Signal loss induced by superparamagnetic iron oxide particle in NMR spin-echo images: The role of diffusion
✍ Scribed by Yoseph Rozenman; Xueming Zou; Howard L. Kantor
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 505 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0740-3194
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
MR contrast agents are used to improve the detectability of pathologic conditions. In this study we clarify the mechanism of action of a newly developed superparamagnetic agent (AMI‐25, Advanced Magnetics Inc., Cambridge, MA). Transverse relaxation rates were measured from segments of rat brain, heart, and liver using a CPMG pulse sequence. Relaxation rates varied with the time interval between the refocusing pulses in the sequence ( τ)The diffusion effect on signal intensity was quantitated from the variation of T~2~with τ. We find that diffusion in the presence of microscopic field gradients reduces T~2~ and that this effect differs in magnitude among tissues. Superparamagnetic iron oxide particles enhance this T~2~reduction. The dependence of T~2~upon τ suggests a model of restricted diffusion. Tissue image contrast induced by superparamagnetic iron oxide in spin‐echo NMR studies is the result of a combination of diffusion‐dependent and diffusion‐independent differences in transverse relaxation. © 1990 Academic Press, Inc.