SEMAC-VAT and MSVAT-SPACE Sequence Strategies for Metal Artifact Reduction in 1.5T Magnetic Resonance Imaging
SEMAC-VAT and MSVAT-SPACE Sequence Strategies for Metal Artifact Reduction in 1.5T Magnetic Resonance Imaging
复制标题
用于减少 1.5T 磁共振成像中金属伪影的 SEMAC-VAT 和 MSVAT-SPACE 序列策略
DOI：
10.1097/rli.0b013e318240a919
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发表时间：
2012-05-01
影响因子：
6.7
通讯作者：
Runge, Val M.
中科院分区：
文献类型：
--
作者：
Ai, Tao;Padua, Abraham;Runge, Val M.
目的：评价四种磁共振成像（MRI）技术纠正金属伪影的能力。这些技术包括3个2D技术和一个3D技术。在2D成像中，评价了视角倾斜（VAT）技术、金属薄片校正的切片编码（SEMAC）技术和采用前两者组合的技术（SEMAC-VAT）。在3D成像中，评价了基于SPACE序列的VAT多板采集技术（MSVAT-SPACE）。材料和方法：在1.5T下，对两种常用金属种植体（不锈钢和钛）的琼脂糖体模和组织体模以及两名志愿者的金属种植体进行成像。所有体模和志愿者使用VAT，SEMAC，SEMAC-VAT和MSVAT-SPACE技术，以及2D和3D常规成像技术进行成像。每种技术都针对不同的图像对比机制进行了优化。通过体积测量在琼脂糖模型中定量评估琼脂糖还原。通过采用两名阅片员的盲法阅片对图像质量进行定性评估。每名阅片员独立查看组织体模图像和体内人体图像。使用Friedman检验、Wilcoxon检验和加权Cohen kappa检验进行统计学分析。结果：T1加权，T2加权，PD加权和STIR图像对比与评价伪影减少序列在两个体模实验和在体图像成功地实现。对于所有评价的图像对比度和两种金属植入物，与2D常规采集相比，金属伪影的体积减少。对于增值税、SEMAC和SEMAC-增值税采集，2D金属伪影体积平均分别减少了49% ± 16%、56% ± 15%和63% ± 15%。当应用Friedman和Wilcoxon检验时，当VAT、SEMAC和SEMAC-VAT与2D常规技术进行比较时，发现金属伪影体积的差异具有统计学显著性。在3D成像中，对于所有评价的图像对比度和两种金属植入物，与3D传统成像技术相比，MSVAT-SPACE平均减少了72% ± 23%的金属伪影体积。MSVAT-SPACE与3D常规技术相比，金属伪影体积差异具有统计学意义。盲法读数表明，与常规采集相比，SEMAC-VAT和MSVAT-SPACE具有明显优越的上级质量。根据伪影大小、失真、图像质量和金属植入物附近骨髓和软组织的可视化来测量质量。组织体模图像和人体图像的情况都是如此，观察者之间具有良好的一致性。结论：SEMAC-VAT（2D）和MSVAT-SPACE（3D）证明了不同金属植入物的金属伪影的一致、显著减少，并提供了灵活的图像对比度（T1、T2、PD和STIR）和高图像质量。这些技术可能会改善金属植入物术后患者的评价。
Objectives:To evaluate the ability of four magnetic resonance imaging (MRI) techniques to correct for metallic artifacts. These techniques consisted of 3 2D techniques and one 3D technique. In 2D imaging the techniques View Angle Tilting (VAT), Slice Encoding for Metal Artifact Correction (SEMAC) and a technique that employed a combination of the first two (SEMAC-VAT) were evaluated. In 3D imaging the technique Multiple Slab acquisition with VAT based on a SPACE sequence was evaluated (MSVAT-SPACE). Materials and Methods:Agarose phantoms and tissue phantoms with two commonly used metal implants (stainless steel and titanium) as well as two volunteers with metal implants were imaged at 1.5T. All phantoms and volunteers were imaged using VAT, SEMAC, SEMAC-VAT and MSVAT-SPACE techniques, as well as 2D and 3D conventional imaging techniques. Each technique was optimized for different image contrast mechanisms. Artifact reduction was quantitatively assessed in the agarose phantoms by volumetric measurement. Image quality was qualitatively assessed by blinded reads employing two readers. Each reader independently viewed the tissue phantom images and in vivo human images. Statistical analysis was performed using a Friedman test, Wilcoxon test and weighted Cohen's kappa test. Results:T1-weighted, T2-weighted, PD-weighted and STIR image contrasts were successfully implemented with the evaluated artifact reduction sequences in both the phantom experiments and in vivo images. For all evaluated image contrasts and both metal implants, a reduction in the volume of metal artifacts was seen when compared with 2D conventional acquisitions. The 2D metal artifact volumes on average were reduced by 49% ± 16%, 56% ± 15% and 63% ± 15% for VAT, SEMAC and SEMAC-VAT acquisitions respectively. When Friedman and Wilcoxon tests were applied the difference in metal artifact volume was found to be statistically significant when VAT, SEMAC and SEMAC-VAT were compared with the 2D conventional techniques. In 3D imaging on average MSVAT-SPACE reduced metal artifact volume compared with the 3D conventional imaging technique by 72% ± 23% for all evaluated image contrasts and both metal implants. The metal artifact volume differences were statistically significant when MSVAT-SPACE was compared with the 3D conventional technique. The blinded reads demonstrated that SEMAC-VAT and MSVAT-SPACE had distinctly superior quality compared with conventional acquisitions. Quality was measured in terms of artifact size, distortions, image quality and visualization of bone marrow and soft tissues adjacent to metal implants. This was the case for both tissue phantom images and human images with good interobserver agreement. Conclusions:SEMAC-VAT (2D) and MSVAT-SPACE (3D) demonstrated a consistent, marked reduction of metal artifacts for different metal implants and offered flexible image contrasts (T1, T2, PD and STIR) with high image quality. These techniques likely will improve the evaluation of postoperative patients with metal implants.