Multimodality imaging for characterization, classification, and staging of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is the most common primary malignancy of the pleura and is associated with asbestos exposure in approximately 80% of patients. The patient prognosis is poor, with a median survival of 9-17 months after diagnosis. However, improved survival and decreased morbidity and mortality have been demonstrated when the diagnosis is made in the early stages of disease and specific treatment strategies are implemented. A staging system that focuses on the extent of primary tumor (T), lymph node involvement (N), and metastatic disease (M) has been devised by the International Mesothelioma Interest Group and emphasizes factors related to overall survival. Radiologists should recognize the manifestations of MPM across multiple imaging modalities, translate these findings into the updated staging system, and understand the effects of appropriate staging on treatment and survival. Computed tomography (CT) remains the primary imaging modality used to evaluate MPM and efficiently demonstrates the extent of primary tumor, intrathoracic lymphadenopathy, and extrathoracic spread. However, additional imaging modalities, such as magnetic resonance (MR) imaging of the thorax and positron emission tomography (PET)/CT with fluorodeoxyglucose, have emerged in recent years and are complementary to CT for disease staging and evaluation of patients with MPM. Thoracic MR imaging is particularly useful for identifying invasion of the chest wall, mediastinum, and diaphragm, and PET/CT can accurately demonstrate intrathoracic and extrathoracic lymphadenopathy and metastatic disease.