PICTORIAL REVIEW - THE RADIOLOGICAL INVESTIGATION OF LUMBAR SPONDYLOLYSIS

Lumbar spondylolysis represents a stress fracture of the pars interart icularis and occurs most commonly at the L5 level. Pars defects can be imaged with plain radiography, bone scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI). Plain radiographic project ions of particular value include the coned lateral view of the lumbosa cral junction, which displays the majority of defects, and the anterop osterior view with 30 degrees cranial angulation. The value of oblique radiography is unproven. Planar bone scintigraphy (PBS) is more sensi tive than radiography and single photon emission computed tomography ( SPECT) more sensitive and specific than PBS. Both these techniques, ho wever, are less specific than radiography and CT. CT, when performed w ith a reverse gantry angle and thin sections, is the investigation of choice for identifying radiographically occult lyses, Conventional lum bar spine MRI techniques are valuable for demonstrating normality of t he pars, but may be associated with a high false positive rate for the diagnosis of pars defects.