“…A second, often overlooked, advantage of MRSI is the ability to separate white and gray matter components using post-processing methods. This is often done by linear regression (Hetherington et al, 1996;Tal, Kirov, Grossman, & Gonen, 2012) or spectral decomposition methods (Goryawala, Sheriff, Stoyanova, & Maudsley, 2018), which combine information from multiple voxels with knowledge of the relative tissue content in each voxel. Linear regression can be applied in any number of (n≥2) voxels to investigate small regions such as the hippocampus (<10 voxels; Meyer et al, 2016), larger areas such as 2D slabs (McLean et al, 2000;Gasparovic et al, 2011), in entire brain lobes (Maudsley et al, 2009), and/or in global brain white matter/gray matter metabolism (100s of voxels; Tal et al, 2012).…”