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Background MRI is a standard of care tool to measure liver iron concentration (LIC). Compared with regulatory-approved R2 MRI, R2* MRI has superior speed and is available in most MRI scanners; however, the cross-vendor reproducibility of R2*-based LIC estimation remains unknown. Purpose To evaluate the reproducibility of LIC via single-breath-hold R2* MRI at both 1.5 T and 3.0 T with use of a multicenter, multivendor study. Materials and Methods Four academic medical centers using MRI scanners from three different vendors (three 1.5-T scanners, one 2.89-T scanner, and two 3.0-T scanners) participated in this prospective cross-sectional study. Participants with known or suspected liver iron overload were recruited to undergo multiecho gradient-echo MRI for R2* mapping at 1.5 T and 3.0 T (2.89 T or 3.0 T) on the same day. R2* maps were reconstructed from the multiecho images and analyzed at a single center. Reference LIC measurements were obtained with a commercial R2 MRI method performed using standardized 1.5-T spin-echo imaging. R2*-versus-LIC calibrations were generated across centers and field strengths using linear regression and compared using F tests. Receiver operating characteristic (ROC) curve analysis was used to determine the diagnostic performance of R2* MRI in the detection of clinically relevant LIC thresholds. Results A total of 207 participants (mean age, 38 years ± 20 [SD]; 117 male participants) were evaluated between March 2015 and September 2019. A linear relationship was confirmed between R2* and LIC. All calibrations within the same field strength were highly reproducible, showing no evidence of statistically significant center-specific differences ( P > .43 across all comparisons). Calibrations for 1.5 T and 3.0 T were generated, as follows: for 1.5 T, LIC (in milligrams per gram [dry weight]) = -0.16 + 2.603 × 10 -2 R2* (in seconds -1 ); for 2.89 T, LIC (in milligrams per gram) = -0.03 + 1.400 × 10 -2 R2* (in seconds -1 ); for 3.0 T, LIC (in milligrams per gram) = -0.03 + 1.349 × 10 -2 R2* (in seconds -1 ). Liver R2* had high diagnostic performance in the detection of clinically relevant LIC thresholds (area under the ROC curve, >0.98). Conclusion R2* MRI enabled accurate and reproducible quantification of liver iron overload over clinically relevant ranges of liver iron concentration (LIC). The data generated in this study provide the necessary calibrations for broad clinical dissemination of R2*-based LIC quantification. ClinicalTrials.gov registration no.: NCT02025543 © RSNA, 2022 Online supplemental material is available for this article.

Purpose: To 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. Methods: This 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. Results: A 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). Conclusion: QSM 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. [ABSTRACT FROM AUTHOR]

Iron-overload associated endocrinopathy is the most frequently reported complication of chronic transfusion therapy in patients with thalassaemia (Thal). This study compared iron-overloaded subjects with Thal ( n = 142; 54%M; age 25·8 ± 8·1 years) and transfused sickle-cell disease (Tx-SCD; n = 199; 43%M, 24·9 ± 13·2 years) to non-transfused SCD subjects (non-Tx-SCD; n = 64, 50%M, 25·3 ± 11·3 years), to explore whether the underlying haemoglobinopathy influences the development of endocrinopathy. Subjects were recruited from 31 centres in the USA, Canada and the UK. Subjects with Thal had more evidence of diabetes (13% vs. 2%, P < 0·001), hypogonadism (40% vs. 4%, P < 0·001), hypothyroidism (10% vs. 2%, P = <0·001) and growth failure (33% vs. 7%, P < 0·001), versus Tx-SCD. Fifty-six per cent of Thal had more than one endocrinopathy compared with only 13% of Tx-SCD ( P < 0·001). In contrast, Tx-SCD was not different from non-Tx-SCD. Multivariate analysis indicated that endocrinopathy was more likely in Thal than SCD [Odds Ratio (OR) = 9·4, P < 0·001], with duration of chronic transfusion a significant predictor (OR = 1·4 per 10 years of transfusion, P = 0·04). Despite iron overload, endocrinopathy was not increased in Tx-SCD versus non-Tx-SCD, suggesting that the underlying disease may modulate iron-related endocrine injury. However, because transfusion duration remained a significant predictor of endocrinopathy, these data should be confirmed in SCD subjects that have been chronically transfused for longer periods of time. [ABSTRACT FROM AUTHOR]