Iwashita Koya, Hirai Toshinori, Kitajima Mika, Shigematsu Yoshinori, Uetani Hiroyuki, Iryo Yasuhiko, Azuma Minako, Hayashida Eri, Ando Yukio, Murakami Ryuji, Yamashita Yasuyuki
Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
J Comput Assist Tomogr. 2013 May-Jun;37(3):338-42. doi: 10.1097/RCT.0b013e318288a661.
The purpose of this study was to determine how the gray-to-white matter contrast in healthy subjects changes on high-b-value diffusion-weighted imaging (DWI) acquired at 3 T and evaluate whether high-b-value DWI at 3 T is useful for the detection of cortical lesions in inflammatory brain diseases.
Ten healthy volunteers underwent DWI at b = 1000, 2000, 3000, 4000, and 5000 s/mm(2) on a 3-T MRI unit. On DW images, 1 radiologist performed region-of-interest measurements of the signal intensity of 8 gray matter structures. The gray-to-white matter contrast ratio (GWCR) was calculated. Ten patients with inflammatory cortical lesions were also included. All patients underwent conventional MRI and DWI at b = 1000 and 3000 s/mm(2). Using a 4-point grading system, 2 radiologists independently assessed the presence of additional information on DW images compared with fluid-attenuated inversion recovery images. Interobserver agreement was assessed by κ statistics.
In the healthy subjects, the b value increased as the GWCR decreased in all evaluated gray matter structures. On DW images acquired at b = 3000 s/mm(2), mean GWCR was less than 1.0 in 7 of 8 structures. For both reviewers, DWI at b = 3000 s/mm(2) yielded significantly more additional information than did DWI at b = 1000 s/mm(2) (P < 0.05). Interobserver agreement for DWI at b = 1000 s/mm(2) and b = 3000 s/mm(2) was fair (κ = 0.35) and excellent (κ = 1.0), respectively.
At 3-T DWI, the gray-to-white matter contrast in most gray matter structures reverses at b = 3000 s/mm. In the evaluation of cortical lesions in patients with inflammatory brain diseases, 3-T DWI at b = 3000 s/mm was more useful than b = 1000 s/mm(2).
本研究旨在确定健康受试者在3T场强下高b值扩散加权成像（DWI）中灰质与白质对比度如何变化，并评估3T场强下的高b值DWI对检测炎症性脑疾病中的皮质病变是否有用。
10名健康志愿者在3T磁共振成像设备上分别于b值为1000、2000、3000、4000和5000 s/mm²时进行DWI检查。在DWI图像上，1名放射科医生对8个灰质结构的信号强度进行感兴趣区测量。计算灰质与白质对比度比值（GWCR）。还纳入了10例患有炎症性皮质病变的患者。所有患者均接受了常规MRI检查以及b值为1000和3000 s/mm²时的DWI检查。2名放射科医生使用4分评分系统独立评估与液体衰减反转恢复图像相比，DWI图像上是否存在额外信息。观察者间一致性通过κ统计量进行评估。
在健康受试者中，所有评估的灰质结构中，随着b值增加，GWCR降低。在b = 3000 s/mm²时采集的DWI图像上，8个结构中有7个的平均GWCR小于1.0。对于两位评估者而言，b = 3000 s/mm²时的DWI比b = 1000 s/mm²时的DWI产生的额外信息显著更多（P < 0.05）。b = 1000 s/mm²和b = 3000 s/mm²时DWI的观察者间一致性分别为中等（κ = 0.35）和优秀（κ = 1.0）。
在3T DWI中，大多数灰质结构在b = 3000 s/mm²时灰质与白质对比度发生反转。在评估炎症性脑疾病患者的皮质病变时，b = 3000 s/mm²的3T DWI比b = 1000 s/mm²更有用。
