Three-phase bone scintigraphy: its contribution to diagnosing and staging avascular necrosis of the carpal lunate

Thirty-two patients with avascular necrosis of os lunatum (Kienbock's disease) were examined in three groups according to stage of the disease as follows: first - I stage of disease (10 cases); second - II stage (13) and third - III and IV stages (9). All patients underwent three-phase bone scintigraphy after i v injecting of 20 mCi 99mTc-MDP. Blood pool index and skeletal index were duly calculated (normal value 1.15). Three-phase bone scintigraphy was within normal limits at 3 patients from the first group. Decreased values of perfusion and bone metabolism were obtained at 2 and 3 patients from the second and third group, respectively. Decreased perfusion and increased bone metabolism (skeletal index < 1.20) were found at 4 patients (group one), 6 (group two) and 3 (group three). Increased blood flow and enhanced uptake of tracer in the late phase were observed at one patient (group one), at 4 group two) and at 6 (group three). False negative results were documented in three cases (group one), and false positive - at one patient each from group two and three. The results show a high sensitivity (91%) of the method in Kienbock's disease and proves that three-phase bone scintigraphy may be used for staging avascular necrosis of the lunate bone. (author)