Mri evaluation of pituitary iron overload in beta-thalassemia patients-correlation of the results with biochemical parameters and liver iron overload

Introduction and Objective: β-Thalassemia major is a hereditary hemolytic anemia characterized by ineffective erythropoiesis due to defective production of β-chains of hemoglobin. Conventional treatment of β-thalassemia major is based on regular blood transfusions and this lead to iron overload and toxicicity in many various organs. Iron overload of the anterior pituitary gland may cause hypogonadotropic hypogonadism leading to delayed puberty as the most frequent endocrine complication of beta-thalassemic patients. MRI has the potential to estimate the severity of iron overload in the pituitary gland by detecting the paramagnetic effect of iron. The magnetic resonance imaging (MRI) relaxation parameter R2 was used to determine anterior pituitary iron loading in patients with TM. In this study, our objective is to evaluate the relationship between the pituitary R2 value obtained by pituitary MRİ and pubertal status in transfusion-dependent beta thalassemia major patients, to compare pituitary R2 values with healthy controls of pituitary R2 values and to correlate the pituitary R2 findings of TM patients with hepatic iron overload R2 values, clinical and biochemical parameters such as the serum ferritin level. Material and Methods: A retrospective analysis of 38 patients with beta-thalassemia major and 17 healthy controls individuals who underwent MRI using a 1.5T unit between October 2014-April 2015 was performed. 38 beta-thalassemic patients between the ages of 19 and 30 were divided into two groups; 18 with hypogonadotropic hypogonadism as group A and 20 without HH as group B. 17 healthy control individuals between the ages of 20 and 30 were also included (Grup C). Pituitary and hepatic R2 of TM patients and pituitary R2 of healthy control individuals were calculated by using multi-echo spin-echo sequences. Pituitary and hepatic R2 values were correlated with each other and with serum ferritin levels. Results: As a result of the analysis; we found that pituitary-R2 values were significantly higher in group A as compared with group B (p<0.05), but there was no significant difference between group B and C (p=0.052). Also liver-R2 values were significantly higher in group A according to group B (p<0.05). We found significant correlation between pituitary-R2 and liver-R2 values in group A (p<0.01), but no significant correlation was seen in group B (p>0.01). In thalassemia major patients pituitary-R2 were moderately correlated with serum ferritin levels (r=0.522, p<0.01). However we found a stronger correlation between the serum ferritin levels and liver-R2 as compared to pituitary-R2 (r=0.681, p<0.01). Conclusion: Pituitary-R2 assesed by pituitary MRI seems to differentiate TM patients with iron-mediated HH from TM patients without HH. So pituitary-R2 can be used to detect the patients who are in great danger of developing HH before it is clinically observable. High serum ferritin levels seems to be a risk factor of developing HH in TM patients; so MRI evaluation of pituitary can be necessary in TM patients who have normal pituitary hormonal function but higher serum ferritin levels. Also hepatic-R2 alone is not enough to predict pituitary iron overload; so it is important to evaluate pituitary iron overload with pituitary MRI examination.