Directional and inter‐acquisition variability in diffusion‐weighted imaging and editing for restricted diffusion

作者：Batuhan Gündoğdu, Jay M. Pittman, Aritrick Chatterjee, Teodora Szasz, Grace Lee, Mihai Giurcanu, Milica Medved, Roger Engelmann, Xiaodong Guo, Ambereen Yousuf, Tatjana Antic, Ajit Devaraj, Xiaobing Fan, Aytekin Oto, Gregory S. Karczmar · 发表于：Magnetic Resonance in Medicine · 年份：2022 · DOI：10.1002/mrm.29385 · 被引用次数：7 · 研究领域：MRI in cancer diagnosis、Advanced Neuroimaging Techniques and Applications、Prostate Cancer Diagnosis and Treatment

Purpose To evaluate and quantify inter‐directional and inter‐acquisition variation in diffusion‐weighted imaging (DWI) and emphasize signals that report restricted diffusion to enhance cancer conspicuity, while reducing the effects of local microscopic motion and magnetic field fluctuations. Methods Ten patients with biopsy‐proven prostate cancer were studied under an Institutional Review Board‐approved protocol. Individual acquisitions of DWI signal intensities were reconstructed to calculate inter‐acquisition distributions and their statistics, which were compared for healthy versus cancer tissue. A method was proposed to detect and filter the acquisitions affected by motion‐induced signal loss. First, signals that reflect restricted diffusion were separated from the acquisitions that suffer from signal loss, likely due to microscopic motion, by imposing a cutoff value. Furthermore, corrected apparent diffusion coefficient maps were calculated by employing a weighted sum of the multiple acquisitions, instead of conventional averaging. These weights were calculated by applying a soft‐max function to the set of acquisitions per‐voxel, making the analysis immune to acquisitions with significant signal loss, even if the number of such acquisitions is high. Results Inter‐acquisition variation is much larger than the Rician noise variance, local spatial variations, and the estimates of diffusion anisotropy based on the current data, as well as the published values of anisotropy. ...