Imaging plays a significant role in the diagnosis and successful management of patients with pleural diseases. Correct and timely diagnosis is crucial for the optimal treatment of patients with pathologies of the pleura. As known, the diagnosis of the pleural diseases and follow-up after treatment is facilitated by various imaging methods, including X-ray, ultrasound, computed and magnetic resonance tomography, and hybrid imaging. Recently, quantitative imaging (QI) in radiology has become part of the routine examinations of the various modalities. QI facilitates assessments of morphological, parametric, functional, and other quantitative features due to enhanced volumetric data sets. The rationale for the application of QI in pleural diseases, including pleural effusion, non-malignant lesion (fibroma), and malignant mesothelioma, is presented in this chapter.