I can’t locate a representative case for a particular physician (or sonographer). Should I leave them off the application?
You are obligated to list all of the sonographers who perform echocardiograms in your lab and all of the physicians who read those studies. You must plan to represent the staff appropriately, even if it means switching sonographers or readers for a particular study. As a practical matter, you may omit staff members from your application only if they scan/read very irregularly (for example, just to cover for a vacation) and their volumes in your lab are very low.