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BACKGROUND

Free-running cardiac and respiratory motion-resolved whole-heart five-dimensional (5D) cardiovascular magnetic resonance (CMR) can reduce scan planning and provide a means of evaluating respiratory-driven changes in clinical parameters of interest. However, respiratory-resolved imaging can be limited by user-defined parameters which create trade-offs between residual artifact and motion blur. In this work, we develop and validate strategies for both correction of intra-bin and compensation of inter-bin respiratory motion to improve the quality of 5D CMR.

METHODS

Each component of the reconstruction framework was systematically validated and compared to the previously established 5D approach using simulated free-running data (N = 50) and a cohort of 32 patients with congenital heart disease. The impact of intra-bin respiratory motion correction was evaluated in terms of image sharpness while inter-bin respiratory motion compensation was evaluated in terms of reconstruction error, compression of respiratory motion, and image sharpness. The full reconstruction framework (intra-acquisition correction and inter-acquisition compensation of respiratory motion [IIMC] 5D) was evaluated in terms of image sharpness and scoring of image quality by expert reviewers.

RESULTS

Intra-bin motion correction provides significantly (p < 0.001) sharper images for both simulated and patient data. Inter-bin motion compensation results in significant (p < 0.001) lower reconstruction error, lower motion compression, and higher sharpness in both simulated (10/11) and patient (9/11) data. The combined framework resulted in significantly (p < 0.001) sharper IIMC 5D reconstructions (End-expiration (End-Exp): 0.45 ± 0.09, End-inspiration (End-Ins): 0.46 ± 0.10) relative to the previously established 5D implementation (End-Exp: 0.43 ± 0.08, End-Ins: 0.39 ± 0.09). Similarly, image scoring by three expert reviewers was significantly (p < 0.001) higher using IIMC 5D (End-Exp: 3.39 ± 0.44, End-Ins: 3.32 ± 0.45) relative to 5D images (End-Exp: 3.02 ± 0.54, End-Ins: 2.45 ± 0.52).

CONCLUSION

The proposed IIMC reconstruction significantly improves the quality of 5D whole-heart MRI. This may be exploited for higher resolution or abbreviated scanning. Further investigation of the diagnostic impact of this framework and comparison to gold standards is needed to understand its full clinical utility, including exploration of respiratory-driven changes in physiological measurements of interest.

背景

自由运行的心脏和呼吸运动分辨率的全心脏五维（5D）心血管磁共振（CMR）可以减少扫描规划，并提供一种评估临床相关参数呼吸驱动变化的方法。然而，呼吸分辨率成像可能会受到用户定义参数的限制，这些参数会在残余伪影和运动模糊之间产生折衷。在这项工作中，我们开发并验证了用于校正每 bin 内和补偿 bin 间呼吸运动的策略，以提高 5D CMR 的质量。

方法

系统地验证了重建框架的每个组成部分，并将其与以前使用模拟自由运行数据（N=50）和 32 名先天性心脏病患者队列建立的 5D 方法进行比较。通过评估图像锐度来评估每 bin 内呼吸运动校正的影响，通过评估重建误差、呼吸运动压缩和图像锐度来评估 bin 间呼吸运动补偿的影响。通过专家评审员评估图像锐度和图像质量评分，对完整的重建框架（呼吸运动采集内校正和采集间补偿[IIMC]5D）进行评估。

结果

对于模拟数据和患者数据，每 bin 运动校正都显著（p<0.001）提高了图像的锐度。Bin 间运动补偿导致重建误差显著（p<0.001）降低、运动压缩显著（p<0.001）降低，模拟数据（10/11）和患者数据（9/11）的图像锐度均显著提高。与以前建立的 5D 实现（End-Exp：0.43±0.08，End-Ins：0.39±0.09）相比，联合框架显著（p<0.001）提高了 IIMC 5D 的重建锐度（End-Exp：0.45±0.09，End-Ins：0.46±0.10）。同样，三位专家评审员的图像评分也显著（p<0.001）提高了 IIMC 5D（End-Exp：3.39±0.44，End-Ins：3.32±0.45），而不是 5D 图像（End-Exp：3.02±0.54，End-Ins：2.45±0.52）。