Publication Date:
2005-11-16
Description:
Using a new magnetic resonance method that separately estimates the two principal forms of storage iron, ferritin and hemosiderin, in the heart, we examined the relationship between myocardial storage iron fractions and left ventricular function in thalassemia major. In patients with iron overload, the amount of iron in functional and transport pools changes only slightly. Virtually all of the excess is sequestered in storage forms of iron, as ferritin, a diffuse, soluble fraction, and as hemosiderin, an aggregate, insoluble fraction. The two storage forms of iron strongly affect signal intensity in both T2 and T2* weighted images but influence MRI signal decay through different means because of their differences in solubility and in intracellular distribution (Magn Reson Med2002; 47:1131–8). Separate estimates of the iron concentrations of the two forms of storage iron may be obtained by measuring two distinct relaxation parameters, the “ferritin iron index” (“reduced” transverse relaxation rate) RR2, and the “hemosiderin iron index”, A. We studied 14 patients with thalassemia major, all being treated with subcutaneous deferoxamine. Study participants were examined with a Philips 1.5 T Intera scanner using three Carr-Purcell-Meiboom-Gill (CPMG)-like multi-echo spin echo sequences with varied inter-echo times, using electrocardiographic triggering and respiratory navigator gating to estimate RR2 and A. The left ventricular shortening fraction was measured using standard echocardiographic methods. The Figure shows the relationship (R=0.91, p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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