Effect of concentration of SH U 555A labeled human melanoma cells on MR spin echo and gradient echo signal decay at 0.2, 1.5, and 3T

• Published in: Magma (New York, N.Y.) N.Y.), 2006-05, Vol.19 (2), p.71-77
• Main Authors: Pintaske, J, Bantleon, R, Kehlbach, R, Claussen, C D, Wiskirchen, J, Schick, F
• Format: Article
• Language: English
• Subjects: Calibration; Cells, Cultured; Contrast Media; Decay; Dextrans; Echo-Planar Imaging; Ferric Compounds - chemistry; Ferrosoferric Oxide; Humans; Image Processing, Computer-Assisted; Iron; Iron oxides; Magnetic fields; Magnetic Resonance Imaging; Magnetite Nanoparticles; Melanoma; Melanoma - pathology; Oxides; Staining and Labeling
• ISSN: 0968-5243; 1352-8661
• DOI: 10.1007/s10334-006-0029-z

In the current study the effect of increasing concentrations of superparamagnetic iron oxide labeled cells on the MRI signal decay at magnetic field strengths of 0.2, 1.5, and 3 T was evaluated. The spin echo and gradient echo cellular transverse relaxivity was systematically studied for various concentrations (N = 1, 5, 10, 20, 40, and 80 cells/microl(gel)) of homogeneously suspended SH U 555A labeled SK-Mel28 human melanoma cells. For all field strengths investigated a linear relationship between cellular transverse relaxation enhancement and cell concentration was found. In the spin echo case, the cellular relaxivities [i.e., d(deltaR2)/dN] were determined to 0.12 s(-1) (cell/microl)(-1) at 0.2 T, 0.16 s(-1) (cell/microl)(-1) at 1.5 T, and 0.17 s(-1) (cell/microl) at 3 T. In the gradient echo case, the calculated cellular relaxivities (i.e., d(deltaR2*)/dN) were 0.51 s(-1) (cell/microl)(-1) at 0.2 T, 0.69 s(-1) (cell/microl)(-1) at 1.5 T, and 0.71 s(-1) (cell/microl)(-1) at 3 T. The proposed preparation technique has proven to be a simple and reliable approach to quantify effects of magnetically labeled cells in vitro. On the basis of this quantification well suited tissue specific models can be derived.