在1.5和3T场强下，存在金属植入物时膝关节MRI的体外评估：比较MAVRIC-SL序列和传统快速自旋回波序列
In vitro assessment of knee MRI in the presence of metal implants comparing MAVRIC-SL and conventional fast spin echo sequences at 1.5 and 3 T field strength.
作者信息
Liebl Hans, Heilmeier Ursula, Lee Sonia, Nardo Lorenzo, Patsch Janina, Schuppert Christopher, Han Misung, Rondak Ina-Christine, Banerjee Suchandrima, Koch Kevin, Link Thomas M, Krug Roland
机构信息
Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA; Institut fuer diagnostische und interventionelle Radiologie, Technische Universitaet Muenchen, Munich, Germany.
出版信息
J Magn Reson Imaging. 2015 May;41(5):1291-9. doi: 10.1002/jmri.24668. Epub 2014 Jun 10.
PURPOSE
To assess lesion detection and artifact size reduction of a multiacquisition variable-resonance image combination, slice encoding for metal artifact correction (MAVRIC-SEMAC) hybrid sequence (MAVRIC-SL) compared to standard sequences at 1.5T and 3T in porcine knee specimens with metal hardware.
MATERIALS AND METHODS
Artificial cartilage and bone lesions of defined size were created in the proximity of titanium and steel screws with 2.5 mm diameter in 12 porcine knee specimens and were imaged at 1.5T and 3T magnetic resonance imaging (MRI) with MAVRIC-SL PD and short T1 inversion recovery (STIR), standard fast spin echo (FSE) T2 PD, and STIR and fat-saturated T2 FSE sequences. Three radiologists blinded to the lesion locations assessed lesion detection rates on randomized images for each sequence using receiver operating characteristic (ROC). Artifact length and width were measured.
RESULTS
Metal artifact sizes were largest in the presence of steel screws at 3T (FSE T2 FS: 28.7 cm(2) ) and 1.5T (16.03 cm(2) ). MAVRIC-SL PD and STIR reduced artifact sizes at both 3T (1.43 cm(2) ; 2.46 cm(2) ) and 1.5T (1.16 cm(2) ; 1.59 cm(2) ) compared to FS T2 FSE sequences (27.57 cm(2) ; 13.20 cm(2) ). At 3T, ROC-derived AUC values using MAVRIC-SL sequences were significantly higher compared to standard sequences (MAVRIC-PD: 0.87, versus FSE-T2 -FS: 0.73 [P = 0.025]; MAVRIC-STIR: 0.9 vs. T2 -STIR: 0.78 [P = 0.001] and vs. FSE-T2 -FS: 0.73 [P = 0.026]). Similar values were observed at 1.5T. Comparison of 3T and 1.5T showed no significant differences (MAVRIC-SL PD: P = 0.382; MAVRIC-SL STIR: P = 0.071).
CONCLUSION
MAVRIC-SL sequences provided superior lesion detection and reduced metal artifact size at both 1.5T and 3T compared to conventionally used FSE sequences. No significant disadvantage was found comparing MAVRIC-SL at 3T and 1.5T, although metal artifacts at 3T were larger. J. Magn. Reson. Imaging 2015;41:1291-1299. © 2014 Wiley Periodicals, Inc.
目的
评估在1.5T和3T场强下，与标准序列相比，多采集可变共振图像组合、切片编码金属伪影校正（MAVRIC - SEMAC）混合序列（MAVRIC - SL）在有金属植入物的猪膝关节标本中对病变的检测能力及伪影大小的减少情况。
材料与方法
在12个猪膝关节标本中，于直径2.5mm的钛合金和钢质螺钉附近制造出特定大小的人工软骨和骨病变，并在1.5T和3T磁共振成像（MRI）下，使用MAVRIC - SL的质子密度加权成像（PD）和短T1反转恢复序列（STIR）、标准快速自旋回波（FSE）T2加权质子密度加权成像（T2 PD）、STIR以及脂肪抑制T2加权快速自旋回波序列进行成像。三位对病变位置不知情的放射科医生使用受试者操作特征（ROC）曲线，对每个序列的随机图像进行病变检测率评估。同时测量伪影的长度和宽度。
结果
在3T场强下，钢质螺钉存在时金属伪影尺寸最大（FSE T2脂肪抑制序列：28.7平方厘米），在1.5T场强下为（16.03平方厘米）。与FSE T2脂肪抑制序列（27.57平方厘米；13.20平方厘米）相比，MAVRIC - SL的PD和STIR序列在3T（1.43平方厘米；2.46平方厘米）和1.5T（1.16平方厘米；1.59平方厘米）场强下均减小了伪影尺寸。在3T场强下，使用MAVRIC - SL序列的ROC曲线下面积（AUC）值显著高于标准序列（MAVRIC - PD：0.87，而FSE - T2 - FS：0.73 [P = 0.025]；MAVRIC - STIR：0.9，而T2 - STIR：0.78 [P = 0.001]以及FSE - T2 - FS：0.73 [P = 0.026]）。在1.5T场强下观察到类似结果。3T和1.5T场强的比较显示无显著差异（MAVRIC - SL PD：P = 0.382；MAVRIC - SL STIR：P = 0.071）。
结论
与传统使用的FSE序列相比，MAVRIC - SL序列在1.5T和3T场强下均能提供更好的病变检测能力并减小金属伪影尺寸。尽管3T场强下的金属伪影更大，但比较3T和1.5T场强下的MAVRIC - SL序列未发现明显劣势。《磁共振成像杂志》2015年；41：1291 - 1299。©2014威利期刊公司
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