Franson Dominique, Dupuis Andrew, Gulani Vikas, Griswold Mark, Seiberlich Nicole
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA.
J Imaging. 2021 Dec 14;7(12):274. doi: 10.3390/jimaging7120274.
Image-guided cardiovascular interventions are rapidly evolving procedures that necessitate imaging systems capable of rapid data acquisition and low-latency image reconstruction and visualization. Compared to alternative modalities, Magnetic Resonance Imaging (MRI) is attractive for guidance in complex interventional settings thanks to excellent soft tissue contrast and large fields-of-view without exposure to ionizing radiation. However, most clinically deployed MRI sequences and visualization pipelines exhibit poor latency characteristics, and spatial integration of complex anatomy and device orientation can be challenging on conventional 2D displays. This work demonstrates a proof-of-concept system linking real-time cardiac MR image acquisition, online low-latency reconstruction, and a stereoscopic display to support further development in real-time MR-guided intervention. Data are acquired using an undersampled, radial trajectory and reconstructed via parallelized through-time radial generalized autocalibrating partially parallel acquisition (GRAPPA) implemented on graphics processing units. Images are rendered for display in a stereoscopic mixed-reality head-mounted display. The system is successfully tested by imaging standard cardiac views in healthy volunteers. Datasets comprised of one slice (46 ms), two slices (92 ms), and three slices (138 ms) are collected, with the acquisition time of each listed in parentheses. Images are displayed with latencies of 42 ms/frame or less for all three conditions. Volumetric data are acquired at one volume per heartbeat with acquisition times of 467 ms and 588 ms when 8 and 12 partitions are acquired, respectively. Volumes are displayed with a latency of 286 ms or less. The faster-than-acquisition latencies for both planar and volumetric display enable real-time 3D visualization of the heart.
图像引导的心血管介入手术是快速发展的程序，需要能够进行快速数据采集以及低延迟图像重建和可视化的成像系统。与其他成像方式相比，磁共振成像（MRI）因其出色的软组织对比度、大视野且无需暴露于电离辐射，在复杂介入手术的引导方面具有吸引力。然而，大多数临床应用的MRI序列和可视化流程表现出较差的延迟特性，并且在传统二维显示器上对复杂解剖结构和设备方位进行空间整合可能具有挑战性。这项工作展示了一个概念验证系统，该系统将实时心脏磁共振图像采集、在线低延迟重建和立体显示器相连接，以支持实时磁共振引导介入的进一步发展。数据使用欠采样的径向轨迹进行采集，并通过在图形处理单元上实现的并行时间径向广义自校准部分并行采集（GRAPPA）进行重建。图像渲染后在立体混合现实头戴式显示器中显示。该系统通过对健康志愿者的标准心脏视图成像进行了成功测试。收集了由一层（46毫秒）、两层（92毫秒）和三层（138毫秒）组成的数据集，每个数据集的采集时间列于括号内。在所有三种情况下，图像显示延迟均为42毫秒/帧或更低。当分别采集8个和12个分区时，以每个心跳采集一个容积的方式采集容积数据，采集时间分别为467毫秒和588毫秒。容积数据显示延迟为286毫秒或更低。平面和容积显示的快于采集的延迟使得能够对心脏进行实时3D可视化。
