Anatomically, this organ is situated at the anterior superior mediastinum, exactly behind the sternum and in front of large blood vessels.1 The most common congenital cyanotic heart disease in adults is the tetralogy of Fallot (TOF).2 Complete correction of TOF is performed under cardiovascular bypass surgery. Long-term evidence regarding the prognosis of such patients is not available; however, most affected children are treated

or at least become asymptomatic throughout childhood or at the beginning of adulthood.3 Access to the heart and large learn more vessels is difficult in infancy Inhibitors,research,lifescience,medical and the first months of life because of the size of the thymus. Therefore in children with congenital heart disease, a thymectomy is performed in order to facilitate cardiac surgery. This procedure leads to ectopic thymus tissue and ultimately thymus hyperplasia in the mediastinum.4,5 Magnetic resonance imaging (MRI) is a suitable method for evaluating a normal or hyperplasic thymus and related tumors. When compared Inhibitors,research,lifescience,medical with computed tomography, it is safer because patients are not exposed to a higher dose of radiation.6,7 In patients who undergo median sternotomy because of congenital heart disease, thymectomy is performed to enable better access to the cardiac system. However, the main question is whether the thymus is able to regenerate after surgery. Therefore, considering the increasing prevalence of congenital

Inhibitors,research,lifescience,medical heart diseases worldwide (including Iran) and few existing studies in this regard, it is necessary to evaluate the changes in the thymus after surgery and during follow-up to take the necessary therapeutic approaches. We aimed to evaluate the changes in size, shape, and location of the thymus after midsternatomy using MRI. Materials and Methods This case-control Inhibitors,research,lifescience,medical study was performed during 2011-2012 in the MRI Center of Shahid Faghihi Hospital, affiliated with Shiraz University of Medical Sciences,

Inhibitors,research,lifescience,medical Shiraz, Iran. Participants were selected according to the simple sample selection method. Eligible individuals were divided into case and control groups. The control group (n=13) consisted of individuals with no history of chest surgery or known illness who referred for MRI for any other reasons. The case group (n=13) consisted of patients with TOF who were 5-17 years of age and had undergone median sternotomy only once (complete correction) at least one year prior to the study. The one-year period was considered necessary in order to bypass any transient thymic hyperplasia that might occur in the first only few months after surgery. The sample size was calculated using the simple calculation method. We excluded patients with any accompanying pathology such as DiGeorge syndrome, those who used steroids, or those who had recent infections over the previous two weeks. After obtaining written informed consent and approval from the Ethics Committee at Shiraz University, patients were interviewed to complete the related questionnaire.