Real-World Experience Measurement of Liver Iron Concentration by R2 vs. R2 Star MRI in Hemoglobinopathies.

Riad Abou Zahr,Amanda Potersnak,Zora Rogers,Gerald Greil,Barbara E U Burkhardt,Tarique Hussain,Jeanne Dillenbeck,Lubaina Ehsan

doi:10.3390/diagnostics10100768

Abstract

Background: Non-invasive determination of liver iron concentration (LIC) is a valuable tool that guides iron chelation therapy in transfusion-dependent patients. Multiple methods have been utilized to measure LIC by MRI. The purpose of this study was to compare free breathing R2* (1/T2*) to whole-liver Ferriscan R2 method for estimation of LIC in a pediatric and young adult population who predominantly have hemoglobinopathies. Methods: Clinical liver and cardiac MRI scans from April 2016 to May 2018 on a Phillips 1.5 T scanner were reviewed. Free breathing T2 and T2* weighted images were acquired on each patient. For T2, multi-slice spin echo sequences were obtained. For T2*, a single mid-liver slice fast gradient echo was performed starting at 0.6 ms with 1.2 ms increments with signal averaging. R2 measurements were performed by Ferriscan analysis. R2* measurements were performed by quantitative T2* map analysis. Results: 107 patients underwent liver scans with the following diagnoses: 76 sickle cell anemia, 20 Thalassemia, 9 malignancies and 2 Blackfan Diamond anemia. Mean age was 12.5 ± 4.5 years. Average scan time for R2 sequences was 10 min, while R2* sequence time was 20 s. R2* estimation of LIC correlated closely with R2 with a correlation coefficient of 0.94. Agreement was strongest for LIC < 15 mg Fe/g dry weight. Overall bias from Bland–Altman plot was 0.66 with a standard deviation of 2.8 and 95% limits of agreement −4.8 to 6.1. Conclusion: LIC estimation by R2* correlates well with R2-Ferriscan in the pediatric age group. Due to the very short scan time of R2*, it allows imaging without sedation or anesthesia. Cardiac involvement was uncommon in this cohort.

Highlights

Chronic iron overload affects predominantly the liver, pancreas and heart, leading to systemic complications, including liver fibrosis, diabetes and cardiomyopathy [1,2]
Studies have shown that liver iron concentration (LIC) is directly proportional to total body iron stores [3]
We describe our real-world experience where we compare simultaneous LIC derived from R2 (Ferriscan) to that derived from free breathing single slice R2* in a cohort of pediatric and young adult patients who predominantly have hemoglobinopathies receiving chronic transfusion therapy

Summary

Introduction

Chronic iron overload affects predominantly the liver, pancreas and heart, leading to systemic complications, including liver fibrosis, diabetes and cardiomyopathy [1,2]. Studies have shown that liver iron concentration (LIC) is directly proportional to total body iron stores [3]. Diagnostics 2020, 10, 768 of LIC is indicated prior to initiation of chelation therapy and during therapy to guide management in chronically transfused patients [4]. LIC was measured via liver biopsy [5]. Non-invasive determination of liver iron concentration (LIC) is a valuable tool that guides iron chelation therapy in transfusion-dependent patients. Multiple methods have been utilized to measure LIC by MRI. The purpose of this study was to compare free breathing R2*. (1/T2*) to whole-liver Ferriscan R2 method for estimation of LIC in a pediatric and young adult population who predominantly have hemoglobinopathies. For T2*, a single mid-liver slice fast gradient echo was performed starting at 0.6 ms with

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