Lee Seung Jin, Park Ilwoo, Talbott Jason F, Gordon Jeremy
Department of Radiology, Chonnam National University Hospital, 42 Jaebongro, Donggu, Gwangju, 61469, South Korea.
Department of Radiology, Chonnam National University, 42 Jaebongro, Donggu, Gwangju, 61469, South Korea.
Mol Imaging Biol. 2022 Jun;24(3):371-376. doi: 10.1007/s11307-021-01682-1. Epub 2021 Nov 15.
This study examined the feasibility of using two novel agents, hyperpolarized [C]t-butanol and [C,N]urea, for assessing in vivo perfusion of the intact spinal cord in rodents. Due to their distinct permeabilities to blood brain barrier (BBB), we hypothesized that [C]t-butanol and [C,N]urea exhibit unique C signal characteristics in the spinal cord.
Dynamic C t-butanol MRI data were acquired from healthy Long-Evans rats using a symmetric, ramp-sampled, partial-Fourier C echo-planar imaging sequence after the injection of hyperpolarized [C]t-butanol solution. In subsequent scans, dynamic C urea MRI data were acquired after the injection of hyperpolarized [C,N]urea. The SNRs of t-butanol and urea were calculated for regions corresponding to spine, supratentorial brain, and blood vessels and plotted over time. Mean peak SNR and AUC were calculated from the dynamic plots for each region and compared between t-butanol and urea.
In spine and supratentorial brain, the mean peak SNR and AUC of t-butanol were significantly higher than those of urea (p < 0.05). In contrast, urea was predominantly contained within vasculature and exhibited significantly higher levels of mean peak SNR and AUC compared to t-butanol in blood vessels (p < 0.05).
This study has demonstrated the feasibility of using hyperpolarized [C]t-butanol and [C,N]urea for assessing in vivo perfusion in cervical spinal cord. Due to differences in blood-brain barrier permeability, t-butanol rapidly crossed the blood-brain barrier and diffused into spine and brain tissue, while urea predominantly remained in vasculature. The results from this study suggest that this technique may provide unique non-invasive imaging tracers that are able to directly monitor hemodynamic processes in the normal and injured spinal cord.
本研究探讨使用两种新型试剂——超极化[C]叔丁醇和[C,N]尿素评估啮齿动物完整脊髓的体内灌注情况的可行性。由于它们对血脑屏障（BBB）的通透性不同，我们推测[C]叔丁醇和[C,N]尿素在脊髓中表现出独特的C信号特征。
在注射超极化[C]叔丁醇溶液后，使用对称、斜坡采样、部分傅里叶C回波平面成像序列从健康的Long-Evans大鼠获取动态C叔丁醇MRI数据。在随后的扫描中，注射超极化[C,N]尿素后获取动态C尿素MRI数据。计算与脊柱、幕上脑和血管相对应区域的叔丁醇和尿素的信噪比，并随时间绘制。从每个区域的动态图计算平均峰值信噪比和AUC，并在叔丁醇和尿素之间进行比较。
在脊柱和幕上脑中，叔丁醇的平均峰值信噪比和AUC显著高于尿素（p < 0.05）。相比之下，尿素主要存在于脉管系统中，与血管中的叔丁醇相比，其平均峰值信噪比和AUC水平显著更高（p < 0.05）。
本研究证明了使用超极化[C]叔丁醇和[C,N]尿素评估颈髓体内灌注的可行性。由于血脑屏障通透性的差异，叔丁醇迅速穿过血脑屏障并扩散到脊柱和脑组织中，而尿素主要保留在脉管系统中。本研究结果表明，该技术可能提供独特的非侵入性成像示踪剂，能够直接监测正常和损伤脊髓中的血流动力学过程。
