The invention provides methods, devices and compositions that employ EuGd203 nanoparticles, e.g., for imaging. The invention provides for devices having lanthanide doped gadolinium nanoparticles and uses for lanthanide doped, for instance, europium doped, gadolinium (e.g., Eu—Gd203) nanoparticles in sequential imaging. For example, Eu—Gd203 nanoparticles are employed as multimodal/sequential contrast agents for combinations of MRI, CT, ultrasound, and photoacoustics or other imaging modalities such as optical imaging. The invention provides a method comprising administering, for instance, injecting, a composition comprising lanthanide doped gadolinium nanoparticles into a subject, e.g., a human； applying ultrasound, laser pulses, x-rays or a magnetic field, or sequentially applying two or more of ultrasound, laser pulses, x-rays or a magnetic field, or sequentially applying two or more of ultrasound, laser pulses, x-rays or a magnetic field, to the subject； acquiring signals from the nanoparticles； and reconstructing an image from the acquired signals.
