A comparison of computed tomography with magnetic resonance imaging for the diagnosis of thoracic extramedullary hemopoiesis in patients with leukemia: A non-inferiority retrospective diagnostic study.

At present, MRI is the primary choice of examination for the diagnosis of thoracic extramedullary hemopoiesis. When thoracic extramedullary hemopoiesis presents as posterior mediastinum masses in specific clinical contexts, the diagnosis is not challenging. Other radiological presentations may be more difficult for diagnosis and require biopsy. Needle biopsy is typically preferred for the diagnosis of extramedullary hemopoiesis however, the high vascularization of tissues is one of the complications of this method thus, it is avoided. The aim of the present study was to compare the diagnostic parameters of CT with MRI for the diagnosis of thoracic extramedullary hemopoiesis in patients with leukemia, with an open lung biopsy as a reference standard. Chest CT, chest MRI and open lung biopsy data from a total of 912 patients with leukemia with a sign(s) and symptoms of suspected paravertebral and/or pulmonary extramedullary hemopoiesis were reviewed. In the present study, thoracic extramedullary hemopoiesis was defined as diffusivity of both lung fields being increased compared with the blood pool and no other abnormal focal of lungs being increased compared with the blood pool. The beneficial score was calculated for CT and MRI and plotted for the decision making of irradiation. With respect to open lung biopsy, MRI had a higher sensitivity compared with CT (0.865 vs. 0.809; P<0.0001; q=1691) however, CT had a higher accuracy compared with MRI (0.833 vs. 0.733; P<0.0001; q=3020). The low rate of overdiagnosis was observed for both methods for the detection of thoracic extramedullary hemopoiesis however, the working area for detecting thoracic extramedullary hemopoiesis at least once in images was higher for MRI compared with CT. CT and MRI both have diagnostic importance in the detection of thoracic extramedullary hemopoiesis in patients with leukemia however, chest MRI misdiagnoses the condition while CT can confirm it (level of evidence, 3).