Spinal cord neural anatomy in rats examined by in vivo magnetic resonance microscopy.
OBJECTIVE
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Benveniste
H
H
Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Qui
H
H
Hedlund
L W
LW
D'Ercole
F
F
Johnson
G A
GA
D000818:Animals; D001696:Biomechanical Phenomena; D002408:Catheters, Indwelling; D002574:Cervical Vertebrae; D004396:Coloring Agents; D003287:Contrast Media; D004058:Diffusion; D004487:Edema / Q000175:diagnosis / Q000473:pathology; D004824:Epidural Space; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D007278:Injections, Spinal / Q000295:instrumentation; D007511:Ischemia / Q000175:diagnosis / Q000473:pathology; D008137:Longitudinal Studies; D008159:Lumbar Vertebrae; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008853:Microscopy / Q000379:methods*; D009441:Neurilemma; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344; D012039:Regional Blood Flow / Q000502:physiology; D013116:Spinal Cord / Q000033:anatomy & histology* / Q000098:blood supply; D013118:Spinal Cord Diseases / Q000175:diagnosis / Q000473:pathology; D013127:Spinal Nerves / Q000033:anatomy & histology / Q000098:blood supply
D004396:Coloring Agents; D003287:Contrast Media