Utility of MRI in assessment of pituitary iron overload

Beta thalassemia is highly prevalent in Pakistan with a carrier rate of 5-8%. The main complication of beta thalassemia major is iron overload, especially in reticuloendothelial system, heart, joints and endocrine glands. Pituitary siderosis leads to hypogonadotropic hypogonadism and growth hormone deficiency. Measures of plasma ferritin levels and hepatic iron level are used for assessing body iron overload but these are limited for various reasons particularly in case of pituitary siderosis. Magnetic Resonance Imaging (MRI) is a reliable, non invasive and easily available utility for assessing tissue siderosis. We assessed a 20 year old female beta thalassemic diagnosed with hypogonadotropic hypogonadism and pituitary siderosis using routine spin echo (SE) T1 and T2 weighted sequences of MRI and special Gradient Recalled Echo (GRE) sequence of MRI. We found MRI signal intensity to be decreased on all three sequences but most so on GRE suggesting its greatest sensitivity to pituitary iron deposition. MRI signal hypo-intensity due to paramagnetic effects of iron has been validated for liver siderosis but is still under investigation for pituitary siderosis. Our findings suggest that MRI especially GRE sequence can be used in conjunction with laboratory data to evaluate pituitary siderosis and to prevent further pituitary dysfunction.