Department of Radiology, Children's Healthcare of Atlanta, Atlanta, GA, USA.
Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA, USA.
Sci Rep. 2022 Sep 5;12(1):15099. doi: 10.1038/s41598-022-18191-y.
Current dynamic MRA techniques are limited by temporal resolution and signal-to-noise penalties. GRASP, a fast and flexible MRI technique combining compressed-sensing, parallel imaging, and golden-angle radial sampling, acquires volumetric data continuously and can be reconstructed post hoc for user-defined applications. We describe a custom pipeline to retrospectively reconstruct ultrahigh temporal resolution, dynamic MRA from GRASP imaging obtained in the course of routine practice. GRASP scans were reconstructed using a custom implementation of the GRASP algorithm and post-processed with MeVisLab (MeVis Medical Solutions AG, Germany). Twenty consecutive examinations were scored by three neuroradiologists for angiographic quality of specific vascular segments and imaging artifacts using a 4-point scale. Unsubtracted images, baseline-subtracted images, and a temporal gradient dataset were available in 2D and 3D reconstructions. Distinct arterial and capillary phases were identified in all reconstructions, with a median of 2 frames (IQR1-3 and 2-3, respectively). Median rating for vascular segments was 3 (excellent) in all reconstructions and for nearly all segments, with excellent intraclass correlation (range 0.91-1.00). No cases were degraded by artifacts. GRASP-MRI obtained in routine practice can be seamlessly repurposed to produce high quality 4D MRA with 1-2-s resolved isotropic cerebrovascular angiography. Further exploration into diagnostic accuracy in disease-specific applications is warranted.
当前的动态 MRA 技术受到时间分辨率和信噪比限制。GRASP 是一种快速灵活的 MRI 技术，结合了压缩感知、并行成像和黄金角度径向采样，可连续采集容积数据，并可在事后针对用户定义的应用进行重建。我们描述了一种自定义管道，用于从常规实践中获得的 GRASP 成像中回顾性重建超高时间分辨率的动态 MRA。GRASP 扫描使用 GRASP 算法的自定义实现进行重建，并使用 MeVisLab（德国 MeVis Medical Solutions AG）进行后处理。20 项连续检查由 3 名神经放射科医生对特定血管段的血管造影质量和成像伪影进行评分，采用 4 分制。2D 和 3D 重建均提供未减影图像、基线减影图像和时间梯度数据集。所有重建中均能识别出明显的动脉期和毛细血管期，中位数为 2 帧（IQR1-3 和 2-3）。所有重建中血管段的中位数评分为 3（优秀），且几乎所有段的评分都具有极好的组内相关性（范围 0.91-1.00）。没有因伪影而导致图像质量下降的情况。在常规实践中获得的 GRASP-MRI 可以无缝地重新用于生成具有 1-2 秒分辨率的各向同性脑血管造影的高质量 4D MRA。进一步探索特定疾病应用中的诊断准确性是有必要的。
