Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.
Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.
Magn Reson Med. 2019 Jun;81(6):3808-3818. doi: 10.1002/mrm.27679. Epub 2019 Feb 8.
Ultra-short echo time MRI is a promising alternative to chest CT for cystic fibrosis patients. Black-blood imaging in particular could help discern small-sized anomalies, such as mucoid plugging, which may otherwise be confused with neighboring blood vessels, particularly when contrast agent is not used. We, therefore, implemented and tested an ultra-short echo time sequence with black-blood preparation. Additionally, this sequence may also be used to generate bright-blood angiograms.
Using this sequence, data was acquired during free breathing in 10 healthy volunteers to obtain respiratory-motion-resolved 3D volumes covering the entire thorax with an isotropic resolution of (1 mm) . The magnitude of signal suppression relative to a bright-blood reference acquisition was quantified and compared with that obtained with a turbo-spin echo (TSE) acquisition. Bright-blood angiograms were also generated by subtraction. Finally, an initial feasibility assessment was performed in 2 cystic fibrosis patients, and images were visually compared with contrast-enhanced images and with CT data.
Black-blood preparation significantly decreased the average normalized signal intensity in the vessel lumen (-66%; P < 0.001). Similarly, blood signal was significantly lowered (-60%; P = 0.001) compared with the TSE acquisition. In patients, mucoid plugging could be emphasized in the black-blood datasets. An intercostal artery could also be visualized in the subtraction angiograms.
Black-blood free-breathing ultra-short echo time imaging was successfully implemented and motion-resolved full volumetric coverage of the lungs with high spatial resolution was achieved, while obtaining an angiogram without contrast agent injection. Encouraging initial results in patients prompt further investigations in a larger cohort.
超短回波时间 MRI 是囊性纤维化患者胸部 CT 的一种有前途的替代方法。特别是黑血成像可以帮助辨别小尺寸异常，例如黏液栓，否则可能与相邻血管混淆，特别是在不使用造影剂时。因此，我们实现并测试了一种带有黑血准备的超短回波时间序列。此外，该序列也可用于生成亮血血管造影图。
使用该序列，在 10 名健康志愿者的自由呼吸期间采集数据，以获得具有各向同性分辨率（1mm）的呼吸运动分辨 3D 容积，覆盖整个胸部。量化并比较相对于亮血参考采集的信号抑制程度，并与涡轮自旋回波（TSE）采集进行比较。还通过减影生成亮血血管造影图。最后，在 2 例囊性纤维化患者中进行了初步可行性评估，并将图像与对比增强图像和 CT 数据进行了视觉比较。
黑血准备显著降低了血管腔中的平均归一化信号强度（-66%；P < 0.001）。同样，与 TSE 采集相比，血液信号也显著降低（-60%；P = 0.001）。在患者中，可以在黑血数据集强调黏液栓。也可以在减影血管造影图中可视化肋间动脉。
成功实现了自由呼吸的黑血超短回波时间成像，实现了具有高空间分辨率的肺部全容积运动分辨覆盖，同时在不注射造影剂的情况下获得血管造影图。在患者中获得的令人鼓舞的初步结果促使进一步在更大的队列中进行研究。
