NON-INVASIVE MYOCARDIAL IRON ASSESSMENT IN THALASSAEMIC PATIENTS. T2 relaxometry and magnetization transfer ratio measurements

Abstract

Purpose: To compare T2 relaxometry and magnetization transfer ratio (MTR) measurements of myocardial tissue in normal volunteers and thalassaemic patients for assessment of the myocardial iron levels. Material and Methods: All examinations were done on a 1 T MR system using a multi‐echo spin‐echo sequence with 8 echoes for T2 measurements and a gradient echo sequence for MTR measurements. Diastolic cardiac triggering was used in both sequences. Ten patients and 10 normal subjects were included in the study. T2 and MTR measurements were correlated with serum ferritin levels. Results: Regression analysis between T2 and MTR measurements and ferritin demonstrated a reversed linear relationship, (r=−0.932, p<0.05) and (r=−0.824, p<0.05), respectively. Mean T2 relaxation time and mean MTR of the normal subjects (57.95±4.9 ms and 43.70±3.3%) was significantly higher than that of the thalassaemic patients (38.8±6.2 ms and 26.40±6.1%) (p<0.01), respectively. Conclusion: MTR measurements can be used to complement T2 measurements for non‐invasive myocardial iron assessment.

Evaluation of myocardial iron by magnetic resonance imaging during iron chelation therapy with deferrioxamine: indication of close relation between myocardial iron content and chelatable iron pool

“…Contrary to other studies 15,16 including the present study, Anderson et al 32 did not find a significant correlation between their myocardial iron index (T2*) and the serum ferritin concentration. One likely explanation is that the relation does not exist over the whole range of ferritin values.…”

“…Accordingly, the ferritin levels were markedly lower (1250 Ϯ 508 g/L). Significant relations between ferritin levels and MRIderived myocardial iron indexes was also demonstrated by Mavrogeni et al 15 and Papanikolaou et al 16 Both studies also included patients with high ferritin levels.…”

“…[7][8][9][10][11][12][13] Estimation of myocardial iron by the SQUID has so far not been reported, but a few studies have explored the use of MRI for this purpose. [14][15][16][17][18] Except for 2 studies, 14,18 all studies demonstrated a significant correlation between the applied myocardial MRI index and the serum ferritin concentration by heart-to-muscle signal intensity ratio (SIR) measurements obtained from spin-echo images, 15,17 by T2 relaxometry, 15,16 or by magnetization transfer ratio measurements. 16 Anderson et al 18 did not find this relationship, but demonstrated an interesting, strong relationship between declining myocardial T2-star (T2*) and impaired ventricular function by use of gradient-echo imaging.…”

“…[14][15][16][17][18] Except for 2 studies, 14,18 all studies demonstrated a significant correlation between the applied myocardial MRI index and the serum ferritin concentration by heart-to-muscle signal intensity ratio (SIR) measurements obtained from spin-echo images, 15,17 by T2 relaxometry, 15,16 or by magnetization transfer ratio measurements. 16 Anderson et al 18 did not find this relationship, but demonstrated an interesting, strong relationship between declining myocardial T2-star (T2*) and impaired ventricular function by use of gradient-echo imaging. A limitation of all these studies is the lack of a definitive prediction of the myocardial iron concentration from the applied myocardial MRI iron indexes, because no validation is performed with endomyocardial tissue.…”

Myocardial iron loading in transfusion-dependent thalassemia and sickle cell disease

“…1,3 The magnetic resonance imaging (MRI) relaxation parameters T2 and T2* have been used to infer cardiac iron loading in patients with TM. [5][6][7][8] Low T2*, suggesting high myocardial iron content, has been associated with poor ventricular function, myocardial arrhythmias, and need for cardiac medications. 5 Although abnormal T2* is common in adults, its prevalence and functional significance in pediatric patients is unknown.…”