benign and 144 malignant lesions. Whole liver T1 mapping sequences were obtained before and 2 min after the administration of Gd-DTPA to acquire native T1 and enhanced T1 and ΔT1%. Additionally, DWI sequence was conducted to generate apparent diffusion coefficient (ADC) maps. These quantitative parameters were compared using one-way analysis of variance, and the diagnostic accuracy of T1 mapping and ADC for FLLs was calculated by area under the curve (AUC).

RESULTS

Significant differences were observed regarding the native T1, enhanced T1, ΔT1%, and ADC between benign and malignant FLLs. Furthermore, the sensitivity and specificity of the parameters are as follows: native T1 0.797/0.702 (cut off value 1635.5 ms); enhanced T1, 0.911/0.976 (cutoff value 339.2 ms); ΔT1%, 0.901/0.905 (cutoff value 70.8%); and ADC, 0.975/0.952 (cutoff value 1.21 × 10^-3 mm²/s). The ideal cutoff values for native T1 and ADC in identifying cyst and haemangioma were 2422.9 ms (AUC 0.990, P < 0.01) and 2.077 × 10^-3 mm²/s (AUC 0.949, P < 0.01), respectively, with a sensitivity and specificity of 0.963/1 and 0.852/0.892, respectively. ADC was significantly positively correlated with T1 and ΔT1%, and significantly negatively correlated with enhanced T1.

CONCLUSION

The 3D Variable flip angle T1 mapping technique with Gd-DTPA has a high clinical potential for identifying benign and malignant FLLs. The enhanced T1 and ΔT1% values have similar diagnostic accuracy compared with DWI in evaluating FLLs. Native T1 shows better performance than DWI in distinguishing benign liver lesions, specifically, cysts, and haemangioma.