Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel.
Department of Diagnostic Imaging, Sheba Medical Center, Ramat Gan, Israel.
Magn Reson Med. 2023 Aug;90(2):643-654. doi: 10.1002/mrm.29641. Epub 2023 Apr 3.
To assess the feasibility and reliability of a DWI protocol based on spatiotemporally encoding (SPEN), to target prostate lesions along guidelines normally used in EPI-based DWI clinical practice.
Prostate Imaging-Reporting and Data System recommendations underlying clinical prostate scans were used to develop a SPEN-based DWI protocol, which included a novel, local, low-rank regularization algorithm. These DWI acquisitions were run at 3 T under similar nominal spatial resolutions and diffusion-weighting b-values as used in EPI-based clinical studies. Prostates of 11 patients suspected of clinically significant prostate cancer lesions were therefore scanned using the two methods, with the same number of slices, same slice thickness, and same interslice gaps.
Of the 11 patients scanned, SPEN and EPI provided comparable information in 7 of the cases, whereas EPI was deemed superior in a case for which SPEN images had to be acquired with a shorter effective TR owing to scan-time constraints. SPEN provided reduced susceptibility to field-derived distortions in 3 of the cases.
SPEN's ability to provide prostate lesion contrast was most clearly evidenced for DW images acquired with b ≥ 900 s/mm . SPEN also succeeded in decreasing occasional image distortions in regions close to the rectum, affected by field inhomogeneities. EPI advantages arose when using short effective TRs, a regime in which SPEN-based DWI was handicapped by its use of nonselective spin inversions, leading to the onset of an additional T weighting.
评估基于时空编码（SPEN）的 DWI 方案的可行性和可靠性，以针对沿 EPI 基 DWI 临床实践中常用指南定位前列腺病变。
根据临床前列腺扫描的前列腺成像报告和数据系统（PI-RADS）建议制定了基于 SPEN 的 DWI 方案，该方案包括一种新颖的局部低秩正则化算法。这些 DWI 采集是在 3 T 下进行的，空间分辨率和扩散加权 b 值与 EPI 临床研究中使用的类似。因此，使用这两种方法对 11 例疑似有临床意义的前列腺癌病变的前列腺进行了扫描，这些病例的切片数、切片厚度和切片间间隔相同。
在扫描的 11 例患者中，SPEN 和 EPI 在 7 例中提供了可比的信息，而在 1 例中由于扫描时间限制，SPEN 图像必须采用较短的有效 TR 进行采集，因此 EPI 被认为更优。SPEN 在 3 例中减少了源自磁场的失真。
SPEN 提供 DW 图像的能力对于 b ≥ 900 s/mm 时的前列腺病变对比最为明显。SPEN 还成功减少了靠近直肠的区域（受磁场不均匀性影响）偶尔出现的图像失真。EPI 的优势出现在使用短有效 TR 时，在这种情况下，SPEN 基 DWI 受到其非选择性自旋反转的限制，导致额外的 T 权重出现。
