Liver iron concentration evaluated by two magnetic methods: Magnetic resonance imaging and magnetic susceptometry

Determination of liver iron concentration by magnetic resonance imaging (MRI) is becoming the new technique of choice for the diagnosis of iron overload in hereditary haemochromatosis and other liver iron surcharge diseases. Determination of hepatic iron concentration obtained by liver biopsy has been the gold standard for years. The development of MRI techniques, via signal intensity ratio methods or relaxometry, has provided a non-invasive and more accurate approach to the diagnosis of liver iron overload. This article reviews the available MRI methods for the determination of liver iron concentration and also evaluates the technique for the diagnosis and quantification of iron overload in different clinical practice scenarios.

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Noninvasive measurement and imaging of liver iron concentrations using proton magnetic resonance

Blood ◽

10.1182/blood-2004-01-0177 ◽

2005 ◽

Vol 105 (2) ◽

pp. 855-861 ◽

Cited By ~ 570

Author(s):

Timothy G. St. Pierre ◽

Paul R. Clark ◽

Wanida Chua-anusorn ◽

Adam J. Fleming ◽

Gary P. Jeffrey ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Needle Biopsy ◽

Hereditary Hemochromatosis ◽

Iron Concentration ◽

Relaxation Rates ◽

Resonance Imaging ◽

Liver Iron ◽

Transverse Relaxation

AbstractMeasurement of liver iron concentration (LIC) is necessary for a range of iron-loading disorders such as hereditary hemochromatosis, thalassemia, sickle cell disease, aplastic anemia, and myelodysplasia. Currently, chemical analysis of needle biopsy specimens is the most common accepted method of measurement. This study presents a readily available noninvasive method of measuring and imaging LICs in vivo using clinical 1.5-T magnetic resonance imaging units. Mean liver proton transverse relaxation rates (R2) were measured for 105 humans. A value for the LIC for each subject was obtained by chemical assay of a needle biopsy specimen. High degrees of sensitivity and specificity of R2 to biopsy LICs were found at the clinically significant LIC thresholds of 1.8, 3.2, 7.0, and 15.0 mg Fe/g dry tissue. A calibration curve relating liver R2 to LIC has been deduced from the data covering the range of LICs from 0.3 to 42.7 mg Fe/g dry tissue. Proton transverse relaxation rates in aqueous paramagnetic solutions were also measured on each magnetic resonance imaging unit to ensure instrument-independent results. Measurements of proton transverse relaxivity of aqueous MnCl2 phantoms on 13 different magnetic resonance imaging units using the method yielded a coefficient of variation of 2.1%.

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Chelation use and iron burden in North American and British thalassemia patients: a report from the Thalassemia Longitudinal Cohort

Blood ◽

10.1182/blood-2011-04-344507 ◽

2012 ◽

Vol 119 (12) ◽

pp. 2746-2753 ◽

Cited By ~ 54

Author(s):

Janet L. Kwiatkowski ◽

Hae-Young Kim ◽

Alexis A. Thompson ◽

Charles T. Quinn ◽

Brigitta U. Mueller ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Clinical Care ◽

Iron Concentration ◽

Dry Weight ◽

Combination Therapies ◽

Resonance Imaging ◽

Liver Iron ◽

Organ Specific

Abstract Morbidity and mortality in thalassemia are associated with iron burden. Recent advances in organ-specific iron imaging and the availability of oral deferasirox are expected to improve clinical care, but the extent of use of these resources and current chelation practices have not been well described. In the present study, we studied chelation use and the change in iron measurements in 327 subjects with transfusion-dependent thalassemia (mean entry age, 22.1 ± 2.5 years) from 2002-2011, with a mean follow-up of 8.0 years (range, 4.4-9.0 years). The predominant chelator currently used is deferasirox, followed by deferoxamine and then combination therapies. The use of both hepatic and cardiac magnetic resonance imaging increased more than 5-fold (P < .001) during the study period, leading to an 80% increase in the number of subjects undergoing liver iron concentration (LIC) measurements. Overall, LIC significantly improved (median, 10.7 to 5.1 mg/g dry weight, P < .001) with a nonsignificant improvement in cardiac T2* (median, 23.55 to 34.50 ms, P = .23). The percentage of patients with markers of inadequate chelation (ferritin > 2500 ng/mL, LIC > 15 mg/g dry weight, and/or cardiac T2* < 10 ms) also declined from 33% to 26%. In summary, increasing use of magnetic resonance imaging and oral chelation in thalassemia management has likely contributed to improved iron burden.

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