Administered activity optimization in renal scintigraphy with DMSA - 99mTc

RESUMO

A method, which consists in constructing a discriminant function of the image quality is proposed. The dependent parameter is referred image quality by expert criterion. The function is able to select which of the measured parameters determine the referred image quality. The minimum activity to permit good image quality can be proposed as optimum among a group of tested activities. The method was tested in 36 patients underwent to DMSA-99mTc scintigraphy. They were divided into 3 groups of 12 patients each. Each group was monitored by a different acquisition protocol and for two activities (72 MBq and 133 MBq). The measured parameters were the age, sex and weight of the patients, the labeling yield (LY), the acquisition time and some Signal-to-Background ratios. The constructed function could classify 91.7 percent of the cases correctly. The ratios Right Kidney/Bladder, Left Kidney/Bladder, LY and Right Kidney/Liver were the determinant parameters. 72 MBq-700 kcounts was selected as the optimal combination to obtain good image quality