In magnetic resonance imaging (MRI) many factors can contribute to non-tissue specific image intensity inhomogeneity. However, the potential clinical impact or systematic biases of these effects have not been extensively investigated across multiple MRI vendors and models for neuroimaging applications. Specifically, left-right intensity comparisons are commonly used by radiologists to verify/identify pathology. If significant systematic left-right intensity asymmetries (LRIA) exist, it may lead to diagnostic uncertainty and result in unnecessary imaging follow-up and patient burden. This study shows that LRIA are common, system specific, systematic, can mimic disease, create diagnostic uncertainty, and can impact multiple sequences (T1-weighted and FLAIR).