Abstract:
Objective To explore the effect of radiologists' qualifications and region of interest (ROI) settings on the evaluation of liver proton density fat fraction (PDFF) by iterative decomposition of water and fat with echo asymmetry and least-squares estimation and image quantification (IDEAL-IQ).
Methods A total of 43 patients(39 males and 4 females, 40.37±14.65 years old) underwent 3D IDEAL-IQ scanning by a GE Discovery MR750W 3.0 T MRI scanner at the First People's Hospital of Foshan. PDFFs were determined on fat fraction maps by three different radiologists with ROIs of 10, 25, and 50 mm2. When the measurement data showed a normal distribution and the variance was homogeneous, one-way ANOVA was used for statistical analysis. The consistency of the same group of data measured repeatedly by the same researcher according to the ROI of different areas with that measured by different radiologists was evaluated via reliability analysis by using SPSS 17.0. Intra-group correlation coefficients (ICC) were used to compare the repeatability of the test results. In this work, alpha>0.8 and ICC>0.75 were used to demonstrate high reliability and repeatability.
Results The PDFFs measured with three different ROIs by the same doctor were (14.17±8.40)%, (13.49±8.42)%, and (13.25±8.39)%, respectively. There was not significant difference (F=0.138, P=0.871).The PDFFs measured by three doctors according to the same ROI respectively were (14.10±8.81)%, (12.75±8.48)% and (14.06±8.22)%, respectively. The difference was not statistically significant (F=0.352, P=0.704). The same radiologists determined the same group of data on the fat fraction maps with different ROIs, and reliability analysis indicated alpha>0.8 and ICC>0.75. These results indicate that the determination of PDFFs with different ROIs has high reliability and repeatability. The three radiologists then measured the same group of data on fat fraction maps with the same ROI, and reliability analysis indicated alpha>0.8 and ICC>0.75. Differences between the PDFFs measured at 10, 20, and 30 mm involved the vertical distance between the center of the ROI and the hepatic envelope.
Conclusions Radiologists' qualifications and ROI settings have no effect on the IDEAL-IQ sequence evaluation of liver PDFF. Measurements made under different qualifications and ROIs by using the IDEAL-IQ technique have high reliability and repeatability.