The displacement values may be employed to produce {HEAD ~ a signal} indicative of {TAIL ~ a respiration phase} that can be used in connection with motion artifact reduction techniques 
indicative of
The displacement values may be employed to produce { HEAD ~ a signal } indicative of { TAIL ~ a respiration phase } that can be used in connection with motion artifact reduction techniques
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH