使用常规和压缩感知 SEMAC 对 3T 介入 MRI 进行器械可视化。
Instrument visualization using conventional and compressed sensing SEMAC for interventional MRI at 3T.
机构信息
Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
出版信息
J Magn Reson Imaging. 2018 May;47(5):1306-1315. doi: 10.1002/jmri.25858. Epub 2017 Sep 21.
BACKGROUND
Interventional magnetic resonance imaging (MRI) at 3T benefits from higher spatial and temporal resolution, but artifacts of metallic instruments are often larger and may obscure target structures.
PURPOSE
To test that compressed sensing (CS) slice-encoding metal artifact correction (SEMAC) is feasible for 3T interventional MRI and affords more accurate instrument visualization than turbo spin echo (TSE) and gradient echo (GRE) techniques, and facilitates faster data acquisition than conventional SEMAC.
STUDY TYPE
Prospective.
PHANTOM AND SUBJECTS
Cadaveric animal and 20 human subjects.
FIELD STRENGTH/SEQUENCE: TSE (acquisition time 31 sec), GRE (28-33 sec), SEMAC (128 sec), and CS-SEMAC (57 sec) pulse sequences were evaluated at 3T.
ASSESSMENT
Artifact width and length, signal-to-noise (SNR), and contrast-to-noise (CNR) ratios of 14-22G MR-conditional needles were measured in a phantom. Subsequently, high-bandwidth TSE and CS-SEMAC sequences were assessed in vivo with 20 patient procedures for the size of the metal artifact, image sharpness, image noise, motion artifacts, image contrast, and target, instrument, and structural visibility.
STATISTICAL TESTS
Repeated-measures-analysis-of-variances and Mann-Whitney U-tests were applied. P ≤ 0.05 was considered statistically significant.
RESULTS
CS-SEMAC and SEMAC created the smallest needle artifact widths (3.2-3.3 ± 0.4 mm, P = 1.0), whereas GRE showed the largest needle artifact widths (8.5-8.6 ± 0.4 mm) (P < 0.001). The artifact width difference between high-bandwidth TSE and CS-SEMAC was 0.8 ± 0.6 mm (P < 0.01). SEMAC and CS-SEMAC created the lowest average needle tip errors (0.3-0.4 ± 0.1 mm, P = 1.0). The average tip error difference between high-bandwidth TSE and SEMAC/CS-SEMAC was 2.0 ± 1.7 mm (P < 0.01). SNR and CNR were similar on TSE, SEMAC, and CS-SEMAC, and lowest on GRE. CS-SEMAC yielded smaller artifacts, less noise, less motion, and better instrument visibility (P < 0.001); high-bandwidth TSE showed better sharpness (P < 0.001) and targets visibility (P = 0.007); whereas image contrast (P = 0.273) and structural visibility (P = 0.1) were similar.
DATA CONCLUSION
CS-SEMAC is feasible for interventional MRI at 3T, visualizes instruments with higher accuracy than high-bandwidth TSE and GRE, and can be acquired 55% faster than conventional SEMAC.
LEVEL OF EVIDENCE
2 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2018;47:1306-1315.
背景
3T 下的介入性磁共振成像（MRI）得益于更高的空间和时间分辨率，但金属器械的伪影通常更大，可能会使目标结构模糊。
目的
测试压缩感知（CS）切片编码金属伪影校正（SEMAC）在 3T 介入性 MRI 中是否可行，与涡轮自旋回波（TSE）和梯度回波（GRE）技术相比，提供更准确的器械可视化效果，并比传统的 SEMAC 更有利于更快的数据采集。
研究类型
前瞻性。
标本和受试者
尸体动物和 20 名人类受试者。
磁场强度/序列：在 3T 下评估 TSE（采集时间 31 秒）、GRE（28-33 秒）、SEMAC（128 秒）和 CS-SEMAC（57 秒）脉冲序列。
评估
在体模中测量 14-22G MR 条件下的针的伪影宽度和长度、信噪比（SNR）和对比噪声比（CNR）。随后，在 20 例患者的程序中，对高带宽 TSE 和 CS-SEMAC 序列进行评估，评估金属伪影的大小、图像清晰度、图像噪声、运动伪影、图像对比度以及目标、器械和结构的可视性。
统计学检验
应用重复测量方差分析和曼-惠特尼 U 检验。P ≤ 0.05 被认为具有统计学意义。
结果
CS-SEMAC 和 SEMAC 产生的针伪影宽度最小（3.2-3.3 ± 0.4mm，P = 1.0），而 GRE 显示的针伪影宽度最大（8.5-8.6 ± 0.4mm）（P < 0.001）。高带宽 TSE 和 CS-SEMAC 之间的伪影宽度差异为 0.8 ± 0.6mm（P < 0.01）。SEMAC 和 CS-SEMAC 产生的针尖端误差最低（0.3-0.4 ± 0.1mm，P = 1.0）。高带宽 TSE 和 SEMAC/CS-SEMAC 之间的平均尖端误差差异为 2.0 ± 1.7mm（P < 0.01）。TSE、SEMAC 和 CS-SEMAC 的 SNR 和 CNR 相似，而 GRE 的 SNR 和 CNR 最低。CS-SEMAC 产生的伪影更小，噪声更小，运动伪影更少，器械可视性更好（P < 0.001）；高带宽 TSE 显示出更好的清晰度（P < 0.001）和目标可视性（P = 0.007）；而图像对比度（P = 0.273）和结构可视性（P = 0.1）相似。
数据结论
CS-SEMAC 可用于 3T 下的介入性 MRI，与高带宽 TSE 和 GRE 相比，可更准确地可视化器械，且采集速度比传统的 SEMAC 快 55%。
证据水平
2 技术功效：第 6 阶段 J. Magn. Reson. Imaging 2018;47:1306-1315.
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