Background <p>Magnetic resonance imaging (MRI) is one of the common non-invasive examinations for diagnosing brain abnormalities. However, the use of MRI is often accompanied by the risk of adverse events and MRI-related accidents during intrahospital transport (IHT) of critically ill patients in the intensive care unit (ICU) or emergency department (ED). Portable MRI (pMRI) has been proposed as a safer imaging modality than conventional MRI for neuroimaging critically ill patients in the ICU or ED.</p> Aim <p>This review identifies the type of brain abnormalities that pMRI can diagnose for critically ill patients in the ICU or ED and evaluates its feasibility features.</p> Methods <p>A systematic review was performed through a comprehensive literature search in PubMed, Scopus, and the Hyperfine website. Two reviewers independently reviewed relevant studies based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.</p> Results <p>Nine studies were included, comprising 410 adults and 14 neonates from the ICU and ED. The review identified five types of brain abnormalities that can be diagnosed using pMRI during neuroimaging of critically ill patients in ICU and ED: (i) hemorrhage, (ii) stroke, (iii) infections, (iv) injury, and (v) neoplasms. The feasibility features of pMRI included (i) short scan duration, (ii) high safety, and (iii) high mobility.</p> Conclusions <p>Notably, pMRI can diagnose multiple brain abnormalities and is feasible for use on critically ill patients in ICU and ED. In support of the current evidence, the use of pMRI in emergency radiology for diagnosing brain abnormalities of critically ill patients is recommended.</p>