Validation of liver quantitative susceptibility mapping across imaging parameters at 1.5 T and 3.0 T using SQUID susceptometry as reference
Ruiyang Zhao, Julia Velikina, Scott B. Reeder, Shreyas Vasanawala, Michael Jeng, Diego Hernando
Abstract
Purpose
To validate QSM-based biomagnetic liver susceptometry (BLS) to measure liver iron overload at 1.5 T and 3.0 T using superconducting quantum interference devices (SQUID)-based BLS as reference.
Methods
Subjects with known or suspected iron overload were recruited for QSM-BLS at 1.5T and 3.0T using 8 different protocols. SQUID-BLS was also obtained in each subject, to provide a susceptibility reference. A recent QSM method based on data-adaptive regularization was used to obtain susceptibility and R2* maps. Measurements of susceptibility and R2* were obtained in the right liver lobe. Linear mixed-effects analysis was used to estimate the contribution of specific acquisition parameters to QSM-BLS. Linear regression and Bland-Altman analyses were used to assess the relationship between QSM-BLS and SQUID-BLS/R2*.
Results
Susceptibility maps showed high subjective quality for each acquisition protocol across different iron levels. High linear correlation was observed between QSM-BLS and SQUID-BLS at 1.5T (r2 range: [0.82, 0.84]) and 3.0T (r2 range: [0.77, 0.85]) across different acquisition protocols. QSM-BLS and R2* were highly correlated at both field strengths (r2 range at 1.5T: [0.94, 0.99], 3.0T: [0.93, 0.99]). High correlation (r2 = 0.99) between 1.5T and 3.0T QSM-BLS, with narrow reproducibility coefficients (range: [0.13, 0.21] ppm) were observed for each protocol.
Conclusion
This work evaluated the feasibility and performance of liver QSM-BLS across iron levels and acquisition protocols at 1.5 T and 3.0 T. High correlation and reproducibility were observed between QSM-BLS and SQUID-BLS across protocols and field strengths. In summary, QSM-BLS may enable reliable and reproducible quantification of liver iron concentration.