Factor analysis of bone mineral dynamics in patients with renal osteodystrophy

: Remarkably high accumulation of Tc-99m-MDP is seen in the skull on bone scintigraphy of patients with renal osteodystrophy (ROD), especially with secondary hyperparathyroidism. For the quantitative evaluation, the Factor Analysis (FA) was used for the early phase of bone scan. Tc-99m-MDP (14.8 MBq/body weight kg) was injected as a bolus through the medial antecubital vein. Dynamic acquisition of 40 x 30 sec frames were performed in a 64 x 64 matrix. For pre-processing, nine points smoothing was carried out, and then the region of interest was set on the frontal image of the head for the FA. The FA was performed with an 8 x 8 sampling corresponding to 64 dixels from 4,096 dixels. Bone factor was clearly extracted by the FA. Then, two original parameters were calculated. One is the bone radionuclide uptake counts (Bu) which is the product of the total radionuclide counts of skull and the contribution ratio, the other is the uptake ratio (Br) derived by the time activity curve (physiological component) of the FA. These parameters of ROD were significantly different compared to those of controls. The FA seems to be useful in quantitative evaluation of bone mineral dynamics.