Longitudinal and Transverse Relaxivity Analysis of Native Ferritin and Magnetoferritin at 7 T MRI

Abstract

Magnetite mineralization in human tissue is associated with various pathological processes, especially neurodegenerative disorders. Ferritin’s mineral core is believed to be a precursor of magnetite mineralization. Magnetoferritin (MF) was prepared with different iron loading factors (LFs) as a model system for pathological ferritin to analyze its MRI relaxivity properties compared to those of native ferritin (NF). The results revealed that MF differs statistically significantly from NF, with the same LF, for all studied relaxation parameters at 7 T: r1, r2, r2*, r2/r1, r2*/r1. Distinguishability of MF from NF may be useful in non-invasive MRI diagnosis of pathological processes associated with iron accumulation and magnetite mineralization (e.g., neurodegenerative disorders, cancer, and diseases of the heart, lung and liver). In addition, it was found that MF samples possess very strong correlation and MF’s relaxivity is linearly dependent on the LF, and the transverse and longitudinal ratios r2/r1 and r2*/r1 possess complementary information. This is useful in eliminating false-positive hypointensive artefacts and diagnosis of the different stages of pathology. These findings could contribute to the exploitation of MRI techniques in the non-invasive diagnosis of iron-related pathological processes in human tissue.

In-depth magnetometry and EPR analysis of the spin structure of human-liver ferritin: from DC to 9 GHz

“…As such, the magnetism of the protein influences the contrast of R2 and R2*-weighted MRI images. [7][8][9] In the past decades, 'bulk' magnetometry techniques have been used to characterize the magnetic and mineral state of ferritin, 10,11 along with spectroscopy techniques such as Mo ¨ssbauer spectroscopy, 11,12 electron paramagnetic resonance (EPR), 13,14 nuclear magnetic resonance (NMR), [15][16][17] as well as electron and X-ray microscopy techniques, 18,19 and diamondbased quantum spin relaxometry to study the ferritin room temperature magnetic properties. 20 Electron paramagnetic resonance (EPR), sometimes also referred to by the more general term electron magnetic resonance (EMR), has also been applied to ferritin, 13,14,[21][22][23][24][25] in spite of intrinsic challenges related to extreme spectral broadening.…”

“…As such, the magnetism of the protein influences the contrast of R2 and R2*-weighted MRI images. 7–9…”

Polymeric Metal Contrast Agents for T1-Weighted Magnetic Resonance Imaging of the Brain

“…The relaxivity ratio, r 2 / r 1 , helps evaluate a CA’s aptitude for use as either a T 1 or T 2 CA. CAs with low r 2 / r 1 values (less than 4) are considered good candidates for enhancing T 1 -weighted images, while high r 2 / r 1 values (10 or greater) suggest the best compatibility with T 2 -weighted images. , It is important to note when comparing different CAs that relaxivity is dependent on magnetic field strengthincreasing magnetic field strength tends to decrease r 1 while increasing r 2 so direct comparisons should only be made with systems operating under the same MRI conditions.…”

A Theoretical Analysis of Magnetic Particle Alignment in External Magnetic Fields Affected by Viscosity and Brownian Motion

“…When subjected to an external magnetic field, a magnetic particle will respond with translational motion in the gradient magnetic field and its self-rotation, or rotation of its magnetic moment, to the direction of the external magnetic field as it is applied in various cases of biomedical applications widely studied experimentally and theoretically [1][2][3][4][5][6][7][8][9][10]. These latter effects are simply denoted as magnetic alignment and are inverse processes to Brownian and Néel relaxation [11,12].…”

“…Both magnetic alignment and relaxation are important in, for example, magnetic particle contrast imaging and quantification in magnetic resonance and particle imaging [8,9,[13][14][15], electromagnetic hyperthermia [6,7,16,17], theranostics [18][19][20], magnetorelaxometry [10,21,22], and navigation in the geomagnetic field [23][24][25][26][27]. Magnetic particle alignment at the nano-and micro-scale requires a complex approach for simulating a wide range of possible strengths of an acting external magnetic field.…”