Institute of Radiology, Kantonsspital Winterthur, Winterthur, Switzerland.
Faculty of Medicine, University of Zürich, Zürich, Switzerland.
Br J Radiol. 2021 May 1;94(1121):20200869. doi: 10.1259/bjr.20200869. Epub 2021 Feb 17.
Diffusion-weighted imaging (DWI) plays a crucial role in the diagnosis of ischemic stroke. We assessed the value of computed and acquired high b-value DWI in comparison with conventional = 1000 s mm DWI for ischemic stroke at 3T.
We included 36 patients with acute ischemic stroke who presented with diffusion abnormalities on DWI performed within 24 h of symptom onset. B-values of 0, 500, 1000 and 2000 s mm were acquired. Synthetic images with b-values of 1000, 1500, 2000 and 2500 s mm were computed. Two readers compared synthetic (syn) and acquired (acq) = 2000 s mm images with acquired = 1000 s mm images in terms of lesion detection rate, image quality, presence of uncertain hyperintensities and lesion conspicuity. Readers also selected their preferred b-value. Contrast ratio (CR) measurements were performed. Non-parametrical statistical tests and weighted Cohens' κ tests were computed.
Syn1000 and syn1500 matched acq1000 images in terms of lesion detection rate, image quality and presence of uncertain hyperintensities but presented with significantly improved lesion conspicuity ( < 0.01) and were frequently selected as preferred b-values. Acq2000 images exhibited a similar lesion detection rate and improved lesion conspicuity ( < 0.01) but worse image quality ( < 0.01) than acq1000 images. Syn2000 and syn2500 images performed significantly worse ( < 0.01) than acq1000 images in most or all categories. CR significantly increased with increasing b-values.
Synthetic images at = 1000 and 1500 s mm and acquired DWI images at = 2000 s mm may be of clinical value due to improved lesion conspicuity.
Synthetic b-values enable improved lesion conspicuity for DWI of ischemic stroke.
弥散加权成像（DWI）在缺血性脑卒中的诊断中起着至关重要的作用。我们评估了计算和采集的高 b 值 DWI 与常规 = 1000 s/mm DWI 在 3T 下对缺血性脑卒中的诊断价值。
我们纳入了 36 例在症状发作后 24 小时内行 DWI 检查显示弥散异常的急性缺血性脑卒中患者。采集 b 值为 0、500、1000 和 2000 s/mm 的 DWI 图像。计算 b 值为 1000、1500、2000 和 2500 s/mm 的合成图像。两位观察者比较了合成（syn）和采集（acq）b 值为 2000 s/mm 图像与采集 b 值为 1000 s/mm 图像的病灶检出率、图像质量、不确定高信号的存在和病灶显示程度。观察者还选择了他们喜欢的 b 值。进行对比比（CR）测量。采用非参数统计检验和加权 Cohen κ 检验进行计算。
syn1000 和 syn1500 与 acq1000 图像在病灶检出率、图像质量和不确定高信号的存在方面匹配，而病灶显示程度显著提高（ < 0.01），且常被选为优选 b 值。acq2000 图像的病灶检出率相似，病灶显示程度提高（ < 0.01），但图像质量较差（ < 0.01）。syn2000 和 syn2500 图像在大多数或所有类别中均显著劣于 acq1000 图像（ < 0.01）。CR 随 b 值的增加而显著增加。
由于病灶显示程度提高，b 值为 = 1000 和 1500 s/mm 的合成图像和 b 值为 = 2000 s/mm 的采集 DWI 图像可能具有临床价值。
合成 b 值可提高缺血性脑卒中 DWI 的病灶显示程度。
