Anterior mediastinal tissue volume is correlated with antiacetylcholine receptor antibody level in myasthenia gravis

Abstract

ObjectivesExtended thymectomy is a treatment option for myasthenia gravis (MG), but the surgical indications are controversial. Pathologic features of the thymus can be used to predict surgical outcomes, but there is no reliable method for evaluating these characteristics preoperatively. The purpose of this study was to determine whether anterior mediastinal tissue volume, as measured via 3-dimensional computed tomography (3DCT) volumetry, correlates with serum anti-acetylcholine receptor antibody (AChRAb) levels in patients undergoing thymectomy for myasthenia gravis. Therefore, we investigated the relationships among anterior mediastinal tissue volume determined by 3DCT volumetry and AChRAb levels. MethodsThe subjects were 28 patients who underwent extended thymectomy and were enrolled retrospectively. We measured volume of the anterior mediastinum and calculated the volumes of more than −30 Hounsfield units (V−30) by using 3DCT volumetry and compared them with perioperative AChRAb levels. The significance of their volumes in MG was examined by comparison with 53 patients without MG. ResultsV−30 values were related to age and were significantly greater in patients with MG than in patients without MG (P < .001). V−30 values were correlated positively with preoperative AChRAb levels (ρ = 0.505, P = .006) and inversely with the post/preoperative AChRAb ratio (ρ = −0.453, P = .018). The histologic nonadipose tissue ratio was correlated with the V−30/volume of the anterior mediastinum (ρ = 0.700, P < .001). ConclusionsThis method for evaluation of the anterior mediastinal tissue volume and AChRAb production may be helpful in establishing a treatment plan for MG.