OBJECTIVE: To standardize a method and determine normal values for absolute renal uptake of 99mTc-DMSA in children with normal creatinine clearance. MATERIALS AND METHODS: Twenty-two children (between 7 months and 10 years of age; mean 4.5 years) without clinical evidence of renal disease were studied using 99mTc-DMSA scintigraphy. Eighteen had normal renal ultrasonography, micturating urethrocystography, creatinine clearance and visual interpretation of the scintigraphy with 99mTc-DMSA. Four children were excluded, one with incomplete creatinine clearance and three due to reduction in the creatinine clearance. Absolute renal uptake of 99mTc-DMSA (DMSA-Abs) was expressed as the fraction of the administered dose retained by each kidney six hours after administration of the radiopharmaceutical. RESULTS: DMSA-Abs was 21.8 ± 3.2% for the right kidney and 23.1 ±3.3% for the left kidney. There was no correlation between renal uptake and the age groups studied, although there was a tendency to an increase in the creatinine clearance with age. CONCLUSION: Normal values of DMSA-Abs can be used as an additional parameter for the initial diagnostic evaluation and during follow-up of renal diseases, mainly when bilateral impairment of renal function is suspected or in a patient with a single functioning kidney (in which renal differential function is of limited value).

Keywords: Renal function, Quantification, 99mTc-DMSA, Children, Scintigraphy

OBJECTIVE: Thyroid tissue stunning after iodine-131 doses is a known cause of low uptake and unsatisfactory response to subsequent therapeutic doses. The objective of this study was to develop an experimental model of postactinic thyroid stunning. METHODS: A total of 63 mice received an equivalent dose of 45 Sv on the thyroid, by iodine-123 irradiation. This dose is similar to the estimated dose for the thyroidal remnants after administration of 185 MBq (5 mCi) of iodine-131 for whole body scans. The thyroid uptake of iodine-131 tracer doses were measured in subgroups of 9 animals, 2, 3, 5, 7, 12 and 26 days after irradiation and compared to a control group. RESULTS: The iodine uptake in the control group was 9.26%. The mean uptake value variation during the studied period was not significant. There was an increase in variance of the measures performed 5 days after irradiation, when 4 of 9 animals presented uptake 60% lower than the control group mean. CONCLUSION: There was not a systematic uptake fall in the animals submitted to the 45 Sv dose, although there was a trend for higher fluctuation in the uptake 5 days after irradiation. These findings may be due to interspecies differences or may indicate that the stunning with such doses may depend on individual characteristics or previous functional thyroid abnormalities, in addition to the radiation effect.

Keywords: Thyroid cancer, Iodine radioisotopes, Thyroidectomy, Follicular adenocarcinoma, Papillary adenocarcinoma, Radionuclide imaging