Upright, Weight-Bearing, Dynamic-Kinetic MRI of the Spine pMRI/kMRI

Abstract

The purpose of this study was to demonstrate the general utility of the first dedicated magnetic resonance imaging (MRI) unit enabling upright, weight-bearing positional evaluation of the spinal column ( pMRI) during various dynamic- kinetic maneuvers ( kMRI) in patients with degenerative conditions of the spine. This study consisted of a prospective analysis of cervical and lumbar imaging examinations. All studies were performed on a recently introduced whole body MRI system (Stand-Up™ MRI, Fonar Corp, Melville, NY). The system operates at 0.6T using an electromagnet with a horizontal field, transverse to the longitudinal axis of the patient's body. Depending upon spinal level, all examinations were acquired with either a cervical or lumbar solenoidal radiofrequency receiver coil. This unit is configured with a top/front-open design, incorporating a patient-scanning table with tilt, translation and elevation functions. The unique motorized patient handling system developed for the scanner allows for vertical (upright, weight bearing) and horizontal (recumbent) positioning of all patients. The top/front-open construction also allows dynamic-kinetic flexion and extension maneuvers of the spine. Patterns of bony and soft tissue change occurring among recumbent ( rMRI) and upright neutral positions ( pMRI), and dynamic- kinetic acquisitions ( kMRI) were sought. Depending on the specific underlying pathologic degenerative condition, significant alterations observed on pMRI and kMRI that were either more or less pronounced than on rMRI included: fluctuating anterior and posterior disc herniations, hypermobile spinal instability, central spinal canal and spinal neural foramen stenosis and general sagittal spinal contour changes. No patient suffered from feelings of claustrophobia that resulted in termination of the examination. In conclusion, the potential relative beneficial aspects of upright, weight-bearing ( pMRI), dynamic-kinetic ( kMRI) spinal imaging on this system over that of recumbent MRI ( rMRI) include: the revelation of occult disease dependent on true axial loading, the unmasking of kinetic-dependent disease, and the ability to scan the patient in the position of clinically relevant signs and symptoms. This imaging unit also demonstrated low claustrophobic potential and yielded relatively high-resolution images with little motion/chemical-shift artifact.