对软组织颈部 MRI 中常规自旋回波和非对称自旋回波迭代分解中组织对比度和成像伪影的主观和客观比较。
A subjective and objective comparison of tissue contrast and imaging artifacts present in routine spin echoes and in iterative decomposition of asymmetric spin echoes for soft tissue neck MRI.
机构信息
Department of Radiologic Technology & Medical Imaging, New York City College of Technology, The City University of New York, New York, NY, United States.
Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States.
出版信息
Eur J Radiol. 2018 May;102:202-207. doi: 10.1016/j.ejrad.2018.03.016. Epub 2018 Mar 14.
OBJECTIVE
FSE sequences play key roles in neck MRI despite the susceptibility issues in neck region. Iterative decomposition of asymmetric echoes (IDEAL, GE) is a promising method that separates fat and water images resulting in high SNR and improved fat suppression. We tested how neck tissue contrasts, image artifacts and fat separation as opposed to fat suppression in terms of image quality compare between routine and IDEAL FSE.
METHODS
IDEAL based and routine T and T-weighted FSE sequences were applied for neck MRI at 1.5T and 3T. Overall image quality including fat suppression, tissue contrast, image artifacts and lesion conspicuity were subjectively assessed for 20 patients clinically indicated for neck MRI. Quantitative tissue contrast estimates from parotid area were compared between IDEAL and routine FSE for 7 patients. Four patients with oncocytoma were also reviewed to assess benefits of separately reconstructed fat specific image sets.
RESULTS
Subjective tissue contrast and overall image quality including image sharpness, fat suppression and image artifacts were superior for IDEAL sequences. For oncocytoma fat specific IDEAL images provided additional information. Objective CNR estimates from a central slice were equivalent for IDEAL and routine FSE at both field strengths.
CONCLUSIONS
We demonstrated that high SNR inherent in IDEAL FSE consistently translates into high tissue contrast with image quality advantages in neck anatomy where large susceptibility variation and physiological motions reduce image quality for conventional FSE T and T. However, the objective contrast estimates for parotid gland at isocenter were statistically equivalent for IDEAL and conventional FSE perhaps because at or near isocenter routine FSE works well. Additionally, fat specific IDEAL image sets add to diagnostic specificity for fat deficient lesions.
目的
尽管颈部区域存在磁敏感性问题，但 FSE 序列在颈部 MRI 中仍起着关键作用。迭代分解非对称回波（IDEAL，GE）是一种很有前途的方法，它可以分离脂肪和水图像，从而提高 SNR 和改善脂肪抑制效果。我们测试了在常规 FSE 和 IDEAL FSE 中，颈部组织对比度、图像伪影和脂肪分离与脂肪抑制在图像质量方面的差异。
方法
在 1.5T 和 3T 磁共振成像仪上对颈部进行基于 IDEAL 的和常规 T1 和 T2 加权 FSE 序列检查。对 20 例临床需要行颈部 MRI 的患者的总体图像质量（包括脂肪抑制、组织对比度、图像伪影和病变显示）进行主观评估。对 7 例患者的腮腺区进行定量组织对比度评估，比较 IDEAL 和常规 FSE 之间的差异。对 4 例嗜酸细胞瘤患者进行评估，以评估分别重建的脂肪特异性图像组的益处。
结果
主观组织对比度和总体图像质量（包括图像清晰度、脂肪抑制和图像伪影）IDEAL 序列更好。对于嗜酸细胞瘤，脂肪特异性 IDEAL 图像提供了更多信息。在两种场强下，中央层面的客观 CNR 估计值在 IDEAL 和常规 FSE 之间是等效的。
结论
我们证明了 IDEAL FSE 固有的高 SNR 始终可以转化为高组织对比度，并在颈部解剖结构中具有图像质量优势，在该区域中，大的磁敏感性变化和生理运动降低了常规 FSE T1 和 T2 的图像质量。然而，在等中心处，IDEAL 和常规 FSE 的腮腺客观对比度估计值在统计学上是等效的，这可能是因为在等中心处常规 FSE 工作良好。此外，脂肪特异性 IDEAL 图像集增加了对脂肪缺乏病变的诊断特异性。
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