R2* as a surrogate measure of ferriscan iron quantification in thalassemia

Chan, Wesley; Tejani, Zahra; Budhani, Faisal; Massey, Christine; Haider, Masoom A.

doi:10.1002/jmri.24216

Cited by 22 publications

(23 citation statements)

References 19 publications

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“…Garbowski et al directly compared T2* MRI with biopsy and indirectly against R2 generated LIC [11]. Chan et al has performed a MRI retrospective analysis [12] and Wood et al prospectively compared R2 and R2* derived LIC in both Thalassaemia major and Sickle cell disease patients [10]. These studies observed a close relationship between R2* and R2 LIC however the relationships were not as robust as demonstrated in our study.…”

Section: Discussioncontrasting

confidence: 65%

T2* MRI Correlates with R2 Liver Iron Concentration in Transfusion Dependent Thalassaemia

Clarke¹,

Kidson‐Gerber²,

Moses³

et al. 2016

Journal of Hematology and Blood Disorders

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Research ArticleOpen Access Regular transfusion in thalassaemia major results in progressive iron overload and its complications. Chelation therapy can prevent these complications and has been pivotal in the improved survival of these patients. With inadequate chelation, cardiac arrhythmias and cardiomyopathy are the predominant causes of death, while endocrinopathies and cirrhosis contribute to both morbidity and mortality [1][2][3]. Each chelating agent has potential risks and benefits. The accurate assessment of iron overload is therefore critical in guiding the appropriate choice of therapy and in managing adherence. AbstractRelaxometry based Magnetic Resonance Imaging (MRI) techniques have increasingly been adopted as a means of non invasive measurement of tissue iron concentration in patients with transfusion dependent thalassaemia. Currently, different MRI techniques are utilised to assess cardiac and hepatic iron concentrations, which correlate poorly. In an attempt to simplify the assessment of tissue iron concentration, we prospectively compared T2* MRI with R2 (FerriScan®) derived liver iron concentration. A strong correlation exists between these two modalities, particularly at lower iron burdens. These findings would enable the concurrent assessment of cardiac and liver iron concentration thus streamlining total body iron assessment. Method: 34 patients with β-thalassemia major underwent MRI assessment. R2 and T2* images were generated concurrently and R2 LIC calculated. Data was analysed with SAS/STAT 9. Conclusion:These results indicate there is a strong correlation between T2* MRI and R2 generated LIC. These findings have the potential to streamline iron assessment by facilitating the concurrent assessment of cardiac and liver iron concentration.

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Section: Discussioncontrasting

confidence: 65%

T2* MRI Correlates with R2 Liver Iron Concentration in Transfusion Dependent Thalassaemia

Clarke¹,

Kidson‐Gerber²,

Moses³

et al. 2016

Journal of Hematology and Blood Disorders

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“…Quantitative measurements were only performed on 12 mice (6 groups of n = 2), all of which had measured LICs of less than 0.8 mg/g of wet tissue. Other studies conducted on human liver tissues have reported significantly higher LIC measurements, with a maximum around 7 mg/g of wet tissue . Therefore, in order to more accurately develop a standardized susceptibility‐to‐LIC conversion factor, a larger sample size covering a wider range of LIC values should be evaluated.…”

Section: Discussionmentioning

confidence: 99%

Assessment of MR‐based and quantitative susceptibility mapping for the quantification of liver iron concentration in a mouse model at 7T

Simchick

Liu

Nagy

et al. 2018

Magnetic Resonance in Med

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The feasibility of quantifying LIC using MR-based R2* and QSM at a high field strength of 7T is demonstrated. Susceptibility quantification, which is an intrinsic property of tissues and benefits from being field-strength independent, is more robust than R2* quantification in this ex vivo study. A susceptibility-to-LIC conversion factor is presented that agrees relatively well with previously published QSM derived results obtained at 1.5T and 3T.

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“…A number of MRI‐based LIC quantification methods have been proposed as alternatives to FerriScan . However, strong evidence of a technique's validity would be required before it could be considered as an acceptable alternative.…”

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confidence: 99%

Prospective Evaluation of an R2* Method for Assessing Liver Iron Concentration (LIC) Against FerriScan: Derivation of the Calibration Curve and Characterization of the Nature and Source of Uncertainty in the Relationship

Jhaveri

Kannengießer

Ward

et al. 2018

Magnetic Resonance Imaging

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Background FerriScan is the method‐of‐choice for noninvasive liver iron concentration (LIC) quantification. However, it has a number of drawbacks including cost and expediency. Purpose/Hypothesis To characterize an R2*‐based MRI technique that may potentially be used as an alternative to FerriScan. This was accomplished through the derivation of a calibration curve that characterized the relationship between FerriScan‐derived LIC and R2*. The nature and source of uncertainty in this curve were investigated. It was hypothesized that the source of uncertainty is heterogeneity of LIC across the liver. Study Type Prospective. Subjects In all, 125 patients (69 women, 56 men) undergoing chelation treatment for iron overload prospectively underwent FerriScan and R2* MRI during the same exam. Field Strength/Sequence Pulse sequences included 2D multislice spin‐echo pulse for FerriScan, and a prototype 3D 6‐echo gradient echo acquisition for R2* mapping at 1.5T. Assessment A linear calibration curve was derived from the relationship between FerriScan‐derived LIC estimates and R2* through least‐squares fitting. Statistical Tests The nature of the uncertainty in the curve was characterized through tests of normality and homoscedasticity. The source of uncertainty was tested by comparing the magnitude of LIC variation over the FerriScan ROI to the observed uncertainty in the R2*‐derived LIC estimates. Results A linear relationship between logarithmically transformed FerriScan‐derived LIC and R2* (log{FerriScan‐derived LIC} = 1.029 log{R2*} – 3.822) was confirmed. Uncertainty was random, with a behaviour that was normal and homoscedastic. The source of uncertainty was confirmed as iron heterogeneity across the liver. The nontransformed calibration curve was: FerriScan‐derived LIC = 0.0266⋅R2*, with a constant coefficient‐of‐variation of 0.32. Data Conclusion FerriScan and R2* techniques were found to provide equivalent quantification of LIC in this study. Any difference in accuracy or precision was at a level lower than the uncertainty caused by variation in LIC over the liver. Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1467–1474.

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R2* as a surrogate measure of ferriscan iron quantification in thalassemia

Abstract: R2* values can predict HIC determined by FerriScan using a linear calibration curve. This technique may provide a potentially cost-saving alternative for hepatic iron determination and improve acceptance by referring physicians.

Cited by 22 publications

References 19 publications

T2* MRI Correlates with R2 Liver Iron Concentration in Transfusion Dependent Thalassaemia

T2* MRI Correlates with R2 Liver Iron Concentration in Transfusion Dependent Thalassaemia

Assessment of MR‐based and quantitative susceptibility mapping for the quantification of liver iron concentration in a mouse model at 7T

Prospective Evaluation of an R2* Method for Assessing Liver Iron Concentration (LIC) Against FerriScan: Derivation of the Calibration Curve and Characterization of the Nature and Source of Uncertainty in the Relationship

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