Advantages of additional PET vs. MRI in the clinical diagnosis of anterior mediastinal tumors.

The present study retrospectively examined the diagnostic utility of adding positron emission tomography (PET) or magnetic resonance imaging (MRI) to computed tomography (CT) alone for preoperative diagnosis of anterior mediastinal tumors. A total of 104 consecutive patients who had undergone surgical resection of anterior mediastinal tumors were divided into two groups: Additional PET to another modality and no additional PET to another modality, and further subdivided into three groups: CT alone, additional MRI to CT and additional PET to CT. The sensitivity, specificity, and accuracy for diagnosing malignant tumors in each subgroup was calculated. Comparing the two groups, the diagnostic sensitivity was similar for additional PET (98.0%) and no additional PET (95.2%) groups; however, the specificity and accuracy for additional PET (75.0 and 92.2%, respectively) were significantly improved compared with no additional PET (31.6 and 65.0%, respectively). In the subgroup analysis, adding PET to CT showed an improvement in specificity and positive predictive value for detecting malignant tumors, compared with either additional MRI to CT or CT alone. Additional PET, but not MRI, has advantages over CT alone in clinically distinguishing benign from malignant tumors of the mediastinum.