In vivo magnetic resonance imaging at 11.7 Tesla visualized the effects of neonatal transection of infraorbital nerve upon primary and secondary trigeminal pathways in rats

Abstract

Using 11.7T ultra high-field T2-weighted MRI, the present study aimed to investigate pathological changes of primary and secondary trigeminal pathways following neonatal transection of infraorbital nerve in rats. The trigeminal pathways consist of spinal trigeminal tract, trigeminal sensory nuclear complex, medial lemniscus, ventromedial portion of external medullary lamina and ventral posterior nucleus of thalamus. By selecting optimum parameters of MRI such as repetition time, echo time, and slice orientation, this study visualized the trigeminal pathways in rats without any contrast agents. Pathological changes due to the nerve transection were found at 8 weeks of age as a marked reduction of the areas of the trigeminal pathways connecting from the injured nerve. In addition, T2-weighted MR images of the trigeminal nerve trunk and the spinal trigeminal tract suggest a communication of CSF through the trigeminal nerve between the inside and outside of the brain stem. These results support the utility of ultra high-field MRI system for noninvasive assessment of effects of trigeminal nerve injury upon the trigeminal pathways.

Future demands for high field MRI diagnostic

“…13,20 These complexes show their suitable r 1 -relaxivity at clinical magnetic field strengths (1.5-3.0 T). However, much higher magnetic fields ([7 T) are used for small animal (pre-clinical) imaging as the signal-to-noise, and thus resolution, is obtained at high field strength 4,21 but smaller Gd 3?based chelates tumble very fast (faster than 10 -10 s) which drastically decreases their r 1 -relaxivity at higher fields. 16 Moreover, these chelates have short circulation time due to fast renal excretion limiting further their usefulness in small-animal studies.…”