Various derivatives of DTPA , including those disclosed herein, are {HEAD ~ preferred chelators} for {TAIL ~ such ions} in compounds according to the present invention 
Various derivatives of DTPA , including those disclosed herein , are { HEAD ~ preferred chelators } for { TAIL ~ such ions } in compounds according to the present invention
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH