This chapter examines the complexities of neuroimaging in the follow-up of brain tumors, with a particular focus on pseudoprogression. Pseudoprogression, a phenomenon wherein imaging findings may mimic true tumor progression, poses significant diagnostic and therapeutic challenges. Misidentifying pseudoprogression can lead to inappropriate clinical decisions, with potentially detrimental consequences for patient care. The chapter offers a thorough exploration of the clinical and imaging criteria that define pseudoprogression, alongside its incidence and underlying pathophysiology. It also highlights the inherent limitations of conventional Magnetic Resonance Imaging (MRI) techniques in differentiating pseudoprogression from true progression. Imaging modalities, such as diffusion-weighted imaging, magnetic resonance spectroscopy, perfusion-weighted imaging, and positron emission tomography, are critically analyzed for their ability to enhance diagnostic accuracy and reliability. Furthermore, the text emphasizes the importance of integrating imaging findings with clinical evaluation, employing standardized frameworks such as the Response Assessment in Neuro-Oncology (RANO) criteria. By synthesizing these approaches, the chapter aims to provide insights into optimizing management strategies and improving decision-making in neuro-oncology, ultimately contributing to better outcomes for patients with brain tumors.