[Modern Radiological Approaches to the Diagnosis and Staging of Pleural Mesothelioma].

Abstract

Pleural mesothelioma (PM) is a highly aggressive tumour, mainly associated with prior asbestos exposure. Symptoms typically do not manifest until 20 to 50 years after exposure. Depending on the histological subtype of PM, the prognosis varies, though the median survival time is only 12-18 months. Imaging plays a central role in the management of PM patients, particularly in assessing operability and treatment response. However, PM presents a unique challenge for radiology due to its rarity, complex morphology, and tendency to invade multiple tissue layers simultaneously. Contrast-enhanced computed tomography (CT) is the central imaging modality in the diagnosis, preoperative planning and therapy monitoring of pleural mesothelioma (PM). Ideally, CT should include both the thorax and abdomen to capture the entire pleural space. Tumour thickness and volume, as determined by CT, are important prognostic factors for patient survival in PM. In addition, PET/CT, using radioactively labelled fluorodeoxyglucose (¹⁸F-FDG), offers additional valuable insights into tumour metabolism. Since PM is typically metabolically active, PET/CT is particularly effective in detecting smaller lesions, occult metastases, and assessing morphologically ambiguous lesions. Magnetic resonance imaging (MRI), on the other hand, offers distinct advantages over CT, due to its superior soft tissue contrast, particularly in visualizing tumour extent and infiltration of adjacent structures. Dynamic contrast-enhanced imaging, diffusion-weighted imaging, and 4D sequences provide valuable additional information. On the basis of the "Best Practices" of the expert panel from the International Mesothelioma Interest Group (iMig), we provide an overview of the common imaging modalities, including conventional X-ray, CT, MRI, and PET/CT. Additionally, we discuss staging based on the TNM classification (Tumour, Node, Metastasis), which evaluates the local invasion of the tumour (T), lymph node involvement (N), and the presence of metastases (M). We also present examples of assessing treatment response and highlight recent developments in diagnostic imaging.