Department of Medical Radiation Physics, Lund University, Skåne University Hospital, Malmö, Sweden.
Magn Reson Med. 2014 Jan;71(1):219-29. doi: 10.1002/mrm.24657. Epub 2013 Feb 14.
To investigate the accuracy and noise performance of fat quantification with multiple gradient-echo images acquired using bipolar read-out gradients and compare them with those of the well-established unipolar technique.
The bipolar read-out technique induces phase and amplitude errors caused by gradient delays, eddy currents, and frequency-dependent coil sensitivity. In this study, these errors were corrected for jointly with the fat/water separation by modeling the impact of these effects on the signal. This approach did not require acquisition of reference data or modification of the pulse sequence.
Simulations and a phantom experiment were used to investigate the accuracy and noise performance of the technique and compare them with those of a well-established technique using unipolar read-out gradients. Also, the in vivo feasibility was demonstrated for abdominal applications.
The phantom experiment demonstrated similar accuracy of the bipolar and unipolar fat quantification techniques. In addition, the noise performance was shown not to be affected by the added estimations of the phase and amplitude errors for most inter-echo times.
The bipolar technique was found to provide accurate fat quantification with noise performance similar to the unipolar technique given an appropriate choice of inter-echo time.
研究使用双极读出梯度采集的多梯度回波图像进行脂肪定量的准确性和噪声性能，并将其与成熟的单极技术进行比较。
双极读出技术会因梯度延迟、涡流和频率相关线圈灵敏度而产生相位和幅度误差。在本研究中，通过对这些影响信号的影响进行建模，联合对脂肪/水分离进行了这些误差的校正。这种方法不需要采集参考数据或修改脉冲序列。
使用仿真和体模实验研究了该技术的准确性和噪声性能，并与使用单极读出梯度的成熟技术进行了比较。此外，还证明了该技术在腹部应用中的体内可行性。
体模实验表明，双极和单极脂肪定量技术具有相似的准确性。此外，对于大多数回波时间间隔，噪声性能并未受到增加的相位和幅度误差估计的影响。
在适当选择回波时间间隔的情况下，发现双极技术可提供准确的脂肪定量，且噪声性能与单极技术相似。
