Lumbar Spinal Fusion Assessment of Functional Stability with Magnetic Resonance ImagingLANG, PHILIPP, MD; CHAFETZ, NEIL, MD; GENANT, HARRY K., MD; MORRIS, JAMES M., MDSpine: June 1990 - Volume 15 - Issue 6 - p 581–588 EUROPEAN EDITION: PDF Only Buy Abstract Author InformationAuthors Segmental spinal instability was evaluated with magnetic resonance (MR) imaging, computed tomography (CT), and conventional radiography in 33 patients who had undergone surgical spinal fusion. In 16 of the 19 patients who had a diagnosis of solid fusion, the immobilized vertebral bodies demonstrated areas of high signal intensity on images with short repetition time (TR) and echo time (TE). The signal intensity of these areas was either less intense or normal on images with long TR and TE. In 10 of the 14 patients with segmental instability at the fusion site, subchondral vertebral bands of low signal intensity were shown on short TR/TE images. All but two of the patients showed vertebral signal changes 12 or more months past fusion or onset of clinical symptoms. The vertebral MR signal intensity in solid lumbar fusions might be related to marrow composition changes resulting from decreased biomechanical stress, while the vertebral signal intensities in patients with unstable fusions might be related to reparative granulation tissue, inflammation, edema, and hyperemic changes. Magnetic resonance imaging appears to be unique in its assessment of functional fusion stability. Magnetic resonance may be most useful in patients symptomatic of fusion pseudarthrosis in whom conventional radiography and CT fail to demonstrate anatomic disruption. From the Department of Radiology and the Department of Orthopedic Surgery, University of California, San Francisco, and the Radiologische Klinik, Universitatsklinikum Rudolf Virchow, Standort Charlottenburg, Freie Universitat Berlin, Berlin, West Germany. © Lippincott-Raven Publishers.