On Dr Barkin's call in show, pcref.org, there is an excellent presentation on Color Doppler By Dr Bahn. He gives examples of how staging and treatment options change when Color Doppler is used to DX and stage PC. He also goes into new technologies in imaging such as Elastoplasty.
Well worth the time to view the presentation. He also gives his criteria for active survelience which has more data points than the Hopkins criteria.
JohnT