Deferiprone versus desferrioxamine in thalassaemia, and T2* validation and utility

Influence of myocardial fibrosis and blood oxygenation on heart T2* values in thalassemia patients

“…Second, we studied the effects of variations in blood oxygenation on the T2* values. Patients with thalassemia major can have varying deoxyhemoglobin concentrations and myocardial capillary densities (13). We found that blood oxygenation did not significantly affect global T2* values (Spearman's coefficient of correlation ϭ 0.99).…”

“…However, T2* values in the heart could be potentially affected by other factors besides tissue iron concentration, such as myocardial fibrosis and variations in blood oxygenation within the capillary networks of the myocardium (13). Although it was suggested that there was a high probability that myocardial iron concentration was the major factor that determined the T2* value of the tissue (22), the dominance of the myocardial iron concentration over other factors affecting T2* has not been experimentally proven.…”

“…However, T2* heart measurements, in order to quantify myocardial iron burden, could be susceptible to other factors besides tissue iron concentration as myocardial fibrosis and blood oxygenation (13).…”

Cardiac Iron Determines Cardiac T2*, T2, and T1 in the Gerbil Model of Iron Cardiomyopathy

“…There is little a priori reason to suspect that changes in the BOLD signal accounted for the observed 1/T2* changes. 17 Animals were asymptomatic and had a degree of iron loading that previously has not been associated with ECG abnormalities, decreased ventricular function, or exercise intolerance. 21,22 Furthermore, BOLD effects are small (20% with maximal vasodilation) 30 compared with the 300% to 500% changes observed in cardiac 1/T2 and 1/T2* relaxivities.…”

“…However, some investigators have questioned whether cardiac T2* changes represent cardiac iron or instead represent changes in tissue oxygenation and blood flow. 16,17 In humans, liver T2* correlates well with hepatic iron concentration. 12,18 However, direct tissue validation of cardiac T2* measurements has not been performed because endomyocardial biopsy is a dangerous and unreliable indicator of cardiac iron overload.…”