Liposomes, loaded with gadolinium (Gd) ions using different membrane-incorporated chelating lipids and functionalized with monoclonal anti-CD138 (syndecan-1) antibody were prepared. Nuclear Magnetic Resonance Dispersion (NMRD) analysis showed that use of the polychelating amphiphilic polymer (PAP) increases both the Gd content and the spin–lattice relaxivity of the Gd-loaded-PAP–liposomes as compared to Gd–DTPA–BSA equivalents. The potential application of contrast syndecan-1– and Rituximab–liposomes, for application as a novel minimally invasive diagnostic agent for multiple myeloma and non Hodgkin's lymphoma was investigated.