Ferritin effect on the transverse relaxation of water: NMR microscopy at 9.4 T

Accumulation of ferritin, the iron storage protein, has been linked recently to aging and a number of pathologies. Noninvasive detection of iron storage by MRI relies on its extremely strong effect on water relaxation. The aim of this article is to characterize the effect of ferritin on transverse water relaxation in a high magnetic field, using an imaging Carr-Purcell Meiboom-Gill (CPMG) preparation sequence. Ferritin-induced water relaxation showed quadratic dependence on the iron loading factor, implying a paramagnetic mechanism. However, an additional zero order term was found, that could be due to the initial stages of the iron core loading. Significant enhancement of ferritin contrast was obtained at very short tau(CPMG) durations. This approach for enhancing ferritin contrast was demonstrated by NMR microscopy of ferritin-injected Xenopus oocytes, thus showing the feasibility of ferritin detection in a high magnetic field, even in systems with short transverse relaxation.