Kinetics of MRI contrast agents with a size ranging between Gd-DTPA and albumin-Gd-DTPA: Use of cascade-Gd-DTPA-24 polymer

A unified kinetic theory describing the dynamic properties of magnetic resonance imaging (MRI) contrast agents with a size ranging between that of Gd-DTPA and albumin-(Gd-DTPA)(30) was developed and tested in disease models of cancer and myocardial reperfusion injury. Specifically, a two-compartment kinetic model was solved analytically, and a range of special cases of the model was studied. MRI was performed with strongly T-1-weighted sequences before and dynamically after administration of albumin-(Gd-DTPA)(30) a prototype macromolecular contrast medium (MMCM) designed for blood-pool enhancement; a new MMCM: Gd-DTPA-cascade polymer (Schering AC, Berlin, Germany, MW < 30 kDa); or Gd-DTPA, representing small paramagnetic extracellular agents. The greatest dynamic range of contrast-agent sensitivity to disease was found for albumin-(Gd-DTPA)(30).