Abstract: Magnetically-sensitive surgical tags are attached to an anatomical feature of a subject prior to a surgical procedure. The magnetically-sensitive surgical tags measure the magnitude of a plurality of applied magnetic fields that have respective magnetic field gradients. The magnitudes of the applied magnetic fields are used to determine a first and a second relative three-dimensional position of each magnetically-sensitive surgical tag at first and second times, respectively. When the first and second relative three-dimensional positions of a magnetically-sensitive surgical tag are not substantially the same or within a desired offset distance range, the magnetically-sensitive surgical tag can be repositioned and the new position can be determined and compared to the first position.

Abstract: Provided are ultrasound imaging methods that include administering to a subject a contrast agent that includes a plurality of collapsible gas vesicles, obtaining ultrasound data of a target site of interest, and analyzing the ultrasound data to produce an ultrasound image of the target site. Ultrasound contrast agents are also provided. The subject methods and contrast agents find use in ultrasound imaging applications.

Abstract: Magnetic resonance imaging contrast agents that include a plurality of gas vesicles configured to associate with a noble gas are provided. Also provided are magnetic resonance imaging methods that include administering to a subject a contrast agent that includes a plurality of gas vesicles, obtaining a magnetic resonance data of a target site of interest, and analyzing the data to produce a magnetic resonance image of the target site. The subject contrast agents and methods find use in magnetic resonance imaging applications.