Toward forward-looking OCT needle tip vision of the spinal neuroforamen: animal studies

Neurologic complications have been reported with spinal transforaminal injections. Causes include intraneural injection, plus embolization occlusion of the radicular artery with subsequent spinal cord infarction. 1 Optical coherence tomography (OCT) is a non-invasive imaging modality, which is used to image tissue microstructure with very high resolution (less than 20 microns) in real-time. With a view toward needle tip OCT visualization of the spinal neuroforamen, we conducted animal studies to explore OCT imaging of paraspinal neurovascular structures. With institutional animal care committee approval, we performed ex-vivo and in situ OCT studies in a euthanized dog, pig, and rabbit. Image data was gathered on spinal nerve roots, dura, and brachial plexus. Two systems were used: frequency domain OCT imaging system developed at California Institute of Technology, and time domain Imalux NIRIS system with a 2.7 mm diameter probe. In a euthanized pig, excised dura was punctured with a 17-gauge Tuohy needle. FDOCT dural images of the puncture showed a subsurface cone-shaped defect. In a rabbit in situ study, puncture of the dura with a 26-gauge needle is imaged as a discontinuity. FDOCT imaging of both small artery and large arteries will be presented, along with H&E and OCT images of the brachial plexus