Department of Radiology, University Hospital, LMU Munich, Munich, Germany.
Comprehensive Pneumology Center, German Center for Lung Research, Munich, Germany.
PLoS One. 2020 Dec 23;15(12):e0244382. doi: 10.1371/journal.pone.0244382. eCollection 2020.
CT serves as gold standard for the evaluation of pulmonary nodules. However, CT exposes patients to ionizing radiation, a concern especially in screening scenarios with repeated examinations. Due to recent technological advances, MRI emerges as a potential alternative for lung imaging using 3D steady state free precession and ultra-short echo-time sequences. Therefore, in this study we assessed the performance of three state-of-the-art MRI sequences for the evaluation of pulmonary nodules.
Lesions of variable sizes were simulated in porcine lungs placed in a dedicated chest phantom mimicking a human thorax, followed by CT and MRI examinations. Two blinded readers evaluated the acquired MR-images locating and measuring every suspect lesion. Using the CT-images as reference, logistic regression was performed to investigate the sensitivity of the tested MRI-sequences for the detection of pulmonary nodules.
For nodules with a diameter of 6 mm, all three sequences achieved high sensitivity values above 0.91. However, the sensitivity dropped for smaller nodules, yielding an average of 0.83 for lesions with 4 mm in diameter and less than 0.69 for lesions with 2 mm in diameter. The positive predictive values ranged between 0.91 and 0.96, indicating a low amount of false positive findings. Furthermore, the size measurements done on the MR-images were subject to a bias ranging from 0.83 mm to -1.77 mm with standard deviations ranging from 1.40 mm to 2.11 mm. There was no statistically significant difference between the three tested sequences.
While showing promising sensitivity values for lesions larger than 4 mm, MRI appears to be not yet suited for lung cancer screening. Nonetheless, the three tested MRI sequences yielded high positive predictive values and accurate size measurements; therefore, MRI could potentially figure as imaging method of the chest in selected follow-up scenarios, e.g. of incidental findings subject to the Fleischner Criteria.
CT 是评估肺结节的金标准。然而，CT 会使患者暴露在电离辐射下，这在需要重复检查的筛查情况下尤其令人担忧。由于最近的技术进步，磁共振成像 (MRI) 作为一种使用三维稳态自由进动和超短回波时间序列进行肺部成像的潜在替代方法出现了。因此，在这项研究中，我们评估了三种最先进的 MRI 序列在评估肺结节方面的性能。
在模拟人体胸部的专用胸部体模中放置猪肺，模拟各种大小的病变，然后进行 CT 和 MRI 检查。两位盲法读者评估采集的 MR 图像，定位并测量每个可疑病变。使用 CT 图像作为参考，进行逻辑回归分析，以研究测试的 MRI 序列对检测肺结节的敏感性。
对于直径为 6 毫米的结节，所有三种序列的敏感性值均高于 0.91。然而，对于较小的结节，敏感性下降，直径为 4 毫米的结节平均敏感性为 0.83，直径为 2 毫米的结节敏感性小于 0.69。阳性预测值在 0.91 到 0.96 之间，表明假阳性发现的数量较少。此外，MR 图像上的尺寸测量值存在从 0.83 毫米到-1.77 毫米的偏差，标准偏差从 1.40 毫米到 2.11 毫米不等。三种测试序列之间没有统计学上的显著差异。
虽然对于大于 4 毫米的病变显示出有希望的敏感性值，但 MRI 似乎还不适合用于肺癌筛查。尽管如此，三种测试的 MRI 序列产生了高的阳性预测值和准确的尺寸测量值；因此，MRI 可能在特定的随访情况下（例如，根据 Fleischner 标准的偶然发现）作为胸部成像方法。
