Bone scan SPECT/CT for the diagnosis of late complications after spinal fusion: Definition and evaluation of interpretation criteria

Introduction. - Late complications after spinal fusion are usually evaluated using conventional radiographs, CT or MRI. Unfortunately, these postoperative imaging are sometimes inconclusive mainly due to artifacts formation. Aims. - Assessment of criteria for bone scan SPECT/CT interpretation in the diagnosis of late postoperative complications after spinal fusion in patients with inconclusive conventional imaging. Materiel and methods. - Fifty-four patients with painful spinal arthrodesis and available final diagnosis were retrospectively studied. Bone scan SPECT/CT were interpreted thanks to a systematic reading: adjacent articular uptake suggested adjacent level degeneration (ALD), bone grafts uptake suggested pseudarthrosis and bone uptake surrounding screw suggested hardware loosening. These results were confronted with operative data in case of revision surgery, with interventional radiology gesture or clinico-radiologic follow-up. Results. - Sensibility and specificity for ALD diagnosis were 88.2% and 93.9% respectively, 80.7% and 82.7% for posterior pseudarthrosis, 100% and 60% for interbody pseudarthrosis and 68.2% and 91.7% for hardware loosening assessment. Conclusion. - Despite some limitations, bone scan SPECT/CT may be useful for guiding the diagnosis of spinal fusion complications. (authors)