Hanne Laakso1,2, Lauri J Lehto1,2,3, Jaakko Paasonen1, Raimo Salo1, Antonietta Canna2,4, Igor Lavrov5,6,7, Shalom Michaeli2, Olli Gröhn1, Silvia Mangia2. 1. A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland. 2. Center for Magnetic Resonance in Research, University of Minnesota, Minneapolis, Minnesota, USA. 3. Department of Radiology, Kanta-Häme Central Hospital, Hämeenlinna, Finland. 4. Department of Medicine, Surgery and Dentistry, "Scuola Medica Salernitana", Salerno, Italy. 5. Kazan Federal University, Kazan, Russia. 6. Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA. 7. Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA.
Abstract
PURPOSE: Electrical epidural spinal cord stimulation (SCS) is used as a treatment for chronic pain as well as to partially restore motor function after a spinal cord injury. Monitoring the spinal cord activity during SCS with fMRI could provide important and objective measures of integrative responses to treatment. Unfortunately, spinal cord fMRI is severely challenged by motion and susceptibility artifacts induced by the implanted electrode and bones. This pilot study introduces multi-band sweep imaging with Fourier transformation (MB-SWIFT) technique for spinal cord fMRI during SCS in rats. Given the close to zero acquisition delay and high bandwidth in 3 dimensions, MB-SWIFT is demonstrated to be highly tolerant to motion and susceptibility-induced artifacts and thus holds promise for fMRI during SCS. METHODS: MB-SWIFT with 0.78 × 0.78 × 1.50 mm3 spatial resolution and 3-s temporal resolution was used at 9.4 Tesla in rats undergoing epidural SCS at different frequencies. Its performance was compared with spin echo EPI. The origin of the functional contrast was also explored using suppression bands. RESULTS: MB-SWIFT was tolerant to electrode-induced artifacts and respiratory motion, leading to substantially higher fMRI sensitivity than spin echo fMRI. Clear stimulation frequency-dependent responses to SCS were detected in the rat spinal cord close to the stimulation site. The origin of MB-SWIFT fMRI signals was consistent with dominant inflow effects. CONCLUSION: fMRI of the rat spinal cord during SCS can be consistently achieved with MB-SWIFT, thus providing a valuable experimental framework for assessing the effects of SCS on the central nervous system.
PURPOSE: Electrical epidural spinal cord stimulation (SCS) is used as a treatment for chronic pain as well as to partially restore motor function after a spinal cord injury. Monitoring the spinal cord activity during SCS with fMRI could provide important and objective measures of integrative responses to treatment. Unfortunately, spinal cord fMRI is severely challenged by motion and susceptibility artifacts induced by the implanted electrode and bones. This pilot study introduces multi-band sweep imaging with Fourier transformation (MB-SWIFT) technique for spinal cord fMRI during SCS in rats. Given the close to zero acquisition delay and high bandwidth in 3 dimensions, MB-SWIFT is demonstrated to be highly tolerant to motion and susceptibility-induced artifacts and thus holds promise for fMRI during SCS. METHODS: MB-SWIFT with 0.78 × 0.78 × 1.50 mm3 spatial resolution and 3-s temporal resolution was used at 9.4 Tesla in rats undergoing epidural SCS at different frequencies. Its performance was compared with spin echo EPI. The origin of the functional contrast was also explored using suppression bands. RESULTS: MB-SWIFT was tolerant to electrode-induced artifacts and respiratory motion, leading to substantially higher fMRI sensitivity than spin echo fMRI. Clear stimulation frequency-dependent responses to SCS were detected in the rat spinal cord close to the stimulation site. The origin of MB-SWIFT fMRI signals was consistent with dominant inflow effects. CONCLUSION: fMRI of the rat spinal cord during SCS can be consistently achieved with MB-SWIFT, thus providing a valuable experimental framework for assessing the effects of SCS on the central nervous system.
Authors: Jaakko Paasonen; Petteri Stenroos; Hanne Laakso; Tiina Pirttimäki; Ekaterina Paasonen; Raimo A Salo; Heikki Tanila; Djaudat Idiyatullin; Michael Garwood; Shalom Michaeli; Silvia Mangia; Olli Gröhn Journal: Neuroimage Date: 2022-01-19 Impact factor: 7.400