Dynamic bone imaging in the differential diagnosis of skeletal lesions

Dynamic bone imaging differs from routine multiphase bone scintigraphy by the use of time-activity curves (TACs) and quantitation of data. TACs were divided into an arterial plus blood pool phase (first 60 s at 1 frame/s) and a subsequent early bone uptake phase (24 min at 1 frame/min). Ratios of normalized integrals, from analogous regions were calculated to determine whether blood flow was abnormal. A key feature of the technique is the monitoring of the flow proximally and distally to the area of involvement. This was of importance in distinguishing between two diseases producing the same degree of local hyperemia. Dynamic bone imaging was applied to the differential diagnosis of arthritis, septic arthritis, cellulitis, osteomyelitis, tumor, avascular necrosis, Charcot joint, Legg-Perthes (LP) disease, and Osteochondritis Dissecans (OCD). Although the method is straightforward, there are technical and clinical factors that may affect interpretation of data. Asymmetries in flow may arise due to injection technique, interfering activity of bladder and/or bowel, vascular abnormalities, AV malformation, and venous backflow. The dynamic study is also sensitive to the effects of various modes of therapy. Consideration must be given to these technical and clinical factors for the avoidance of pitfalls in interpretation of the dynamic study.