• Lopes de LimaMariana da CunhaMda CDivision of Nuclear Medicine, Department of Radiology, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil. mailto:mar.lima@terra.com.br, Celso Darío Ramos, Sérgio Quirino Brunetto, Lopes de LimaMarceloM, Ubirajara Ferreira, Elba Cristina Sá Camargo Etchebehere, SantosAllan de OliveiraAde O, Nelson Rodrigues Netto Júnior, and Edwaldo Eduardo Camargo.
• Division of Nuclear Medicine, Department of Radiology, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil. mailto:mar.lima@terra.com.br
• Sao Paulo Med J. 2008 May 1; 126 (3): 150155150-5.

Context And ObjectiveStudies using radionuclides are the most appropriate method for estimating renal function. Dimercaptosuccinic acid chelate labeled with technetium-99m (99mTc-DMSA) is the radiopharmaceutical of choice for high-resolution imaging of the renal cortex and estimation of the functional renal mass. The aim of this study was to evaluate a simplified method for determining the absolute renal uptake (ARU) of 99mTc-DMSA prior to nephrectomy, using the radioactivity counts of nephrectomy specimens as the gold standard.Design And SettingProspective study at the Division of Nuclear Medicine, Department of Radiology, Universidade Estadual de Campinas.MethodsSeventeen patients (12 females; range 22-82 years old; mean age 50.8 years old) underwent nephrectomy for various reasons. Renal scintigraphy was performed three to four hours after intravenous administration of a mean dose of 188.7 MBq (5.1 mCi) of 99mTc-DMSA, which was done six to 24 hours before surgery. The in vivo renal uptake of 99mTc-DMSA was determined using the radioactivity of the syringe before the injection (measured using a dose calibrator) and the images of the syringe and kidneys, obtained from a scintillation camera. After surgery, the reference value for renal uptake of 99mTc-DMSA was determined by measuring the radioactivity of the nephrectomy specimen using the same dose calibrator.ResultsThe ARU measurements were very similar to those obtained using the reference method, as determined by linear regression (r-squared = 0.96).ConclusionARU estimation using the proposed method before nephrectomy seems to be accurate and feasible for routine use.

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