Manual segmentation of the human bed nucleus of the stria terminalis using 3T MRI

The bed nucleus of the stria terminalis (BNST)-a small gray matter region located in the basal forebrain-has been implicated in both anxiety and addiction based on compelling evidence from rodent and non-human primate studies. However, the BNST's small size and proximity to other gray matter regions has hindered non-invasive study in human subjects using standard neuroimaging methods. While initial studies have benefitted from a BNST mask created from a single human subject using a 7T scanner, individual variability is likely-especially in patient populations-thus a manual segmentation protocol is needed. Here we report on the development of a reliable manual segmentation protocol performed on 3T MRI images using a scanning sequence that provides high gray matter/white matter/cerebrospinal fluid contrast. Inter- and intra-rater reliabilities, measured in 10 healthy individuals, demonstrate that the protocol can be reliably implemented (intra-rater Dice similarity coefficient≥0.85, inter-rater≥0.77). This BNST tracing protocol provides the necessary foundation for future 3T MRI studies of the BNST in healthy controls and patient populations.