The magnetic susceptibilities of iron deposits in thalassaemic spleen tissue

The iron-specific magnetic susceptibility of tissue iron deposits is used in the field of non-invasive measurement of tissue iron concentrations. It has generally been assumed to be a constant for all tissue and disease types. The iron-specific magnetic susceptibilities χFe for spleen tissue samples from 7 transfusion dependent β-thalassaemia (β-thal) patients and 11 non-transfusion dependent β-thalassaemia/Haemoglobin E (β/E) patients were measured at 37 °C. Both groups of patients were iron loaded with no significant difference in the distribution of spleen iron concentrations between the two groups. There was a significant difference between the mean χFe of the spleen tissue from each group. The non-transfusion dependent β/E patients had a higher mean (± standard deviation) spleen χFe (1.55 ± 0.23 × 10− 6 m3/kg Fe) than the transfusion dependent β-thal patients (1.16 ± 0.25 × 10− 6 m3/kg Fe). Correlations were observed between χFe of the spleen tissue and the fraction of magnetic hyperfine split sextet in the 57Fe Mössbauer spectra of the tissues at 78 K (Spearman rank order correlation r = − 0.54, p = 0.03) and between χFe of the spleen tissue and the fraction of doublet in the spectra at 5 K (r = 0.58, p = 0.02) indicating that χFe of the spleen tissue is related to the chemical speciation of the iron deposits in the tissue.