Normalized Residue Ratio Scale (NRRS)
The links provided explain how to measure the severity of residue in the valleculae and piriform sinuses using a new, anatomically normalized scale known as the Normalized Residue Ratio Scale, which is described in a recent publication: Pearson, W. G. Jr., Molfenter, S. M., Smith, Z. M. & Steele, C. M. (2013). Image-based measurement of post-swallow residue: The normalized residue ratio scale. Dysphagia, 28, 167-177. DOI 10.1007/s00455-012-9426-9.