Dong Yiming, Atkinson David, Koolstra Kirsten, van Osch Matthias J P, Börnert Peter
C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
Center for Medical Imaging, University College London, London, UK.
Magn Reson Med. 2025 Mar;93(3):1059-1076. doi: 10.1002/mrm.30334. Epub 2024 Oct 14.
DWI is an important contrast for prostate MRI to enable early and accurate detection of cancer. This study introduces a Dixon 3-shot-EPI protocol with structured low-rank reconstruction for navigator-free DWI. The aim is to overcome the limitations of single-shot EPI (ssh-EPI), such as geometric distortions and fat signal interference, while addressing the motion-induced phase variations of multishot EPI and simultaneously allowing water/fat separation.
DWI data were acquired from 7 healthy volunteers using both Dixon 3-shot EPI and standard fat-suppressed ssh-EPI with similar scan times for comparison. Two readers evaluated image quality using a 5-point Likert scale regarding different aspects. The ADC values were quantitatively compared between protocols. To show feasibility in a clinical setting, the protocol was applied to two patients.
From the reader scores, Dixon 3-shot EPI significantly reduced geometric distortion compared with ssh-EPI (p < 0.01), with no significant differences in edge definition, SNR, or overall image quality. There was no significant difference in ADC values between the two protocols. However, the Dixon multishot-EPI protocol offered advantages such as self-referenced B map-driven distortion correction, greater flexibility in imaging parameters, and superior fat suppression. In the patient data, the lesion could be clearly identified in both protocols and on the associated ADC maps.
The proposed Dixon 3-shot-EPI protocol shows promise as an alternative to ssh-EPI for prostate DWI, providing reduced geometric distortions and improved fat suppression. It addresses common DWI issues based on EPI and enhances scanning flexibility, indicating potential for optimized imaging.
扩散加权成像（DWI）是前列腺MRI的一项重要对比技术，可实现癌症的早期准确检测。本研究引入了一种采用结构化低秩重建的狄克逊三激发回波平面成像（Dixon 3-shot-EPI）协议用于无导航器DWI。目的是克服单次激发回波平面成像（ssh-EPI）的局限性，如几何变形和脂肪信号干扰，同时解决多激发回波平面成像的运动诱导相位变化问题，并实现水/脂肪分离。
使用狄克逊三激发回波平面成像和标准脂肪抑制单次激发回波平面成像，对7名健康志愿者采集DWI数据，扫描时间相似以进行比较。两名阅片者使用5分李克特量表从不同方面评估图像质量。对两种协议下的表观扩散系数（ADC）值进行定量比较。为了展示在临床环境中的可行性，将该协议应用于两名患者。
根据阅片者评分，与单次激发回波平面成像相比，狄克逊三激发回波平面成像显著减少了几何变形（p < 0.01），在边缘清晰度、信噪比或整体图像质量方面无显著差异。两种协议下的ADC值无显著差异。然而，狄克逊多激发回波平面成像协议具有诸如自参考B图驱动的变形校正、成像参数更大的灵活性以及更好的脂肪抑制等优点。在患者数据中，两种协议及其相关的ADC图上均能清晰识别病变。
所提出的狄克逊三激发回波平面成像协议有望成为前列腺DWI中单次激发回波平面成像的替代方案，可减少几何变形并改善脂肪抑制。它解决了基于回波平面成像的常见DWI问题并提高了扫描灵活性，显示出优化成像的潜力。
