This paper is facinating.  Dr. Shah is trying to develop objective ways to diagnose active and latent trigger points with ultrasound diagnostic imaging techniques—grayscale (2-D ultrasound), vibration sonoelastography, and Doppler—to differentiate tissue characteristics of MTrPs.

New Frontiers in the Pathophysiology of Myofascial Pain
By JAY P. SHAH, MD, and JULIANA HEIMUR, BA
THE PAIN PRACTITIONER | SUMMER 2012
Full Text Article:  http://www.aapainmanage.org/pain_management_news/NEW_newsletter/email/images/shahmyfascial.pdf

Here’s another full text by Shah on the same subject from the Journal of Bodywork & Movement therapy:
http://www.360nmt.com/pdfs/myofascial_trigger_points.pdf