Quantitative regional blood-flow analysis and its clinical application during routine bone-scanning

A method of combined dynamic and static bone-imaging using technetium 99-labeled phosphonate is described. During the dynamic part of the study, immediately after intravenous injection of the radionuclide, counts per second were recorded over a period of time for analogous regions of normal and diseased bones. The counts per second then were plotted against time to give time-activity curves for each of these regions. The time-activity curves were divided into arterial, venous, and blood-pool phases. Each phase was integrated and then divided by the time-span of the phase to give average total counts per unit of time. The values of these normalized integrals were directly proportional to the blood flow to the regions of bone from which they were calculated. Ratios of normalized integrals from the analogous regions of the diseased bone to the normal bone were calculated to determine whether the blood flow to the diseased bone was decreased or increased. Static images of the bone structures analyzed during the dynamic portion of the study were obtained two hours after the initial injection of the radionuclide and the total number of counts for analogous regions on the static images of the normal and diseased bones were static images of the normal and diseased bones were recorded. The total number of counts for each region was divided by the area of that region to give average total counts. Ratios of the normalized counts were calculated for analogous regions of the diseased to the normal bone to determine whether there was an increase or decrease in concentration of the radionuclide. The method first was used to evaluate hip pain in children and adults. In order to recognize an abnormal result, mean values and two standard deviations were calculated for the dynamic and static ratios in a group of fifty patients who had no clinical complaints about the hips or lower extremities. Any ratios outside of the range of two standard deviations were considered abnormal. The method later was used to evaluate other bones, such as the tibia and humerus. Any value for the ratios beyond 1 +/- 0.20 was considered abnormal for these studies.