Pattern recognition in five-phase bone scintigraphy: diagnostic patterns of reflex sympathetic dystrophy in adults

The objective of this study was to assess qualitative and quantitative patterns of tracer accumulation to increase the diagnostic utility of bone scintigraphy in reflex sympathetic dystrophy (RSD). Of 120 patients with high clinical suspicion for RSD, 96 were confirmed as having RSD during follow-up, while the remaining 24 were used as controls. Clinical parameters were measured and correlated to five activity ratios (0-30 s, 0.5-5 min, 5-15 min, 3 h, 24 h) and five scintigraphic signs. Monitoring three dynamic phases revealed different tracer kinetics of potential diagnostic utility; however, the 24-h bone phase offered no additional diagnostic contribution and can be omitted. Quantification provided objective parameters for the duration of symptoms, pain and impairment of movement but not for surface temperature differences, swelling and impairment of physical force. It is of limited use for diagnosis except for the exclusion of disease. Discriminant analysis revealed the combination of three signs (diffuse uptake in carpus/tarsus+diffuse uptake in all small joints+increased activity ratio in the late blood pool phase) to be the pattern with the highest diagnostic accuracy independent of localisation, sex, age and precipitating factors. It is concluded that the scintigraphic confirmation of RSD is based on lateralisation in the late blood pool phase and the described pattern in the early bone phase.