Role of different imaging modalities in the evaluation of normal and diseased thymus

Abstract

Abstract Background The appearance of the thymus on imaging studies showed great variability. Thymus imaging is a great challenge. This cross-sectional prospective study investigated the diagnostic value of different imaging modalities in the evaluation of normal and diseased thymus. Chest X-ray was done as a primary survey. Chest computed tomography (CT) was done for 82 patients, chest magnetic resonant imaging (MRI) was done for 40 patients, and 18 flurodeoxy glucose positron emission tomography (18 FDG-PET) was done for 2 patients. Ultrasonography (US) of the anterior mediastinum was done for 2 pediatric patients. Histopathological assessment was done for all cases with diseased thymus. Results The study included 158 patients divided into 2 groups: group A, 79 patients with normal thymus for age and group B, 79 patients with thymic lesions detected by one or more of the used modalities. The large-sized thymus was in 79 patients, who were subcategorized to patients with myasthenia gravis (12 patients) and patients with mediastinal masses (67 patients). Imaging findings in normal and diseased thymus gland were compared and lesion analysis by various modalities displayed with histopathological correlation. Conclusion There are different imaging modalities for thymus gland evaluation. CT is beneficial for primary assessment giving the morphology and density, and MRI is the imaging modality of choice in diseased thymus owing to functional assessment of the gland; however, X-ray may be helpful as a primary survey tool before CT and MRI. Chest ultrasound could be a suitable primary assessment tool in pediatrics before MRI because it is an easy bedside test.

Keywords

• Thymus gland
• Imaging modalities
• Histopathological correlation