From the Departments of Radiology (D.W.L., J.K.K.) and Convergence Medicine (H.H., D.C.W.), Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea; Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea (D.C.W.); and Department of Radiation Convergence Engineering, Yonsei University, Baekwun Hall 1, Room 417, Yonseidae-gil, Wonju 26493, Republic of Korea (D.H.L.).
Radiology. 2021 May;299(2):428-434. doi: 10.1148/radiol.2021203766. Epub 2021 Mar 16.
Background Investigations of amide proton signal changes in the white matter of demyelinating diseases may provide important biophysical information for diagnostic and prognostic assessments. Purpose To evaluate amide proton signals in cuprizone-induced rats using amide proton transfer-weighted (APT) MRI, which provides in vivo image contrast by changing amide proton concentrations during demyelination (DEM) and subsequent remyelination (REM). Materials and Methods In this animal study, APT 7-T MRI was performed in 21 male Wistar rats divided into cuprizone-induced ( = 14) and control ( = 7) groups from February to August 2020. The cuprizone-induced group was further subdivided into DEM ( = 7) and REM ( = 7) groups. Seven weeks after cuprizone feeding, rats in the DEM group were killed prior to transmission electron microscopy and myelin staining, while rats in the REM group were changed to a normal chow diet and fed for 5 weeks. In each group, the APT signals were calculated using a conventional magnetization transfer ratio at 3.5 ppm based on regions of interest in the corpus callosum. Statistical differences in APT signals among the groups were analyzed with one-way analysis of variance followed by Tukey post hoc tests. Results The mean APT signals in the control and DEM groups were -4.42% ± 0.60 (standard deviation) (95% CI: -4.98, -3.86) and -2.57% ± 0.48 (95% CI: -3.01, -2.12), respectively, indicating higher in vivo APT signals in the DEM lesion ( < .001). After REM, mean APT signal in the REM group was -3.83% ± 0.67 (95% CI: -4.45, -3.22), similar to that in the control group ( = .18) and lower than that in the DEM group ( < .001). Conclusion Significant amide proton transfer-weighted (APT) metric changes coupled with the histologic characteristics of the demyelination and remyelination processes indicate the potential usefulness of APT 7-T MRI to monitor earlier myelination processes. © RSNA, 2021 See also the editorial by van Zijl in this issue.
背景 脱髓鞘疾病白质中酰胺质子信号的变化研究可为诊断和预后评估提供重要的生物物理信息。目的 采用酰胺质子转移加权（APT）MRI 评估铜诱导大鼠模型中的酰胺质子信号，该方法通过改变脱髓鞘（DEM）和随后的髓鞘再生（REM）过程中的酰胺质子浓度来提供体内图像对比。材料与方法 本动物研究于 2020 年 2 月至 8 月在 21 只雄性 Wistar 大鼠中进行，分为铜诱导组（ = 14 只）和对照组（ = 7 只）。铜诱导组进一步分为 DEM 组（ = 7 只）和 REM 组（ = 7 只）。铜诱导喂养 7 周后，处死 DEM 组大鼠进行透射电镜和髓鞘染色检查，而 REM 组大鼠则更换为正常的饲料并喂养 5 周。在每组中，通过在胼胝体感兴趣区计算基于 3.5 ppm 的传统磁化转移比来计算 APT 信号。采用单因素方差分析比较各组间 APT 信号的差异，然后采用 Tukey 事后检验进行多重比较。结果 对照组和 DEM 组的平均 APT 信号分别为-4.42%±0.60（标准差）（95%CI：-4.98，-3.86）和-2.57%±0.48（95%CI：-3.01，-2.12），提示 DEM 病变中体内 APT 信号更高（ <.001）。REM 后，REM 组的平均 APT 信号为-3.83%±0.67（95%CI：-4.45，-3.22），与对照组（ =.18）相似，低于 DEM 组（ <.001）。结论 明显的酰胺质子转移加权（APT）指标变化与脱髓鞘和髓鞘再生过程的组织学特征相结合，表明 APT 7-T MRI 具有监测早期髓鞘形成过程的潜在作用。
