Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, NTNU, Norwegian University of Science and Technology, Trondheim, Norway.
Department of Radiology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
Magn Reson Med. 2018 May;79(5):2524-2532. doi: 10.1002/mrm.26899. Epub 2017 Sep 1.
To evaluate the effect of correction for B inhomogeneity-induced geometric distortion in echo-planar diffusion-weighted imaging on quantitative apparent diffusion coefficient (ADC) analysis in multiparametric prostate MRI.
Geometric distortion correction was performed in echo-planar diffusion-weighted images (b = 0, 50, 400, 800 s/mm ) of 28 patients, using two b scans with opposing phase-encoding polarities. Histology-matched tumor and healthy tissue volumes of interest delineated on T -weighted images were mapped to the nondistortion-corrected and distortion-corrected data sets by resampling with and without spatial coregistration. The ADC values were calculated on the volume and voxel level. The effect of distortion correction on ADC quantification and tissue classification was evaluated using linear-mixed models and logistic regression, respectively.
Without coregistration, the absolute differences in tumor ADC (range: 0.0002-0.189 mm /s×10 (volume level); 0.014-0.493 mm /s×10 (voxel level)) between the nondistortion-corrected and distortion-corrected were significantly associated (P < 0.05) with distortion distance (mean: 1.4 ± 1.3 mm; range: 0.3-5.3 mm). No significant associations were found upon coregistration; however, in patients with high rectal gas residue, distortion correction resulted in improved spatial representation and significantly better classification of healthy versus tumor voxels (P < 0.05).
Geometric distortion correction in DWI could improve quantitative ADC analysis in multiparametric prostate MRI. Magn Reson Med 79:2524-2532, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
评估在多参数前列腺 MRI 中，对回波平面扩散加权成像中 B 不均匀性引起的几何变形进行校正，对定量表观扩散系数（ADC）分析的影响。
对 28 例患者的回波平面扩散加权图像（b=0、50、400、800 s/mm）进行几何变形校正，使用两个相位编码极性相反的 b 扫描。在 T1 加权图像上对肿瘤和正常组织的感兴趣容积进行勾画，然后通过无空间配准和有空间配准的重采样，将这些感兴趣容积映射到未校正和校正后的数据集上。在容积和体素水平上计算 ADC 值。采用线性混合模型和逻辑回归分别评估变形校正对 ADC 定量和组织分类的影响。
在未配准的情况下，肿瘤 ADC（容积水平的范围为 0.0002-0.189 mm/s×10；体素水平的范围为 0.014-0.493 mm/s×10）在未校正和校正之间的绝对值差异与变形距离显著相关（P<0.05）（平均值：1.4±1.3mm；范围：0.3-5.3mm）。在配准后未发现显著相关性；然而，在直肠积气较多的患者中，变形校正可改善空间表示，并显著提高对健康和肿瘤体素的分类（P<0.05）。
在 DWI 中进行几何变形校正可以改善多参数前列腺 MRI 中的定量 ADC 分析。磁共振医学 79:2524-2532, 2018。© 2017 国际磁共振学会。
