A chronic in situ coil system adapted for intracerebral stimulation during MRI in rats

• Published in: Journal of neuroscience methods 2017-06, Vol.284, p.85-95
• Main Authors: Madularu, Dan, Kumaragamage, Chathura, Mathieu, Axel P., Kulkarni, Praveen, Rajah, M. Natasha, Gratton, Alain P., Near, Jamie
• Format: Article
• Language: English
• Subjects: Animal imaging; Animals; BOLD; Brain - diagnostic imaging; Cranial implant; Deep Brain Stimulation - instrumentation; Deep Brain Stimulation - veterinary; Equipment Design; Equipment Failure Analysis; Implantable RF coil; Infusion Pumps, Implantable; Magnetic Resonance Imaging - instrumentation; Magnetic Resonance Imaging - veterinary; Male; Microinjections - instrumentation; Microinjections - veterinary; Prostheses and Implants; Rats; Rats, Long-Evans; Reproducibility of Results; Sensitivity and Specificity; SNR; Transducers - veterinary
• ISSN: 0165-0270; 1872-678X
• DOI: 10.1016/j.jneumeth.2017.04.018

•An implantable receive-only RF coil was designed to facilitate the combination of MR scanning with other neurochemical techniques in rats, such as microinfusions.•The coil allows for the additional intracranial implantation of MR-compatible cannulae.•SNR comparisons between the implantable coils and commercially-available rat coils shows the custom coils yielding significantly increased SNR throughout the brain.•Increases in BOLD have been recorded in response to intracranial infusions of morphine and bicuculline during image acquisition. We describe the fabrication and performance of a chronic in situ coil system designed to allow focal brain stimulation in rats while acquiring functional MRI data. An implantable receive-only surface radiofrequency coil (iCoil) was designed to be fitted subcutaneously, directly onto to the rat skull surface during the intracerebral cannulation procedure. The coil is fixed in place using acrylic dental cement anchored to four screws threaded into the skull. To demonstrate the use of this coil system in situ, whole-brain functional MRI scans were acquired during various stimuli, including intracranial microinfusions of bicuculline and morphine in the prefrontal cortex and ventral tegmental area, respectively. SNR performance of the iCoil was superior to three commercially-available coils, in some instances by a factor of two. Widespread BOLD activation was observed in response to bicuculline and morphine microinfusions. A new approach was demonstrated for high-SNR MR imaging of the brain in rats with intracranial implants using an implantable surface coil. This approach enables mapping the functional response to highly targeted stimuli such as intracranial microinfusions.