Figure 10a. Facet joint osteoarthritis in a 64-year-old woman. (a, b) Sagittal (a) and transverse (b) SPECT images show unilateral increased uptake in the posterior arch and in the same horizontal plane as the disk space (arrows; d in a). sp = spinous process, v = vertebral body. (c) Corresponding oblique radiograph shows facet joint osteoarthritis at the L4-5 level (arrows).