Microbubbles as novel pressure-sensitive MR contrast agents

Andrew L. Alexander, Thomas T. McCreery, Terry R. Barrette, Arthur F. Gmitro, Evan C. Unger

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


Magnetic resonance imaging contrast agents that are sensitive to pressure would be useful for evaluating cardiovascular function. One such potential contrast agent consists of gas-filled liposome microbubbles. The magnetic susceptibility of the microbubbles locally perturb the static magnetic field, which influences the transverse-relaxation properties of the surrounding medium. Changes in the pressure alter the bubble dimensions, which affects the magnetic field perturbations and, hence, the transverse-relaxation. The effect of these microbubbles on the T2 relaxation times of a water-based medium was measured for liposomes filled with different gases-nitrogen, argon, air, oxygen, xenon, neon, perfluoropentane, perfluorobutane, and sulfur hexafluoride. The air-filled, perfluoropentane-filled and the oxygen- filled liposomes demonstrated the largest effect on transverse-relaxation. The influence of pressure on both gradient-echo and spin-echo signal intensities for air-filled microbubbles was also evaluated. Pressure-induced changes in signal intensity were consistently observed for both the spin- echo and gradient-echo pulses sequences.

Original languageEnglish (US)
Pages (from-to)801-806
Number of pages6
JournalMagnetic Resonance in Medicine
Issue number6
StatePublished - Jun 1996


  • magnetic resonance contrast agents
  • microbubbles
  • pressure
  • transverse relaxation

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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