Figure 8.

Influence of changes in extracellular iron on the correlation between cellular iron content and MR transverse relaxation rates. To examine the influence of extracellular iron, THP-1 cells were cultured in the absence (−Fe) or in the presence (+Fe) of iron-supplemented medium containing 25 µM ferric nitrate for 7 days. Cells were then harvested and scanned either immediately (−Fe and +Fe) or cultured an additional 1 (1 h-Fe), 2 (2 h-Fe), 4 (4 h-Fe) and 24 (24 h-Fe) hours after removal of extracellular iron supplementation. Total cellular iron content was assessed by ICP-MS and was normalized to the amount of protein. There is a moderate positive correlation between cellular iron content and both R₂* (A) and R₂’ (B). For both graphs, n = 19 and p < 0.01.