To evaluate the spectrum of MR feature of normal and abnormal thymus and to determine the indicated of thymic diseases, MR imaging of the mediastinum in 11 patients with myasthenia gravis who underwent thymectomy (7 patients: two with a final
diagnosis
of invasive thymoma, one with thymoma, and four with thymic hyperplasia) and underwent medical treatment(4patients) were compared with normal control group consist of 14 patients in whom there were no underlying diseases knwon to be associated
thymic
enlargement.
In myasthenia. Gravis patients as compared with normal control group, there were abnormal focal bulging in thymus contour, inhomogenous signal intensities in focal bulged or mass area. right lobe equal to or larger than left lobe in size(width,
thickness and length) and loss of adjacent mediastinal fat planes. It is concluded that if above abnormal MR imaging feature are obserbed in myasthenia gravis patients, thymectomy should be considred to be undertaken.
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