Iwazaki Kazuma, Fujita Naoto, Yamada Shigehito, Terada Yasuhiko
Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan.
Congenital Anomaly Research Center, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
Tomography. 2025 Aug 2;11(8):88. doi: 10.3390/tomography11080088.
: This study investigates whether scan time in the high-resolution magnetic resonance imaging (MRI) of human embryos can be reduced without compromising spatial resolution by applying zero-shot self-supervised learning (ZS-SSL), a deep-learning-based reconstruction method. : Simulations using a numerical phantom were conducted to evaluate spatial resolution across various acceleration factors (AF = 2, 4, 6, and 8) and signal-to-noise ratio (SNR) levels. Resolution was quantified using a blur-based estimation method based on the Sparrow criterion. ZS-SSL was compared to conventional compressed sensing (CS). Experimental imaging of a human embryo at Carnegie stage 21 was performed at a spatial resolution of (30 μm) using both retrospective and prospective undersampling at AF = 4 and 8. : ZS-SSL preserved spatial resolution more effectively than CS at low SNRs. At AF = 4, image quality was comparable to that of fully sampled data, while noticeable degradation occurred at AF = 8. Experimental validation confirmed these findings, with clear visualization of anatomical structures-such as the accessory nerve-at AF = 4; there was reduced structural clarity at AF = 8. : ZS-SSL enables significant scan time reduction in high-resolution MRI of human embryos while maintaining spatial resolution at AF = 4, assuming an SNR above approximately 15. This trade-off between acceleration and image quality is particularly beneficial in studies with limited imaging time or specimen availability. The method facilitates the efficient acquisition of ultra-high-resolution data and supports future efforts to construct detailed developmental atlases.
本研究调查了通过应用零样本自监督学习(ZS-SSL,一种基于深度学习的重建方法),在不影响空间分辨率的情况下,能否减少人类胚胎高分辨率磁共振成像(MRI)的扫描时间。使用数值体模进行模拟,以评估在各种加速因子(AF = 2、4、6和8)和信噪比(SNR)水平下的空间分辨率。使用基于Sparrow准则的基于模糊的估计方法对分辨率进行量化。将ZS-SSL与传统压缩感知(CS)进行比较。在AF = 4和8时,使用回顾性和前瞻性欠采样,以(30μm)的空间分辨率对卡内基21期的人类胚胎进行实验成像。在低信噪比下,ZS-SSL比CS更有效地保持空间分辨率。在AF = 4时,图像质量与全采样数据相当,而在AF = 8时出现明显退化。实验验证证实了这些发现,在AF = 4时可清晰可视化诸如副神经等解剖结构;在AF = 8时结构清晰度降低。假设SNR高于约15,ZS-SSL能够在保持AF = 4时的空间分辨率的同时,显著减少人类胚胎高分辨率MRI的扫描时间。这种加速与图像质量之间的权衡在成像时间或标本可用性有限的研究中特别有益。该方法有助于高效获取超高分辨率数据,并支持未来构建详细发育图谱的努力。