Background: Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. Radiology, MRI, CT, and PET scans play an important role in the evaluation, diagnosis, and triage of patients with TBI. Recent studies suggest that it will also help predict patients' outcomes. Objective: This study aimed to investigate the benefits from using MRI, CT, and PET scans to diagnose brain injuries or diseases, radiologically. Methods: PubMed, Google scholar and Science direct were searched using the following keywords: Brain injury, brain disease, MRI, CT and PET scans. The authors also screened references from the relevant literature, including all the identified studies and reviews, only the most recent or complete study was included between December 2007 and January 2022. Documents in a language apart from English have been excluded as sources for interpretation. Papers apart from main scientific studies had been excluded (documents unavailable as total written text, conversation, conference abstract papers and dissertations). Conclusion: Primary and metastatic brain tumours are frequently observed in neuroimaging practice. Because of the wide number of treatment options currently available to treat these tumours, post-treatment imaging interpretation has proven to be challenging. Understanding post-treatment imaging methods, treatment response criteria, and common treatment-related issues will help you tackle this tough topic more easily.