Abstract：
:It has been demonstrated that gas-filled microbubble contrast agents, based on their volume changes, can serve as pressure probes in an MR field. It was recently reported that such an MR-based pressure measurement with microbubbles at 1.5 T must make use of microbubbles that have a volumetric magnetic susceptibility difference with the blood of at least 34 ppm in SI units. In this work, we show through analytical approximations and numerical simulations that such a microbubble formulation can be achieved by coating typical lipid-shelled microbubbles with particles of high dipole moment. Through finite-element simulations we demonstrate that the effective volumetric magnetic susceptibility of a coated microbubble is dependent on the radius, the shell volume fraction and the magnetic susceptibility of the particulates on the shell. Our calculations suggest that a suitable microbubble formulation which will be MR-sensitive to small pressure changes at 1.5 T must be 2-3 microm in radius and be uniformly coated with single-domain magnetic nanoparticles, such as magnetite, at shell volume fractions below 5%.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Dharmakumar R,Plewes DB,Wright GAdoi
10.1088/0031-9155/50/20/001subject
Has Abstractpub_date
2005-10-21 00:00:00pages
4745-62issue
20eissn
0031-9155issn
1361-6560pii
S0031-9155(05)01599-Xjournal_volume
50pub_type
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