Investigation of relationships between transverse relaxation rate, diffusion coefficient, and labeled cell concentration in ischemic rat brain using MRI

✍ Scribed by Hemanthkumar Athiraman; Quan Jiang; Guang Liang Ding; Li Zhang; Zheng Gang Zhang; Lei Wang; Ali S. Arbab; Qingjiang Li; Swayam Panda; Karen Ledbetter; Ali M. Rad; Michael Chopp

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 456 KB
• Volume: 61
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.21480

✦ Synopsis

Abstract

MRI has been used to evaluate labeled cell migration and distribution. However, quantitative determination of labeled cell concentration using MRI has not been systematically investigated. In the current study, we investigated the relationships between labeled cell concentration and MRI parameters of transverse relaxation rate, R~2~, and apparent diffusion coefficient (ADC), in vitro in phantoms and in vivo in rats after stroke. Significant correlations were detected between iron concentration or labeled cell concentration and MRI measurements of R~2~, ADC, and ADC×R~2~ in vitro. In contrast, in vivo labeled cell concentration did not significantly correlate with R~2~, ADC, and ADC×R~2~. A major factor for the absence of a significant correlation between labeled cell concentration and MRI measurements in vivo may be attributed to background effects of ischemic tissue. By correcting the background effects caused by ischemic damage, Δ__R__~2~ (difference in R~2~ values in the ischemic tissue with and without labeled cells) exhibited a significant correlation to labeled cell concentration. Our study suggests that MRI parameters have the potential to quantitatively determine labeled cell concentration in vivo. Magn Reson Med, 2009. © 2008 Wiley‐Liss, Inc.