MRI‐based quantitative susceptibility mapping (QSM) and R2* mapping of liver iron overload: Comparison with SQUID‐based biomagnetic liver susceptometry

Abstract

Purpose We aimed to determine the agreement between quantitative susceptibility mapping (QSM)-based biomagnetic liver susceptometry (BLS) and confounder-corrected R2* mapping with superconducting quantum interference device (SQUID)-based biomagnetic liver susceptometry in patients with liver iron overload. Methods Data were acquired from two healthy controls and 22 patients undergoing MRI and SQUID-BLS as part of routine monitoring for iron overload. MR imaging was performed on a 3T system using a 3D multi-echo, gradient-echo acquisition. Both magnetic susceptibility and R2* of the liver were estimated from this acquisition. Linear regression was used to compare estimates of QSM-BLS and R2* to SQUID-BLS. Results Both QSM-BLS and confounder-corrected R2* were sensitive to the presence of iron in the liver. Linear regression between QSM-BLS and SQUID-BLS demonstrated the following relationship: QSM-BLS = (−0.22 ± 0.11) + (0.49 ± 0.05) · SQUID-BLS with r2 = 0.88. The coefficient of determination between liver R2* and SQUID-BLS was also r2 = 0.88. Conclusion We determined a strong correlation between both QSM-BLS and confounder-corrected R2* to SQUID-BLS. This study demonstrates the feasibility of QSM-BLS and confounder-corrected R2* for assessing liver iron overload, particularly when SQUID systems are not accessible.

Clinical quantitative susceptibility mapping (QSM): Biometal imaging and its emerging roles in patient care

“…Fortunately, QSM has a simple linear relationship with these intravoxel contents according to chemical decomposition, allowing linear extraction of iron content. Furthermore, except fat (quantifiable according to its chemical shifts and phase data (45)), other intravoxel contents, including fibrosis and edema, have a susceptibility that is virtually zero relative to water, making QSM ideally suited for determining the iron concentration of liver, heart, and other tissues (45,187) (Fig. 11).…”

Multicenter reproducibility of quantitative susceptibility mapping in a gadolinium phantom using MEDI+0 automatic zero referencing

“…From its initial applications to endogenous brain iron quantification, quantitative susceptibility mapping (QSM) has seen increasing applications to a wide range of quantitative research on disease conditions including intracerebral hemorrhage, liver iron overload, bone mineral quantification, and preclinical contrast agent toxicity studies . These applications require confidence in the reproducibility of QSM for a wider range of susceptibility values, field strengths, and vendor platforms than has been previously reported by researchers …”

Assessment of MR‐based and quantitative susceptibility mapping for the quantification of liver iron concentration in a mouse model at 7T

“…Magnetic susceptibility is an inherent property of tissues that, unlike , is independent of the magnetic field strength and, similar to , increases with increasing LIC. Superconducting quantum interference devices are able to accurately measure magnetic susceptibility in the liver, and LIC quantification using these devices has been shown to correlate well with biopsy LIC measurements . However, the operation of these devices is expensive, and their availability is extremely limited.…”