Journal of Hong Kong College of Radiologists

Volume 6 Number 2, 2003
Abstract

Upright, Weight-bearing, Dynamic-kinetic Magnetic Resonance Imaging of the Spine - Review of the First Clinical Results

JR Jinkins,1 JS Dworkin,2 CA Green,2 JF Greenhalgh,2 M Gianni,2 M Gelbien,2
RB Wolf,2 J Damadian,2 RV Damadian2
1Department of Radiological Sciences, Medical College of Pennsylvania-Hahnemann, Drexel University, Philadelphia, Pennsylvania, and 2Fonar Corporation, Melville, New York, USA

Magnetic resonance imaging has, until recently, been limited to scans with patients in the recumbent position. However, a new fully open magnetic resonance imaging unit has been configured to allow upright, partially upright, and recumbent imaging, enabling weight-bearing positional evaluation of the spinal column during various dynamic-kinetic manoeuvres for patients with degenerative conditions of the spine. In a prospective non-statistical analysis of cervical or lumbar imaging examinations, all studies were performed on a whole body magnetic resonance imaging system. The system operates at 0.6 T using an electromagnet with a horizontal field, transverse to the longitudinal axis of the patient's body. The unit was configured with a top/front-open design, incorporating a patient-scanning table with tilt, translation, and elevation functions. The unique motorised 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 for dynamic-kinetic flexion and extension manoeuvres of the spine. Patterns of bony and soft tissue change occurring among recumbent and upright neutral positions, and dynamic-kinetic acquisitions were sought. Depending on the specific underlying pathological degenerative condition, significant alterations observed on positional and dynamic-kinetic magnetic resonance imaging that were either more or less pronounced than on recumbent magnetic resonance imaging 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 patients had claustrophobia that resulted in termination of the examination. The potential relative benefits of upright, weight-bearing, dynamickinetic spinal imaging over that of recumbent magnetic resonance imaging 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 a position clinically relevant to the signs and symptoms. This imaging technique demonstrated a low claustrophobic potential and yielded relatively high-resolution images with little motion/magnetic susceptibility/chemical shift artifacts. Overall, it was found that recumbent imaging underestimated the maximum degree of degenerative spinal pathology and missed its dynamic nature altogether - factors that are optimally revealed with positional/dynamic-kinetic magnetic resonance imaging. (J HK Coll Radiol 2003;6:55-74)

Key Words: Kinetics, Magnetic resonance imaging, Spine, Weight bearing


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