arXiv:2409.00798eess.IVeess.SP2024-09

优化腹部弥散MRI运动伪影,减少扫描时间与数据缺失。

An Optimized Binning and Probabilistic Slice Sharing Algorithm for Motion Correction in Abdominal DW-MRI

  • 用动态规划与前缀和优化初始分块,提升分组效率。
  • 引入概率性切片共享,使缺失切片减少81.74%以上。
  • 适合需快速精准成像的腹部肿瘤早期诊断场景。

弥散加权磁共振成像(DW-MRI)是无创检测和表征腹部病灶的重要工具,但呼吸运动会降低图像质量并影响定量生物标志物准确性。呼吸分块技术通过导航信号将图像切片按呼吸相位分组,可缓解运动伪影,但在标准分块中常导致上下方向出现切片缺失,需更长扫描时间补全。本文提出一种两阶段新分块方法:首先采用动态规划与前缀和优化初始分块;随后引入概率性切片共享策略,让部分切片同时归属相邻分块,进一步减少缺失。在8名受试者(含1名肿瘤患者)的自由呼吸腹部DW-MRI数据上验证,相比标准分块,该方法显著减少缺失切片(平均减少81.74±7.58%,p<1.0×10⁻¹⁵),改善恶性病灶可见性。经修正的自由呼吸扫描生成的表观扩散系数(ADC)图具更低个体间差异(p<0.001),且与浅呼吸扫描结果更一致(p<0.01)。该方法在不增加扫描时间的前提下,同时实现运动校正与切片完整性提升,支持更短采集时长。

原文摘要 · Abstract (English)

Diffusion-weighted magnetic resonance imaging (DW-MRI) is a powerful, non-invasive tool for detecting and characterizing abdominal lesions to facilitate early diagnosis, but respiratory motion during a scan reduces image quality and accuracy of quantitative biomarkers. Respiratory binning, which groups image slices into motion phase bins based on a navigator signal, can help mitigate motion artifacts. However, in DW-MRI, the standard binning technique often generates volumes with missing slices along the superior-inferior axis. Thus, longer scans are required to obtain volumes without gaps. In this study, we proposed a new binning technique to minimize missing slices without increasing scan time. We first designed an algorithm using dynamic programming and prefix sum approaches to optimize the initial binning of MR images. Then, we developed a probabilistic refinement phase, selecting some slices to belong in two neighboring bins to further reduce missing slices. We tested our two-phase technique on free-breathing abdominal DW-MRI scans from eight subjects, including one with tumors. The proposed technique significantly reduced missing slices compared to standard binning (p<1.0*10-15), yielding an average reduction of 81.74+/-7.58%. Our technique also reduced motion artifacts, improving the conspicuity of malignant lesions. Apparent Diffusion Coefficient (ADC) maps generated from free-breathing scans corrected using the proposed technique had lower intra-subject variability compared to ADC maps from uncorrected free-breathing and shallow-breathing scans (p<0.001). Additionally, ADC maps from shallow-breathing scans were more consistent with corrected free-breathing maps rather than uncorrected free-breathing maps (p<0.01). The proposed technique corrects for motion while simultaneously reducing missing slices, allowing for shorter acquisition times compared to standard binning.

MRI运动校正分块算法弥散成像

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