Positron Emission Tomography/Computed Tomography for the Pleural Staging of Malignant Pleural Mesothelioma: How Accurate Is It?

BACKGROUND Careful clinical staging in patients with malignant pleural mesothelioma (MPM) is fundamental in management planning. Positron emission tomography/computed tomography (PET/CT) is increasingly recognized as an important staging modality. OBJECTIVES The purpose of this study was to assess whether the metabolic activity of the pleural tumor detected with PET/CT correlates with specific endoscopic features and pleural distribution of the lesions as assessed by medical thoracoscopy. METHODS Consecutive patients with MPM and available PET/CT performed before thoracoscopy were separated into 2 groups, according to their standardized uptake value (SUV). Kaplan-Meier-analysis for survival was performed on groups with low and high SUV. Agreement between PET/CT and thoracoscopy evaluation was analyzed using Cohen's kappa coefficient. The Wilcoxon test was used to compare the median SUV, and the χ(2) test was used to evaluate differences in endoscopic findings. RESULTS A total of 32 patients were included. The median maximum SUV (SUV max) was 6.1 and patients were separated into 2 groups based on this cutoff. Patients with SUV max <6.1 had a better survival than those with SUV max ≥6.1 (p = 0.005). The comparison between PET/CT and thoracoscopy showed a fair agreement for visceral and diaphragmatic pleural involvement and moderate agreement for the presence of nodular lesions. There was a statistically significant association between median SUV max and visceral pleural involvement; nodular lesions and visceral pleural involvement were more common in the high-SUV group than in the low-SUV group (p = 0.0012 and p = 0.03, respectively). CONCLUSIONS PET/CT data may be predictive of thoracoscopic features of MPM associated with prognosis and staging, but the correlation is moderate at best. A degree of disagreement exists between these two modalities, which supports thoracoscopy as the gold standard for assessment of local invasion in MPM.