Multicenter, multivendor validation of liver quantitative susceptibility mapping in patients with iron overload at 1.5T and 3T

PurposeTo evaluate the repeatability and reproducibility of QSM of the liver via single breath‐hold chemical shift–encoded MRI at both 1.5 T and 3 T in a multicenter, multivendor study in subjects with iron overload.MethodsThis prospective study included four academic medical centers with three different MRI vendors at 1.5 T and 3 T. Subjects with known or suspected liver iron overload underwent multi‐echo spoiled gradient‐recalled‐echo scans at each field strength. A subset received repeatability testing at either 1.5 T or 3 T. Susceptibility and R2*$$ {\mathrm{R}}_2^{\ast } $$ maps were reconstructed from the multi‐echo images and analyzed at a single center. QSM‐measured susceptibility was compared with R2*$$ {\mathrm{R}}_2^{\ast } $$ and a commercial R2‐based liver iron concentration method across centers and field strengths using linear regression and F‐tests on the intercept and slope. Field‐strength reproducibility and test/retest repeatability were evaluated using Bland–Altman analysis.ResultsA total of 155/80 data sets (test/retest) were available at 1.5 T, and 159/70 data sets (test/retest) were available at 3 T. Calibrations across sites were reproducible, with some variability (e.g., susceptibility slope with liver iron concentration ranged from 0.102 to 0.123 g/[mg·$$ \cdotp $$ppm] across centers at 1.5 T). Field strength reproducibility was good (concordance correlation coefficient = 0.862), and test/retest repeatability was excellent (intraclass correlation coefficient = 0.951).ConclusionQSM as an imaging biomarker of liver iron overload is feasible and repeatable across centers and MR vendors. It may be complementary with R2*$$ {\mathrm{R}}_2^{\ast } $$ as they are obtained from the same acquisition. Although good reproducibility was observed, liver QSM may benefit from standardization of acquisition parameters. Overall, QSM is a promising method for liver iron quantification.