So your post a lot misleading. Prolonged Speech is not "standard best practices" it is one of a host of therapy protocols that have an empirical evidence base. And I'm not sure exactly how you're quantifying that MPI is twice as effective as prolonged speech. The results look rather equivocal to me. This is from the first paragraph of the discussion of the AJSLP paper: > In summary, the comparison between MPI treatment and PS treatment showed that participants who completed either program achieved similar and substantial reductions in the frequency of stuttering and required essentially the same amount of time to complete their programs. All successful participants, from either program, maintained zero or very low stuttering, with speech rates and speech naturalness levels that were similar to those produced by control speakers, throughout extended Transfer and Maintenance phases that totaled an average of more than 3 years. I don't feel like googling right now ... how is DSI different from DTI (diffusion tnesor imaging).