Exploration of the value of 99mTc thyroid/neck background rectified ratio in thyroid disease

49 normal subjects and 250 patients with thyroid disease were performed thyroid imaging. The parameters reflecting the function of thyroid were calculated, including rectified ratio (RR), uptake ratio (UR) and 99mTc percentage uptake (PU). The identity between RR and PU was compared with the identify between UR and PU. The parameters in disease groups were also compared with that of normal group. The results showed that the real identify percentage (95.6%) between RR and PU was significantly higher than that of UR and PU (77.9%) (x2 = 40.9, P < 0.001). RR were significantly higher in groups of hyperthyroidism and recurrence after thyroidectomy than normal group (P < 0.05-0.005), and significantly lower in subacute thyroiditis group (P < 0.001). RR may be normal or increased in simple goiter and may be normal, increased or decreased in hypothyroidism. Thereby, RR is obviously better than UR in determining the level of thyroid 99mTc uptake. It is difficult in discriminating between hyperthyroidism and hypothyroidism by RR, but it still has important significance in correlation with clinical and other examination data for comprehensive judgement