Noninvasive MRI-Based Liver Iron Quantification: Methodic Approaches, Practical Applicability and Significance

Abstract

Pathophysiology of iron overload ▼Normal iron content plays an important role in the physiological processes of the human body. A disturbance to the precisely regulated iron metabolism system has serious consequences. Therefore, for example, iron overload results in oxidative damage to membrane lipids and proteins and in DNA damage that can cause mitochondrial and lysosomal dysfunction, changes in gene expression, and changes in tumor suppressor genes (p53). Organ damage due to iron overload primarily affects the heart and liver as well as the endocrine organs, i. e., the pituitary gland, pancreas, thyroid, parathyroid, and gonads [1]. Cardiac insufficiency and arrhythmia as a result of myocardial siderosis are the most Abstract ▼Due to the dependence of transverse relaxation times T 2 and T 2 * on tissue iron content, MRI offers different options for the determination of iron concentration. These are the timeconsuming spin-echo sequence as well as the gradient-echo sequence. For the latter, several data analysis approaches have been proposed, with different requirements for acquisition and post-processing: the mathematically challenging R 2 * analysis and the signal-intensity ratio method with its high demand on the signal homogeneity of MR images. Furthermore, special procedures currently under evaluation are presented as future prospects: quantitative susceptibility imaging, as a third approach for analyzing gradient echo data, and multicontrast spin-echo using repeated refocusing pulses. MR theory, as far as needed for understanding the methods, is briefly depicted.

A Combined Use of Intravoxel Incoherent Motion MRI Parameters Can Differentiate Early-Stage Hepatitis-b Fibrotic Livers from Healthy Livers

“…Additionally, it is known that liver fat and iron can be quantified by MRI. 62,63 It is expected that with a better IVIM imaging protocol with more b values and better image postprocessing, differentiation of early-stage fibrotic liver from healthy liver should have increased reliability. The use of Bayesian prediction, incorporating relevant findings from the available methods, is also a promising technique for liver fibrosis evaluation.…”

A combined use of intravoxel incoherent motion MRI parameters can differentiate early stage hepatitis-b fibrotic livers from healthy livers

“…Additionally, it is known that liver fat and iron can be quantified by MRI. 62, 63 It is expected that with better IVIM imaging protocol with more b-values and better image post-procession, differentiation of early stage fibrotic liver from healthy liver should have increased reliability. The use of Bayesian prediction, incorporating relevant findings from the available methods, is also a promising technique for liver fibrosis evaluation.…”

“…The question which requires important attention is to detect F1 and F2 stage liver fibrosis. Additionally, liver fat and iron can reliably be quantified by MRI [55, 56]. The use of Bayesian prediction, incorporating relevant findings from the available methods, is also a promising technique for liver fibrosis evaluation [57].…”

Non-invasive measurement of liver iron concentration by magnetic resonance imaging and its clinical usefulness

“…Magnetic resonance units 1-4 correspond to four other machines located in the same city. shown that it overestimates patients with moderate overload [25][26][27] and recently it has been replaced by a new T2* relaxometry method (www. MRQuantif.org) that is also able to perform SIR calculations.…”

“…MRQuantif.org) that is also able to perform SIR calculations. Additionally, the Spanish Society of Abdominal Imaging (SEDIA, www.sedia.es) has developed a specific mathematical model to estimate LIC that shows a good correlation with relaxometry techniques [26,27] (https://imagemed. univ-rennes1.fr/en/mrquantif/quantif.php).…”