This is renal osteodystrophy. Chronic kidney disease leads to metabolic changes associated with hyperparathyroidism with abnormal bone turnover and mineralization. There is characteristic increased bone density at the vertebral endplates, secondary to increased osteoblast activity. This leads to alternating bands of increased and normal density on plain films and CT of the spine, and alternating bands of increased and normal uptake in the spine on a bone scan and the sign is called the "rugger jersey" sign. These bands are likened to the stripes of a rugby jersey.