Contrast Agent Distribution Function (CADF), a new dynamic MRI parameter from simultaneous measurement of relaxation rates R1 and R2* by a new Saturation-Recovery Multi-Gradient-Echo Snapshot sequence: Concept and first application to colorectal tumor xenografts in mice
Heilmann M, Dimicoli J, Thomas C, Walczak C, Volk A
Institut Curie - Research Center
Dynamic MRI with administration of paramagnetic contrast agents (CA) typically needs computation of CA concentration from relaxation rates and assumed in vivo CA relaxivities. We developed a new protocol, providing a so-called CA distribution function (CADF(t)), which reflects evolution of CA induced susceptibility gradients, without requiring estimation of CA concentrations. CADF(t) was obtained from R1(t) and R2*(t), measured simultaneously by means of a new Saturation-Recovery Multi-Gradient-Echo Snapshot sequence. First in-vivo measurements of CADF in colorectal tumor xenografts of nude mice suggested the relevance of CADF parameters (CADFmax,ka,kb), related to blood volume, perfusion and permeability, for investigation of tumor microvasculature.