Reproducibility of liver R2* quantification for liver iron quantification from cardiac R2* acquisitions

Abstract

Objectives To evaluate the reproducibility of liver R2* measurements between a 2D cardiac ECG-gated and a 3D breath-hold liver CSE-MRI acquisition for liver iron quantification. Methods A total of 54 1.5 T MRI exams from 51 subjects (18 women, 36 men, age 35.2 ± 21.8) were included. These included two sub-studies with 23 clinical MRI exams from 19 patients identified retrospectively, 24 participants with known or suspected iron overload, and 7 healthy volunteers acquired prospectively. The 2D cardiac and the 3D liver R2* maps were acquired in the same exam. Either acquisitions were reconstructed using a complex R2* algorithm that accounts for the presence of fat and residual phase errors due to eddy currents. Data were analyzed using colocalized ROIs in the liver. Results Linear regression analysis demonstrated high Pearson’s correlation and Lin’s concordance coefficient for the overall study and both sub-studies. Bland–Altman analysis also showed good agreement, except for a slight increase of the mean R2* value above ~ 400 s−1. The Kolmogorow–Smirnow test revealed a non-normal distribution for (R2* 3D–R2* 2D) values from 0 to 600 s−1 in contrast to the 0–200 s−1 and 0–400 s−1 subpopulations. Linear regression analysis showed no relevant differences other than the intercept, likely due to only 7 measurements above 400 s−1. Conclusions The results demonstrate that R2*-measurements in the liver are feasible using 2D cardiac R2* maps compared to 3D liver R2* maps as the reference. Liver R2* may be underestimated for R2* > 400 s−1 using the 2D cardiac R2* mapping method.

Hepatic Iron Quantification Using a Free‐Breathing 3D Radial Gradient Echo Technique and Validation With a 2D Biopsy‐Calibrated R2* Relaxometry Method

“…This study results show that, despite the differences in acquisition and fitting methods, R 2 * values obtained with 3D BH cGRE and 3D FB rGRE showed excellent agreement between each other and with biopsy‐calibrated 2D BH GRE across a wide range of HIC values, with slopes close to unity and very low mean biases. Further, the 95% LOA for both R 2 * and FF comparisons between the different acquisition methods in this study were similar as in the previously reported R 2 * and FF inter‐method and inter‐scanner reproducibility studies 19,32 . Notably, compared to 2D and 3D Cartesian fitting methods, the absence of magnitude noise correction for 3D rGRE did not lead to a strong bias in the R 2 * range, and for the acquisition parameters used in this study.…”

“…Further, the 95% LOA for both R 2 * and FF comparisons between the different acquisition methods in this study were similar as in the previously reported R 2 * and FF inter-method and interscanner reproducibility studies. 19,32 Notably, compared to 2D and 3D Cartesian fitting methods, the absence of magnitude noise correction for 3D rGRE did not lead to a strong bias in the R 2 * range, and for the acquisition parameters used in this study. A recent study by Henninger et al performed in a large group of adult patients demonstrated a very good agreement (R 2 = 0.95) between R 2 * values obtained with 3D BH cGRE and those obtained with a different biopsy-calibrated 2D BH GRE method.…”

Quantifying Liver Heterogeneity via R2*-MRI with Super-Paramagnetic Iron Oxide Nanoparticles (SPION) to Characterize Liver Function and Tumor

“…When T2* is transformed into reciprocal R2* (i.e., R2* [Hz] = 1000/T2* [ms]), it shows a strong correlation with hepatic iron deposition in the liver [ 20 ] as well as the breath-hold gradient echo (GRE)-based 2D and 3D T2*- and R2*-MRI. For these reasons, T2* is increasingly used to image the entire liver in a shorter acquisition time [ 21 ].…”