Benveniste H, Qui H, Hedlund L W, D'Ercole F, Johnson G A
Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Reg Anesth Pain Med. 1998 Nov-Dec;23(6):589-99. doi: 10.1016/s1098-7339(98)90087-6.
Magnetic resonance microscopy (MRM) is a technique that is worthwhile for anesthesiologists because it allows spinal cord and plexus anatomy to be visualized three dimensionally and followed over time in the same animal. For example, the long-term effect of indwelling intrathecal or plexus catheters can be studied in situ, and convective and diffusive forces within intrathecal, epidural, or nerve sheath spaces can be investigated. Further, diffusion-weighted MRM, which measures an "apparent diffusion coefficient" (ADC), can be used to track the presence of ischemia, hypoperfusion, or cytotoxic edema. This study investigates problems associated with the use of in vivo MRM for spinal cord and peripheral nerve studies in the rat.
Twenty-one anesthetized female Fisher CDF rats were used. Group 1 (n=7) was used for anatomic three-dimensional studies. Groups 2 (n=4), 3 (n=4), and 4 (n=6) were used for measurements of the ADC. Group 2 served as controls, group 3 received lumbar intrathecal catheters, and group 4 received cervical intrathecal catheters.
Cervical spine, lumbar spine, and spinal nerves and ganglia were accurately visualized with MRM. As a rule, spinal cord gray and white matter were better demonstrated using diffusion-weighted proton stains. By contrast, T2-weighted proton staining superiorly demonstrated structures surrounding the spinal cord. In groups 3 and 4, indwelling intrathecal catheters did not affect the spinal cord ADC, indicating normal blood flow and no cytotoxic edema. Contrast studies revealed nonhomogeneous distribution of contrast predominately in the lateral and ventral intrathecal space.
Three-dimensional diffusion-weighted MRM displays cervical and lumbar spine anatomy accurately in vivo. Apparent diffusion coefficients measurements are feasible in rat cervical spinal cord with intrathecal catheters. Spinal cord ADCs are unaffected by intrathecal catheters, indicating normal spinal cord perfusion.
磁共振显微镜（MRM）技术对麻醉医生来说很有价值，因为它能在同一动物体内对脊髓和神经丛进行三维可视化观察并长期跟踪。例如，可以在原位研究鞘内或神经丛留置导管的长期影响，还能研究鞘内、硬膜外或神经鞘间隙内的对流和扩散力。此外，测量“表观扩散系数”（ADC）的扩散加权MRM可用于追踪缺血、灌注不足或细胞毒性水肿的存在情况。本研究调查了在大鼠体内使用MRM进行脊髓和周围神经研究时出现的问题。
使用21只麻醉的雌性Fisher CDF大鼠。第1组（n = 7）用于解剖学三维研究。第2组（n = 4）、第3组（n = 4）和第4组（n = 6）用于测量ADC。第2组作为对照组，第3组接受腰段鞘内导管置入，第4组接受颈段鞘内导管置入。
通过MRM可准确显示颈椎、腰椎以及脊神经和神经节。通常，使用扩散加权质子染色能更好地显示脊髓灰质和白质。相比之下，T2加权质子染色能更好地显示脊髓周围结构。在第3组和第4组中，鞘内留置导管不影响脊髓ADC，表明血流正常且无细胞毒性水肿。造影研究显示造影剂在鞘内空间的外侧和腹侧分布不均匀。
三维扩散加权MRM能在体内准确显示颈椎和腰椎解剖结构。在有鞘内导管的大鼠颈段脊髓中测量表观扩散系数是可行的。脊髓ADC不受鞘内导管影响，表明脊髓灌注正常。
