J Korean Radiol Soc.  2008 Apr;58(4):435-442. 10.3348/jkrs.2008.58.4.435.

The Impact of the Amount of Intracellular SPIO on MR Signal Intensity during In Vivo Tracking of Macrophage Homing

• Kim DY
• Lee JS
• Kang J
• Sohn JY
• Kim ST
• Woo CW

• KMID: 1479110
• DOI: http://doi.org/10.3348/jkrs.2008.58.4.435

Abstract

PURPOSE
To determine whether the amount of intracellular superparamagnetic iron oxide (SPIO) in macrophages influences MR signal intensity during in vivo celluar tracking.
MATERIALS AND METHODS
Peritoneal macrophages harvested from thioglycolate-treated mice were labeled with SPIO using concentrations of 112, 56, and 28 microgramFe/ml, and different incubation times of 3h, 6h, 12h, 24h and 48 h, respectively. The iron concentration was quantified with the use of absorption spectrophotometry. Each group of macrophages labeled with different concentrations of SPIO was intravenously injected into 18 mice, after inoculation with S. aureus to the thigh. The relative signal intensity (SI) of the abscess wall (SI of the abscess wall/SI of muscle) was measured on MR and was analyzed by the use of the Kruskal-Wallis test.
RESULTS
A higher concentration of SPIO in the labeling solution and a longer incubation time resulted in a higher concentration of SPIO in the macrophages. The relative SI of the abscess wall (0.63 for 112 microgramFe/mL; 0.67 for 56 microgramFe/ml; 0.89 for 28 microgramFe/mL) significantly decreased with an increase of SPIO concentration (k2=10.53, p < 0.005).
CONCLUSION
The amount of intracellular SPIO influences the MR signal intensity by the susceptibility effect, and it is recommended to use sufficient iron-oxide label as long as it does not affect cellular function and viability.

Keyword

Superparamagnetic iron oxide; Macrophage; Magnetic resonance (MR); Mouse

MeSH Terms

Abscess
Absorption
Animals
Ferric Compounds
Iron
Macrophages
Macrophages, Peritoneal
Mice
Spectrophotometry
Thigh
Track and Field
Ferric Compounds
Iron