FDG PET-derived parameters as prognostic tool in progressive malignant pleural mesothelioma treated patients

Imaging of Malignant Pleural, Pericardial, and Peritoneal Mesothelioma

Malignant mesothelioma is a rare tumor arising from the mesothelial cells that line the pleura, pericardium, peritoneum, and tunica vaginalis. Imaging plays a primary role in the diagnosis, staging, and management of malignant mesothelioma. Multimodality imaging, including radiography, computed tomography (CT), magnetic resonance imaging (MRI), and F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT), is used in a variety of scenarios, including diagnosis, guidance for tissue sampling, staging, and reassessment of disease after therapy. CT is the primary imaging modality used in staging. MRI has superior contrast resolution compared with CT and can add value in terms of determining surgical resectability in equivocal cases. MRI can further assess the degree of local invasion, particularly into the mediastinum, chest wall, and diaphragm, for malignant pleural and pericardial mesotheliomas. FDG PET/CT plays a role in the diagnosis and staging of malignant pleural mesothelioma (MPM) and has been shown to be more accurate than CT, MRI, and PET alone in the staging of malignant pleural mesothelioma. PET/CT can also be used to target lesions for biopsy and to assess prognosis, treatment response, and tumor recurrence.

The Prognostic Value of 18F-FDG PET Imaging at Staging in Patients with Malignant Pleural Mesothelioma: A Literature Review

Malignant pleural mesothelioma (MPM) is an aggressive malignancy, frequently diagnosed at locally-advanced/metastatic stages. Due to a very poor prognosis and limited treatment options, the need to identify new prognostic markers represents a great clinical challenge. The prognostic role of metabolic information derived from Positron Emission Tomography (PET) with ¹⁸F-Fluoro-deoxy-glucose (¹⁸F-FDG) has been investigated in different MPM settings, however with no definitive consensus. In this comprehensive review, the prognostic value of FDG-PET imaging exclusively performed at staging in MPM patients was evaluated, conducting a literature search on PubMed/MEDLINE from 2010 to 2020. From the 19 selected studies, despite heterogeneity in several aspects, staging FDG-PET imaging emerges as a valuable prognostic biomarker, with higher tumor uptake predictive of worse prognosis, and with volumetric metabolic parameters like Metabolic Tumor Volume, (MTV) and Total Lesion Glycolisis (TLG) performing better than SUVmax. However, PET uptake parameters were not always confirmed as independent prognostic factors, especially in patients previously treated with pleurodesis and with a non-epithelioid histotype. Future prospective studies in larger and clinically homogeneous populations, and using more standardized methods of PET images analysis, are needed to further validate the value of staging FDG-PET in the prognostic MPM stratification, with a potential impact on better patient-tailored treatment planning, in the perspective of personalized medicine.

Imaging of Malignant Pleural Mesothelioma: Pearls and Pitfalls

Malignant pleural mesothelioma is a rare tumor arising from the pleural mesothelial cells. Imaging plays a crucial role in the diagnosis, staging, and management of patients with mesothelioma. Accurate staging to stratify patients into homogeneous groups is required to evaluate the effectiveness of multimodality therapeutic regimens. CT and PET/CT are recommended for the initial staging of MPM. MRI adds value to further assess invasion of the tumor into the diaphragm, chest wall, and mediastinum. This review will discuss pearls and pitfalls in the imaging of mesothelioma with emphasis on the roles of CT, MRI, and PET/CT.

18F-fluorodeoxyglucose positron emission tomography in malignant pleural mesothelioma: diagnostic and prognostic performance and its correlation to pathological results

Although 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scan has been generally validated in the staging of malignant pleural mesothelioma (MPM), its diagnostic and prognostic performances are not clearly established. Aiming to identify possible factors causing 18F-fluorodeoxyglucose PET/CT false-negative results and influencing prognosis in MPM patients, we analysed clinical, radiometabolic and pathological features in 141 MPM patients who underwent diagnostic 18F-fluorodeoxyglucose PET/CT scan (January 2009-July 2018) at 2 high-volume institutions. The Fisher's exact test and the Cox model were used in statistical analysis. Overall detection rate was 88.3% with 16 patients (11.6%) presenting with a standardized uptake value (SUV) max <2.5 (PET-negative). PET-negative cases were more frequently detected in older patients (P = 0.027) and early-stage tumours (33.3% false-negative in stage I and 40.0% false-negative in T1-tumours, with P = 0.014 both). Mean SUVmax value was higher in sarcomatoid (11.8 ± 4.6) and biphasic MPM (9.3 ± 7.0), rather than in epithelioid MPM (6.9 ± 3.8, P < 0.001). Concerning overall survival, SUVmax (both as continuous and as categorical variable) was found to be a prognostic factor, in addition to stage (P = 0.032) and histology (P = 0.014) as confirmed by multivariable analysis (hazard ratio 2.65, confidence interval 1.23-5.70; P < 0.001). In the light of such results, we highlight that a low fluorodeoxyglucose uptake might be observed in more than 10% MPMs, especially in early-stage tumours affecting elderly patients. Furthermore, high SUVmax values significantly correlated with a worse prognosis.

Radiologic Considerations and Standardization of Malignant Pleural Mesothelioma Imaging Within Clinical Trials: Consensus Statement from the NCI Thoracic Malignancy Steering Committee - International Association for the Study of Lung Cancer - Mesothelioma Applied Research Foundation Clinical Trials Planning Meeting

Detailed guidelines pertaining to radiological assessment of malignant pleural mesothelioma are currently lacking due to the rarity of the disease, complex morphology, propensity to invade multiple planes simultaneously, and lack of specific recommendations within the radiology community about assessment, reporting, and follow-up. In March 2017, a multidisciplinary meeting of mesothelioma experts was co-sponsored by the National Cancer Institute Thoracic Malignancy Steering Committee, International Association for the Study of Lung Cancer, and the Mesothelioma Applied Research Foundation. One of the outcomes of this conference was the foundation of detailed, multidisciplinary consensus imaging and management guidelines. Here, we present the recommendations for radiologic assessment of malignant pleural mesothelioma in the setting of clinical trial enrollment. We discuss optimization of imaging parameters across modalities, standardized reporting, and response assessment within clinical trials.