Simchick Gregory, Hernando Diego
Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Magn Reson Med. 2025 Jul 22. doi: 10.1002/mrm.70005.
Design a b-value, first-order motion moment (M), and echo time (TE)-optimized data acquisition for simultaneous intravoxel incoherent motion (IVIM) and R quantification in the liver.
The b-M-optimized (i.e., single TE) and b-M-TE-optimized (i.e., multi-TE) IVIM acquisitions were determined using Cramer-Rao lower-bound optimization. Eleven healthy volunteers underwent MRI of the liver where each optimized acquisition was acquired twice (test-retest). For each data set, IVIM estimates (diffusion coefficient [D], perfusion signal fractions [f and f], blood velocity standard deviations [SDs] [V and V], and/or relaxation rates of tissue and blood [R and R]) were obtained in the right and left liver lobes within distinct spatial locations associated with slow (f and V) and fast (f and V) microvascular flow. Six R-correction methods using combinations of estimated and/or fixed values of R and R were performed. Test-retest repeatability and interlobar agreement were evaluated using coefficients of variation (CVs) and relative mean differences (rMDs).
The b-M-TE-optimized acquisition demonstrated acceptable to excellent right-lobe test-retest repeatability (CV = 4.58%, 8.94%, 8.62%, 27.5%, 18.8%, 2.85%, and 17.7% for D, V, V, f, f, R, and R, respectively) and interlobar agreement (|rMD| = 8.82%, 1.84%, 8.72%, 3.08%, and 0.20% for D, V, V, R, and R, respectively), except for interlobar agreement of f and f (rMD ≥ 37.7%). For the b-M-optimized acquisition, R correction of f and f provided similar estimates as the b-M-TE-optimized acquisition (|MD| ≤ 1.98%).
The b-M-TE-optimized IVIM acquisition enabled simultaneous and repeatable IVIM and R quantification in the liver. For single-TE IVIM data, R correction of f estimates using fixed values of R and R may be acceptable.
设计一种b值、一阶运动矩（M）和回波时间（TE）优化的数据采集方法，用于在肝脏中同时进行体素内不相干运动（IVIM）和R定量分析。
使用克拉美-罗下界优化确定b-M优化（即单TE）和b-M-TE优化（即多TE）的IVIM采集。11名健康志愿者接受肝脏MRI检查，每种优化采集重复进行两次（重测）。对于每个数据集，在与缓慢（f和V）和快速（f和V）微血管血流相关的不同空间位置的左右肝叶中获得IVIM估计值（扩散系数[D]、灌注信号分数[f和f]、血流速度标准差[SDs][V和V]，和/或组织和血液的弛豫率[R和R]）。使用R和R的估计值和/或固定值的组合进行了六种R校正方法。使用变异系数（CVs）和相对平均差异（rMDs）评估重测重复性和叶间一致性。
b-M-TE优化采集显示右叶重测重复性可接受至优秀（D、V、V、f、f、R和R的CV分别为4.58%、8.94%、8.62%、27.5%、18.8%、2.85%和17.7%），叶间一致性方面，D、V、V、R和R的|rMD|分别为8.82%、1.84%、8.72%、3.08%和0.20%，f和f的叶间一致性除外（rMD≥37.7%）。对于b-M优化采集，f和f的R校正提供了与b-M-TE优化采集相似的估计值（|MD|≤1.98%）。
b-M-TE优化的IVIM采集能够在肝脏中同时且可重复地进行IVIM和R定量分析。对于单TE IVIM数据，使用R和R的固定值对f估计值进行R校正可能是可接受的。
