Department of Radiology, Cappagh National Orthopaedic Hospital, Finglas, Dublin 11, Republic of Ireland.
AJR Am J Roentgenol. 2010 Jan;194(1):W60-4. doi: 10.2214/AJR.08.1740.
The purpose of this study was to compare metal artifact reduction techniques at 1.5-T and 3-T MRI.
A titanium plate with steel screws was placed in a freshly harvested pig leg. The leg was imaged with 1.5-T and 3-T MRI. A T2-weighted turbo spin-echo sequence was used with echo-train lengths of 8, 16, 32, and 64 and a constant readout bandwidth of 31.2 kHz. The images were compared qualitatively, and the optimal echo-train length was selected. Images were acquired at the optimal echo-train length with four different readout bandwidths. Artifact was measured quantitatively, and image quality was ranked qualitatively. The qualitatively best image acquired at 1.5 T was compared with the qualitatively highest-ranked image acquired at 3 T.
At both 1.5 T and 3 T, optimal images of equal quality were produced at echo-train lengths of 8 and 16. At higher readout bandwidths, there was quantitatively less artifact. The qualitatively best images were acquired at a readout bandwidth of 31.2 kHz at 1.5 T and 62.5 kHz at 3 T (Cronbach's alpha=1.00). The optimal image at 3 T was qualitatively superior to that at 1.5 T.
Optimizing image acquisition parameters in this phantom model resulted in similar quantitative susceptibility artifact at 3 T and 1.5 T and better qualitative images at 3 T than at 1.5 T.
本研究旨在比较 1.5T 和 3T MRI 下的金属伪影减少技术。
将一块带有钢钉的钛板放置在新鲜采集的猪腿中。使用 1.5T 和 3T MRI 对腿部进行成像。使用 T2 加权涡轮自旋回波序列，回波链长度为 8、16、32 和 64，且读出带宽恒定为 31.2kHz。对图像进行定性比较，并选择最佳回波链长度。在最佳回波链长度下，使用四种不同的读出带宽获取图像。对伪影进行定量测量，并对图像质量进行定性评分。将在 1.5T 下获得的定性最佳图像与在 3T 下获得的定性评分最高的图像进行比较。
在 1.5T 和 3T 下，在回波链长度为 8 和 16 时，都可以获得质量相等的最佳图像。在更高的读出带宽下，伪影的定量减少。在 1.5T 下，使用 31.2kHz 的读出带宽可获得定性最佳图像，在 3T 下，使用 62.5kHz 的读出带宽可获得定性最佳图像（Cronbach's alpha=1.00）。3T 下的最佳图像在定性上优于 1.5T 下的图像。
在该体模模型中优化图像采集参数可导致在 3T 和 1.5T 下产生相似的定量磁化率伪影，并在 3T 下获得优于 1.5T 的更好的定性图像。
