Sharma Samir D, Hernando Diego, Horng Debra E, Reeder Scott B
Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA.
Magn Reson Med. 2015 Sep;74(3):673-83. doi: 10.1002/mrm.25448. Epub 2014 Sep 8.
The purpose of this work was to develop and demonstrate feasibility and initial clinical validation of quantitative susceptibility mapping (QSM) in the abdomen as an imaging biomarker of hepatic iron overload.
In general, QSM is faced with the challenges of background field removal and dipole inversion. Respiratory motion, the presence of fat, and severe iron overload further complicate QSM in the abdomen. We propose a technique for QSM in the abdomen that addresses these challenges. Data were acquired from 10 subjects without hepatic iron overload and 33 subjects with known or suspected iron overload. The proposed technique was used to estimate the susceptibility map in the abdomen, from which hepatic iron overload was measured. As a reference, spin-echo data were acquired for R2-based LIC estimation. Liver R2* was measured for correlation with liver susceptibility estimates.
Correlation between susceptibility and R2-based LIC estimation was R(2) = 0.76 at 1.5 Tesla (T) and R(2) = 0.83 at 3T. Furthermore, high correlation between liver susceptibility and liver R2* (R(2) = 0.94 at 1.5T; R(2) = 0.93 at 3T) was observed.
We have developed and demonstrated initial validation of QSM in the abdomen as an imaging biomarker of hepatic iron overload.
本研究旨在开发并验证腹部定量磁化率成像（QSM）作为肝铁过载成像生物标志物的可行性及初步临床有效性。
一般而言，QSM面临背景场去除和偶极反转的挑战。呼吸运动、脂肪的存在以及严重的铁过载使腹部QSM更加复杂。我们提出了一种应对这些挑战的腹部QSM技术。从10名无肝铁过载的受试者和33名已知或疑似铁过载的受试者获取数据。使用所提出的技术估计腹部的磁化率图，从中测量肝铁过载。作为参考，采集自旋回波数据用于基于R2的肝铁浓度（LIC）估计。测量肝脏R2*以与肝脏磁化率估计值进行相关性分析。
在1.5特斯拉（T）时，磁化率与基于R2的LIC估计值之间的相关性为R(2)=0.76，在3T时为R(2)=0.83。此外，观察到肝脏磁化率与肝脏R2*之间具有高度相关性（在1.5T时R(2)=0.94；在3T时R(2)=0.93）。
我们已开发并验证了腹部QSM作为肝铁过载成像生物标志物的初步有效性。
