Recommendation for the contouring of limbic system in patients receiving radiation treatment: A pictorial review for the everyday practice and education

Aims: The limbic circuit (LC) is devoted to linking emotion to behavior and cognition. The injury this system results in post-RT cognitive dysfunction. The aim of this study is to create the first radiation oncologist's practical MR-based contouring guide for the delineation of the LC for the everyday clinical practice and education.Methods: An anonymized diagnostic 3.0 T T1-weighted BRAVO MRI sequence from a healthy patient with typical brain anatomy was used to delineate LC. For each structure key anatomical contours were completed by radiation oncologists, along with a neuro-radiologist to generate the final version of the LC atlas.Results: a step-by-step MR-based atlas of LC was created. Key structures of the LC, such as, cingulate gyrus, fornix, septal region, mammillary bodies, thalamus and the hippocampal-amygdala formation were contoured.Conclusions: This article provides the recommendations for the first contouring atlas of LC in the setting of patients receiving RT and education.