• Timothy P Maus, Joel P Felmlee, Mark D Unger, and Andreas S Beutler.
• Department of Radiology, Mayo Graduate School, Mayo Clinic, Rochester, MN, 55902, USA. Electronic address: maus.timothy@mayo.edu.
• J. Neurosci. Methods. 2019 Jan 15; 312: 182-186.

BackgroundDevelopment of new analgesic drugs or gene therapy vectors for spinal delivery will be facilitated by "hyperlocal" targeting of small therapeutic injectate volumes if spine imaging technology can be used that is ready for future clinical translation.New MethodThis study provides methods for MRI-guided drug delivery to the periganglionic epidural space and the dorsal root ganglion (DRG) in the Yucatan swine.ResultsPhantom studies showed artifact-corrected needle localization with frequency encoding parallel to the needle shaft, while maximizing bandwidth (125 KHz) minimized needle artifact. A custom constructed 8-12 element surface coil (phased array) wrapped over the spine in conjunction with lateral recumbent positioning achieved diagnostic quality signal to noise ratio at the depth of the DRG and afforded transforaminal access via anterolateral or posterolateral vectors, as well as interlaminar access. Swine epidural anatomy was homologous with human anatomy. Injectate containing 2% gadolinium allowed imaging of injectate volumes in increments as small as 10 microliters and discrimination of epidural flow from intraparenchymal injectate delivery into a DRG. All technical and technological elements of the procedure appear clinically translatable.Comparison With Existing MethodsComputed tomographic or fluoroscopic guidance cannot directly visualize drug delivery into the DRG due to contrast medium toxicity, nor reliably identify epidural injection volumes of < 50 microliters.ConclusionsMRI-guided hyperlocal delivery in swine provides a translatable and faithful model of future human spinal novel drug- or gene therapy vector delivery.Copyright © 2018 Elsevier B.V. All rights reserved.

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